Dissolution dialysis studies of metronidazole-montmorillonite adsorbates.

In the context of the potential usefulness of clays in retarding the rate of release of adsorbed drugs, dissolution dialysis studies of the release of metronidazole from montmorillonite adsorbates have been conducted. The goal was to develop a means for improving local gastrointestinal therapy of amebiasis while concurrently maintaining efficacy in treating hepatic amebiasis. At acidic pH, the clay was in a flocculated state and the rate of drug release was inhibited. This effect was apparently due to slow diffusion of the drug throughout the clay flocculate. A physical admixture of montmorillonite and metronidazole was also effective in inhibiting the rate of release of metronidazole. Upon increasing the pH to 7, the clay particles progressively deflocculated and the rate of release increased significantly.