DEVELOPMENT OF A DISSOLUTION MODEL FOR SLIGHTLY SOLUBLE DRUGS

A kinetic dissolution model was developed for interpretation of the di ssolved plots derived from the in vitro testing of the conventional so lid preparations of nimodipine and nifedipine. It was shown that the d issolution rates of drug particles were influenced by two factors : th e difference between the saturated concentration and the particle conc entration of the solute at time t, and the total surfaces of the parti cles at time t. It was assumed that the total surfaces altered accordi ng to variations of particle number and size. A model was therefore de veloped which consisted of three drug states, namely the solid prepara tion, the fine particles and the dissolved solution. The dissolution c urves were well fitted, and it was evident that the values of the para meters in this model can reflect the characteristics of the preparatio n.