U.S. patent application number 13/429624 was filed with the patent office on 2012-07-19 for optimised formulation of tobramycin for aerosolization.
This patent application is currently assigned to Chiesi Farmaceutici S.p.A.. Invention is credited to Raffaella Garzia, Chiara MALVOLTI.
Application Number | 20120184502 13/429624 |
Document ID | / |
Family ID | 8177921 |
Filed Date | 2012-07-19 |
United States Patent
Application |
20120184502 |
Kind Code |
A1 |
MALVOLTI; Chiara ; et
al. |
July 19, 2012 |
OPTIMISED FORMULATION OF TOBRAMYCIN FOR AEROSOLIZATION
Abstract
The invention provides a tobramycin formulation for delivery by
aerosolization in the form of additive-free, isotonic solution
whose pH has been optimised to ensure adequate shelf-life at room
temperature. Said formulation can be advantageously used for the
treatment and prophylaxis of acute and chronic endobronchial
infections, in particular those caused by the bacterium Pseudomonas
aeruginosa associated to lung diseases such as cystic fibrosis.
Inventors: |
MALVOLTI; Chiara; (Parma,
IT) ; Garzia; Raffaella; (Parma, IT) |
Assignee: |
Chiesi Farmaceutici S.p.A.
Parma
IT
|
Family ID: |
8177921 |
Appl. No.: |
13/429624 |
Filed: |
March 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13102378 |
May 6, 2011 |
8168598 |
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13429624 |
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12642336 |
Dec 18, 2009 |
7939502 |
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13102378 |
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11083139 |
Mar 18, 2005 |
7696178 |
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12642336 |
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10482224 |
Apr 28, 2004 |
6987094 |
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PCT/EP02/06544 |
Jun 14, 2002 |
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11083139 |
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Current U.S.
Class: |
514/40 |
Current CPC
Class: |
A61P 11/08 20180101;
A61P 11/06 20180101; A61P 31/04 20180101; A61P 11/12 20180101; A61K
31/7036 20130101; A61P 11/00 20180101; A61P 31/00 20180101; A61K
9/0078 20130101 |
Class at
Publication: |
514/40 |
International
Class: |
A61K 31/7036 20060101
A61K031/7036; A61P 11/00 20060101 A61P011/00; A61P 31/04 20060101
A61P031/04; A61P 31/00 20060101 A61P031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 2, 2001 |
EP |
01116071.0 |
Claims
1. A method for treating a lung infection, said method comprising
administering an effective amount of an aerosol formulation to a
subject in need thereof, said aerosol formulation comprising: 75
mg/ml of tobramycin dissolved in an aqueous solution containing
0.45% w/v of sodium chloride; wherein the pH is between 4.5 and 5.5
and the osmolarity ranges between 250 and 450 mOsm/l, and said
formulation is free of preservatives and anti-oxidants.
2. The method according to claim 1, wherein said lung infection is
due to Gram positive bacteria.
3. The method according to claim 1, wherein said lung infection is
due to Gram negative bacteria.
4. The method according to claim 1, wherein said subject is
suffering from cystic fibrosis.
5. The method according to claim 1, wherein said subject is
suffering from bronchiectasis.
6. The method according to claim 1, wherein said subject is
suffering from bronchiectasis and infected with Pseudomonas
aeruginosa.
7. The method according to claim 1, wherein said subject is
suffering from a chronic pneumopathy.
8. The method according to claim 1, wherein said subject is
suffering from bronchial asthma.
9. The method according to claim 1, wherein the pH of said aerosol
formulation is 5.2 and the osmolarity thereof is between 280 and
350 mOsm/l.
10. The method according to claim 1, wherein said osmolarity of
said aerosol formulation is from 280 to 350 mOsm/l.
Description
[0001] The present invention relates to tobramycin formulations for
delivery by aerosolization.
SUMMARY OF THE INVENTION
[0002] The invention provides a tobramycin formulation for delivery
by aerosolization in the form of additive-free, isotonic solution
whose pH has been optimised to ensure adequate shelf-life at room
temperature.
[0003] Said formulation can be advantageously used for the
treatment and prophylaxis of acute and chronic endobronchial
infections, in particular those caused by the bacterium Pseudomonas
aeruginosa associated to lung diseases such as cystic fibrosis.
PRIOR ART
[0004] Although pressurised metered dose inhalers (MDIs) and dry
powder inhalers (DPIs) are the most commonly used inhalation drug
delivery systems, nebulisers have become increasingly popular for
the treatment of airway obstruction, particularly in young children
with asthma and in patients with severe asthma or chronic airflow
obstruction. Nebulisers use ultrasound or compressed gas to produce
aerosol droplets in the respirable size range (1-to 5 .mu.m) from
liquids, usually aqueous solutions or suspensions of drugs. They
have the advantage over MDIs and DPIs that the drug may be inhaled
during normal breathing through a mouth-piece or a face-mask. Thus,
they can be employed to deliver aerosolised drug to patients, such
as children, who experience difficulties using other devices.
[0005] Several types of therapeutically useful drug can be
delivered by nebulisers, including .beta.2-agonists,
corticosteroids, anticholinergics, anti-allergies, mucolytics and
antibiotics. The major clinical setting in which therapy with
aerosolised antibiotics has been tried is the management of
patients with cystic fibrosis (CF).
[0006] CF is a common genetic disease that is characterised by the
inflammation and progressive destruction of lung tissue. The
debilitation of the lungs in CF patients is associated with
accumulation of purulent sputum produced as a result of
endobronchial infections caused in particular by Pseudomonas
aeruginosa. The latter ones are a major cause of morbidity and
mortality among patients with CF.
[0007] Tobramycin is an aminoglycoside antibiotic, specifically
active against Pseudomonas aeruginosa. It penetrates endobronchial
secretions (sputum) poorly, necessitating large intravenous doses
to attain an efficacious concentration at the site of infection.
These high doses place the patient at risk for nephrotoxic and
ototoxic effects. The direct delivery of tobramycin to the lower
airways by aerosol administration is attractive, since it produces
high concentrations of antibiotic at the site of infection. In view
of the limited absorption into the circulation, aerosol delivery of
tobramycin should be associated with minimal systemic toxicity.
This would allow for the development of a safer, long-term
therapy.
[0008] At this regard, being its therapeutic dose quite large,
nebulisation turns out to be extremely convenient due to the
impossibility of formulating tobramycin into an MDI or DPI.
[0009] The clinical studies reported in the literature show
contradictory results in terms of benefit from aerosolised
tobramycin in patients with CF. The variability among these studies
might, in part, result from the differences in the patient
population, therapeutic modalities, nebulisers, formulations and
their mode of administration. Furthermore, most of the studies have
been carried out through the extemporaneous use of the commercially
available injectable solutions. These preparations normally contain
anti-oxidant and preservatives which are known to cause paradoxical
reactions such as bronchospasm and cough (Nikolaizik et al Eur J
Pediatr 1996, 155, 608-611; The Lancet, Jul. 23, 1988, 202).
[0010] For all these reasons, there is a need for standardised
procedures as well as for improvement in aerosol administration of
antibiotic such as tobramycin to CF patients.
[0011] Therefore, in consideration of all problems outlined, it
would be highly advantageous to provide a tobramycin formulation of
a therapeutically useful concentration deliverable by
aerosolization into the endobronchial space which: i) could be
efficiently nebulised in a relatively short time using both jet and
ultrasonic nebulisers; ii) could permit generation of aerosol
well-tolerated by patients; iii) is able to produce aerosol
particles which can efficaciously reach the therapeutic target
area; iv) is rid of substances (preservatives and others) that may
give rise to undesirable side effects; v) could guarantee as long
as possible a shelf-life, in particular at room temperature.
[0012] Accordingly, in order to obtain an optimised formulation for
tobramycin aerosol administration, the following parameters need to
be carefully adjusted: [0013] The ratio dose/volume. Formulation
for aerosol delivery should contain the minimal yet efficacious
amount of tobramycin formulated in the smallest as possible volume
of solution. In fact, the smallest the volume, the shortest the
nebulisation time. A short nebulisation time, in turn, is an
important determinant of patient compliance and within hospitals
has implications for staff time (McCallion et al Int J Pharm 1996,
130, 1-11). [0014] The osmolarity. It is well known that adverse
reactions to inhalation therapy may be caused by hypo- or
hyper-osmolarity of drug solutions. On the contrary, isotonic
solutions remove the risk of paradoxical bronchoconstriction and
cough (The Lancet, 1988, op. cit.; Mann et al Br Med J 1984, 289,
469). The osmolarity also affects the performances of the
nebulisers in terms of output rate and particle size distribution
(vide ultra). [0015] The particle size distribution upon
nebulisation. The efficacy of a clinical aerosol is dependent on
its ability to penetrate the respiratory tract. To penetrate to the
peripheral regions, aerosols require a size from 0.8 to 5 .mu.m,
with a size of about 3 .mu.m preferable for alveolar deposition.
Particles smaller than 0.5 .mu.m are mainly exhaled. Besides the
therapeutic purposes, the size of aerosol particles is important in
respect to the side effects of the drugs. Larger droplets deposited
in the upper respiratory tract are indeed rapidly cleared from the
lung by the mucociliary clearance process, with the effect that
drug becomes available for systemic absorption and potentially
adverse effects. The same problems could occur with too small
aerosol particles which, due to deep lung penetration, might give
rise to higher systemic exposure so enhancing the undesired
systemic effects of the drugs. Several authors (Newman et al Thorax
1988, 43, 318-322; Smaldone et al J Aerosol med, 1988, 1, 113-126;
Thomas et al. Eur Respir J 1991, 4, 616-622) have suggested that
close attention to the droplet size of the aerosolised drug for the
antibiotic treatment of CF must be paid, since penetration to the
peripheral airways is particularly desirable. [0016] The pH of the
formulation. An important requirement for an acceptable formulation
is its adequate shelf-life suitable for commercial, distribution,
storage and use. Generally, tobramycin intravenous solutions
contain phenol or other preservatives and anti-oxidants to maintain
potency and to minimise the formation of degradation products that
may colour the solution. However, as already pointed out, said
substances may induce unwanted reactions in patients with lung
diseases such as CF. The stability of tobramycin strictly depends
on the pH. Therefore, the pH of its formulations need to be
carefully adjusted in order to slow or prevent degradation products
formation without the aid of preservatives and/or anti-oxidants; it
would also be advantageous to adjust pH in such a way as to prevent
as much as possible discoloration although the depth of colour is
not a reliable indicator of the extent of oxidation. Formulations
provided of adequate shelf-life under environmental storage
conditions (room temperature and, at the occurrence, protected form
light) would be particularly preferred, since the stability at room
temperature of the preparations of the prior art are rather
unsatisfactory. During use, the formulation prepared according to
EP 734249 marketed under the trade-name of Tobi.RTM. could be
indeed kept at room temperature for only 28 days.
OBJECT OF THE INVENTION
[0017] It is an object of the invention to provide a formulation to
be administered by nebulisation suitable for well-tolerated and
efficacious delivery of tobramycin into the endobronchial space for
treating Pseudomonas aeruginosa and/or other susceptible bacterial
infections associated to pulmonary diseases such as CF.
[0018] In particular, it is an object of the invention to provide a
formulation in the form of aqueous solution to be administered by
nebulisation, wherein tobramycin concentration, tonicity and pH
have been optimised for guaranteeing better compliance of the
patients, maximal tolerance and efficacy and as long as possible a
shelf-life at room temperature.
[0019] According to the present invention there is provided a
formulation constituted of 7.5% w/v tobramycin in an aqueous
solution having a pH of between 4.0. and 5.5 and osmolarity between
250 and 450 mOsm/l (approximately equivalent to mOsm/kg).
[0020] In a preferred embodiment of the invention, the formulation
contains 300 mg of tobramycin sulfate in 4 ml of half-saline
aqueous solution (0.45% of sodium chloride) in order to have an
osmolarity ranging from 280 to 350 mOsm/l and it has a pH of
5.2.
[0021] In the prior art, several tobramycin formulations for
inhalation have been proposed for the treatment of patients with CF
and Pseudornonas aeruginosa infections.
[0022] Most of the commercially available tobramycin solution for
injection when extemporarily used for inhalation can cause
significant bronchial obstruction as they are not preservative-free
but contain anti-oxidants such as sodium EDTA and/or sodium
metabisulphite and preservatives such as phenol.
[0023] Wall et al (The Lancet, 1983, Jun. 11, 1325) reported the
result of a clinical study upon inhalation of 80 mg tobramycin plus
1 g ticarcillin twice daily from a hand-held nebuliser. On their
own admission, one of the drawbacks of the regimen is the time
required for inhalation (about 30 min).
[0024] Ramsey et al (New Eng J Med 1993, 328, 1740-1746) conducted
an extensive study to evaluate the safety and efficacy of
aerosolised tobramycin. For reaching the target concentration
(.gtoreq.400 .mu.g per gram of sputum), they used 600 mg of
preservative-free tobramycin sulfate dissolved in 30 ml of
half-strength physiologic saline, adjusted to a pH of 6.85 to 7.05.
The large volume was required by the ultrasonic nebuliser used
(DeVilbiss). Besides the long term required for inhalation, the pH
is not optimal either. From a stability point of view, it is known
that, at pH around neutrality, tobramycin rapidly oxidises although
it is very stable towards hydrolysis (Brandt et al Drug Dev Ind
Pharm 1992, 18, 1423-1436). Common Compendia (Martindale, Physician
Desk Reference) suggest indeed to maintain tobramycin solution at a
pH comprised between 3.0 and 6.5.
[0025] EP 734249 claims a formulation comprising from 200 mg to 400
mg of aminoglycoside dissolved in about 5 ml of solution containing
0.225% of sodium chloride (1/4 normal saline --NS--) and having pH
between 5.5 and 6.5. According to the inventors, the formulation
contains minimal yet efficacious amount of aminoglycoside
formulated in a small as possible a volume of physiologically
acceptable solution having a salinity adjusted to permit generation
of aminoglycoside aerosol well-tolerated by patients but preventing
the development of secondary undesirable effects, such as
bronchospasm and cough (pg. 4, lines 51-55). The preferred
tobramycin formulation containing 1/4 NS with 60 mg of tobramycin
per ml of 1/4 NS (which equates to 6% w/v) has a pH of about 6.0
and an osmolarity in the range of 165-190 mOsm/l. According to the
inventors, the osmolarity range is within the safe range of
aerosols administered to a cystic fibrosis patient and a further
advantage of the quarter normal saline, i.e. saline containing
0.225% of sodium chloride with 60 mg/ml tobramycin is that this
formulation is more efficiently nebulised by an ultrasonic
nebuliser compared to tobramycin formulated in a solution 0.9%
normal saline (pg. 5, lines 50-54). The inventors state that a more
concentrated solution (in comparison to 60 mg per ml) will increase
the osmolarity of the solution, thus decreasing the output of the
formulation with both jet and ultrasonic nebulisers. Alternatively,
a more concentrated solution in a smaller volume is also
disadvantageous due to the typical dead space volume of the
nebulisers (1 ml): that means that the last 1 ml of solution is
wasted because the nebuliser is not fully performing (pg. 6, lines
35-38). The claimed pH range was found to be optimal from the
storage and longer shelf-life point of view (page 7 lines 2-3) but,
indeed, it allows to achieve completely stable solutions at
5.degree. C. and effectively stable ones at room temperature for 6
months; moreover the claimed formulation remain within an
acceptable range of color obtained upon storage in pouch (so
protected from light), but there is no data referring to its
behaviour outside the pouch.
[0026] A pH between 5.5 and 6.5 was claimed because, in the Opinion
of the inventors, any aerosol with a pH of less than 4.5 usually
will induce bronchospasm in a susceptible individual and aerosols
with a pH between 4.5 and 5.5 will occasionally cause this problem
(pg. 5, line 58-pg. 6, line 1) Le Brun et al Int J Pharm 1999, 189,
205-214 disclosed a 10% w/v tobramycin solution for inhalation
having a pH of 7.5. The same authors (Int J Pharm 1999, 189,
215-225), in a further study aiming at developing highly
concentrated solutions, have studied the aerosolization properties
of several tobramycin solutions, ranging from 5 to 30% w/v. All the
solutions disclosed in this paper have a pH around the neutrality
and exhibit an osmolarity far away from an isotonic value (282
mOsm/l).
[0027] In none of aforementioned documents the features of the
formulation of the present invention are disclosed and none of the
teaching therein disclosed fully contributes to the solution of the
problem underlying the invention, to provide a concentrated
solution to be delivered by aerosol in a smaller volume, with a
tonicity closer to the physiological value.
[0028] The use of a more concentrated solution with respect to that
reported as optimal in the prior art (7.5% vs. 6.0% w/v) allows to
employ vials with a smaller volume, so allowing, in turn, to reduce
the time of nebulisation. Although it is true that some nebulisers
have a dead space volume of 1 ml, other have a minor one (0.5 ml or
less), so the wasting of using vials of 4 ml would be only approx.
10% or less.
[0029] According to the invention, the osmolarity of the
formulation is within the range of solutions considered as
isotonic, whereas both the formulations of EP 734249 and Ramsey et
al have an osmolarity, i.e. 165-190 mOsm/l, typical of solutions
considered as hypotonic (Derbracher et al Atemwegs and Lung 1994,
20, 381-382). Although the formulations of the prior art turned out
to be safe, only isotonic solutions may completely prevent the risk
of paradoxical bronchoconstriction. Moreover, the results reported
in the example 2 indicate that the formulations having an
osmolarity in the range claimed, contrary to what stated in EP
734249, are efficiently nebulised despite their higher
concentration.
[0030] The pH between 4.0 and 5.5, preferably 5.2, was found to be
optimal in terms of storage and shelf-life at room temperature.
Long-term stability studies show that tobramycin in the formulation
of the present invention is stable for over nine months. Moreover,
for all that period, its colour does not significantly change and
remains within an acceptable range even if not stored in a foil
overpouch.
[0031] According to a further embodiment of the invention, there is
also provided a process for the preparation of such formulation,
said process including the steps of: [0032] i) preparing an aqueous
solution containing 0.45% w/v of sodium chloride; [0033] ii)
adjusting the pH with a concentrated strong acid; [0034] iii)
adding the active ingredient and mixing to complete dissolution;
[0035] iv) re-adjusting the pH to the desired value; [0036] v)
filling the solution in suitable containers, preferably
pre-sterilised by filtration.
[0037] The aerosol formulations of the invention refer to a 7.5%
w/v aqueous solution of an antibiotic of the aminoglycoside family,
preferably tobramycin and salts thereof, for the treatment of lung
infections due to Gram positive and negative bacteria, in pulmonary
diseases such as cystic fibrosis, non-CF bronchiectasis infected
with Pseudomonas aeruginosa and other chronic pneumopathies,
particularly in an exacerbation phase, such as bronchiectasis, COPD
and bronchial asthma.
[0038] The osmolarity of the formulation should range between 250
and 450 mOsm/l, preferably between 260 and 400, even more
preferably between 280 and 350 mOsm/l; it can be adjusted by using
any physiologically acceptable salt or non-volatile compounds;
preferably, tobramycin is dissolved in a 0.45% sodium chloride
aqueous solution.
[0039] The pH can be adjusted by using any concentrated strong
acid, preferably sulfuric acid and should range from 4.0 to 5.5,
preferably from 5.0 to 5.4.
[0040] The formulations of the invention can be distributed in
suitable containers such as multidose vials or pre-sterilised unit
dose vials of 2 or 4 ml, depending on the therapeutic indication;
otherwise, the vials can be aseptically filled using the "blow,
fill and seal" technology. The filling is preferably carried out
under inert atmosphere. The solution formulations can be
advantageously sterilised by filtration.
[0041] The invention is illustrated by the following examples.
Example 1
Preparation of the 7.5% w/v Tobramvcin Solution at pH 5.2 and
Stability Studies
[0042] The composition refers to 1 unit-dose vial (2 ml)
TABLE-US-00001 Ingredient Quantity Tobramycin 150 mg Sodium
chloride 9 mg Sulphuric Acid 2N q.s. to pH 5.2 .+-. 0.2 Sodium
hydroxide 1M * q.s to pH 5.2 .+-. 0.2 Purified water q.s. to 2 ml *
added only if required.
[0043] Sodium chloride is dissolved into 40 l of purified water
(mix for 15 minutes to guarantee the NaCl complete dissolution).
Then, 30 l of sulphuric acid (2N H.sub.2S0.sub.4) is added to the
saline solution; during the operation, the solution temperature is
monitored. When the solution temperature is about 25+30.degree. C.,
N.sub.2 is insufflated to obtain a value of dissolved O.sub.2 less
than 1 mg/l. Afterwards, tobramycin is added and mixed to complete
dissolution (for not less than 15 minutes) while the temperature is
maintained below 25-30.degree. C. The pH value is checked and, if
necessary, sulphuric acid 2N or sodium hydroxide solution 1M are
added to obtain a pH value of 5.2.+-.0.2. When the solution
temperature is 25.degree. C..+-.2.degree. C., purified water is
added to reach the final volume. The resulting solution is mixed
for 15 minutes. The pH value is checked again and, if necessary,
sulphuric acid 2N or sodium hydroxide solution 1M are added to
obtain a pH value of 5.2.+-.0.2. The solution is filtered through
one 0.45 .mu.m Nylon filter, and through two 0.2 .mu.m Nylon
filters.
[0044] The solution is distributed in 2 ml polyethylene colorless
unit dose vials under nitrogen purging.
[0045] The stability of the vials was evaluated both under
long-term (25.degree. C., 60% R.H.) and accelerated conditions
(40.degree. C., 75% R.H.) [R.H.=relative humidity]. Results are
reported in Tables 1 and 2, respectively. Assays of tobramycin and
of its main related substances (degradation products) were
determined by HPLC. Residual oxygen, pH and osmolarity were also
assayed. The osmolarity was measured using a freezing-point
depression osmometer.
[0046] The formulation of the invention turns out to be stable for
at least 9 months at room temperature and for 6 months under
accelerated conditions. pH and osmolarity remain substantially
unchanged under both conditions. At room temperature, the colour of
the formulation of the invention does not significantly change and
remains within an acceptable range even if not stored in a foil
overpouch.
TABLE-US-00002 TABLE 1 Stability under long-term conditions
(25.degree. C., 60% R.H.) TECHNOLOGICAL CONTROLS CHEMICAL CONTROLS
Solution Oxygen Osmolarity Tobramyicin Related substances Analysis
appearance mg/l mOsm/l mg/ml (%) pH % Specification Clear pale (a)
260-350 67.5-82.5 4.5-5.5 (a) range yellow solution t = 0 Clear
pale 2.8 321 75.8 (100) 5.2 6.39 yellow solution t = 3 months Clear
pale 2.9 314 76.6 (101.1) 5.2 6.35 yellow solution t = 6 months
Clear pale 3.0 304 75.4 (99.5) 5.0 5.84 yellow solution t = 9
months Clear pale 2.8 293 76.5 (100.9) 5.1 6.27 yellow solution (a)
not established
TABLE-US-00003 TABLE 2 Solution of example 1 - Stability under
accelerated conditions (40.degree. C., 75% R.H.) TECHNOLOGICAL
CONTROLS CHEMICAL CONTROLS Solution Oxygen Osmolarity Tobramycin
Related substances Analysis appearance mg/l mOsm/l mg/ml (%) pH %
Specification Clear pale (a) 260-350 67.5-82.5 4.5-5.5 (a) range
yellow solution t = 0 Clear pale 2.8 321 75.8 (100) 5.2 6.39 yellow
solution t = 1 months Clear pale 2.7 n.d. 78.3 (103.3) 5.1 6.42
yellow solution t = 3 months Clear 2.8 311 75.3 (99.3) 5.1 5.48
yellow solution t = 6 months Clear 3.2 292 77.1 (101.7) 4.7 6.17
yellow solution (a) not established; (n.d.) not determined
Example 2
[0047] The nebulisation efficiency of the solution for inhalation
of example 1, expressed as percentage of active ingredient
nebulised, was evaluated using a commercial jet nebuliser
(PARI-BOY) for a 5-minute nebulisation time. The size profile of
the droplets produced by nebulisation of the solution, expressed as
diameter (.mu.m) below which respectively 10%, 50% and 90% of the
droplets are included, was also characterised by Malvern
analysis.
[0048] A formulation prepared according to the teaching of the
preferred embodiment of EP 734249, i.e. containing 60 mg of active
ingredient per ml of 0.225% sodium chloride aqueous solution and
having a pH of about 6, was nebulised for comparison. Both
formulations were filled in 2 ml unit dose vials. The results are
reported in Table 3 as a mean of two determinations.
TABLE-US-00004 TABLE 3 Malvern Analysis Osmolarity (.mu.m)
Efficiency (mOsm/l) 10% 50% 90% (%) Formulation 295 1.61 6.26 13.46
47.4 of ex. 1 Formulation 222 1.78 6.24 13.46 42.2 of EP 734249
[0049] The results indicate that the formulation according to
example 1 having an osmolarity near isotonicity is efficiently
nebulised.
[0050] The size profile of the droplets produced by nebulisation is
instead practically the same.
* * * * *