Immediate drug release from solid oral dosage forms.

Fast drug release from solid dosage forms requires a very fast contact of the vast majority of the drug particles with the solvent; this, however, is particularly delayed in tablets and granulations. Starch and cellulose substances favor the matrix disintegration during the starting phase and the generation of the effective dissolution surface of the drug substance, thereby. To investigate the very complex interrelation between the functionality of commonly used excipients and the structural effects of the production processes, wettability, porosity, water uptake, and drug release rates of several ketoprofen-excipient preparations (powder blends, granulations, tablets) were measured.

Comparison of effects of different ointment bases on the penetration of ketoprofen through heat-separated human epidermis and artificial lipid barriers.

In vitro tests were performed to understand the effects of topical vehicles on the permeability of ketoprofen through artificial lipid barriers and heat-separated human epidermis consisting of stratum corneum and viable epidermis. Ketoprofen was selected as the model penetrant. Human epidermis and artificial membranes made from several mixtures of free fatty acids, cholesterol, cholesteryl ester, ceramides, and triglycerides were used as permeation matrices in untreated conditions and after pretreatment with petrolatum, wool alcohols ointment, or triglycerides.

Statistical testing of drug accumulation in skin tissues by linear regression versus contents of stratum corneum lipids.

This investigation is a contribution to standardization in in vitro drug penetration measurements using excised human skin and to statistical treatment of the observations. The wide variations observed in measurements of drug accumulation in and drug permeation through the stratum corneum are caused not only by analytical errors but also by the variability of the horny layer lipid composition. The last-mentioned systematic influence can be compensated for by stepwise (multiple) linear regression using the contents of the main lipid classes as independent variables.

Methoxy-polyethoxy side-chain silastomers as materials controlling drug delivery by diffusion flux.

The density of a diffusion medium and the solubility of the diffusant in this material are predominant parameters which control the diffusion flux. Side-chain silastomers can be structurally modified in such a manner that density and polarity are widely varied and adjustable to distinct conditions. The synthesis of cross-linked methoxy-polyethoxy side-chain polysiloxanes is performed by reaction of alpha, omega-bis-(trimethyl-silyloxy)-poly-(methyl-hydrogen-siloxane), alpha, omega-divinyl-poly-(dimethyl-siloxane), and 4-propenyloxy-(4'-methoxy-polyethoxy)-biphenyl.