# Patent

## Title
Low dose oral pharmaceutical composition of isotretinoin

## Abstract

The present invention provides a low dose oral pharmaceutical composition of isotretinoin having reduced food effect, in particular no food effect. The present invention further relates to a process for preparing the oral pharmaceutical composition of the present invention.

## Background
FIELD OF THE INVENTION
The present invention provides a low dose oral pharmaceutical composition of isotretinoin having reduced food effect, in particular no food effect. The present invention further relates to a process for preparing the oral pharmaceutical composition of the present invention.
BACKGROUND OF THE INVENTION
Isotretinoin is a retinoid (also known as 13-cis retinoic acid). Owing to its low water solubility, the oral bioavailability of isotretinoin is low. PCT Publication No. WO 00/25772 discloses that the presently marketed formulation of isotretinoin, i.e., Accutane®, contains isotretinoin at a mean particle size of about 100 μm resulting in only 20% oral bioavailability.
U.S. Pat. Nos. 7,435,427 and 8,367,102 cover the marketed formulation of Absorica®. These patents disclose capsules comprising a semi-solid suspension of isotretinoin containing at least two lipidic excipients, one having an HLB value equal to or greater than 10 and the other being an oily vehicle. These patents are based on the use of the “Lidose® technology” to provide a formulation of isotretinoin with enhanced bioavailability.
Isotretinoin has a very high teratogenic potential. This drug may be prescribed only by or under the supervision of a consultant dermatologist. Therefore, reduction of dose in case of such a teratogenic drug is highly beneficial. Further, isotretinoin is known to have a “food effect”, i.e., its absorption is dependent on the presence of food in the stomach. Therefore, there is a need to develop a composition of isotretinoin which has a lower dose and reduced food effect. The present inventors have developed an oral pharmaceutical composition of isotretinoin, wherein said composition has enhanced bioavailability, lower dose and reduced food affect, in particular no food effect in comparison to the marketed formulations of isotretinoin, e.g. Roaccutane® and Absorica®. These advantages would lead to better patient compliance.
Further, the present inventors were able to develop an isotretinoin composition having low isotretinoin to excipient ratio which would allow for it to be filled in a capsule smaller than Absorica®. The smaller sized capsule would be advantageous for patients as it would be easier for swallowing.
SUMMARY OF THE INVENTION
The present invention provides a low dose oral pharmaceutical composition of isotretinoin having reduced food effect, in particular no food effect. The oral pharmaceutical composition of the present invention comprises isotretinoin and a pharmaceutically acceptable excipient. The present composition is in the form of a dispersion which is further filled into capsules. The present invention further provides a process for preparing the oral pharmaceutical composition of the present invention. It also provides a method of treating severe acne by administering the oral pharmaceutical composition of the present invention.


DETAILED DESCRIPTION OF THE INVENTION
In one aspect, the present invention provides a low dose oral pharmaceutical composition comprising isotretinoin and a pharmaceutically acceptable excipient.
In another aspect, the present invention provides a low dose oral pharmaceutical composition comprising isotretinoin and a pharmaceutically acceptable excipient, wherein said composition, when administered orally, provides an equivalent efficacy at a lower dose of isotretinoin in comparison to the marketed Absorica® capsules, wherein said dose is at least 10% lower.
In another aspect, the present invention provides a low dose oral pharmaceutical composition comprising isotretinoin and a pharmaceutically acceptable excipient, wherein said composition, when administered orally, provides an equivalent efficacy at a lower dose of isotretinoin in comparison to the marketed Absorica® capsules, wherein said dose is at least 20% lower.
In another aspect, the present invention provides a low dose oral pharmaceutical composition comprising isotretinoin and a pharmaceutically acceptable excipient, wherein said composition exhibits reduced food effect in particular no food effect as indicated by comparable Cmax in fasting and fed states.
In an embodiment of the above aspect, the composition exhibits a mean Cmax of about 451.38 ng/mL under fed condition and a mean Cmax of about 454.92 ng/mL under fasting condition.
In another embodiment of the above aspect, the composition exhibits a mean AUC of about 6514.86 ng·h/mL under fed condition and a mean AUC of about 5566.90 ng·h/mL under fasting condition.
In another embodiment of the above aspect, the composition, when administered orally, has a mean fed/fasted ratio of AUC of about 1.17 and a mean fed/fasted ratio of Cmax of about 0.99.
In another aspect, the present invention provides an oral pharmaceutical composition comprising isotretinoin and a pharmaceutically acceptable excipient, wherein the composition has a mean Cmax value in the range of about 9 ng/mL/mg to about 40 ng/mL/mg when administered in a dose of about 0.4 mg/kg to about 1.6 mg/kg of the body weight in a human subjects under fasting conditions.
In one embodiment of the above aspect, the composition further provides AUC0-t value in the range of about 125 ng·h/mL/mg to about 500 ng·h/mL/mg under fasting condition.
In another aspect, the present invention provides a pharmaceutical composition of isotretinoin and a pharmaceutically acceptable excipient wherein the composition exhibits no food effect and has a mean fed/fasted ratio of Cmax value of about 0.85 to about 1.22, when administered in a dose of about 0.4 mg/kg to about 1.6 mg/kg of the body weight in a human subjects.
The term “no food effect” as used herein means that formulation can be given with or without food. Further, there is no significant impact on Cmax value when given in fed or fasted state. The mean fed/fasted ratio of Cmax value are preferably in the range of about 0.85 to about 1.22.
In one embodiment of the above aspect, the composition has a mean fed/fasted ratio of AUC0-t value of about 0.9 to about 1.40.
In another aspect, the present invention provides a low dose oral pharmaceutical composition comprising:
(a) isotretinoin; and
(b) an oily vehicle.
In another embodiment of the above aspects, the composition comprises:

    
    
        (a) isotretinoin in an amount of about 5.0 w/w to about 15 w/w based on the total weight;
        (b) an oily vehicle, and
        (c) surfactant in amount of about 0.05% w/w to about 10% w/w based on the total weight.
    
    


In one embodiment of the above aspect, said composition comprises isotretinoin in an amount of about 1 mg to 100 mg, 5 mg to 50 mg, 10 mg to 40 mg, 9 mg to 36 mg, or 8 mg to 32 mg.
In another embodiment of the above aspect, said composition comprises isotretinoin in an amount of about 8 mg, 16 mg, 20 mg, 24 mg, 28 mg, or 32 mg.
In another embodiment of the above aspect, said composition comprises isotretinoin in an amount of about















High dose marketed 



Lower dose isotretinoin
capsule comprising



composition
semi-solid suspension



(dose/capsule)
(dose/capsule)









about 6.5 mg to about 9.0 mg
10 mg



about 13 mg to about 18 mg
20 mg



about 16.25 mg to about 22.5 mg
25 mg



about 19.5 mg to about 27 mg
30 mg



about 22.75 mg to about 31.5 mg
35 mg



about 26 mg to about 36 mg
40 mg










In another embodiment of the above aspect, said composition is in the form of a dispersion which is further filled into capsules.
In another embodiment of the above aspect, the oily vehicle includes, but is not limited to, groundnut oil, olive oil, soybean oil, kernel oil, almond oil, safflower oil, sunflower oil, palm oil, sesame oil, canola oil, corn oil, castor oil, coconut oil, cotton seed oil, grape seed oil, and mixtures thereof.
In another embodiment of the above aspect, the oily vehicle is present in an amount of about 1% w/w to about 99% w/w by the total weight of the composition; preferably in an amount of about 10% w/w to about 95% w/w by the total weight of the composition.
In another embodiment of the above aspect, the oily vehicle is present in an amount of about 71% w/w to about 95% w/w by the total weight of the composition.
In another embodiment of the above aspect, the ratio of isotretinoin to the oily vehicle ranges from about 1:99 to about 99:1.
In another embodiment of the above aspect, the composition further comprises a surfactant.
In another embodiment of the above aspect, the surfactant includes, but is not limited to, anionic, cationic, or non-ionic surfactants; sorbitan fatty acid esters; polysorbates prepared from lauric, palmitic, stearic, and oleic acids; mononylphenyl ethers of polyethylene glycols such as nanoxynols; polyoxyethylene monoesters such as polyoxyethylethylene monostearate, polyoxyethylene monolaurate, and polyoxyethylene monooleate; dioctyl sodium sulfosuccinate; sodium lauryl sulphate; lecithin; fatty acid esters of propylene glycol; fatty acid esters of glycerol; poloxamers; and mixtures thereof.
In another embodiment of the above aspect, the surfactant is present in an amount of about 0.05% w/w to about 10.0% w/w by the total weight of the composition.
In yet another embodiment of the above aspect, the composition further comprises other excipients like antioxidants, preservatives, and alkaline stabilizers.
In yet another embodiment of the above aspect, the composition is substantially free of wax.
The term “substantially free of wax” as used herein means that the composition contains wax less than about 10% by weight of the composition, in particular less than 8% by weight.
In yet another embodiment of the above aspect, the composition is free of wax.
In yet another embodiment of the above aspect, the composition comprises isotretinoin wherein the particle size distribution of isotretinoin is such that the D90 is less than 60 μm, less than 55 μm, less than 50 μm, less than 45 μm, less than 40 μm, less than 35 μm, less than 30 μm, less than 25 μm, less than 20 μm, less than 15 μm, or less than 10 μm.
In yet another embodiment of the above aspect, the composition comprises isotretinoin wherein the particle size distribution of isotretinoin is such that the D90 is less than 30 μm.
In another embodiment of the above aspect, the composition comprises isotretinoin wherein the particle size distribution of isotretinoin is such that the D50 is less than 40 μm, less than 35 μm, less than 30 μm, less than 25 μm, less than 20 μm, less than 15 μm, less than 10 μm, or less than 5 μm.
In yet another embodiment of the above aspect, the composition comprises isotretinoin wherein the particle size distribution of isotretinoin is such that the D50 is less than 15 μm.
In another embodiment of the above aspect, the composition comprises isotretinoin wherein the particle size distribution of isotretinoin is such that the D10 is less than 20 μm, less than 18 μm, less than 17 μm, less than 15 μm, less than 12 μm, less than 10 μm, less than 8 μm, less than 7 μm, less than 5 μm, or less than 2 μm.
In yet another embodiment of the above aspect, the composition comprises isotretinoin wherein the particle size distribution of isotretinoin is such that the D10 is less than 7 μm.
In yet another embodiment of the above aspect, the composition comprises isotretinoin wherein the particle size distribution of isotretinoin is such that the D90 is less than 60 μm and the D50 is less than 40 μm.
In yet another embodiment of the above aspect, the composition comprises isotretinoin wherein the particle size distribution of isotretinoin is such that the D90 is less than 60 μm, D50 is less than 40 μm, and D10 is less than 20 μm.
In yet another embodiment of the above aspect, the composition comprises isotretinoin wherein the particle size distribution of isotretinoin is such that the D90 is less than 30 μm, D50 is less than 15 μm, and D10 is less than 10 μm.
In yet another embodiment of the above aspect, the composition comprises isotretinoin wherein the particle size distribution of isotretinoin is such that the ratio of D90/D50 is about 1.5-2.5 μm, D50/D10 is about 1.8 to 3.3 and D90/D10 is about 3.0 to 6.1.
In another aspect, the present invention provides a stable oral pharmaceutical composition comprising isotretinoin and a pharmaceutically acceptable excipient wherein the composition contains not more than 1% w/w 5, 6-epoxy-13-cis retinoic acid when stored at a temperature 40° C. and 75% relative humidity for a period of six months.
In one embodiment of the above aspect, the composition is filled in a capsule having a fill occupancy more than 40%.
In another embodiment of the above aspect, the composition in the form of dispersion is filled in hard gelatin capsule.
In another aspect, the present invention provides a stable oral pharmaceutical composition comprising isotretinoin and a pharmaceutically acceptable excipient wherein said composition is filled in a following capsule size:











Dose/Capsule
Capsule size







 8 mg
Size 2 or smaller


16 mg
Size 1 or smaller


20 mg
Size 0 or smaller


24 mg
Size 0 or smaller


28 mg
Size 00 or smaller


32 mg
Size 00 or smaller









In one embodiment of the above aspect, the composition has isotretinoin to excipient ratio 1:5 to 1:18.
In another embodiment of the above aspect, the composition has fill weight of less than 600 mg (excluding capsule shell weight).
In another aspect, there is provided a process for the preparation of a low dose oral pharmaceutical composition comprising isotretinoin and an oily vehicle wherein the process comprises:
(a) dispersing isotretinoin in an oily carrier;
(b) milling the dispersion to get the desired particle size;
(c) adding one or more excipients to the above dispersion;
(d) optionally adding an oily carrier to the dispersion of step (c); and
(e) filling the dispersion into capsules.
In another aspect, there is provided a process for the preparation of a low dose oral pharmaceutical composition comprising isotretinoin and an oily vehicle wherein the process comprises:
(f) dispersing isotretinoin in an oily carrier;
(g) milling the dispersion to get the desired particle size;
(h) adding one or more excipients to the above dispersion;
(i) adding an oily carrier to the dispersion of step (c); and
(j) filling the dispersion into capsules.
In one embodiment of the above aspect, the oily carrier used in step (a) is present in an amount which is at least 25% w/w of the total amount of the oily carrier.
In another embodiment of the above aspect, the composition has a density of 0.8 to 1.1 g/mL.
In still another aspect, the present invention provides a method of treating severe acne, musculoskeletal and connective tissue inflammations, emphysema, ulcerating diseases, cervical tumors in HIV positive women, lung cancer in smokers, skin cancer, neuroblastoma, recurrent prostate cancer, leukemia, high-grade glioma, head and neck cancers, multiple myeloma, gram-negative folliculitis, recalcitrant rosacea, pyoderma faciale, psoriasis, cutaneous lupus erythematosus, acne fulminans, squamous cell carcinoma, or cutaneous photoaging by administering to the individual in need thereof, a low dose oral pharmaceutical composition of the present invention.
In one embodiment of the above aspect, the present invention provides a method of treating acne by administering to the individual in need thereof, a low dose oral pharmaceutical composition of the present invention.
In another aspect, the present invention provides a method of treating severe recalcitrant nodular acne in a patient in need thereof wherein said method comprises administering isotretinoin in an amount of about 0.4 to about 1.6 mg per kilogram of the body weight; wherein the body weight of the patient and the selected dose correlate to one of the following:











Body Weight
Total Daily (mg)











Kg
Pounds
0.4 mg/kg
0.8 mg/kg
1.6 mg/kg














40
88
16
32
64


50
110
20
40
80


60
132
24
48
96


70
154
28
56
112


80
176
32
64
128


90
198
36
72
144


100
220
40
80
160









In one embodiment of the above aspect, the dose is given twice daily for 15-20 weeks.
In another aspect, the present invention provides an oral pharmaceutical composition comprising isotretinoin and a pharmaceutically acceptable excipient, wherein said composition has an isotretinoin to excipient ratio of about 1:5 to about 1:18 and releases not less than 50% of isotretinoin in 15 minutes when measured in United States Pharmacopeia (USP) type II dissolution apparatus, paddle at 75 rpm, in 900 mL of pH 7.4 phosphate buffer with 70 mg/L Pancreatin and 4.5% lauryldimethylamine oxide (as 30% solution) with spiral coated sinker.
In one embodiment of the above aspect, the composition releases not less than 85% in 30 minutes.
In another embodiment of the above aspect, the composition has viscosity of about 50 to 450 cps at room temperature. The viscosity was measured by Brookfield Viscometer, spindle number S-02 stirred at 20 RPM.
In another aspect, the present invention provides an oral pharmaceutical composition comprising isotretinoin and a pharmaceutically acceptable excipient, wherein said composition releases not less than 50% of isotretinoin in 15 minutes when measured in United States Pharmacopeia (USP) type II dissolution apparatus, paddle at 75 rpm, in 900 mL of borate Buffer (pH 8.0) containing 0.5% cetrimide and 50 mg/L of pancreatin (with alternate sinkers).
The term “isotretinoin” refers to isotretinoin in its crystalline or amorphous form, as well as its esters, salts, or derivatives thereof. Isotretinoin is present in an amount of about 5.5% to about 15% based on the total weight of the composition
The term “low dose,” as used herein, refers to the dose of isotretinoin wherein said dose is at least about 10% lower than the presently approved dose.
The bioequivalence is established by comparing pharmacokinetic parameters, for example, AUC and Cmax of the pharmaceutical composition of the present invention with Absorica® formulation in healthy human subjects in fed as well as fasting conditions.
The term “AUC” refers to the area under the time/plasma concentration curve after administration of the pharmaceutical composition. AUC0-∞ denotes the area under the plasma concentration versus time curve from time 0 to infinity; AUC0-t denotes the area under the plasma concentration versus time curve from time 0 to time t.
The term “Cmax” refers to the maximum concentration of isotretinoin in the blood following administration of the pharmaceutical composition.
The term “tmax” refers to the time in hours when Cmax is achieved following administration of the pharmaceutical composition.
The term “D10” refers to the particle size of isotretinoin where 10% (w/v) of the particles have a size less than the defined D10 value; “D50” refers to the particle size of isotretinoin where 50% (w/v) of the particles have a size less than the defined D50 value; “D90” refers to the particle size of isotretinoin where 90% (w/v) of the particles have a size less than the defined D90 value, when measured through Malvern Instrument Ltd.
“Defined D10 value/D50 value/D90 value” refers to the values defined in the embodiments.
Examples of suitable antioxidants include, but are not limited to, butylated hydroxyl anisole, butylated hydroxyl toluene, tocopherol, ascorbyl palmitate, ascorbic acid, sodium metabisulfite, sodium sulfite, sodium thiosulfate, propyl gallate, and mixtures thereof. The antioxidant is present in an amount of about 0.002% w/w to about 2% w/w of the total composition.
Examples of alkaline stabilizers include, but are not limited to, sodium hydroxide, potassium hydroxide, sodium carbonate or bicarbonate, potassium carbonate or bicarbonate, lithium hydroxide, triethylamine, meglumine, methylamine, and mixtures thereof.
Examples of suitable preservatives include, but are not limited to, methyl paraben, ethyl paraben, propyl paraben, butyl paraben, benzoic acid, sodium benzoate, benzyl alcohol, sorbic acid, potassium sorbate, and mixtures thereof.
The term “stable,” as used herein, refers to chemical stability, wherein not more than 1.5% w/w of total related substances (excluding tretinoin) are formed on storage at accelerated conditions of stability at 40° C. and 75% relative humidity or at 25° C. and 60% relative humidity for a period of at least six months or to the extent necessary for use of the composition. Further, composition contains not more than 1% w/w 5, 6-epoxy-13-cis retinoic acid when stored at a temperature 40° C. and 75% relative humidity for a period of six months.
The size reduction of isotretinoin is achieved by wet milling the dispersion of isotretinoin in an oily vehicle using mechanical means such as a jet mill, ball mill, or media mills such as a sand mill, DYNO®-mill, or a bead mill. The grinding media in these mills can comprise spherical particles such as stainless steel beads or zirconium oxide balls.
The term “about”, as used herein, refers to any value which lies within the range defined by a variation of up to ±10% of the value.
The invention may be further illustrated by the following examples, which are for illustrative purposes only and should not be construed as limiting the scope of the invention in any way.
EXAMPLES
Example 1












S. No.
Ingredients
Quantity (% w/w)

















1
Isotretinoin
6.67


2
Butylated hydroxy anisole
0.04


3
Polysorbate 80
1.85


4
Soybean oil
91.44









Procedure:

    
    
        1. Butylated hydroxy anisole and polysorbate 80 were dissolved in soybean oil (39.36% w/v of the total composition) to form a clear solution.
        2. Isotretinoin was added to the step 1 solution under stirring to obtain a uniform dispersion.
        3. The dispersion of step 2 was milled to get the particle size of isotretinoin such that D90 was about 20 μm.
        4. The remaining quantity of soybean oil (52.08% w/v of the total composition) was added to the micronized dispersion of step 3 under stirring to obtain a uniform dispersion.
        5. The dispersion of step 4 was filled into hard gelatin capsules.

Dissolution Studies

    
    


The pharmaceutical composition of Example 1 (containing 16 mg of isotretinoin) was compared with the marketed formulation of isotretinoin (20 mg Absorica® capsules) for the release profile in an FDA recommended dissolution medium as given in the following tables:
Reference (R): Absorica® 20 mg capsules
Test (T): Isotretinoin 16 mg capsules (Example 1)
















Dissolution Media
pH 7.8 phosphate buffer with 0.5% w/v 




N,N-dimethyl dodecylamine N-oxide



Apparatus/RPM/Vol
USP Type I (20 mesh basket)/100/900 mL






















% of Drug Released Over Time (minutes)
















Sample
10
15
20
30
45
60
90
120
150



















Test
34
—
58
73
93
99
100
101
100


Reference
0
—
2
6
24
37
58
76
83









Pharmacokinetic Study Under Fed Conditions

The pharmaceutical composition of Example 1 (containing 16 mg of isotretinoin) was compared with the marketed formulation of isotretinoin (20 mg Absorica® capsules) under fed conditions on 15 healthy adult male subjects.
Values for various pharmacokinetic parameters, including observed Cmax, AUC0-t, and AUC0-inf were calculated and are provided in Table 1 below.
Reference (R): Absorica® 20 mg capsules
Test (T): Isotretinoin 16 mg capsules (Example 1)







TABLE 1







Comparative pharmacokinetic data for test and reference 


in 15 healthy adult human male subjects













In Cmax
In AUC0-t
In AUC0-inf







Ratio (T/R)
111.07
90.12
91.59



90% CI
91.54-134.76
84.30-96.35
86.32-97.19










    
    
        Average tmax values for both the test and reference are 4.7888 hours and 5.5111 hours, respectively, which indicate a comparable absorption pattern.
        Under fed conditions, the test prototype shows a comparable extent of absorption to reference product with T/R ratios of 90.12% and 91.59% for AUC0-t and AUC0-inf, respectively. These values are within the regulatory acceptance criteria of 80% to 125%. However, for rate of absorption (Cmax), the ratio is observed to be slightly on a higher side (111.07%) with 90% CI ranging between 91.54% and 134.76%.

Pharmacokinetic Study Comparing the Formulation of Example 1 Under Fed and Fasting Conditions

    
    


The pharmaceutical composition of Example 1 (16 mg Test capsule) was compared in fed and fasting conditions on 15 healthy adult male subjects.
Values for various pharmacokinetic parameters, including observed Cmax, AUC0-t, and AUC0-inf were calculated and are provided in Table 2 below.
Test (A): Isotretinoin 16 mg capsules (Example 1) under fasting conditions
Test (B): Isotretinoin 16 mg capsules (Example 1) under fed conditions







TABLE 2







Comparative pharmacokinetic data for test (B) vs test (A) 


in 15 healthy adult human male subjects:











In Cmax
In AUC0-t
In AUC0-inf





Ratio (B/A)
99.22
116.34
117.02


90% CI
81.78-120.38
108.82-124.37
110.29-124.17









    
    
        Average tmax for the test prototype under fasting condition (3.7667 hours) is  ̃1.02 hours earlier than when administered under fed condition (4.7888 hours).
        On comparing the test prototype under fasting and fed conditions, it is observed that B/A ratio for rate of absorption (Cmax) is close to unity (99.22%). Even though B/A ratios are on higher side for the AUC values, (approx. 116% to 117%), the 90% CI for all three PK parameters (Cmax, AUC0-t, and AUC0-inf) are within the 80% to 125% regulatory acceptance criteria.

Conclusion:

        The 16 mg test prototype has comparable bioavailability to the reference product (Absorica® 20 mg) under fed conditions. This provides positive support for up to 20% reduction in the test dose.
        There is no indication that food will significantly impact the rate and extent of drug absorption from the test prototype. In fact, we observe that T/R ratios and 90% CI for the PK parameters are within the 80% to 125% regulatory acceptance criteria.
    
    


Example 2












S. No
Name of Ingredient
Quantity (% w/w)

















1.
Isotretinoin
13.91


2.
Polysorbate 80
3.86


3.
Butylated hydroxy anisole
0.08


4.
Soybean Oil
82.15









Procedure:

    
    
        1. Butylated hydroxy anisole and polysorbate 80 were dissolved in the soybean oil to form a clear solution.
        2. Isotretinoin was added to the step 1 solution under stirring to obtain a uniform dispersion.
        3. The dispersion of step 2 was milled to get the particle size of isotretinoin such that D90 was about 20 μm.
        4. The dispersion of step 3 was filled into hard gelatin capsules.
        5. The filled capsules of step 4 were sealed using a gelatin solution.
    
    


Example 3












S. No
Name of Ingredient
Quantity (% w/w)

















1.
Isotretinoin
6.67


2.
Butylated Hydroxy Anisole
0.04


3.
Soybean Oil
93.29









Procedure:

    
    
        1. Butylated hydroxy anisole was dissolved in soybean oil (39.36% w/v of the total composition) to form a clear solution.
        2. Isotretinoin was added to the step 1 solution under stirring to obtain a uniform dispersion.
        3. The dispersion of step 2 was milled to get the particle size of isotretinoin such that D90 was about 20 μm.
        4. The remaining quantity of soybean oil (53.93% w/v of the total composition) was added to the micronized dispersion of step 3 under stirring to obtain a uniform dispersion.
        5. The dispersion of step 4 was filled into hard gelatin capsules.
        6. The filled capsules of step 5 were sealed using a gelatin solution.

Dissolution Studies (USP Test-4)

    
    


The pharmaceutical composition according to Example 1 (containing 24 mg of isotretinoin) was compared with the marketed formulation of high dose isotretinoin (30 mg Absorica® capsules) for the release profile in a USP Test-4 as given in the following Table 3:
Reference (R): Absorica® 30 mg capsules
Test (T): Isotretinoin 24 mg capsules (Example 1)







TABLE 3





Percent drug release in USP Test-4
















Dissolution Media
Phosphate Buffer (pH 7.4) containing 


(USP Test-4)
with 70 mg/L Pancreatin and 4.5% 



LDAO as 30% solution


Apparatus/RPM/Vol
USP Type II (with coated spiral 



sinkers)/75/900 mL










% of Drug Released Over Time (minutes)









Sample Time













15
30
45
60
90





Test
80
97
97
96
95


Reference
6
29
54
74
89









Dissolution Studies (USP Test-3)

The pharmaceutical composition of Example 1 (containing 32 mg of isotretinoin) was compared with the marketed formulation of isotretinoin (40 mg Absorica® capsules) for the release profile in a USP Test-3 as given in the following Table 4:
Reference (R): Absorica® 40 mg capsules
Test (T): Isotretinoin 32 mg capsules (Example 1)







TABLE 4





Percent drug release in USP Test-3
















Dissolution Media
Borate Buffer (pH 8.0) containing 0.5% 


(USP Test-3)
cetrimide and 50 mg/L of pancreatin


Apparatus/RPM/Vol
USP Type II (with alternative sinkers)/75/900 mL










% of Drug Released Over Time (minutes)









Sample Time













15
30
45
60
90





Reference
 3
21
48
67
84


Test
64
86
91
93
96









Pharmacokinetic Study Comparing the Formulation of Example 1 Under Fed and Fasting Conditions

The pharmaceutical composition according to Example 1 (32 mg Test capsule) was compared in fed and fasting conditions on 72 healthy adult male and female subjects. The study has been conducted as an open-label, multiple-(clinical) centre, balanced randomized, single-dose, three-treatment, three-period, six-sequence, crossover study.
Values for various pharmacokinetic parameters, including observed Cmax, AUC0-t, and AUC0-inf were calculated and are provided in Table 5 below.
Test (A): Isotretinoin 32 mg capsules (Example 1) under fasting conditions
Test (B): Isotretinoin 32 mg capsules (Example 1) under fed conditions







TABLE 5







Comparative pharmacokinetic data for test (B) vs test (A) 


in 72 healthy adult human subjects:


Study 1











Mean Cmax
Mean AUC0-t
Mean AUC0-∞













Fasted
539.4
8042
8711


Condition (A)





Fed condition (B)
583.9
10039
10736


Ratio (B/A)
1.08
1.24
1.23


90% CI
94.42-124.12
117.29-132.88
115.93-131.01


Per mg values
16.84
251.31
272.22









Conclusion:

The results summarized in Table 5 demonstrates that there is no effect on Cmax and only marginal increase of AUC. Hence, food does not affect bioavailability of test formulation of Example 1.
Stability Data:
Table 6 provides the impurity profile of Example 1 (16 mg) when stored at a temperature of 40° C. and 75% relative humidity for the period of six months. Impurities were determined using HPLC system.







TABLE 6







Stability data of isotretinoin when stored at a temperature of 40° C. 


and 75% relative humidity for the period of six months.








Impurities
6 months/40° C./75% RH





5,6-epoxy-13-cis retinoic acid
0.28


Total impurities
1.24









Example 4












S. No.
Ingredients
Qty/capsule (mg)


















1
Isotretinoin
8
16


2
Butylated hydroxy
0.045
0.090



anisole




3
Polysorbate 80
2.220
4.440


4
Soybean oil
109.735
219.470



Total weight
120.00
240.00









Procedure:

    
    
        1. Butylated hydroxy anisole and polysorbate 80 were dissolved in soybean oil (39.36% w/v of the total composition) to form a clear solution.
        2. Isotretinoin was added to the step 1 solution under stirring to obtain a uniform dispersion.
        3. The dispersion of step 2 was milled to get the particle size of isotretinoin such that D90 was about 20 μm.
        4. The remaining quantity of soybean oil (52.08% w/v of the total composition) was added to the micronized dispersion of step 3 under stirring to obtain a uniform dispersion.
        5. The dispersion of step 4 was filled into hard gelatin capsules.
    
    









TABLE 7







Composition parameters of Example 4










Composition parameters
16 mg







Density
0.95 g/mL



Fill Occupancy
68.38%



Viscosity
264 Centipoise (at room temperature)

## Claims

1. An oral pharmaceutical composition in the form of a capsule comprising isotretinoin and a pharmaceutically acceptable excipient, wherein the composition has a mean Cmax value in the range of about 9 ng/mL/mg to about 40 ng/mL/mg when administered in a dose of about 0.4 mg/kg to about 1.6 mg/kg of the body weight in a human subjects under fasting conditions.

2. The oral pharmaceutical composition in the form of a capsule of isotretinoin according to claim 1 wherein the composition has AUC0-t in the range of about 125 ng·h/mL/mg to about 500 ng·h/mL/mg under fasting condition.

3. The oral pharmaceutical composition in the form of a capsule of isotretinoin according to claim 2 wherein composition exhibits mean fed/fasted ratio of AUC0-t value of about 0.9 to about 1.40.

4. The oral pharmaceutical composition in the form of a capsule composition according to claim 1 wherein the composition is in the form of a dispersion which is further filled into the capsules.

5. The oral pharmaceutical composition in the form of a capsule composition according to claim 1 wherein the isotretinoin is micronized and has D90 less than 30 μm.

6. The oral pharmaceutical composition in the form of a capsule composition according to claim 1 wherein the isotretinoin is present in an amount of about 5.5% to about 15% based on the total weight of the composition.

7. The oral pharmaceutical composition in the form of a capsule composition according to claim 1 wherein the composition further comprises a surfactant.

8. The oral pharmaceutical composition in the form of a capsule composition according to claim 7 wherein the surfactant is selected from the group consisting of anionic, cationic or non-ionic surfactants, sorbitan fatty acid esters; polysorbates; mononylphenyl ethers of polyethyleneglycols; dioctyl sodium sulfosuccinate, sodium lauryl sulphate, lecithin, fatty acid esters of propylene glycol, fatty acid esters of glycerol, poloxamers, and mixtures thereof.

9. The oral pharmaceutical composition in the form of a capsule according to claim 1, wherein the composition releases not less than 50% of isotretinoin in 15 minutes when measured in United States Pharmacopeia (USP) type II dissolution apparatus, paddle at 75 rpm, in 900 mL of pH 7.4 phosphate buffer with 70 mg/L pancreatin and 4.5% LDAO as 30% solution with spiral coated sinker.