The effect of some non-ionic surfactants and a polyoxyethylene glycol on the dissolution rate of griseofulvin

Abstract

Measurements of the dissolution rate of griseofulvin in water, four non-ionic surfactants, and a polyoxyethylene glycol have been made. These results are analysed in terms of a zero order rate constant (k1) for transfer of the drug from the crystal to the bulk of the solution, and a first order constant (k2) for the reverse process. Surfactants greatly increase the dissolution rate, increasing k1 and decreasing k2. Polyoxyethylene glycol is not so effective as the surfactants at increasing dissolution rates. In an attempt to interpret k1 and k2, it appears that both chemical and transport processes are involved in the dissolution, the presence of surfactant decreasing the energy change for transferring griseofulvin molecules from the crystal to the solution.