Physicochemical stability of papaverine hydrochloride-phentolamine mesylate mixtures used for intracavernous injection: a preliminary evaluation.

Physicochemical stability of intracavernous injections of 30 mg. per ml. papaverine hydrochloride with 0.5 or 1.0 mg. per ml. phentolamine mesylate used to induce erection in patients with impotence was examined. The samples were stored at room temperature, in the refrigerator at 4C and in the freezer at -20C for 6 months. The examination consisted of visual observation for change in color or evidence of precipitation, measurement of pH and thin layer chromatography at different intervals. During the 6 months of storage no change had occurred in pH, color development, precipitation or formation of new moieties. Therefore, the aforementioned injection solutions of papaverine hydrochloride with phentolamine mesylate can be dispensed safely with instruction to patients for adequate storage and manipulation.