Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Capsules
Reexamination Certificate
2000-03-06
2002-01-01
Rose, Shep K. (Department: 1614)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Capsules
C424S452000, C424S461000, C514S383000, C514S384000
Reexamination Certificate
active
06335032
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an orally administrable solid dosage form comprising a compacted ribavirin composition. The compacted ribavirin composition of this invention has an advantageously high tap density as well as surprisingly fast disintegration and dissolution rates and contains a freely flowing ribavirin of uniform physical characteristics which is substantially free of other polymorphic forms.
Ribavirin is an antiviral agent which is currently being administered in association with interferon alpha-2b to treat patients with chronic hepatitis C infections.
Ribavirin 200 mg capsules are manufactured and marketed by ICN Pharmaceuticals in Canada under the trade name Virazole™ capsules. The ribavirin used to make the ribavirin composition in the Virazole capsules is a non-freely flowing powder with low and variable tap densities in the range of 0.320 to 0.449 g/mL. A ribavirin composition with a tap density of at least 0.6 g/mL is needed for the uniform filling of the 200 mg capsules. It would be desirable for the ribavirin composition to have a uniformly high tap density of at least 0.6 g/mL to fill any capsule and to avoid excessive weight variation and excessive packing in the capsule shell during the capsule filling operation especially in the high speed capsule filling equipment which operate at a fill rate of over 20,000 capsules per hour.
Dry compacting of the ribavirin formulation would be an attractive solution to this problem so long as the heat produced during the compaction operation does not cause the formation of ribavirin polymorphic forms, which forms are unacceptable for obtaining health registration.
The Virazole capsules exhibited inconsistency in meeting the dissolution specifications which requires that 80% of the ribavirin be dissolved in water in 30 minutes. The disintegration times of the Virazole composition were typically around 20 minutes.
There is a need for a ribavirin composition with a tap density of at least 0.6 g/mL and having improved dissolution rates and reduced disintegration times. There is also a need to compact the ribavirin composition to achieve such high tap densities while maintaining the ribavirin in the physical state substantially free of polymorphic forms.
SUMMARY OF THE INVENTION
The invention provides an orally administrable solid dosage form comprising a rapidly dissolving compacted ribavirin composition comprising ribavirin and a pharmaceutically acceptable disintegrant wherein said composition after dry compaction has a tap density of at least about 0.6 g/mL and wherein more than 80% by weight of the ribavirin dissolves in water in about 30 minutes.
The invention also provides a rapidly dissolving compacted ribavirin composition comprising:
(a) an antivirally effective amount of ribavirin;
(b) an effective amount of at least one filler selected from the group consisting of lactose anhydrous, lactose monohydrate, sucrose, mannitol, microcrystalline cellulose, pregelatinized starches, dibasic calcium phosphate dihydrate,calcium sulfate dihydrate and calcium sulfate trihydrate;
(c) an effective amount of a pharmaceutically acceptable disintegrant selected from the group consisting of croscarmellose sodium, sodium starch glycolate, corn starch, pregelatinized starches, sodium carboxymethyl cellulose, potato starch, microcrystalline cellulose, cross-linked polyvinylpyrrolidone,magnesium aluminium silicate, bentonite, alginic acid and alginates; and;
(d) an effective amount of a lubricant selected from the group consisting of magnesium stearate, calcium stearate, zinc stearate, talc, propylene glycol, PEG 4000, PEG 5000, PEG 6000, and stearic acid;
and, wherein the tap density of the compacted composition is at least about 0.6 g/mL.
In a preferred embodiment, the invention further provides is a rapidly dissolving compacted ribavirin composition comprising of:
Ingredient
mg
Ribavirin USP
150.0 to 250.0
Lactose Monohydrate NF
30.0 to 50.0
Microcrystalline Cellulose NF
37.5 to 62.5
Croscarmellose Sodium NF
4.5 to 7.5
Magnesium Stearate NF
2.25 to 5.0
and wherein the tap density of the compacted composition is at least about 0.6 g/mL.
In a preferred embodiment, the invention provides a rapidly dissolving compacted ribavirin composition comprising:
Ingredient
mg
Ribavirin USP
200.0
Lactose Monohydrate NF
40.0
Microcrystaliine Cellulose NF
50.0
Croscarmellose Sodium NF
6.0
Magnesium Stearate NF
4.0
wherein the tap density of the compacted composition is at least about 0.6 g/mL; and
wherein the ribavirin is substantially free of polymorphic forms of ribavirin.
In another aspect, this invention provides a method of producing a rapidly dissolving compacted ribavirin composition which comprises the steps of:
(a) admixing an antivirally effective amount of ribavirin, an effective amount of a pharmaceutically acceptable disintegrant, and an effective amount of at least one filler for a time sufficient to form a homogeneous mixture;
b) compacting the homogeneous mixture of Step (a) at a compressing force in the range of about 50 to about 75 kN for a time sufficient to produce an acceptable compact wherein the ribavirin is substantially free of polymorphic forms; and
c) admixing the acceptable compact of Step (b) with an effective amount of a lubricant for a time sufficient to produce a rapidly dissolving compacted ribavirin composition.
DETAILED DESCRIPTION OF THE INVENTION
We have surprisingly discovered that we can consistently manufacture a uniform ribavirin composition which consistently meets and exceeds the dissolution specifications which requires that 80% of the ribavirin be dissolved in water in 30 minutes; about 90% of the ribavirin in the compacted ribavirin compositions of this invention is consistently dissolved in water in 15 minutes and about 100% of the ribavirin from the compositions of this invention is dissolved in 30 minutes. The disintegration time of the ribavirin compositions of this invention was reduced to less than 10 minutes compared to the Virazole capsule composition which disintegrated in 20 minutes (see Table 1).
The ribavirin composition of this invention was blended and passed through a roller compactor at a compressing force in the range of about 50 to 75 kiloNewtons (“kN”) for a time sufficient to produce an acceptable compact. An “acceptable compact” as used herein means a compact that is in the form of a ribbon which is homogeneous, and almost completely free, i.e., more than 95% free, of lamination and flaking, and substantially free of polymorphic forms of ribavirin. A compressing force in the range of 50 to about 75 kN consistently produced an acceptable compact. Typically suitable screw speeds and (on the Fitzpatrick roller/compactor) roller speeds include (1) a screw speed of 40 revolutions per minute (“RPM”) with a roller-speed of 10 RPM; (2) a screw speed of 30 RPM with a roller speed of 7 RPM; and (3) a screw speed of 22 RPM with a roller speed of 5 RPM. No definitive range of screw speeds and roller speeds was able to be deduced from these results. However we have discovered that an acceptable compact is consistently obtainable by maintaining the compressing force in the range of about 50 to about 75 kN. The compacted material is milled, combined with a lubricant and the resulting tap density of the resulting ribavirin composition is at least 0.6 g/mL and preferably it is significantly higher, e.g., in the range of about 0.75 to about 0.85 g/mL. The compacted ribavirin composition of this invention surprisingly has substantially uniform physical and chemical characteristics and the ribavirin in the compacted ribavirin composition is substantially free of polymorphic forms of ribavirin, i.e., there are no signs of polymorphic change in the compacted ribavirin as determined by differential scanning calorimetry. This result is particularly surprising in view of the large amount of heat generated during the compaction step which could normally produce polymorphic forms.
The rapidly dissolving ribavirin composition of this invention is stable and
Bowen Frank E.
Chaudry Imtiaz A.
Liebowitz Stephen M.
Stupak Elliot I.
Vadino Winston A.
Hoffman Thomas D.
Rose Shep K.
Schering Corporation
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