A history of biopharmaceutics in the Food and Drug Administration 1968-1993

The history of biopharmaceutics is reviewed, beginning with its origin out of the Division of Clinical Research in The Bureau of Medicine. The reason for the creation of the Division of Biopharmaceutics, the certification of Food and Drug Administration authority over the functions it was to have, and the implementation of that authority are described. The determination of bioequivalence, the bioavailability decision rules, pharmacokinetics, and drug metabolism are explained. The reason for the development of the Scale-Up and Post Approval Regulations and how they were developed are also explained.

Evaluation of the test system used for in vitro release of drugs for topical dermatological drug products

The purpose of this research was to evaluate different parameters that can influence in vitro drug release from topical dermatological drug products such as creams, gels, and ointments. In vitro release from topical dermatological drug products was carried out by using a static diffusion cell, a synthetic membrane, and an appropriate receptor medium. The receptor medium was mixed by means of a magnetic bar rotated at 400 rpm. Experiments were designed to evaluate the influence of (i) receptor media, (ii) different lots of synthetic membranes, and (iii) agitation on drug release. Release experiments were also carried out to study inter- and intralot variability. The in vitro release test was used to evaluate the marketed glucocorticoid products. Among the parameters studied, the receptor medium was found to be the most important and critical variable that influenced drug release. The release rate ranged between 0.61 and 2.68 micrograms/cm2/min0.5 for betamethasone dipropionate, depending on the percentage of ethanol in the receptor medium. The drug release was not influenced by agitation or by different lots of synthetic membranes. Very small inter- and intralot variability was observed. These experiments establish the ruggedness of the in vitro diffusion cell test system used for the drug release measurements.

Development in release testing of topical dosage forms: use of the Enhancer Cell with automated sampling

The aim of this study was to evaluate an automated method using the Enhancer Cell and compare the release of the corticosteroid triamcinolone acetonide (TA) from commercial semisolid formulations. The method used a modified USP Apparatus 2 using the Enhancer Cell in 200 ml capacity flasks instead of the standard 900 ml flasks. The additional equipment included an adapter plate to position the flasks in the center, a cover to reduce the receptor phase evaporation and smaller sized (1/4 in.) shaft and collets. All products were evaluated prior to their expiration date. Effects of system variables such as the temperature and composition of the receptor medium, stirring speed, and the choice of membrane on the drug release were evaluated. Statistical analysis was carried out using SAS Ver. 6.07 and the slopes and intercepts (of the cumulative release/unit area versus square root of time plots) were compared. TA release was a linear function of the square root of time (P < or = 0.0001), in accordance with Higuchi's model (r2 > or = 0.9 in most cases). Temperature (32 and 37 degrees C) did not affect the drug release (P > 0.32) but a significantly higher release rate was observed (P < or = 0.0001) at 50 degrees C. Stirring speed (50, 100, 200 rpm) (P > 0.26) and receptor media composition (38 and 76% ethanol) (P > 0.68) did not significantly alter the release rates. Membrane selection (regenerated cellulose, polyethylene, and rat skin) was found to be a significant variable (P < or = 0.004). This study demonstrates the use of the Enhancer Cell as an automated quality control tool in the in vitro release testing procedure for semisolid drug formulations.