[Interaction between macromolecular adjuvants and drugs. 24. Improvement of the solubility characteristics of benzodiazepine derivatives with polyvinylpyrrolidone].

Solubility and dissolution rate of the benzodiazepine derivatives chlordiazepoxide, diazepam, medazepam, nitrazepam and clonazepam has been improved by adding polyvinylpyrrolidone (PVP K 30). Increasing concentrations of the carrier as well as the preparation of coprecipitates usually supported the effect (less physical mixtures). Regarding to the dissolution PVP has a positive effect on the initial phase of dissolution particularly. Under the experimental conditions described an interaction between drugs and carrier was revealed increasing with the concentration of PVP. These interactions were of endothermic character. Connections between dissolution and binding results were evident. Differential thermal analysis and x-ray diffractometric studies probably refer to a partial amorphous form of the drugs, especially in coprecipitates with a higher concentration of PVP.