Improved bioequivalence assessment of topical dermatological drug products using dermatopharmacokinetics.

Purpose: A dermatopharmacokinetic (DPK) approach, in which drug levels in the stratum corneum (SC) are measured as a function of time post-application and post-removal of the product using tape-strip sampling in vivo in humans, has been considered for the comparative assessment of topical bioavailability. Its application to-date has been limited by contradictory results and concerns that variability in the method necessitates large numbers of treatment sites and volunteers. The objective of this study was to test whether a revised protocol could better assess bioequivalence.

Determining bioequivalence of topical dermatological drug products by tape-stripping.

The maximum level of drug in the stratum corneum (C(max)) and the area under the curve of drug level in the stratum corneum versus time (AUC) have been proposed as metrics for assessing bioequivalence of topical drugs. These metrics, which require that concentrations be measured at eight or more times, were developed for drugs that are absorbed into the bloodstream, and are less appropriate for topical drugs. Concentrations of topical drugs are measured by tape-stripping, and it is difficult to make a large number of precise measurements due to the limited amount of available skin.

Optimizing metrics for the assessment of bioequivalence between topical drug products.

Purpose: Stratum corneum tape stripping post-application of a drug product followed by analysis of the active agent in this tissue layer is an approach being seriously considered for the comparative assessment of topical bioavailability. Key issues revolve around how best to perform this experiment and interpret the data.

Methods: Using previously published results from a comparative study of three 0.

Influence of manufacturing process on tabletting ability of powder: comparison between blending, grinding, and spray drying of two formulations made of theophylline and lactose/cellulose or Cellactose.

Three manufacturing processes were applied to two formulations composed of 20% anhydrous theophylline associated with either 20% microcrystalline cellulose and 60% lactose or 80% Cellactose. The processing method (dry blending, grinding, or spray drying) and the formulation were investigated through the comparison of the physical and flow characteristics and the compactibility of the end products. The results demonstrated that the formulation had a major effect on the mechanical properties, with binary blends exhibiting a higher resistance than ternary ones, whereas flow properties and densification depended on the process.