Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Capsules
Reexamination Certificate
1999-04-06
2001-05-29
Spear, James M. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Capsules
C424S452000, C424S464000, C424S465000
Reexamination Certificate
active
06238695
ABSTRACT:
FIELD OF THE INVENTION
The present invention provides improved oral dosage form formulations of efavirenz that are useful in the inhibition of human immunodeficiency virus (HIV), the prevention or treatment of infection by HIV, and in the treatment of the resulting acquired immune deficiency syndrome (AIDS). In particular, the present invention relates to compressed tablets or capsules comprising efavirenz that contain one or more disintegrants that enhance the dissolution rate of the efavirenz in the gastrointestinal tract thereby improving the rate and extent of absorption of efavirenz in the body. The present invention also relates to the process of making such tablets or capsules.
BACKGROUND OF THE INVENTION
In the dose titration of a patient, the objective is to attain and maintain a blood level of drug substance that exceeds the minimum effective level required for response but does not exceed the minimum toxic level. Absorption of a drug from an oral dosage form such as a tablet or a capsule can be affected by properties of the formulation and its method of manufacture. This is particularly true when the drug has low solubility in water, has a hydrophobic nature, and/or is administered in high therapeutic doses. In such cases, dissolution of the drug from the dosage form in the gastrointestinal tract can be the limiting factor that determines the rate and extent of absorption of drug into the body. Changes in the composition and/or method of manufacture of the dosage form can affect the dissolution rate.
An active area of research is in the discovery of new methods of drug formulation. Drug release from a solid dosage form can be enhanced by addition of materials referred to as disintegrants. Disintegrants are substances or a mixture of substances added to the drug formulation that facilitate the breakup or disintegration of the tablet or capsule contents into smaller particles that dissolve more rapidly than in the absence of the disintegrant (Handbook of Pharmaceutical Excipients, Ainley Wade and Paul J. Weller eds., 2d ed. 1994; The Theory and Practice of Industrial Pharmacy, Leon Lachman, Herbert A. Lieberman, and Joseph L. Kanig eds., 3rd ed. 1986; Disintegrating Agents in Hard Gelatin Capsules, John E. Botzolakis and Larry L. Augsburger, Drug Development and Industrial Pharmacy 14(1), 29-41 1988). Materials that serve as disintegrants include starches, clays, celluloses, algins, gums and cross-linked polymers. A group of disintegrants referred to as “super-disintegrants” are generally used at a low level in the solid dosage form, typically 1 to 10% by weight relative to the total weight of the dosage unit. Examples of super-disintegrants are croscarmelose, crospovidone and sodium starch glycolate, which represent examples of a cross-linked cellulose, a cross-linked polymer and a cross-linked starch, respectively. EP 0,301,006 describes the use of super-disintegrants to enhance the dissolution properties of tablet and capsule formulations containing methylprednisolone, a glucocorticoid steroid.
It is desirable to develop formulations where the tablet or capsule disintegrates rapidly and the pharmaceutical agent dissolves readily. This is especially important where the pharmaceutical agent is highly insoluble and/or must be administered in high-strength dosage forms.
This invention relates to new solid oral dosage form formulations containing the HIV drug efavirenz that enhance the dissolution rate of efavirenz in the gastrointestinal tract in order to improve the rate and extent of absorption into the body, thereby improving its therapeutic effect.
SUMMARY OF THE INVENTION
The present invention provides improved solid dosage forms containing the non-nucleoside HIV reverse transcriptase inhibitor (NNRTI) drug efavirenz that disintegrate and dissolve rapidly thereby enhancing the therapeutic characteristics of the formulation. The present invention also provides processes for the manufacture of capsule and tablet formulations of efavirenz that allow a significantly higher strength of efavirenz to be formulated in a single capsule or tablet.
An embodiment of the present invention includes formulations and processes for manufacturing tablets or capsules containing efavirenz using a high-shear, wet granulation step where a very high level of a super-disintegrant such as sodium starch glycolate is included in the wet granulation step.
Another embodiment of the present invention uses the super-disintegrant sodium starch glycolate in both a wet granulation and a dry blending step in the manufacturing process of tablets and capsules containing efavirenz. In a preferred embodiment of the manufacturing process the quantity of the sodium starch glycolate used in the wet granulation step is in the range from about 20% to about 75% by weight relative to the total dry weight of materials being granulated in the wet granulation step. More preferably the super-disintegrant component in the wet granulation step is in the range from about 20% to about 55% by weight relative to the total dry weight of the materials being granulated in the wet granulation step.
In another embodiment of the present invention the range for the efavirenz in the wet granulation step can vary from about 25% to about 80% by weight relative to the total dry weight of the materials being granulated in the wet granulation step. More preferably the drug substance component will range from about 45% to about 80% by weight relative to total dry weight of the ingredients in the wet granulation step.
In the present invention a surfactant such as sodium lauryl sulfate is preferably used in the wet granulation step of the process for the manufacture of the capsules or tablets of the present invention. The sodium lauryl sulfate is preferably dissolved in the wet granulating fluid. Most preferably the sodium lauryl sulfate will range from about 0.1% to about 5% by weight relative to the total dry weight of the materials being granulated in the wet granulation step.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides improved oral dosage form formulations of efavirenz that are useful in the inhibition of human immunodeficiency virus (HIV), the prevention or treatment of infection by HIV, and in the treatment of the resulting acquired immune deficiency syndrome (AIDS). In particular, the present invention relates to compressed tablets or capsules comprising efavirenz that contain one or more disintegrants that enhance the dissolution rate of the efavirenz in the gastrointestinal tract thereby improving the rate and extent of absorption of efavirenz in the body. The present invention also relates to the process of making such tablets or capsules.
The active ingredient of the formulation of the present invention is the NNRTI efavirenz, which is present in a therapeutically effective amount. Methods for the manufacture of efavirenz are disclosed in U.S. Pat. No. 5,519,021. The disclosure of U.S. Pat. No. 5,519,021 in its entirety is hereby incorporated by reference. Efavirenz is (s)6-chloro-4-(cyclopropylethynyl)-1,4-dihydro-4-(trifluoromethyl)-2H-3,1-benzoxazin-2-one.
In addition to the active ingredient, solid dosage forms contain a number of additional ingredients referred to as excipients. These excipients include among others diluents, binders, lubricants, glidants and disintegrants. Diluents are used to impart bulk to the formulation to make a tablet a practical size for compression. Examples of diluents are lactose and cellulose. Binders are agents used to impart cohesive qualities to the powered material ensuring the tablet will remain intact after compression, as well as improving the free-flowing qualities of the powder. Examples of typical binders are lactose, starch and various sugars. Lubricants have several functions including preventing the adhesion of the tablets to the compression equipment and improving the flow of the granulation prior to compression or encapsulation. Lubricants are in most cases hydrophobic materials. Excessive use of lubricants can result in a formulation with reduced d
Buehler John D.
Landmann Brian R.
Makooi-Morehead William T.
Dolan Peter
DuPont Pharmaceuticals Company
Fuzail Kalim
Spear James M.
Wilk-Orescan Rosemarie
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