U.S. patent application number 12/133977 was filed with the patent office on 2008-10-23 for protectant for uv-induced skin damage.
This patent application is currently assigned to QLT USA, INC.. Invention is credited to David W. Osborne.
Application Number | 20080262095 12/133977 |
Document ID | / |
Family ID | 32174931 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080262095 |
Kind Code |
A1 |
Osborne; David W. |
October 23, 2008 |
Protectant for UV-Induced Skin Damage
Abstract
The present invention provides a method for protecting against
UV radiation-induced skin damage. Specifically, compositions
including dapsone are administered to provide UV protection. The
dapsone compositions may be administered orally, or by other
parenteral routes, such as topically, transdermally, by inhalation,
and the like.
Inventors: |
Osborne; David W.; (Fort
Collins, CO) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG & WOESSNER, P.A.
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Assignee: |
QLT USA, INC.
|
Family ID: |
32174931 |
Appl. No.: |
12/133977 |
Filed: |
July 1, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11011291 |
Dec 14, 2004 |
7399462 |
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12133977 |
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10284682 |
Oct 30, 2002 |
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11011291 |
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Current U.S.
Class: |
514/646 |
Current CPC
Class: |
A61K 31/136 20130101;
A61P 17/00 20180101; A61K 8/46 20130101; A61Q 17/04 20130101 |
Class at
Publication: |
514/646 |
International
Class: |
A61K 31/145 20060101
A61K031/145; A61P 17/00 20060101 A61P017/00 |
Claims
1-29. (canceled)
30. A method for preventing a premalignant skin lesion from
becoming a malignant skin tumor comprising administering a
composition to an individual having at least one premalignant skin
lesion, wherein said composition comprises dapsone.
31. A method for preventing UV-induced malignant skin tumor
formation in an individual comprising: a) selecting the individual
in need of protection from UV radiation; and b) administering a
composition to the individual, wherein said composition comprises
dapsone.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of dermatologic
pharmacology. In particular, UV protectants that reduce the risk of
skin damage are described. The compositions are formulated with
dapsone as the active protective ingredient.
BACKGROUND OF THE INVENTION
[0002] Human skin is a primary target of nonionizing
electromagnetic radiation in the ultraviolet, visible, and infrared
ranges, and consists of three distinct layers: the stratum corneum,
the epidermis, and the dermis. The epidermis and dermis contain
several molecules known as chromophores, that are capable of
absorbing light or UV radiation (UVR). The main chromophores in
human skin include such molecules as nucleic acids, aromatic amino
acids, proteins, porphyrins, carotenoids, steroids, and quinones
(Mary S. Matsui and Vincent A. DeLeo, Skin Cancer: Mechanisms and
Human Relevance Chp. 4, 22 (Hasan Mukhtar ed., 1995)).
[0003] The UV spectrum is divided into A, B, and C ranges. The UVC
range extends from wavelengths between 200 and 290 nm. The UVB
spectrum includes wavelengths between 290 and 320 nm, and is
generally known as the sunburn spectrum because it produces
erythema in human skin. UVA radiation includes wavelengths between
320 to 400 nm. Atmospheric ozone absorbs all UVC and much of the
UVB, so that the spectrum of UV radiation at the earth's surface
consists primarily of UVA. The depth to which a photon penetrates
in vivo is related to its wavelength. Thus, most UVB radiation
transmitted through the ozone layer is absorbed within the first
0.03 mm of the epidermis, whereas one third of UVA radiation
penetrates to a depth of 0.1 mm (Hardie et al., Surgery 87:177
(1980)).
[0004] When the skin is exposed to UVR, energy transferred to
chromophores from the absorbed radiation may result in molecular
reorganization and/or interaction with nearby biomolecules. For
example, after UVR absorption, DNA may form dipyrimidine lesions,
such as cyclobutane pyrimidine dimers. In turn, characteristic
mutations result, e.g., mutations in p53, that have been shown to
be important in producing non-melanoma skin cancer. (A. Ziegler et
al., Nature 372:773-776 (1994)). Furthermore, the UV-induced
conversion of urocanic acid from the trans to cis isomer has been
linked to the subsequent development of non-melanoma skin cancers
(Craig A. Elmets et al., Skin Cancer: Mechanisms and Human
Relevance Chp. 18, 230 (Hasan Mukhtar ed., 1995)).
[0005] Further insight into UV-induced skin tumor formation has
been gained from studies in rodents. UV-induced skin tumors
stimulate a strong immune response. If UV-induced tumors are
implanted into normal, genetically identical mice, they are
promptly rejected by the host immune-system and the animals
survive. If the same tumor is implanted into mice that have been
exposed to subcarcinogenic doses of UVR, immunological destruction
of the tumor does not occur. These results indicate that UVR
produces mutations in skin cells and facilitates tumor growth by
impairing immune surveillance. The presence of both deficiencies is
necessary for clinically apparent skin cancers to develop (J. T.
Krutmann and C. A. Elmets eds. (1995). Photoimmunology. Oxford:
Blackwell Scientific).
[0006] Currently marketed sunscreens function either as ultraviolet
(UV) filters or UV blocks. UV blocks, such as TiO.sub.2 and ZnO, as
well as derivatives of other metal-oxides, form a physical barrier
that scatters UV light. These UV blocks offer the most
comprehensive sunscreen protection, blocking the full spectrum of
UVA and UVB light. However, the most commonly used sunscreens are
UV filters, which are typically organic compounds. A disadvantage
of UV filters is that each organic compound has a limited range of
maximum UV absorptivity, rendering each reagent better suited for
either UVA protection or UVB protection, but not both.
[0007] The UV-induced mouse tumor model has proven very useful not
only in gaining mechanistic understanding of skin tumor formation,
but also in determining if topical products promote or inhibit the
formation of UV-induced tumors. A standard UV carcinogenicity model
accepted for the testing of topical pharmaceuticals employs the
albino hairless Crl:SKH1-hr BR mouse (P. D. Forbes et al.,
Photobiology. 663-669 (E. Riklis ed., 1991)).
[0008] After administration of a topical formulation, experimental
protocols typically instruct that mice be irradiated once daily,
five days per week, for 40 weeks. Intensity and cumulative UV
radiation dose is measured in Robertson-Bergen Units (RBU). The RBU
is a measure of biological effectiveness for UVR, with 400 RBU
being approximately one minimal erythema dose in previously
untanned human skin, i.e., about 30 mJ/cm.sup.2 in a sun-sensitive
skin type I or II. Mouse carcinogenicity studies are completed at
600 RBU per week because this produces an appropriate tumor mean
latent period for comparison with test article treated and
untreated controls. At this radiation level, about half of the
untreated animals will have a first perceptible tumor by week
forty-one. A higher control UVR level of 1200 RBU per week results
in a significant reduction in the median tumor latent period. At
this radiation dose, about half of the untreated animals will have
a first perceptible tumor by week twenty-four. Animals continue to
be observed for 12 weeks after 40 weeks of product application to
provide a total of 52 weeks of tumor data.
[0009] At least two common topical therapies promote tumor
formation in this UV induced mouse carcinogenicity model. Benzoyl
peroxide and retinoids such as tretinoin, which are commonly used
to treat acne, promote the formation of skin tumors compared to
untreated or vehicle controls. (Physicians Desk Reference,
56.sup.th Edition, Medical Economics Company, Inc., Montvale N.J.,
(2002)). While many topical products containing these actives are
currently in use, the patients who use them are strongly encouraged
to avoid sun exposure on their face after using the product.
However, significantly shielding the face from sun exposure,
especially for young adults, is virtually impossible for products
that are often used twice daily.
[0010] U.S. Pat. No. 6,113,888 to Castro et al.; U.S. Pat. No.
6,200,964 to Singleton et al.; and U.S. Pat. No. 6,231,837 to
Stroud et al. describe topical compositions that contain
therapeutics. However, the therapeutic is not included to provide
protection from ultraviolet radiation. If UVR protection is
desired, sunscreens are added to the formulations.
[0011] Topical compositions including dapsone have been described
in U.S. Pat. Nos. 5,863,560 and 6,060,085 to Osborne, and U.S.
application Ser. No. 10/081,050 to Osborne, which are herein
incorporated by reference in their entirety. However, these
compositions were formulated to treat acne, not to prevent skin
damage from UV radiation.
[0012] Therefore, new compositions that protect against UV-induced
skin damage are needed.
SUMMARY OF THE INVENTION
[0013] The present invention is a method for protecting against UV
radiation-induced skin damage in individuals by selecting
individuals in need of protection from UV radiation and
administering to them a composition that includes dapsone. In
general, selection of the individual in need of protection from UV
radiation is based upon factors such as the frequency and duration
of UV radiation exposure, e.g., sun exposure, and/or the risk of
the individual for UV-induced skin damage. In turn, the risk is
typically assessed by examining such factors as the individual's
age and predisposition to sunburn or develop pigmented lesions
after sun exposure, any genetic predisposition to skin cancer,
prior medical history of UV-induced skin damage, and presentation
of V-induced skin damage at the time of examination.
[0014] The dapsone compositions may be provided in formulations
including, but not limited to, gels, creams, lotions, solutions,
hydrophilic or hydrophobic ointments, microemulsions,
shake-powders, aerosol and pump sprays, tablets, capsules, patches,
films, and suppositories. The dapsone used in the compositions may
be in dissolved or particulate form, or a mixture of dissolved and
microparticulate dapsone. The composition that is administered may
also include additives such as preservatives, antioxidants,
fragrances, or colorants.
[0015] Besides protecting against signs of aging (e.g., wrinkles)
and hyperpigmentation, compositions including dapsone may be
administered to protect against the formation, in other words,
prevent the development of, UV-induced premalignant skin lesions
such as actinic keratosis, as well as UV-induced malignant tumors
of the skin. In another embodiment, the dapsone compositions may be
administered to individuals having at least one premalignant skin
lesion to prevent the premalignant skin lesion from becoming a
malignant skin tumor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 shows a decrease in prevalence of tumor formation in
albino hairless mice exposed to UVR at 600 and 1200 RBU with the
use of various topical dapsone compositions.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The inventive methods provide dapsone compositions that
protect against ultraviolet radiation-induced skin damage.
[0018] As used herein, the terms "UV-induced skin damage" or
"UV-induced skin disorder" do not refer to acne. These terms are
used interchangeably and refer to skin damage resulting from
exposure to ultraviolet light in the A (320-400 nm), B (290-320
nm), or C ranges (200-290 nm). Examples of UV-induced skin damage,
also referred to herein as "skin lesions", include wrinkles,
hyperpigmentation, dysplasias such as actinic keratosis, and
malignant skin tumors such as squamous cell or basal cell
carcinoma.
[0019] As used herein, the term "protects" or "protecting" refers
to a reduction in the amount of skin damage which can be
manifested, e.g., by a decrease in the number and/or severity of
individual skin lesions, or prevention of the development of skin
lesions.
[0020] The term "topical" as used herein refers to the route of
administration of a composition that involves direct application to
the body part being treated, e.g., the skin for dermatological
compositions. Examples of topical application include application
to the skin of gels or other semisolids to rub-on, solutions to
spray, or liquids to be applied by an applicator. Rinse-off
application with washes, cleansers, or shampoos are also examples
of topical application. Typically, areas of the body suitable for
application of compositions having dapsone include the skin of the
face, throat, neck, scalp, chest, back, ears, and other skin sites
where sun exposure may occur.
[0021] By use of the term "dapsone" it is meant the chemical
compound dapsone having the chemical formula
C.sub.12H.sub.12N.sub.2O.sub.2S as well as
bis(4-aminophenyl)sulfone, 4',4'-diaminodiphenyl sulfone and its
hydrates, 4,4'-sulfonylbisbenzeneamine, 4,4'-sulfonyldianiline,
diaphenylsulfone, dapsone analogs, and dapsone related compounds.
"Dapsone analogs" refers to chemical compounds that have similar
chemical structures and thus similar therapeutic potential to
dapsone such as the substituted bis(4-aminophenyl)-sulfones.
"Dapsone related compounds" refers to chemical compounds that have
similar therapeutic activity, but are not as closely related by
chemical structure to dapsone such as the substituted
2,4-diamino-5-benzylpyrimidines.
Dapsone Compositions
Dapsone Topical Gel
[0022] The topical gel compositions of this invention utilize
various forms of dapsone. For instance, in one embodiment, dapsone
may be present in the composition as only dissolved dapsone. In
another embodiment, dapsone may be present in the composition only
as microparticulate dapsone. In a further embodiment, the
dermatological composition exhibits an optimal balance between
dissolved dapsone that is available to cross through the stratum
corneum to become systemically available, and microparticulate
dapsone that is retained in or above the stratum corneum to serve
as a reservoir or to provide dapsone to the supracorneum zone. The
microparticulate dapsone may comprise a crystalline precipitant or
an amorphous precipitant.
[0023] In one embodiment, the dermatological composition that is
applied comprises a semi-solid or gel-like vehicle that may include
a polymer thickener, water, preservatives, active surfactants or
emulsifiers, antioxidants, sunscreens, and a solvent or mixed
solvent system. The solvent or mixed solvent system is important to
the formation of the microparticulate to dissolved dapsone ratio.
The formation of the microparticulate, however, should not
interfere with the ability of the polymer thickener or preservative
systems to perform their functions.
[0024] Polymer thickeners that may be used include those known to
one skilled in the art, such as hydrophilic and hydroalcoholic
gelling agents frequently used in the cosmetic and pharmaceutical
industries. Preferably, the hydrophilic or hydroalcoholic gelling
agent comprises "CARBOPOL.RTM." (B.F. Goodrich, Cleveland, Ohio),
"HYPAN.RTM." (Kingston Technologies, Dayton, N.J.), "NATROSOL.RTM."
(Aqualon, Wilmington, Del.), "KLUCEL.RTM." (Aqualon, Wilmington,
Del.), or "STABILEZE.RTM." (ISP Technologies, Wayne, N.J.).
Preferably, the gelling agent comprises between about 0.2% to about
4% by weight of the composition. More particularly, the preferred
compositional weight percent range for "CARBOPOL.RTM." is between
about 0.5% to about 2%, while the preferred weight percent range
for "NATROSOL.RTM. and "KLUCEL.RTM." is between about 0.5% to about
4%. The preferred compositional weight percent range for both
"HYPAN.RTM." and "STABILEZE.RTM." is between about 0.5% to about
4%.
[0025] "CARBOPOL.RTM." is one of numerous cross-linked acrylic acid
polymers that are given the general adopted name carbomer. These
polymers dissolve in water and form a clear or slightly hazy gel
upon neutralization with a base such as sodium hydroxide, potassium
hydroxide, triethanolamine, or other amine bases. "KLUCEL.RTM." is
a cellulose polymer that is dispersed in water and forms a uniform
gel upon complete hydration. Other preferred gelling polymers
include hydroxyethylcellulose, hydroxypropylcellulose, cellulose
gum, MVA/MA copolymers, MVE/MA decadiene crosspolymer, PVM/MA
copolymer, or a combination thereof.
[0026] Preservatives may also be used in this dermatological
composition and preferably comprise about 0.05% to 0.5% by weight
of the total composition. The use of preservatives assures that if
the product is microbially contaminated, the formulation will
prevent or diminish microorganism growth. Some preservatives useful
in this invention include methylparaben, propylparaben,
butylparaben, chloroxylenol, sodium benzoate, DMDM Hydantoin,
3-Iodo-2-Propylbutyl carbamate, potassium sorbate, chlorhexidine
digluconate, or a combination thereof.
[0027] In one embodiment, the dermatological composition that is
applied includes 0.5% to 4.0% carbomer and about 0.5% to 10%
dapsone that exists in both a dissolved state and a
microparticulate state. In another embodiment, the dermatological
composition comprises about 1% carbomer, about 80-90% water, about
10% (diethylene glycol monoethyl ether (DGME), about 0.2%
methylparaben, and about 0.3% to 3.0% dapsone including both
microparticulate dapsone and dissolved dapsone, and about 2% of a
base. More particularly, the carbomer may include "CARBOPOL.RTM.
980" and the base may include sodium hydroxide solution.
[0028] In a another embodiment, the composition comprises dapsone
and ethoxydiglycol, which allows for an optimized ratio of
microparticulate drug to dissolved drug. This ratio determines the
amount of drug delivered, compared to the amount of drug retained
in or above the stratum corneum to function in the supracorneum
domain. The system of dapsone and DGME may include purified water
combined with "CARBOPOL.RTM." gelling polymer, methylparaben,
propylparaben, titanium dioxide, BHA, and a base to neutralize the
"CARBOPOL.RTM.."
[0029] Dapsone Topical Cream or Lotion
[0030] In another embodiment, dapsone may be applied as a topical
cream or lotion in which dapsone may be dissolved or dispersed or
both partially dissolved and partially dispersed. Topical creams or
lotions may be either oil-in-water emulsions or water-in-oil
emulsions. The oil phase may include but is not limited to fatty
alcohols, acids, or esters such as cetyl palmitate, cetyl alcohol,
stearyl alcohol, stearic acid, isopropyl stearate, glycerol
stearate, mineral oil, white petrolatum, or other oils alone or in
combination. The topical creams or lotions may be formulated for
use as sunscreens.
[0031] Emulsifiers that may be added to the composition include,
but are not limited to, steareth 20, ceteth 20, sorbitan
sesquioleate, sorbitan mono-oleate, propylene glycol stearate,
dosium lauroyl sarcosinate, polysorbate 60, or combination.
Preservatives, antioxidants, fragrances, colorants, thickeners, and
other additives required to achieve a pharmaceutically or
cosmetically acceptable or preferred product may also be included.
However, topical creams and lotions are not limited to these
components since one skilled in the art will be aware of additional
components useful in the formulation of topical creams and
lotions.
[0032] Dapsone Topical Solution or Suspension
[0033] In another embodiment, dapsone may be applied as a solution
or suspension. These are fluid solvent or mixed-solvent systems
including, but not limited to, water, ethanol, propylene glycol,
glycerol, polyethylene glycol, ethyl acetate, propylene carbonate,
n-methylpyrrolidone, triethanolamine, 1,4-butanediol, triacetin,
diacetin, dimethyl isosorbide alone or in combination.
Preservatives, antioxidants, fragrances, colorants, thickeners,
suspending agents, enhancers, and other additives required to
achieve pharmaceutically or cosmetically acceptable or preferred
product may also be included. Again, topical solutions or
suspensions are not limited to these components, since one skilled
in the art will be aware of additional components useful in the
formulation of topical solutions or suspensions.
[0034] Additional Dapsone Formulations
[0035] Dapsone may also be topically applied using a pharmaceutical
or cosmetic carrier form such as a hydrophobic or hydrophilic
ointment, roll-on or stick product, microemulsion, shake powder, an
aerosolized spray or mousse, a pump spray or mousse, or bath
additive. Examples of ointments include essentially non-aqueous
mixtures of petrolatum, lanolin, polyethylene glycol, plant or
animal oils, either hydrogenated or otherwise chemically modified.
An ointment may also contain a solvent in which dapsone is either
fully or partially dissolved. Additional pharmaceutical carriers
will be known to those skilled in the art and this list should not
be considered to be limiting.
[0036] In addition to topical compositions, dapsone may be
formulated as pharmaceutical preparations including, but not
limited to, granules, tablets, suppositories, capsules,
suspensions, patches, films, and aerosols. Pharmaceutical grade
organic or inorganic carriers and/or diluents suitable for
inhalation or oral, parenteral, transmucosal, or transdermal
administration may be used to formulate compositions including
dapsone. Stabilizing agents, wetting and emulsifying agents, salts
for varying the osmotic pressure, or buffers for securing an
adequate pH value may also be included in the dapsone
compositions.
Administration of Dapsone Compositions
[0037] In addition to topical administration, dapsone, dapsone
analogs, or dapsone related compounds may have sufficient
partitioning to the skin or sufficient activity in the skin to be
delivered by other routes of administration. For example, systemic
dosing may accompany topical dosing, or systemic dosing for the
purpose of photoprotection may be used as a singular therapy. Other
routes and methods of administration will be known to those skilled
in the art. These include, but are not limited to, oral, rectal,
vaginal, nasal, ocular, oral transmucosal and other transmucosal,
transdermal, parenteral, and pulmonary routes. Parenteral
administration includes, without limitation, intravenous,
subcutaneous, intramuscular, intra-arterial, intrathecal, and
intraperitoneal administration. Pulmonary delivery may be achieved
by nebulization, aerosol inhalation, or dry powder inhalation.
Products developed for administration using these alternate
delivery routes will have compositions recognized by those skilled
in the art, as described in Remington: The Science and Practice of
Pharmacy, 19.sup.th Edition, Mack Publishing Company, Easton Pa.,
(1995).
[0038] In one variation, the dapsone compositions are administered
to protect individuals against UV-induced skin damage such as
sunburn, malignant skin tumors, premalignant lesions, and wrinkles.
Typically, the dapsone compositions are administered once daily,
but may be administered more frequently if desired. In another
variation, the dapsone compositions are administered to prevent
premalignant skin lesions from progressing to malignant skin tumors
in individuals.
[0039] The dapsone compositions are administered to selected
individuals. By "selected" it is meant individuals in whom UV
protection is considered desirable because of age, frequent or long
duration of exposure to UV radiation, e.g., sun, and/or because
they possess an increased risk for UV radiation-induced skin
damage. For example, individuals at increased risk are those who
are more prone to sunburn or develop pigmented lesions after sun
exposure, or who due to genetic makeup, have a condition that
predisposes them to skin cancer, e.g., xeroderma pigmentosum.
Furthermore, individuals with a prior medical history of a
UV-induced skin disorder or who present with UV-induced skin damage
at the time the need for UV protection is determined are at
increased risk.
[0040] The dapsone compositions are typically administered before
the individual engages in an activity that involves UV radiation
exposure. The activity may be an outdoor activity such as
sunbathing, walking, running, swimming, biking, and the like,
engaged in for purposes of recreation or physical fitness. The
dapsone compositions may also be administered to individuals
engaging in indoor activities, e.g., indoor tanning or laboratory
work that involves exposure to ultraviolet light.
Method for Preparing the Dapsone Dermatological Composition
[0041] In general, the method for producing a dermatological gel
composition having dissolved dapsone and microparticulate dapsone
precipitates comprises the steps of completely dissolving dapsone
in a solvent or solvent mixture; adding and adequately dispersing a
polymeric thickener in water; and combining the dissolved dapsone
with the dispersed polymeric thickener. Alternatively, water may be
slowly added to the dissolved dapsone, followed by the addition of
a polymeric thickener. Ethoxydigylcol and 1-methyl-2-pyrollidone
are preferred solvents for use in the topically applied
dermatological composition.
[0042] In one embodiment, the method for preparing a topically
applied dermatological composition having dissolved and
microparticulate dapsone comprises the steps of forming a
homogenous dispersion by stirring purified water vigorously enough
to form a vortex and sifting gel polymer into the vortex formed in
the water while continuing to stir; forming a pharmaceutical
component by dissolving methyl paraben and propylparaben in DGME by
mixing to form a solution, and mixing dapsone with the solution
until the pharmaceutical is dissolved; mixing the pharmaceutical
component with the homogenous dispersion to form a microparticulate
dapsone dispersion; and adding a caustic material.
[0043] In another embodiment, the method for preparing a topically
applied dermatological composition having only dissolved dapsone
includes the steps of dissolving dapsone in an oil phase or mixed
solvent system. The dissolved dapsone is then combined with the
water phase of an emulsion or thickeners or other cosmetic or
pharmaceutical excipients to form a dermatological product. This
topical cream, lotion, solution, ointment or other topical
formulation will contain only dissolved dapsone at ambient
conditions.
[0044] In yet another embodiment, the method for preparing a
topically applied dermatological composition having primarily
dispersed dapsone includes the step of dispersing dapsone in a
water phase, non-solvating solvent or mixed solvent system. The
dispersed dapsone is then combined with the oil phase of an
emulsion or thickeners or other cosmetic or pharmaceutical
excipients to form a dermatological product. This topical cream,
lotion, suspension, ointment or other topical formulation will
contain dispersed dapsone particles and minimal (less than about
5%) dissolved dapsone at ambient conditions.
[0045] The order in which reagents are combined may be important,
depending on the particular reagents necessary for the target
mixture. For example, after a pharmaceutical such as dapsone is
dissolved in a solvent such as DGME, water may be slowly added to
the dapsone in the DGME solution, or the dapsone in DGME solution
may be added to the water with mixing. Adding the dapsone in DGME
solution to water may result in less polydispersity in the size of
the microparticulates than adding water to the dapsone in DGME
solutions. The carbomer is generally dispersed in the water
component of the formulation, while the remaining ingredients will
be dissolved or dispersed in whichever of the two components are
best for dissolving or dispersing the ingredient. For example, it
is suggested to dissolve methylparaben, propylparaben, and BHA in
DGME. After the DGME component and water component are combined,
neutralizer is added to formulate the gel.
EXAMPLES
[0046] The following example is provided to show that dapsone has
an unexpected protective benefit in the treatment of ultraviolet
radiation-induced skin tumors.
[0047] Those skilled in the art will recognize that while specific
embodiments have been illustrated and described, various
modifications and changes may be made without it departing from the
spirit and scope of the invention.
Example 1
Effect of Dapsone on Skin Tumor Formation in Mice
[0048] Example 1 demonstrates the protective effect of dapsone on
UV-induced skin tumor formation. Male and female albino hairless
Crl:SKH1-hrBR mice (36/sex/group) were obtained from Charles River
Laboratories (Wilmington, Mass.) and individually housed in
custom-designed stainless steel irradiation cages.
[0049] The experimental dapsone formulations (50 .mu.l/mouse,
Monday through Friday) were administered to the dorsum and sides of
the mice to an area of approximately 25 cm.sup.2 using a glass rod,
and the mice irradiated once daily, 5 days per week, for 40 weeks.
Aqueous carbomer gels containing 1% dapsone/10% DGME (diethylene
glycol monoethyl ether); 3% dapsone/17.5% DGME; or 5% dapsone/25%
DGME were chosen from range-finding studies. A vehicle control
aqueous carbomer gel contained 25% DGME. Formulations were
administered one hour before irradiation on Monday, Wednesday, and
Friday and one hour after irradiation on Tuesday and Thursday. Mice
were then maintained without being dosed for an additional 12 weeks
for a total of 52 weeks.
[0050] The simulated solar radiation (SSR) source was a 6.5
kilowatt zenon long arc water-cooled burner, filtered by a 1 mm
thick Schott WG 320 doped glass filter. During exposure the mice
were continuously monitored by a customized detector, which records
both intensity and cumulative UVR dose in Robertson-Berger Units
(RBU, 400 RBU approximates one minimal erythema dose (MED) in
previously untanned human skin). The low UVR calibration group (120
RBU/daily, 600 RBU/week) produced an appropriate tumor median
latent period for comparison with other groups. The high UVR
calibration group (240 RBU/day, 1200 RBU/week) produced a
significant decrease in median tumor latent period. The test level
of UVR (600 RBU per week) permits detection of a modified
photocarcinogenic response by the test system in response to a test
article. Over the course of the study, the daily UVR dose was
consistent and the total dose across groups was appropriate.
[0051] All mice were observed for viability at least twice daily,
and weekly for general skin observations. Other clinical
observations were recorded weekly; body weights were recorded
weekly for the first 13 weeks, and then every four weeks thereafter
and at sacrifice. Individual UV-induced skin tumor data (size and
location) were electronically recorded. Any mouse bearing a
tumor>10 mm planar diameter was sacrificed. Furthermore, all
mice in a group were sacrificed when:
1) fewer than 50% of the mice per sex survived; 2) more than 50% of
the surviving mice in the group had tumors of at least 4 mm (planar
diameter); and 3) the Study Director reviewed the data and approved
the sacrifice.
[0052] Tables, graphs, and statistical testing of tumor data were
provided as output from the ROELEE program (P. N. Lee Statistics
and Computing, Ltd., Sutton, United Kingdom). Group comparisons of
tumor prevalence were based on the methods described by Peto and
colleagues (Peto, R., et. al. (1980). Guidelines for Simple,
Sensitive Significance Tests for Carcinogenic Effects in Long-Term
Animal Experiments. IARC Monographs, Supplement 2. Long-Term and
Short-Term Screening Assays for Carcinogens: A Critical
Appraisal).
[0053] Since bi-directiorial effects on carcinogenicity are
plausible, testing was based on two-tailed probabilities (i.e., the
null hypothesis states that the superimposed variable does not
alter carcinogenicity). Evaluations were based on two-group
comparisons. Statistical interpretation was based primarily on
tumors at least 1 mm in diameter using the following descriptive
parameters:
1) "Median Onset" or "Median Week to Tumor": The time at which
one-half of the members of other groups have acquired one or more
qualifying tumors, and the associated 95% confidence interval.
Separate estimates evaluated "biased" medians (based on survivors)
and mortality-adjusted medians. 2. "Mortality-Free Prevalence": The
proportion of mice in a group exhibiting one or more qualifying
tumors, as a function of time, and adjusted for the effects of
competing mortality. This descriptor is the complementary
probability to the Kaplan-Meier "probability of survival without a
tumor" and is derived form calculations of the Kaplan-Meier type
(Kaplan, E. L., and Meier, P. J. Am. Stat. Assoc. 53:457-481
(1958)). 3. "Tumor Yield": The number of tumors present, divided by
the number of surviving mice (i.e., average number of tumors per
mouse). 4. "Survival": The absolute number of mice alive at the
time of observation, compared to the initial number in each
group.
[0054] Table 1 shows that the Unbiased Median Weeks to Tumor was
unaffected by the vehicle formulation (25% DGME vehicle), and
delayed in groups administered the dapsone formulations and exposed
to 600 RBU/week. The group exposed to high UVR (1200 RBU/week),
served as a positive control to show that the Unbiased Median Weeks
to Tumor was accelerated. The unbiased median latent period was not
achieved by the end of the study for the 3% dapsone/17.5% DGME gel
group, or for the 5% dapsone/25% DGME gel group for male mice. An
entry of 53 weeks is used in Table 1 to illustrate this fact.
Dapsone increased the Unbiased Median Weeks to Tumor in a
dose-dependent manner, indicating a reduction in the
photocarcinogenic response of the mice to UVR in these groups.
[0055] FIG. 1 shows the prevalence by week of the first 1 mm tumor
for the sexes combined. In comparison with the 25% DGME vehicle
formulation administration (line 1), all dapsone containing gels
(line 2, 1% dapsone gel; line 3, 3% dapsone gel; line 4, 5% dapsone
gel) significantly reduced the development of skin tumors in mice
exposed to 600 RBU/week for the sexes combined (p<0.001 for 1%,
3%, and 5% dapsone gel), in male mice (data not shown, p<0.01
for 1% dapsone gel, and p<0.001 for 3% dapsone gel, and
<0.001 for 5% dapsone gel), and in female mice (data not shown,
p<0.01 for 1% and 3% dapsone gel and p<0.001 for 5% dapsone
gel). The prevalence of 1 mm tumor formation in untreated mice
exposed to 600 RBU/week (line 5) paralleled that of mice
administered the 25% DGME vehicle formulation (line 1). Line 6
demonstrates the increase in skin tumor formation in untreated mice
exposed to 1200 RBU/week.
[0056] The Tumor Potency Ratio (TPR) expresses the influence of a
test article on the skin's response to UVR exposure. The concept of
TPR depends on the relationship between the weekly UVR dose, as a
measure of stimulus rate, and the chosen response measure of
Unbiased Median Week to Tumor for each group (tumors >1 mm).
With those values and the dose rate calibration for the untreated
600 RBU/week and 1200 RBU/week groups, the apparent radiation dose
rate of the groups was calculated. The difference from the nominal
rate represents the effect of a test variable on UVR dose delivery.
Since unbiased median latent period was not achieved by the end of
the study (52 weeks) for the 3% dapsone gel group, or the 5%
dapsone gel group for males, the estimated TPR was calculated from
the estimated unbiased median latent period of 53 weeks. As shown
in Table 2, the TPR was reduced with dapsone application in a
dose-dependent manner in sexes combined, indicating a
dose-dependent inhibitory effect on UVR-induced skin tumor
production. The vehicle formulation had no effect on TPR.
[0057] Furthermore, biologically important and/or statistically
significant reductions occurred in erythema, edema, flaking and/or
thickening in the groups of male and/or female mice administered
dapsone formulations (data not shown).
[0058] In sum, the administration of the vehicle or dapsone
formulations did not enhance photocarcinogenesis; rather, the
dapsone formulations protected against UV radiation-induced skin
tumor development. This conclusion is supported by the tumor
endpoints Unbiased Median Weeks to Tumor, Peto Analysis of Tumor
Onset, Prevalence Curves, Tumor Yield per Survivor and Tumor
Potency Ratio. These observations also suggest a reduction in the
UV radiation-induced inflammatory process in the groups
administered the dapsone formulations.
[0059] All publications and patent applications cited in this
application are herein incorporated by reference in their entirety.
Although the foregoing invention has been described by way of
illustration and example for purposes of clarity and understanding,
it will be readily apparent to those of ordinary skill in the art
in light of the teachings of this invention that certain changes
and modifications may be made thereto without departing from the
spirit or scope of the appended claims.
TABLE-US-00001 TABLE 1 Unbiased Median Weeks to Tumor for Tumors
.gtoreq.1 mm 25% 1% Dapsone 3% Dapsone 5% Dapsone DGME in a 10% in
a 17.5% in a 25% Formulation Vehicle DGME Gel DGME Gel DGME Gel
None None UVR Exposure RBU/Week 600 600 600 600 600 1200 Sexes
Combined (weeks) 41.5 47.50 48.00 49.00 41.50 24.50 Males (weeks)
45.25 50.00 53.00 53.00 44.00 25.00 Females Median (weeks) 39.50
45.00 45.50 49.00 39.50 24.00
TABLE-US-00002 TABLE 2 Tumor Potency Ratios (.gtoreq.1 mm Tumor
Size) 25% 1% Dapsone 3% Dapsone 5% Dapsone DGME in a 10% in a 17.5%
in a 25% Formulation Vehicle DGME Gel DGME Gel DGME Gel None None
UVR Exposure RBU/Week 600 600 600 600 600 1200 Sexes Combined 1.00
0.84 0.83 0.80 1 2 Males 1.06 0.97 0.85 0.80 1 2 Females Median
1.00 0.86 0.82 0.74 1 2
* * * * *