Em. Ouriemchi et al., ORAL DOSAGE FORMS WITH A CORE AND SHELL WITH THE SAME POLYMER CONTAINING DIFFERENT DRUG CONCENTRATIONS, International journal of pharmaceutics, 102(1-3), 1994, pp. 47-54
In order to achieve the controlled release of a drug, dosage forms mad
e of a core and shell were developed and studied. The core and shell w
ere obtained by dispersing the drug in the same polymer, with differen
t concentrations of drug in the core and in the shell. A numerical mod
el taking into account all the known facts was built and tested. The p
rocess is as follows: the liquid diffuses into the polymer, dissolves
the drug and enables the drug to diffuse out of the form through the l
iquid located in the polymer. Four parameters appear to be of great in
terest: the radius of the core, the thickness of the shell, and the in
itial concentrations of drug in the core and in the shell. The results
are given by using either the kinetics of release of drug or the rate
at which the drug is released during the process.