Solid-state study of Captopril and Metoprolol Tartrate binary system

The structural and thermal characterization of Captopril (CA) and Metoprolol Tartrate (MT) pure compounds and binary system have been obtained. Solid-liquid equilibrium for binary mixture CA-MT was investigated using differential scanning calorimetry. Simple eutectic behavior for this system was observed. The experimental solid-liquid phase temperatures were compared with predictions obtained from available eutectic equilibrium models. The results indicate non-ideality in this mixture. The negative value of the mixing enthalpy indicates the presence of clusters with hydrogen bonds formation in the melt, as confirmed by FT-IR measurements. The preparation of ground mixtures demonstrated that the application of mechanical energy can result in the partial melting of the sample because of the eutectic behavior. Trans-cis iso-merization of CA was observed for the samples annealed at high temperature, anticipated due to the presence of MT in the system.