Abstract
The interaction of mebeverine hydrochloride and Carbopol 934 in aqueous medium was studied using a dialysis technique. The effect of pH, drug and polymer concentration and electrolytes on such interaction were studied.
The results revealed that the interaction of the drug and the polymer (Carbopol 934) was inversely proportional to the initial concentration of the drug and directly proportional to the polymer concentration. The drug-polymer interaction was found to be pH-dependent. The presence of electrolyte decreased the interaction between the drug and the polymer Such a decrease was found to depend on the concentration of the electrolyte. The melting point (MP) and the solubility of the interaction product were found to differ from those of the original compounds.
Differential scanning calorimetery (DSC) revealed the disappearance of the endothermic peak due to mebeverine hydrochloride in the interaction product, whereas the physical mixture shows the same pattern of each component. Infra-red (IR) analysis shows a possible salt formation between the acidic polymer and the basic drug.
X-Ray diffraction revealed that the interaction product contained some crystallinity due to the presence of mebeverine. Kinetic treatment of the release data of the interaction product appeared to follow controlled diffusion mechanism and the half-lifetime t1/2 was 6 h.
Studies in guinea-pig isolated colon showed that the interaction product had a spasmolytic activity towards acetylcholine (Ach) nd barium chloride (BaCl2). The percentage antagonism was 83.8 and 67.7 towards Ach and BaCl2, respectively.