The process of drug release out of dosage forms made of the drug dispersed in a lipidic Gelucire is considered. The process is based on the following three ideas: first, the liquid dissolves the drug in contact with it and occupies its previous place; second, the drug diffuses out of the dosage form through the liquid located in it, and third, the diffusivity of the drug varies with the concentration of the liquid in an exponential way. These assumptions are drawn from the following experimental observations: no change in dimension of the dosage form takes place; the amount of drug release after a long time is greater than that evaluated with a constant diffusivity. Good agreement is obtained between the kinetics of drug release obtained either by calculation or from experiments using in vitro tests.
The process of in-vivo drug transfer is very complex in the case of oral dosage forms with controlled release. A numerical model taking all the known facts into account, including the release of the drug controlled by diffusion through the dosage form along the gastrointestinal tract, the kinetics of absorption in the blood compartment and the kinetics of elimination was constructed. Various parameters intervene in an important manner for a given drug: the size of the dosage form which is associated with the rate of release of the drug, and the dose frequency in multidosing. Some emphasis is placed upon the gastrointestinal tract time which appears to be the main and first parameter to be considered in preparing a dosage form.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.