U.S. patent application number 09/797556 was filed with the patent office on 2001-08-09 for intraspinal botulinum toxin for treating pain.
Invention is credited to Aoki, Kei Roger, Cui, Minglei.
Application Number | 20010012828 09/797556 |
Document ID | / |
Family ID | 23652970 |
Filed Date | 2001-08-09 |
United States Patent
Application |
20010012828 |
Kind Code |
A1 |
Aoki, Kei Roger ; et
al. |
August 9, 2001 |
Intraspinal botulinum toxin for treating pain
Abstract
Methods for treating pain by intrathecal administration to a
human patient of a therapeutically effective amount of a neurotoxin
such as botulinum toxin type A are disclosed.
Inventors: |
Aoki, Kei Roger; (Coto De
Caza, CA) ; Cui, Minglei; (Irvine, CA) |
Correspondence
Address: |
Stephen Donovan
Allergan, Inc.
Tower Two, Seventh Floor
2525 Dupont Drive
Irvine
CA
92612
US
|
Family ID: |
23652970 |
Appl. No.: |
09/797556 |
Filed: |
March 1, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09797556 |
Mar 1, 2001 |
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09578097 |
May 25, 2000 |
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6235289 |
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09578097 |
May 25, 2000 |
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09417195 |
Oct 12, 1999 |
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6113915 |
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Current U.S.
Class: |
424/236.1 ;
514/18.3 |
Current CPC
Class: |
A61K 38/4893 20130101;
A61P 25/04 20180101; Y02A 50/30 20180101; A61P 29/02 20180101; A61K
38/00 20130101 |
Class at
Publication: |
514/2 |
International
Class: |
A61K 038/16 |
Claims
We claim:
1. A method for treating pain, the method comprising the step of
intraspinal administration of a neurotoxin to a mammal, thereby
alleviating pain experienced by the mammal, wherein the neurotoxin
is not attached to a neuronal targeting moiety.
2. The method of claim 1, wherein the neurotoxin is a botulinum
toxin.
3. The method of claim 2, wherein the botulinum toxin is selected
from the group consisting of botulinum toxin types A, B, C, D, E, F
and G.
4. The method of claim 3, wherein the botulinum toxin is botulinum
toxin type A.
5. The method of claim 2, wherein the botulinum toxin is
administered in an amount of between about 10.sup.-3 U/kg and about
60 U/kg.
6. The method of claim 5, wherein the botulinum toxin is
administered in an amount of between about 10.sup.-2 U/kg and about
50 U/kg.
7. The method of claim 6, wherein the botulinum toxin is
administered in an amount of between about 10.sup.-1 U/kg and about
40 U/kg.
8. The method of claim 7, wherein the botulinum toxin is
administered in an amount of between about 1 U/kg and about 30
U/kg.
9. The method of claim 7, wherein the botulinum toxin is
administered in an amount of between about 1 U/kg and about 20
U/kg.
10. The method of claim 1, wherein the pain alleviating effect
persists for up to 10 days.
11. The method of claim 1, wherein the pain alleviating effect
persists for up to 20 days.
12. The method of claim 1, wherein the pain alleviating effect
persists for up to 3 months.
13. The method of claim 1, wherein the neurotoxin is administered
intrathecally.
14. The method of claim 13, wherein the neurotoxin is administered
intrathecally to a cranial region of the central nervous
system.
15. The method of claim 13, wherein the neurotoxin is administered
intrathecally to a cervical region of the central nervous
system.
16. The method of claim 13, wherein the neurotoxin is administered
intrathecally to a thoracic region of the central nervous
system.
17. The method of claim 13, wherein the neurotoxin is administered
intrathecally to a lumbar region of the central nervous system.
18. The method of claim 13, wherein the neurotoxin is administered
intrathecally to a sacral region of the central nervous system.
19. The method of claim 1, wherein the administration step includes
the steps of: (a) accessing a subarachnoid space of the central
nervous system of the mammal, and; (b) injecting the neurotoxin
into the subarachnoid space.
20. The method of claim 19, wherein the accessing step is carried
out by effecting a spinal tap.
21. The method of claim 1, wherein the administration step includes
the steps of: (a) catheterization of a subarachnoid space of the
central nervous system of the mammal, and; (b) injecting the
neurotoxin through a catheter inserted by the catheterization step
into the subarachnoid space.
22. The method of claim 21, wherein the administration step
includes, prior to the injecting step, the step of attaching to or
implanting in the mammal an administration means for administering
the neurotoxin to the central nervous system of the mammal, the
administration means comprising a reservoir of the neurotoxin, the
reservoir being operably connected to a pump means for pumping an
aliquot of the neurotoxin out of the reservoir and into an end of
the catheter in the subarachnoid space.
23. The method of claim 1, wherein the administration step is
carried out prior to the onset of a nociceptive event or syndrome
experienced by the mammal.
24. The method of claim 23, wherein the administration step is
carried out between about more than 0.5 hour before to about 14
days before the onset of the nociceptive event.
25. The method of claim 23, wherein the administration step is
carried out between about more than 0.5 hour before to about 10
days before the onset of the nociceptive event.
26. The method of claim 23, wherein the administration step is
carried out between about more than 0.5 hour before to about 7 days
before the onset of the nociceptive event.
27. The method of claim 23, wherein the administration step is
carried out between about more than 0.5 hour before to about 4 days
before the onset of the nociceptive event.
28. The method of claim 23, wherein the administration step is
carried out between about more than 0.5 hour before to about 24
hours before the onset of the nociceptive event.
29. The method of claim 23, wherein the administration step is
carried out between about more than 0.5 hour before to about 6
hours before the onset of the nociceptive event.
30. The method of claim 23, wherein the administration step is
carried out between about 2 hours before to about 5 hours before
the onset of the nociceptive event.
31. The method of claim 1, wherein the administration step is
carried out subsequent to the onset of a nociceptive event
experienced by the mammal.
32. The method of claim 31, wherein the nociceptive event is a
neuropathic pain syndrome.
33. The method of claim 31, wherein the nociceptive event is
inflammatory pain.
34. The method of claim 1, wherein the neurotoxin is made by a
Clostridial bacterium.
35. The method of claim 34, wherein the neurotoxin is made by a
bacterium selected from the group consisting of Clostridium
botulinum, Clostridium butyricum, Clostridium beratti.
36. The method of claim 1, wherein the neurotoxin is a modified
neurotoxin.
37. The method of claim 36, wherein the modified neurotoxin has at
least one of its amino acids deleted, modified or replaced, as
compared to the native neurotoxin.
38. The method of claim 36, wherein the modified neurotoxin is a
recombinant produced neurotoxin or a derivative or fragment
thereof.
39. A method for the in vivo attenuation of a nociceptive activity
or experience of a human patient, the method comprising the step of
intraspinal administration to a human patient a therapeutically
effective amount of a botulinum toxin, thereby causing an in vivo
attenuation of a nociceptive activity or experience of the human
patient.
40. The method of claim 39, wherein the intraspinal administration
step is carried out subsequent to the onset of the nociceptive
activity or experience.
41. The method of claim 39, wherein the botulinum toxin is selected
from the group consisting of botulinum toxins A, B, C, D, E, F and
G.
42. The method of claim 41, wherein the botulinum toxin is
botulinum toxin type A.
43. A method for treating pain, the method comprising the steps of:
(a) selecting a neurotoxin with antinociceptive activity; (b)
choosing a portion of a central nervous system of a patient which
influences a nociceptive activity; (c) intraspinally administering
to the portion of the central nervous system chosen the neurotoxin
selected.
44. A method for treating pain, the method comprising the step of
administering a pharmaceutical preparation to the central nervous
system or to a dorsal root ganglion of a mammal, thereby
alleviating pain experienced by the mammal, wherein the
pharmaceutical preparation comprises a neurotoxin and the
pharmaceutical preparation is essentially free of any neuronal
targeting moiety.
45. A method for improving patient function, the method comprising
the step of administering a neurotoxin to the central nervous
system or to a dorsal root gang lion of a mammal, thereby improving
patient function as determined by improvement in one or more of the
factors of reduced pain, reduced time spent in bed, increased
ambulation, healthier attitude and a more varied lifestyle.
Description
BACKGROUND
[0001] The present invention relates to methods for treating pain.
In particular, the present invention relates to methods for
treating pain by intraspinal administration of a neurotoxin.
[0002] Many, if not most ailments of the body cause pain. Generally
pain is experienced when the free nerve endings which constitute
the pain receptors in the skin as well as in certain internal
tissues are subjected to mechanical, thermal or chemical stimuli.
The pain receptors transmit signals along afferent neurons into the
central nervous system and thence to the brain.
[0003] The causes of pain can include inflammation, injury,
disease, muscle spasm and the onset of a neuropathic event or
syndrome. Ineffectively treated pain can be devastating to the
person experiencing it by limiting function, reducing mobility,
complicating sleep, and dramatically interfering with the quality
of life.
[0004] Inflammatory pain can occur when tissue is damaged, as can
result from surgery or due to an adverse physical, chemical or
thermal event or to infection by a biologic agent. Although
inflammatory pain is generally reversible and subsides when the
injured tissue has been repaired or the pain inducing stimulus
removed, present methods for treating inflammatory pain have many
drawbacks and deficiencies. Thus, the typical oral, parenteral or
topical administration of an analgesic drug to treat the symptoms
of pain or of, for example, an antibiotic to treat inflammatory
pain causation factors can result in widespread systemic
distribution of the drug and undesirable side effects.
Additionally, current therapy for inflammatory pain suffers from
short drug efficacy durations which necessitate frequent drug
readministration with possible resulting drug resistance, antibody
development and/or drug dependence and addiction, all of which are
unsatisfactory. Furthermore, frequent drug administration increases
the expense of the regimen to the patient and can require the
patient to remember to adhere to a dosing schedule.,
[0005] Neuropathic pain is a persistent or chronic pain syndrome
that can result from damage to the nervous system, the peripheral
nerves, the dorsal root ganglion or dorsal root, or to the central
nervous system. Neuropathic pain syndromes include allodynia,
various neuralgias such as post herpetic neuralgia and trigeminal
neuralgia, phantom pain, and complex regional pain syndromes, such
as reflex sympathetic dystrophy and causalgia. Causalgia is
characterized by spontaneous burning pain combined with
hyperalgesia and allodynia.
[0006] Unfortunately, current methods to treat neuropathic pain,
such as by local anesthetic blocks targeted to trigger points,
peripheral nerves, plexi, dorsal roots, and to the sympathetic
nervous system have only short-lived antinociceptive effects.
Additionally, longer lasting analgesic treatment methods, such as
blocks by phenol injection or cryotherapy raise a considerable risk
of irreversible functional impairment. Furthermore, chronic
epidural or intrathecal (collectively "intraspinal") administration
of drugs such as clonidine, steroids, opioids or midazolam have
significant side effects and questionable efficacy.
[0007] Tragically there is no existing method for adequately,
predictably and specifically treating established neuropathic pain
(Woolf C. et al., Neuropathic Pain: Aetiology, Symptoms,
Mechanisms, and Management, Lancet 1999; 353: 1959-64) as present
treatment methods for neuropathic pain consists of merely trying to
help the patient cope through psychological or occupational
therapy, rather than by reducing or eliminating the pain
experienced.
[0008] Spasticity or muscle spasm can be a serious complication of
trauma to the spinal cord or other disorders that create damage
within the spinal cord and the muscle spasm is often accompanied by
pain. The pain experienced during a muscle spasm can result from
the direct effect of the muscle spasm stimulating mechanosensitive
pain receptors or from the indirect effect of the spasm compressing
blood vessels and causing ischemia. Since the spasm increases the
rate of metabolism in the affected muscle tissue, the relative
ischemia becomes greater creating thereby conditions for the
release of pain inducing substances.
[0009] Within the enclosure by the vertebral canal for the spinal
cord by the bones of the vertebrae, the spinal cord is surrounded
by three meningeal sheaths which are continuous with those which
encapsulate the brain. The outermost of these three meningeal
sheaths is the dura matter, a dense, fibrous membrane which
anteriorally is separated from the periosteum of the vertebral by
the epidural space. Posterior to the dura matter is the subdural
space. The subdural space surrounds the second of the three
meningeal sheaths which surround the spinal cord, the arachnoid
membrane. The arachnoid membrane is separated from the third
meningeal sheath, the pia mater, by the subarachnoid or intrathecal
space. The subarachnoid space is filled with cerebrospinal fluid
(CSF). Underlying the pia mater is the spinal cord. Thus the
progression proceeding inwards or in posterior manner from the
vertebra is the epidural space, dura mater, subdural space,
arachnoid membrane, intrathecal space, pia matter and spinal
cord.
[0010] Therapeutic administration of certain drugs intraspinally,
that is to either the epidural space or to the intrathecal space,
is known. Administration of a drug directly to the intrathecal
space can be by either spinal tap injection or by catheterization.
Intrathecal drug administration can avoid the inactivation of some
drugs when taken orally as well and the systemic effects of oral or
intravenous administration. Additionally, intrathecal
administration permits use of an effective dose which is only a
fraction of the effective dose required by oral or parenteral
administration. Furthermore, the intrathecal space is generally
wide enough to accommodate a small catheter, thereby enabling
chronic drug delivery systems. Thus, it is known to treat
spasticity by intrathecal administration of baclofen. Additionally,
it is known to combine intrathecal administration of baclofen with
intramuscular injections of botulinum toxin for the adjunct effect
of intramuscular botulinum for reduced muscle spasticity.
Furthermore, it is known to treat pain by intraspinal
administration of the opioids morphine and fentanyl, as set forth
in Gianno, J., et al., Intrathecal Drug Therapy for Spasticity and
Pain, Springer-Verlag (1996), the contents of which publication are
incorporated herein by reference in its entirety.
[0011] The current method for intrathecal treatment of chronic pain
is by use of an intrathecal pump, such as the SynchroMed.RTM.
Infusion System, a programmable, implanted pump available from
Medtronic, Inc., of Minneapolis, Minn. A pump is required because
the antinociceptive or antispasmodic drugs in current use have a
short duration of activity and must therefore be frequently
readministered, which readministration is not practically carried
out by daily spinal tap injections. The pump is surgically placed
under the skin of the patient's abdomen. One end of a catheter is
connected to the pump, and the other end of the catheter is
threaded into a CSF filled subarachnoid or intrathecal space in the
patient's spinal cord. The implanted pump can be programmed for
continuous or intermittent infusion of the drug through the
intrathecally located catheter. Complications can arise due the
required surgical implantation procedure and the known
intrathecally administered drugs for pain have the disadvantages of
short duration of activity, lipid solubility which permits passage
out of the intrathecal space and systemic transport and/or
diffusion to higher CNS areas with potential respiratory depression
resulting.
[0012] Thus, a significant problem with many if not all of the
known intrathecally administered drugs used to treat pain, whether
administered by spinal tap or by catheterization, is that due to
the drug's solubility characteristics, the drug can leave the
intrathecal space and additionally due to poor neuronal binding
characteristics, the drug can circulate within the CSF to cranial
areas of the CNS where brain functions can potentially be
affected.
[0013] Botulinum Toxin
[0014] The anaerobic, gram positive bacterium Clostridium botulinum
produces a potent polypeptide neurotoxin, botulinum toxin, which
causes a neuroparalytic illness in humans and animals referred to
as botulism. The spores of Clostridium botulinum are found in soil
and can grow in improperly sterilized and sealed food containers of
home based canneries, which are the cause of many of the cases of
botulism. The effects of botulism typically appear 18 to 36 hours
after eating the foodstuffs infected with a Clostridium botulinum
culture or spores. The botulinum toxin can apparently pass
unattenuated through the lining of the gut and attack the central
nervous system. The highest cranial nerves are affected first,
followed by the lower cranial nerves and then the peripheral motor
neurons. Symptoms of untreated botulinum toxin poisoning can
progress from and include medial rectus paresis, ptosis, sluggish
pupillary response to light, difficulty walking, swallowing, and
speaking, paralysis of the respiratory muscles and death.
[0015] Botulinum toxin type A is the most lethal natural biological
agent known to man. It has been determined that 39 units per
kilogram (U/kg) of intramuscular BOTOX.RTM..sup.1 is a LD.sub.50 in
primates. One unit (U) of botulinum toxin can be defined as the
LD.sub.50 upon intraperitoneal injection into mice. BOTOX.RTM.
contains about 4.8 ng of botulinum toxin type A complex per 100
unit vial. Thus, for a 70 kg human a LD.sub.50 of about 40 U/kg
would be about 134 ng or 28 vials (2800 units) of intramuscular
BOTOX.RTM.. Seven immunologically distinct botulinum neurotoxins
have been characterized, being respectively neurotoxin serotypes A,
B, C1, D, E, F and G each of which is distinguished by
neutralization with type-specific antibodies. The neurotoxin
component is noncovalently bound to nontoxic proteins to form high
molecular weight complexes. The different serotypes of botulinum
toxin vary in the animal species that they affect and in the
severity and duration of the paralysis they evoke. For example, it
has been determined that botulinum toxin type A is 500 times more
potent, as measured by the rate of paralysis produced in the rat,
than is botulinum toxin type B. Additionally, botulinum toxin type
B has been determined to be non-toxic in primates at a dose of 480
U/kg which is about 12 times the primate LD.sub.50 for botulinum
toxin type A (Moyer E et al., Botulinum Toxin Type B: Expenmental
and Clinical Experience, being chapter 6, pages 71-85 of "Therapy
With Botulinum Toxin", edited by Jankovic, J. et al. (1994), Marcel
Dekker, Inc.) .sup.1botulinum toxin type A purified neurotoxin
complex, available from Allergan, Inc., of Irvine, Calif. A
botulinum toxin type A complex is also available from Porton
Products, Ltd., U.K. under the trade name DYSPORT)
[0016] Minute quantities of botulinum toxin have been used to
reduce excess skeletal and smooth muscle and sphincter contraction.
The botulinum toxin can be injected directly into the hyperactive
or hypertonic muscle or its immediate vicinity and is believed to
exert its effect by entering peripheral, presynaptic nerve
terminals at the neuromuscular junction and blocking the release of
acetylcholine. The affected nerve terminals are thereby inhibited
from stimulating muscle contraction, resulting in a reduction of
muscle tone. Thus, when injected intramuscularly at therapeutic
doses, botulinum toxin type A can be used to produce a localized
chemical denervation and hence a localized weakening or paralysis
and relief from excessive involuntary muscle contractions.
[0017] Clinical effects of peripheral intramuscular botulinum toxin
type A are usually seen within one week of injection. The typical
duration of symptomatic relief from a single intramuscular
injection of botulinum toxin type A averages about three months.
Muscles therapeutically treated with a botulinum toxin eventually
recover from the temporary paralysis induced by the toxin, due
possibly to the development of new nerve sprouts or to reoccurrence
of neurotransmission from the original synapse, or both. A nerve
sprout may establishes a new neuromuscular junction. Thus,
neuromuscular transmission can gradually return to normal over a
period of several months.
[0018] In skeletal and smooth muscle tissues botulinum toxin
appears to have no appreciable affinity for organs or tissues other
than cholinergic neurons at the neuromuscular junction where the
toxin binds to and is internalized by neuronal receptors and, as
indicated, block presynaptic release of the neurotransmitter
acetylcholine, without causing neuronal cell death.
[0019] Botulinum toxins have been used for the treatment of an
increasing array of disorders, relating to cholinergic nervous
system transmission, characterized, for example, by hyperactive
neuromuscular activity in specific focal or segmental striated or
smooth muscle regions. Thus, intramuscular injection of one or more
of the botulinum toxin serotypes has been used to treat,
blepharospasm, spasmodic torticollis, hemifacial spasm, spasmodic
dysphonia, oral mandibular dystonia and limb dystonias, myofacial
pain, bruxism, achalasia, trembling chin, spasticity, juvenile
cerebral palsy, hyperhydrosis, excess salivation, non-dystonic
tremors, brow furrows, focal dystonias, tension headache, migraine
headache and lower back pain. Not infrequently, a significant
amount of pain relief has also been experienced by such
intramuscular therapy. These benefits have been observed after
local intramuscular injection of, most commonly botulinum toxin
type A, or one or another of the other botulinum neurotoxin
serotypes. Botulinum toxin serotypes B, C1, D, E and F apparently
have a lower potency and/or a shorter duration of activity as
compared to botulinum toxin type A at a similar dosage level.
[0020] Although all botulinum toxins serotypes apparently inhibit
release of the neurotransmitter acetylcholine at the neuromuscular
junction, they do so by affecting different neurosecretory proteins
and/or cleaving these proteins at different sites. For example,
botulinum types A and E both cleave the 25 kiloDalton (kD)
synaptosomal associated protein (SNAP-25), but they target
different amino acid sequences within this protein. Botulinum toxin
types B, D, F and G act on vesicle-associated protein (VAMP, also
called synaptobrevin), with each serotype cleaving the protein at a
different site. Finally, botulinum toxin type C1 has been shown to
cleave both syntaxin and SNAP-25. These differences in mechanism of
action may affect the relative potency and/or duration of action of
the various botulinum toxin serotypes. The molecular weight of a
secreted botulinum toxin protein molecule, for all seven of the
known botulinum toxin serotypes, is about 150 kD. Interestingly,
the botulinum toxins are released by Clostridial bacterium as
complexes comprising the 150 kD botulinum toxin protein molecule
along with associated non-toxin proteins. Thus, the botulinum toxin
type A complex can be produced by Clostridial bacterium as 900 kD,
500 kD and 300 kD forms. Botulinum toxin types B and C1 is
apparently produced as only a 500 kD complex. Botulinum toxin type
D is produced as both 300 kD and 500 kD complexes. Finally,
botulinum toxin types E and F are produced as only approximately
300 kD complexes. The complexes (i.e. molecular weight greater than
about 150 kD) are believed to contain a non-toxin hemaglutinin
protein and a non-toxin and non-toxic nonhemaglutinin protein.
These two non-toxin proteins (which along with the botulinum toxin
molecule comprise the relevant neurotoxin complex) may act to
provide stability against denaturation to the botulinum toxin
molecule and protection against digestive acids when toxin is
ingested. Additionally, it is possible that the larger (greater
than about 150 kD molecular weight) botulinum toxin complexes may
result in a slower rate of diffusion of the botulinum toxin away
from a site of intramuscular injection of a botulinum toxin
complex.
[0021] The biochemical mechanism of the effects of botulinum toxin
upon central nervous tissues is controversial. Additionally, the
number of CNS neurotransmitters affected as well as the extent and
nature of the effect of botulinum toxin upon the synthesis,
release, accumulation and metabolism of different CNS
neurotransmitters is still being determined. In vitro studies have
indicated that botulinum toxin inhibits potassium cation induced
release of both acetylcholine and norepinephrine from primary cell
cultures of brain tissue. Additionally, it has been reported that
botulinum toxin inhibits the evoked release of both glycine and
glutamate in primary cultures of spinal cord neurons and that in
brain synaptosome preparations botulinum toxin inhibits the release
of each of the neurotransmitters acetylcholine, dopamine,
norepinephrine, CGRP and glutamate.
[0022] Botulinum toxin type A can be obtained by establishing and
growing cultures of Clostridium botulinum in a fermenter and then
harvesting and purifying the fermented mixture in accordance with
known procedures. All the botulinum toxin serotypes are initially
synthesized as inactive single chain proteins which must be cleaved
or nicked by proteases to become neuroactive. The bacterial strains
that make botulinum toxin serotypes A and G possess endogenous
proteases and serotypes A and G can therefore be recovered from
bacterial cultures in predominantly their active form. In contrast,
botulinum toxin serotypes C1, D and E are synthesized by
nonproteolytic strains and are therefore typically unactivated when
recovered from culture. Serotypes B and F are produced by both
proteolytic and nonproteolytic strains and therefore can be
recovered in either the active or inactive form. However, even the
proteolytic strains that produce, for example, the botulinum toxin
type B serotype only cleave a portion of the toxin produced. The
exact proportion of nicked to unnicked molecules depends on the
length of incubation and the temperature of the culture. Therefore,
a certain percentage of any preparation of, for example, the
botulinum toxin type B toxin is likely to be inactive, possibly
accounting for the known significantly lower potency of botulinum
toxin type B as compared to botulinum toxin type A. The presence of
inactive botulinum toxin molecules in a clinical preparation will
contribute to the overall protein load of the preparation, which
has been linked to increased antigenicity, without contributing to
its clinical efficacy. Additionally, it is known that botulinum
toxin type B has, upon intramuscular injection, a shorter duration
of activity and is also less potent than botulinum toxin type A at
the same dose level.
[0023] What is needed therefore is a method for effectively
treating pain and/or spasm by intraspinal administration of a
pharmaceutical which has the characteristics of long duration of
activity, low rates of diffusion out of an intrathecal space where
administered, low rates of diffusion to other intrathecal areas
outside of the site of administration, specificity for the
treatment of pain and limited or insignificant side effects at
therapeutic dose levels.
SUMMARY
[0024] The present invention meets this need and provides methods
for effectively treating pain by intraspinal administration of a
neurotoxin which has the characteristics of long duration of
activity, low rates of diffusion out of an, for example,
intrathecal space where administered, low rates of diffusion to
other intrathecal areas outside of the site of administration,
specificity for the treatment of pain and limited or insignificant
side effects at therapeutic dose levels. A method for treating pain
according to the present invention can have the step of intraspinal
administration of a neurotoxin to a mammal, thereby alleviating
pain experienced by the mammal. Preferably, the neurotoxin used is
a botulinum toxin, such as one of, or a combination of one or more,
of the botulinum toxin serotypes A, B, C, D, E, F and G. Most
preferably, the botulinum toxin used is botulinum toxin type A
because of the high potency, ready availability and long history of
clinical use of botulinum toxin type A to treat various
disorders.
[0025] The neurotoxin intraspinally administered according to the
methods of the present invention has not been conjugated, attached,
adhered to or fused to and is not administered in conjunction with
a neuronal targeting moiety. A neuronal targeting moiety is a
compound which functionally interacts with a binding site on a
neuron causing a physical association between the targeting moiety
and/or a conjugate attached to the targeting moiety and the surface
of the neuron, such as a primary sensory afferent. Thus, the
targeting moiety provides specificity for or binding affinity for
one or more type of neurons. In the present invention, any
pharmaceutical preparation (i.e. a reconstituted solution of
neurotoxin, sodium chloride (saline) and a stabilizer such as
albumin) which incorporates a neurotoxin for use according to the
disclosed methods is devoid of or essentially free of any
deliberately attached or prepared neuronal targeting moiety.
[0026] Use of one or more targeting moiety artifacts or constructs
is excluded from the scope of the present invention as unnecessary
because we have surprisingly discovered that intraspinal neurotoxin
administration according to the present invention provides
significant pain alleviation even though the neurotoxin is not
administrated in conjunction with any non-native or non-inherent to
the neurotoxin neuronal targeting moiety. Thus, we unexpectedly
discovered that a native neurotoxin, such as botulinum toxin type
A, can upon intraspinal administration interact with neurons of the
CNS and provide alleviation of pain even though the neurotoxin has
not been artificially or manipulatively accorded any neuronal
specificity or binding affinity, such as by attachment of a
neuronal targeting moiety to the neurotoxin. Prior to our
invention, it has been believed, as discussed infra, that a
neurotoxin, such as botulinum toxin type A, would upon intraspinal,
including intrathecal, administration, exert widespread, unfocused,
diffuse and deleterious effects upon the CNS, such deleterious
effects including spasticity. Hence, the assumed necessity for a
neuronal targeting moiety deliberately attached to the neurotoxin
to attenuate or eliminate these presumed detrimental effects
resulting from intraspinal administration of a neurotoxin, such a
botulinum toxin type A.
[0027] We have surprising found that a botulinum toxin, such as
botulinum toxin type A, can be intraspinally administered in
amounts between about 10.sup.-3 U/kg and about 60 U/kg to alleviate
pain experienced by a mammal, such as a human patient. Preferably,
the botulinum toxin used is intraspinally administered in an amount
of between about 10.sup.-2 U/kg and about 50 U/kg. More preferably,
the botulinum toxin is administered in an amount of between about
10.sup.-1 U/kg and about 40 U/kg. Most preferably, the botulinum
toxin is administered in an amount of between about 1 U/kg and
about 30 U/kg. In a particularly preferred embodiment of the
present disclosed methods, the botulinum toxin is administered in
an amount of between about 1 U/kg and about 20 U/kg and in some
clinical settings the botulinum toxin can advantageously be
administered in an amount of between about 1 U/kg and about 10
U/kg. Significantly, the pain alleviating effect of the present
disclosed methods can persist for up to 10 days or for up to 20
days and depending upon factors, such as the dosage used, for up to
3 months per neurotoxin administration.
[0028] The intraspinal administration of the neurotoxin is
preferably by intrathecal administration, such as intrathecally to
a cranial, cervical, thoracic, lumbar, sacral or coccygeal region
of the central nervous system and the administration step can
include the steps of accessing a subarachnoid space of the central
nervous system of the mammal, and injecting the neurotoxin into the
subarachnoid space. The accessing step can be carried out by
effecting a spinal tap.
[0029] Alternately, the intraspinal administration step can include
the steps of catheterization of a subarachnoid space of the central
nervous system of the mammal, followed by injection of the
neurotoxin through a catheter inserted by the catheterization step
into the subarachnoid space. Note that prior to the injecting step
there can be the step of attaching to or implanting in the mammal
an administration means for administering the neurotoxin to the
central nervous system of the mammal. The administration means can
be made up of a reservoir of the neurotoxin, where the reservoir is
operably connected to a pump means for pumping an aliquot of the
neurotoxin out of the reservoir and into an end of the catheter in
the subarachnoid space.
[0030] It is important to note that the administration step can be
carried out prior to the onset of or subsequent to the occurrence
of a nociceptive (inflammatory, neuropathic, injury induced,
resulting form a cancer, spasm, etc) event or syndrome experienced
by the mammal. Thus, the administration step can be carried out
between about more than 0.5 hour before to about 14 days before the
onset of the nociceptive event. More preferably, administration
step is carried out between about more than 0.5 hour before to
about 10 days before the onset of the nociceptive event. Most
preferably, the administration step is carried out between about
more than 0.5 hour before to about 7 days, 4 days, 24 hours or 6
hours before the onset of the nociceptive event. In a particularly
preferred embodiment of the present invention, the administration
step is carried out between about 2 hours before to about 5 hours
before the onset of the nociceptive event. The present methods can
be used to treat the pain associated with allodynia.
[0031] A detailed embodiment of a method within the scope of the
present invention can include the steps of firstly catheterization
of a subarachnoid space of the central nervous system of the mammal
by making an incision though the dermis of the mammal, and then
threading a catheter through the incision into the subarachnoid
space, the catheter having an open first end and a remote open
second end. Secondly, attaching to or implanting in the mammal an
administration means for administering a botulinum toxin to the
subarachnoid space of the central nervous system of the mammal, the
administration means comprising a reservoir for holding a multidose
amount of the botulinum toxin, the reservoir being connected to a
pump means for pumping an aliquot of the botulinum toxin out of the
reservoir and into the first end of a catheter, the first end of
the catheter being connected to the pump means. Thirdly, activating
the pump means, and finally, injecting into the subarachnoid space
of the central nervous system of the mammal and through the second
end of the catheter between about 10.sup.-1 U/kg and about 60 U/kg
of the botulinum toxin, thereby alleviating pain experienced by the
mammal.
[0032] Another preferred method within the scope of the present
invention is a method for the in vivo attenuation of a nociceptive
activity or experience of a human patient, the method comprising
the step of intraspinal administration to a human patient a
therapeutically effective amount of a botulinum toxin, thereby
causing an in vivo attenuation of a nociceptive activity or
experience of the human patient. The intraspinal administration
step can be carried out subsequent to or prior to the occurrence or
onset of a nociceptive activity, experience, sensation or
syndrome.
[0033] A further preferred method within the scope of the present
invention is a method for treating pain by selecting a neurotoxin
with antinociceptive activity, choosing a portion of a central
nervous system of a patient which influences a nociceptive
activity; and intraspinally administering to the portion of the
central nervous system chosen the neurotoxin selected.
[0034] Notably, the neurotoxin used to practice the present methods
can be made by a Clostridial bacterium, such as one or more of the
Clostridium botulinum, Clostridium butyricum, and Clostridium
beratti species.
[0035] Another preferred method within the scope of the present
invention is a method for treating pain, the method comprising the
step of administering a neurotoxin to the central nervous system or
to a dorsal root ganglion of a mammal, thereby alleviating pain
experienced by the mammal. A further preferred method within the
scope of the present invention is a method for improving patient
function, the method comprising the step of administering a
neurotoxin to the central nervous system or to dorsal root ganglion
of a mammal, thereby improving patient function as determined by
improvement in one or more of the factors of reduced pain, reduced
time spent in bed, increased ambulation, healthier attitude and a
more varied lifestyle.
[0036] The present invention also includes within its scope a
method which uses a modified neurotoxin. By a modified neurotoxin
it is meant a neurotoxin which has had one or more of its amino
acids deleted, modified or replaced (as compared to the native
neurotoxin) and includes recombinant technology made neurotoxins as
well as derivatives and fragments of a recombinant produced
neurotoxin.
DRAWINGS
[0037] These and other features, aspects, and advantages of the
present invention can become better understood from the following
description, claims and the accompanying drawings, where in all of
FIGS. 1-7 below, "injection" means intrathecal injection.
[0038] FIG. 1 is a dose response graph showing that a method within
the scope of the present invention alleviates induced inflammatory
pain under the rat formalin model. The x axis set forth time in
minutes after commencement of the formalin model in rats. The y
axis sets forth time spent lifting and licking the formalin
injected paw upon use of control (saline, n=11) and BOTOX.RTM.
(botulinum toxin Type A purified neurotoxin complex) injections at
concentrations of 0.0625 U/kg (n=10), 0.625 U/kg (n=14) and 3.125
U/kg (n=9) injected from 2 hours to 5 hours before commencement of
the formalin challenge.
[0039] FIG. 2 is a time course graph showing that a method within
the scope of the present invention alleviates induced inflammatory
pain under the rat formalin model for at least seven days when
injected more than one half hour before commencement of the
formalin test. The x axis set forth time in minutes after
commencement of the formalin model in rats. The y axis sets forth
time spent lifting and licking the formalin injected paw upon use
of control (saline, n=8) and BOTOX.RTM. injections at a
concentration of 0.625 U/kg injected 0.5 hour before, 2 hours to 5
hours before (n=14) and 7 days before (n=5) commencement of the
formalin challenge.
[0040] FIG. 3 is a dose response graph showing that a method within
the scope of the present invention alleviates induced inflammatory
pain under the rat formalin model for at least seven days when
different concentrations of botulinum toxin type A are used. The x
axis set forth time in minutes after commencement of the formalin
model in rats. The y axis sets forth time spent lifting and licking
the formalin injected paw upon use of control (saline, n=11) and
BOTOX.RTM. injections at concentrations of 0.0625 U/kg injected 7
days before (n=8), 0.625 U/kg injected 7 days before (n=7) and
3.125 U/kg injected 7 days before (n=6) commencement of the
formalin challenge.
[0041] FIG. 4 is a time course graph showing that a method within
the scope of the present invention alleviates induced inflammatory
pain in the rat formalin model. The x axis set forth time in
minutes after commencement of the formalin model in rats. The y
axis sets forth time spent lifting and licking the formalin
injected paw upon injection of control (saline, n=11), and
BOTOX.RTM. at a concentration of 0.625 U/kg injected 2 hours 14
days before (n=4) commencement of the formalin challenge.
[0042] FIG. 5 is a graph which shows a comparison of the analgesic
effect of botulinum toxin type A and muscimol upon induced
inflammatory pain in the rat formalin model. The x axis set forth
time in minutes after commencement of the formalin model in rats.
The y axis sets forth time spent lifting and licking the formalin
injected paw upon use of control injection (saline, n=11),
BOTOX.RTM. at a concentration of 0.625 U/kg injected 2 hours to 5
hours before or six days before, and 1 .mu.g of muscimol injected
10 minutes before or six days before commencement of the formalin
challenge.
[0043] FIG. 6 is graph showing that a method within the scope of
the present invention alleviates induced inflammatory pain in the
rat formalin model with a local intrathecal analgesic effect. The x
axis set forth time in minutes after commencement of the formalin
model in rats. The y axis sets forth time spent lifting and licking
the formalin injected paw upon use of control where the catheter
used for intrathecally injecting saline was located either 4.5 cm
(n=1) or 8.5 cm (n=11) caudally (at the lumbar enlargement
therefore) from its insertion point, and BOTOX.RTM. at a
concentration of either 0.625 U/kg (n=3) or 3.125 U/kg (n=4) was
injected through a catheter located only 4.5 cm caudally from its
insertion point.
[0044] FIG. 7 is a graph showing that a method within the scope of
the present invention alleviates surgically induced neuropathic
pain. The x axis sets forth time in hours after injection of either
saline (n=8) or BOTOX.RTM. at a concentration of 0.625 U/kg (n=11)
or 3.125 U/kg (n=9). The y axis sets forth the G value, a measure
of analgesic effect. BL means baseline.
DESCRIPTION
[0045] The present invention encompasses methods for treating pain.
We have discovered that intraspinal administration of a neurotoxin
to the central nervous system of a patient can result in
significant and long lasting alleviation of pain without
significant undesirable side effects. Thus, a method within the
scope of the present invention provides antinociceptive or
analgesic relief.
[0046] As used herein "intraspinal" means into or within the
epidural space, the intrathecal space, the white or gray matter of
the spinal cord or affiliated structures such as the dorsal root
and dorsal root ganglia.
[0047] Prior to our invention it had been believed by those skilled
in the art that intrathecal administration of a neurotoxin, such as
a botulinum toxin, would (1) induce significant spasticity in the
recipient and (2) promote detrimental effects upon spinal cord and
brain functions. Thus, with regard to cited deleterious effect (1):
it was reported, as examples, in Williamson et al., in Clostridial
Neurotoxins and Substrate Proteolysis in Intact Neurons, J. of
Biological Chemistry 271:13; 7694-7699 (1996) that both tetanus
toxin and botulinum toxin type A inhibit the evoked release of the
neurotransmitters glycine and glutamate from fetal mice spinal cord
cell cultures, while it was reported by Hagenah et al., in Effects
of Type A Botulinum Toxin on the Cholinergic Transmission at Spinal
Renshaw Cells and on the Inhibitory Action at la Inhibitory
Intemeurones, Naunyn-Schmiedeberg's Arch. Pharmacol. 299, 267-272
(1977), that direct intraspinal injection of botulinum toxin type A
in experimentally prepared, anaesthetized cats inhibits CNS Renshaw
cell activity. Inhibition of central glycine and glutamate
neurotransmitter release as well as the downregulation of Renshaw
cell activity presumably can both result in vivo in the promotion
of significant motorneuron hyperactivity with ensuing peripheral
muscle spasticity.
[0048] With regard to deleterious effect (2): it is believed that
intrathecal administration of the tetanus neurotoxin exerts, by
retrograde movement of the tetanus toxin along CNS neurons,
significant negative effects upon spinal cord and brain functions,
thereby contraindicating intrathecal administration of a related
neurotoxin, such as a botulinum toxin. Notably, botulinum toxin and
tetanus toxin are both made by Clostridial bacteria, although by
different species of Clostridium. Significantly some researchers
have reported that botulinum toxin shares, at least to some extent,
the noted neural ascent characteristic of tetanus toxin. See e.g.
Habermann E., .sup.125I-Labeled Neurotoxin from Clostridium
Botulinum A: Preparation, Binding to Synaptosomes and Ascent in the
Spinal Cord, Naunyn-Schmiedeberg's Arch. Pharmacol. 281, 47-56
(1974).
[0049] Our invention surprisingly encounters neither of the
deleterious effects (1) or (2), and the disclosed methods of the
present invention can be practiced to provide effective and long
lasting relief from pain and to provide a general improvement in
the quality of life experienced by the treated patient. The pain
experienced by the patient can be due, for example, to injury,
surgery, infection, accident or disease (including cancer and
diabetes), including neuropathic diseases and disorders.
[0050] Preferably, a neurotoxin used to practice a method within
the scope of the present invention is a botulinum toxin, such as
one of the serotype A, B, C, D, E, F or G botulinum toxins.
Preferably, the botulinum toxin used is botulinum toxin type A,
because of its high potency in humans, ready availability, and
known use for the treatment of skeletal and smooth muscle disorders
when locally administered by intramuscular injection. Botulinum
toxin type B is not a preferred toxin to use in the practice of the
disclosed methods because type B is known to have a significantly
lower potency and efficacy as compared, to type A, is not readily
available, and has a limited history of clinical use in humans.
[0051] An intraspinal route for administration of a neurotoxin
according to the present disclosed invention can be selected based
upon criteria such as the solubility characteristics of the
neurotoxin toxin chosen as well as the amount of the neurotoxin to
be administered. The amount of the neurotoxin administered can vary
widely according to the particular disorder being treated, its
severity and other various patient variables including size,
weight, age, and responsiveness to therapy. For example, the extent
of the area of CNS afferent pain neuron somata influenced is
believed to be proportional to the volume of neurotoxin injected,
while the quantity of the analgesia is, for most dose ranges,
believed to be proportional to the concentration of neurotoxin
injected. Furthermore, the particular intraspinal location for
neurotoxin administration can depend upon the dermosome location of
the pain to be treated. Methods for determining the appropriate
route of administration and dosage are generally determined on a
case by case basis by the attending physician. Such determinations
are routine to one of ordinary skill in the art (see for example,
Harrison's Principles of Internal Medicine (1997), edited by
Anthony Fauci et al., 14.sup.th edition, published by McGraw
Hill).
[0052] Preferably, the intraspinal administration is carried out
intrathecally because of the greater ease in which the relatively
larger intrathecal space is accessed and because the preferred
neurotoxin, a botulinum toxin, generally exhibits low solubility in
the lipid rich epidural environment. Additionally, epidural
neurotoxin administration is a less preferred route of intraspinal
administration because the neurotoxin must diffuse through the
intrathecal space to have an antinociceptive effect by, it is
believed, action upon neurons of the CNS and dorsal root ganglia
(DRG). We have found that both inflammatory and neuropathic pain
can be effectively treated by the disclosed methods without
significant muscle spasticity or flaccidity or other side
effects.
[0053] Intraspinal administration of a neurotoxin according to the
present invention can be by various routes such as by
catheterization or by spinal tap injection. The long lasting nature
of the therapeutic effects of the present invention substantially
removes the need for chronic antinociceptive drug administration,
so that the present methods are advantageously practiced by
infrequent spinal tap injection of the neurotoxin. Additionally, an
intrathecal spinal tap neurotoxin administration route facilitates
a more precise and localized delivery of toxin with less danger of
damage to the CNS, as compared to moving a catheter to access other
CNS locations.
[0054] Intrathecal neurotoxin can be administered by bolus
injection or by catheterization. The catheter can be inserted at
L3-4 or at L4-5, a safe distance from the spinal cord which in
humans terminates at L1, and guided upward in the subarachnoid
space to rest at the desired site. For pain management, placement
of the catheter or location of bolus injection by syringe depends
on the site of the perceived pain, and the physicians
preference.
[0055] It is important to note that therapeutic neurotoxin
administration according to the present disclosed methods can be
carried out before the occurrence of or during the experience of a
nociceptive event or syndrome.
[0056] We have found that a neurotoxin, such as a botulinum toxin,
can be intraspinally administered according to the present
disclosed methods in amounts of between about 10.sup.-3 U/kg to
about 60 U/kg. A dose of about 10.sup.-3 U/kg can result in an
antinociceptive effect if delivered directly to or onto the dorsal
horn of the CNS and/or if botulinum toxin delivery is assisted by
methods such as iontophoresis. Intraspinal administration of less
than about 10.sup.-3 U/kg does not result in a significant or
lasting therapeutic result. An intraspinal dose of more than 60
U/kg approaches a lethal dose of a neurotoxin such as a botulinum
toxin. It is desired that the neurotoxin used to obtain either
antinociceptive effect contact the nerves of the CNS so as to
favorably influence or down regulate the perception of pain or
muscle spasm in the innervated organ or tissue. Thus, intraspinal
administration of a neurotoxin by, for example, epidural injection
can require an increase of the dosage by a factor of about ten to
account for dilution of the neurotoxin upon diffusion from the
epidural space to the intrathecal space and thence to the exterior
nerves of the CNS.
[0057] A preferred range for intrathecal administration of a
botulinum toxin, such as botulinum toxin type A, so as to achieve
an antinociceptive effect in the patient treated is from about
10.sup.-2 U/kg to about 50 U/kg. Less than about 10.sup.-2 U/kg
result in a relatively minor, though still observable,
antinociceptive effects, while more than about 50 U/kg can result
in some muscle flaccidity and symptoms of toxin intoxication. A
more preferred range for intrathecal administration of a botulinum
toxin, such as botulinum toxin type A, so as to achieve an
antinociceptive effect in the patient treated is from about
10.sup.-1 U/kg to about 30 U/kg. Less than about 10.sup.-1 U/kg can
result in the desired therapeutic effect being of less than the
optimal or longest possible duration, while more than about 30 U/kg
can still result in some symptoms of muscle flaccidity. A most
preferred range for intrathecal administration of a botulinum
toxin, such as botulinum toxin type A, so as to achieve an
antinociceptive effect in the patient treated is from about 1 U/kg
to about 20 U/kg. Intrathecal administration of a botulinum toxin,
such as botulinum toxin type A, in this preferred range can provide
dramatic therapeutic success. Furthermore, our experimental work
indicates that a dose range of about 1 U/kg to about 10 U/kg can
provide significant and long lasting antinociceptive effect without
significant side effects for the treatment of inflammatory and
neuropathic pain in human patients.
[0058] We have determined by immunohistochemical staining of
cleaved SNAP-25 proteins produced by BOTOX.RTM., that intrathecally
administered BOTOX.RTM. distributes in the superficial layer of the
rat dorsal horn, which is the spinal cord layer in which afferent
pain fibers terminate. Thus, without wishing to be bound to any
particular theory, we hypothesize that the antinociceptive effect
of intrathecal botulinum toxin is due to its specific inhibition of
the release of various neurotransmitters from central terminal
afferent sensory neurons and/or from second order projecting
neurons in the dorsal horn. The present invention includes within
its scope the use of any neurotoxin which has a long duration
antinociceptive effect when locally applied to the central nervous
system of a patient. For example, neurotoxins made by any of the
species of the toxin producing Clostridium bacteria, such as
Clostridium botulinum, Clostridium butyricum, and Clostridium
beratti can be used or adapted for use in the methods of the
present invention. Additionally, all of the botulinum serotypes A,
B, C, D, E, F and G can be advantageously used in the practice of
the present invention, although type A is the most preferred and
type B the least preferred serotype, as explained above. Practice
of the present invention can provide an analgesic effect, per
injection, for 3 months or longer in humans.
[0059] Significantly, a method within the scope of the present
invention can provide improved patient function. "Improved patient
function" can be defined as an improvement measured by factors such
as a reduced pain, reduced time spent in bed, increased ambulation,
healthier attitude, more varied lifestyle and/or healing permitted
by normal muscle tone.
[0060] As set forth above, we have discovered that a surprisingly
effective and long lasting treatment of pain can be achieved by
intraspinal administration of a neurotoxin to an afflicted patient.
In its most preferred embodiment, the present invention is
practiced by intrathecal injection of botulinum toxin type A.
Significantly, we have discovered that dramatic, long term
analgesic and/or improved patient function effects can be achieved
through intraspinal administration of a neurotoxin by the methods
disclosed herein even though the neurotoxin has not had attached or
fused to it, by various manipulative techniques or technologies, a
neuronal targeting moiety, such as a non-neurotoxin protein, to
provide targeting specificity of the neurotoxin for one or more
particular types of neurons. Thus, the present invention excludes
from its scope the use of any neurotoxins with one or more
artificially attached or fused neuronal targeting moieties. A
neurotoxin can display a natural binding affinity for a neuron
(i.e. for a particular receptor on the surface of the neuron) due
to the presence of a binding moiety inherent to the structure of
the native neurotoxin molecule (for example, the binding domain of
the heavy chain of a botulinum toxin, i.e. the H.sub.C fragment).
Thus, for clarity "targeting moiety" or "neuronal targeting moiety"
as used herein means a targeting moiety which provides to a
neurotoxin specific or enhanced neuronal binding affinity and which
is not a natural or inherent feature of the neurotoxin which has
such a targeting moiety. Contrarily, "binding moiety" as used
herein means the inherent component or domain of the native
neurotoxin which provides neuronal binding affinity.
[0061] The present invention does include within its scope: (a)
neurotoxin obtained or processed by bacterial culturing, toxin
extraction, concentration, preservation, freeze drying and/or
reconstitution and; (b) modified or recombinant neurotoxin, that is
neurotoxin that has had one or more amino acids or amino acid
sequences deliberately deleted, modified or replaced by known
chemical/biochemical amino acid modification procedures or by use
of known host cell/recombinant vector recombinant technologies, as
well as derivatives or fragments of neurotoxins so made, but, as
stated, excludes neurotoxins with one or more attached neuronal
targeting moieties.
[0062] Botulinum toxins for use according to the present invention
can be stored in lyophilized or vacuum dried form in containers
under vacuum pressure. Prior to lyophilization the botulinum toxin
can be combined with pharmaceutically acceptable excipients,
stabilizers and/or carriers, such as albumin. The lyophilized
material can be reconstituted with saline or water.
EXAMPLES
[0063] The following examples provide those of ordinary skill in
the art with specific preferred methods within the scope of the
present invention for carrying out the present invention and are
not intended to limit the scope of what the inventors regards as
their invention. Examples 1-4 and 6 show that intrathecal
administration of botulinum A has an analgesic effect upon
inflammatory pain while examples 5 and 7 show that intrathecal
administration of botulinum A has an analgesic effect upon
neuropathic pain.
Example 1
Analgesic Effect of Intrathecally Administered Botulinum Toxin Type
A Upon Inflammatory Pain
[0064] The purpose of this experiment was to investigate the
analgesic effect of botulinum toxin type A on inflammatory pain
using the rat formalin model.
[0065] Male Sprague-Dawley rats weighing 270 g to 350 g each were
anesthetized with isoflurane. In this and in all subsequent
Examples intrathecal administration of a neurotoxin was carried out
by intrathecal cannulation performed by inserting a PE
(polyethylene)-10 tubing about 10 cm long through an incision in
the dura over the cisterna and threaded caudally about 8.5 cm down
the spinal cord of the rat to the vicinity of the lumbar
enlargement, as described in Yaksh T. et al., Chronic
Catheterization of the Spinal Subarachnoid Space, Physio &
Behav 17: 1031-1036 (1976). Either BOTOX.RTM. or the control fluid
saline was administered intrathecally through the lumbar
enlargement located catheter from 0 to 5 hours before the formalin
test.
[0066] The formalin test to assess analgesia, as set forth in
Dubuisson D., et al The Fonmalin Test: A Quantitative Study of the
Analgesic Effects of Morphine, Merperdine, and Brain Stem
Stimulation in Rats and Cats, Pain, 4 (1977), 161-174, was
followed. Thus, formalin (5%, 50 .mu.l) was injected subcutaneously
into rat's right hind paw. We evaluated the number of
formalin-evoked flinching responses and the time spent licking the
injected paw during time intervals. In the formalin test, recording
of the early response (early phase) starts immediately and lasted
for 5 min (0-5 min). The recording of the late response (late
phase) starts 10 min after formalin injection and lasts for 50 min
(10-60 min).
[0067] FIG. 1 shows that intrathecal administration of BOTOX.RTM.
(0.0625 U/kg, 0.625 U/kg or 3.125 U/kg) 2-5 hrs before injection of
the formalin reduced the inflammatory pain induced by the formalin
model. The control group (n-11) was treated with saline
intrathecally. Injection of formalin in rat right hind paw produced
a consistent lift/licking and flinch response in the both first 5
min (first phase) and 10-60 min (second phase). BOTOX.RTM.) at
doses of 0.0625 U/kg (0.003 ng/kg; n=10), 0.625 U/kg (0.03 ng/kg,
n=14) and at 3.125 U/kg (0.15 ng/kg, n=9) significantly decreased
the lift/licking time during first and second phase. By convention
one unit (U) of reconstituted BOTOX.RTM. provides a median lethal
intraperitoneal dose (LD.sub.50) in mice.
[0068] The first phase (from time 0 to about plus 5-10 minutes in
FIG. 1) is believed to be representative of a short lasting burst
of unmyelinated primary afferent neuron activity. In the longer
second phase (from about time plus 5-10 minutes in FIG. 1), it is
believed that an extended low level of C-fiber activity produces a
facilitation in which the output of the WDR (DR meaning dorsal
root) neuron is much exaggerated relative to the C-fiber input.
[0069] This example shows that intrathecal administration of
botulinum toxin type had a significant analgesic effect on
inflammatory pain at doses of 0.0625 U/kg (0.003 ng/kg; n=10),
0.625 U/kg (0.03 ng/kg, n=14) and 3.125 U/kg (0.15 ng/kg, n=9) as
measured by significantly decreased the lift/licking time during
first and second phases.
Example 2
Analgesic Effect of Intrathecally Administered Botulinum Toxin Type
A Upon Inflammatory Pain Persists For At Least Fourteen Days
[0070] Intrathecal cannulation of male Sprague-Dawley rats was
carried out as set forth in Example 1. FIG. 2 (control, n=8) shows
that pretreatment of rats with BOTOX.RTM. (0.03 ng/kg or 0.625
U/kg, n=14) 2 to 5 hrs before injection of formalin reduced the
lift/licking time in both the first and second phases. The
analgesic effect of BOTOX.RTM. persisted for 7 days (0.625 U/kg,
n=5) after treatment with BOTOX.RTM., but is diminished compared to
the 2 hr pre-treatment (FIG. 2). Additionally, as shown by FIG. 3,
the analgesic effect at day 7 after intrathecal botulinum type A
administration is dose dependant. Furthermore, as shown by FIG. 4,
the analgesic effect of BOTOX.RTM. persists for at least 14 days
(0.625 u/KG, N=4). As shown by FIG. 2, pretreatment of rats with
BOTOX.RTM. 0.5 hr before initiation of the formalin challenge
failed to reduce the formalin-induced pain.
[0071] This example shows that a significant analgesic effect of
intrathecal botulinum toxin type A persist for at least 14 days in
rats after administration of the toxin. It can be reasonably
postulated, extrapolating from the data obtained, that the
analgesia persists for at least about 20 days in rats. It can
therefore by expected that an anti-inflammatory pain analgesia from
intrathecal administration of botulinum toxin type A in humans
would persist for at least about 60 days.
Example 3
Comparison of Analgesic Effects of Intrathecally Administered
Botulinum Toxin Type A and Muscimol Upon Inflammatory Pain.
[0072] Intrathecal cannulation of subject rats was carried out as
set forth in Example 1. Either BOTOX.RTM. (0.625 U/kg, 2-5 hours
before or six days before the formalin test) or the short acting
analgesic muscimol (1 .mu.g, 10 minutes before or six days before
the formalin test) was administered intrathecally and the formalin
test carried out at the indicated subsequent times.
[0073] As shown by FIG. 5 (control saline, n=11), the analgesic
effect of BOTOX.RTM. administered six days prior to the formalin
test has a longer duration of analgesic activity, through most of
phase 2, as compared to the analgesic effect of intrathecal
muscimol administered six days prior to the formalin test.
Additionally, FIG. 5 shows that intrathecal BOTOX.RTM. administered
2-5 hours before the formalin challenge and intrathecal muscimol
ten minutes prior to the formalin challenge resulted in comparable
analgesia.
Example 4
Site Specific Analgesic Effect of Intrathecally Administered
Botulinum Type A Upon Inflammatory Pain
[0074] Intrathecal canalization was carried out as set forth in
Example 1 with the exception that the catheter was inserted
caudally only about 4.5 cm, as opposed to the usual 8.5-10 cm.
Control (saline) catheters were inserted at either 8.5 cm (n=11) or
at 4.5 cm (n=1) locations. BOTOX.RTM. was administered through a
catheter inserted caudally 4.5 cm in dosages of either 0.625 U/kg
(n=3) or 3.125 U/kg (n=4). The rat formalin test was then carried
out. As shown by FIG. 6, there was little or no analgesic effect in
the rat formalin test by intrathecal BOTOX.RTM. administration
through catheters placed at 4.5 cm.
[0075] It is known that the heel and bottom of the foot in humans
is a dermatome of the fifth lumbar nerve which emanates from the
lumbar enlargement (see e.g. plate 150 in Netter, F. Atlas of Human
Anatomy, second edition (1997), Novartis), and presumably nerve
distribution is similar in the rat. Thus, it can be hypothesized
that since the rat plantar, where the formalin is injected, is
innervated by nerves which radiate from the lumbar enlargement
disposed about 7.5 cm to 9 cm (depending upon the size of the
subject rat) caudally down the rat's spinal cord, placement of the
intrathecal catheter caudally only 4.5 cm will not result in an
analgesic effect if the intrathecally administered BOTOX.RTM.
exhibits a site specific effect upon spinal cord neurons. And this
hypothesis is confirmed by the data shown in FIG. 5.
[0076] This example supports both the efficacy and safety of
intrathecal botulinum toxin administration to treat pain since we
observed that not only did neither a motor deficit or blood
pressure alteration occur, at the dosages used, from intrathecal
BOTOX.RTM. administration, we also determined (FIG. 5) that
intrathecal BOTOX.RTM. apparently has a localized effect upon the
CNS at only the site of it's intrathecal administration.
Example 5
Analgesic Effect of Intrathecally Administered Botulinum Toxin Type
A Upon Neuropathic Pain
[0077] This example investigated whether botulinum toxin type A
could reduce the allodynia induced by L5, L6 nerve ligation. Male
Sprague Dawley rats (100-120 g) were anesthetized with isoflurane
following a surgical neuropathy procedure according to the method
set forth in Kim S. et al., An Experimental Model for Peripheral
Neuropathy Produced by Segmental Spinal Nerve Ligation in the Rat,
Pain, 50 (1992), 355-363. The L6 transverse process was exposed and
removed. The L4 and L5 spinal nerves were then isolated and visible
and the ligation of L5 was performed by tying tightly with a 3-0
silk thread. The L6 spinal nerve was located just caudal and medial
to the sacroiliac junction and was ligated with 6-0 suture.
Intrathecal cannulation (as set forth in Example 1) was carried out
a month later upon the rats which exhibited allodynia.
[0078] Deformities of the hind paw and growth of the toenails were
noticed after surgery. Rats developed allodynia by showing
sensitive response to normally innocuous mechanical stimuli using
the following protocol. Tactile allodynia was measured using von
Frey hair aesthesiometers. The rats were tested before (Baseline)
and after administration of the botulinum toxin type A as
BOTOX.RTM.. Testing was performed during only the day portion of
the circadian cycle. Rats were placed in a plastic cage with a wire
mesh bottom which allowed full access to the paws. Environmental
acclimation was allowed for approximately 30 minutes until cage
exploration and major grooming activities ceased. The area tested
was the mid plantar left hind paw in the sciatic nerve
distribution, avoiding the less sensitive tori (foot pads). The paw
was touched with one of a series of 8 von Frey hairs with
experimentally incremental stiffness (0.41, 0.70, 1.20, 2.00, 3.63,
5.50, 8.50, and 15.10 g) (Stoelting). The von Frey hair was
presented perpendicular to the plantar surface with sufficient
force to cause slight buckling against the paw and held for
approximately 6-8 seconds. Stimuli were presented at intervals of
several seconds allowing for apparent resolution of any behavioral
responses to previous stimuli. A positive response was noted if the
paw was sharply withdrawn. Ambulating was considered an ambiguous
response, and in such cases the stimulus was repeated. Based on
observations on normal, unoperated on rats and healed,
sham-operated rats, the cutoff of a 15.10 g hair (approximately 10%
of the body weight of the smaller rats) was selected as the upper
limit for testing, since stiffer hairs tended to raise the entire
limb rather than to buckle, thus substantially changing the nature
of the stimulus.
[0079] The 50% withdraw threshold (G Value) was determined using
the up-down method (Dixon W., Efficient Analysis of Experimental
Observations, Ann Rev Pharmacol Toxicol 1980, 20: 441-62). In this
paradigm testing is initiated with the 2.0 g hair, the middle hair
of the series. Stimuli are always presented in a consecutive
fashion, whether ascending or descending. In the absence of a paw
withdrawal response to the initially selected hair a stronger
stimulus is presented. If the paw is withdrawn then the next weaker
stimulus is chosen. Optimal threshold calculation by this method
requires six responses in the immediate vicinity of the 50%
threshold. Since the threshold is not known strings of similar
responses may be generated as the threshold is approached from
either direction. Accordingly, although all responses are noted,
counting of the critical six data points does not begin until the
response threshold has been crossed, at which time the two
responses straddling the threshold are retrospectively designated
as the first two responses of the series of six. Four additional
responses to the continued presentation of stimuli that are varied
sequentially up or down based on the rat's response constitute the
remainder of the series.
[0080] Thus, the number of actual responses collected varied from a
minimum of 4 (in the case of paw withdrawal sequentially to the
first hair, 2.0 g, descending to the weakest hair, 0.4 g: threshold
lies below the range of actual stimuli), to a maximum of 9 (in the
case of the first withdrawal occurring on the fifth ascending
stimulis presentation at 15.1 g followed by elicitation of four
additional responses, assuming that the withdrawals continue to
occur at or below 15.1 g). In cases where continuous positive or
negative responses are observed to continue to occur to the
exhaustion of the stimulis set, values of 15.00 g and 0.25 g are
assigned respectively. The resulting pattern of positive and
negative responses is tabulated using the convention, X=withdrawal
(positive response), 0=no withdrawal (negative response), and the
50% response threshold is interpolated using the formula, 50% gram
threshold=(10[Xf=k.differential.])/10,000, where Xf=the value (in
log units) of the final von Frey hair use; k=the value from the
table prepared for the pattern of positive and negative responses,
and; .differential.=the mean difference (in log units) between
stimuli.
[0081] FIG. 7 (control, n=8) shows that intrathecal administration
of BOTOX.RTM. to the neuropathic rats at a concentration of 0.625
U/kg, 0.03 ng/kg (n=11), or at 3.125 U/kg, 0.15 ng/kg (n=9) clearly
reduced the allodynia in rats, and that the analgesic effect lasted
more than a week. The time intervals along the x axis in FIG. 4 are
time after intrathecal administration of the BOTOX.RTM.. A higher G
value indicates that more force is required before the paw is
withdrawn.
[0082] The examples above show that intrathecal administration of
botulinum toxin type A has a pronounced and long lasting analgesic
effect upon both inflammatory and neuropathic pain and that the
analgesic effect is dose dependent and site specific.
[0083] Additional observations showed that at the doses used
intrathecal BOTOX.RTM. did not produce any significant change in
blood pressure and additionally did not cause any significant motor
deficit in the subject rats.
Example 6
Treatment of Inflammatory Pain
[0084] A patient, age 45, experiencing acute inflammatory pain is
treated by intrathecal administration, for example by spinal tap to
the lumbar region, with between about 0.1 U/kg and 30 U/kg of
botulinum toxin type A, the particular toxin dose and site of
injection, as well as the frequency of toxin administrations depend
upon a variety of factors within the skill of the treating
physician, as previously set forth. Within 1-7 days after toxin
administration the patient's pain is substantially alleviated.
[0085] The botulinum toxin can be injected at different spinal
levels to treat different dermosomes, that is to treat pain in
various body parts. Additionally, a catheter can be percutaneously
inserted into the intrathecal space via lumbar puncture at
vertebral level L3-4 or L4-5 using a Tuohy needle. When CSF flow is
discernible a silastic catheter is threaded cephalad using a C-arm
for verification of catheter placement. The catheter can be
advanced to different vertebral locations and/or used at different
dose concentrations to treat different types of pain and/or spasm.
Thus, the catheter can be placed within the intrathecal space at
the dermatomal level of the pain or spasm experienced.
Example 7
Treatment of Neuropathic Pain
[0086] A patient, age 36, experiencing pain of neuropathic origin
is treated by intrathecal administration through spinal tap to the
lumbar region of between about 0.1 U/kg and 30 U/kg of botulinum
toxin type A. Within 1-7 days the pain symptoms are substantially
alleviated.
Example 8
Treatment of Pain Subsequent to Spinal Cord Injury
[0087] A patient, age 39, experiencing pain subsequent to spinal
cord injury is treated by intrathecal administration, for example
by spinal tap or by catheterization, to the spinal cord, such as to
the lumbar region of the spinal cord, with between about 0.1 U/kg
and 30 U/kg of botulinum toxin type A, the particular toxin dose
and site of injection, as well as the frequency of toxin
administrations depend upon a variety of factors within the skill
of the treating physician, as previously set forth. Within 1-7 days
after toxin administration the patient's pain is substantially
alleviated.
Example 9
Treatment of Pain Subsequent to Limb Injury
[0088] A patient, age 51, experiencing pain subsequent to injury to
his hand, arm, foot or leg is treated by intrathecal
administration, for example by spinal tap or by catheterization, to
the spinal cord, such as to the lumbar region of the spinal cord,
with between about 0.1 U/kg and 30 U/kg of botulinum toxin type A,
the particular toxin dose and site of injection, as well as the
frequency of toxin administrations depend upon a variety of factors
within the skill of the treating physician, as previously set
forth. Within 1-7 days after toxin administration the patient's
pain is substantially alleviated.
Example 10
Treatment of Pain Associated With Cancer
[0089] A patient, age 63, suffering from pain associated with
cancer is treated by intrathecal administration, for example by
spinal tap or by catheterization, to the spinal cord, such as to
the lumbar region of the spinal cord, with between about 0.1 U/kg
and 30 U/kg of botulinum toxin type A, the particular toxin dose
and site of injection, as well as the frequency of toxin
administrations depend upon a variety of factors within the skill
of the treating physician, as previously set forth. Within 1-7 days
after toxin administration the patient's pain is substantially
alleviated.
Example 11
Treatment of Pain Associated With Diabetes
[0090] A patient, age 47, suffering from pain associated with
diabetes is treated by intrathecal administration, for example by
spinal tap or by catheterization, to the spinal cord, such as to
the lumbar region of the spinal cord, with between about 0.1 U/kg
and 30 U/kg of botulinum toxin type A, the particular toxin dose
and site of injection, as well as the frequency of toxin
administrations depend upon a variety of factors within the skill
of the treating physician, as previously set forth. Within 1-7 days
after toxin administration the patient's pain is substantially
alleviated.
[0091] An intraspinal neurotoxin administration method for treating
pain according to the invention disclosed herein for has many
benefits and advantages, including the following:
[0092] 1. the symptoms of pain can be dramatically reduced.
[0093] 2. the symptoms of pain can be reduced for from about two to
about four months per injection of neurotoxin.
[0094] 3. the injected neurotoxin tends to exerts a CNS site
specific antinociceptive effect.
[0095] 4. the injected neurotoxin shows little or no tendency to
diffuse or to be transported away from the CNS injection site.
[0096] 5. few or no significant undesirable side effects occur from
intraspinal injection of the neurotoxin.
[0097] 6. the amount of neurotoxin injected intraspinally can be
considerably less than the amount of the same neurotoxin required
by other routes of administration (i.e. intramuscular,
intrasphincter, oral or parenteral) to achieve a comparable
effect.
[0098] 7. The antinociceptive effects of the present methods often
result in the desirable side effects of greater patient mobility, a
more positive attitude, and an improved quality of life.
[0099] Although the present invention has been described in detail
with regard to certain preferred methods, other embodiments,
versions, and modifications within the scope of the present
invention are possible. For example, a wide variety of neurotoxins
can be effectively used in the methods of the present invention.
Additionally, the present invention includes intraspinal
administration methods wherein two or more neurotoxins, such as two
or more botulinum toxins, are administered concurrently or
consecutively. For example, botulinum toxin type A can be
administered intraspinally until a loss of clinical response or
neutralizing antibodies develop, followed by administration of
botulinum toxin type E. Alternately, a combination of any two or
more of the botulinum serotypes A-G can be intraspinally
administered to control the onset and duration of the desired
therapeutic result. Furthermore, non-neurotoxin compounds can be
intraspinally administered prior to, concurrently with or
subsequent to administration of the neurotoxin to proved adjunct
effect such as enhanced or a more rapid onset of analgesia before
the neurotoxin, such as a botulinum toxin, begins to exert its
analgesic effect.
[0100] Our invention also includes within its scope the use of a
neurotoxin, such as a botulinum toxin, in the preparation of a
medicament for the treatment of pain, by intraspinal administration
of the neurotoxin.
[0101] Accordingly, the spirit and scope of the following claims
should not be limited to the descriptions of the preferred
embodiments set forth above.
* * * * *