Drug release dosage forms

Pressure-controlled Disintegration of the drug release dosage form in the colon... 

Reppas, C., Shah, V. P. Dissolution testing as a prognostic tool for oral drug absorption immediate release dosage forms. Pharm. Res. 1998, 15, 11-22. 

In the treatment of chronic diseases, a long term zero order release dosage form is highly desirable as it reduces fluctuations of drug levels, reduces toxicity and increases patient compliance. Problems in the treatment of both hypertension, a lifetime disorder, and opiate addiction are associated with compliance. The goal of this research is to develop a subcutaneously injectable system which can release drug at constant rates over a long period of time. 

Fig. 10 Blood level versus time profile simulations following (A) a single dose representing 100 units of a drug from a rapidly releasing dosage (B) Three divided ddoses of 33 units each from the same rapidly releasing product and (C) a single 100 unit dose from an optimized controlled-release dosage form. A hypothetical effective level (80 units) and toxic level (160 units) are depicted. The dosing units are typically in mg and the blood level concentration units in pg or ng.

Therefore, for a nondegradable drug dosed in immediate release dosage forms, the absorption and transit in the gastrointestinal tract can be depicted as follows. Stomach ... 

Additional criteria for waiver of evidence of in vivo BA/BE are given in 21 CFR 320.22 (d)(3). For certain solid oral dosage forms (other than a delayed or extended-release dosage forms), a waiver for the submission of in vivo evidence of BA/BE is possible if the drug product has been shown to meet the requirements of an in vitro dissolution test, which in turn has been shown to correlate with in vivo data. A biowaiver may also be addressed to a reformulated solid oral dosage form identical to another drug product except for color, flavor, or preservatives for which the same manufacturer has obtained approval, if BA data are available for the approved... 

For an extended-release dosage form, at least three test time points are chosen to characterize the in vitro drug-release profile for the routine batch-to-batch quality control for approved products. Additional sampling times may be required for formulation development studies, biopharmaceutical evaluations, and drug approval purposes. An early time... 

Degim T, Eglen B, and Ocak O (2006) A sustained release dosage form of acyclovir for buccal application An experimental study in dogs. J. Drug Target 14 35-44. 

Grass et al. [69] evaluated the performance of controlled release dosage forms of the anti-thrombic drug ticlopidine using computer simulations based on data from in vitro intestinal permeability studies in various sections of the intestine of rabbit and monkey. 

Biederman J, Quinn D, Weiss M, et al Efficacy and safety of Ritalin LA, a new, once daily, extended-release dosage form of methylphenidate, in children with attention deficit hyperactivity disorder. Paediatr Drugs 5 833-841, 2003... 

Establishing in vitro in vivo correlation (IVIVC) for modified release dosage form provides a justification for waiving in vivo bioequivalence evaluation only for certain specified post approval changes. Since a correlation is dependent on the mechanism of drug release, it is not used in situations that could potentially alter its mechanism (16). 

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