[Formulation and analysis of suppositories containing papaverine hydrochloride. Part 2. In vitro membrane diffusion studies].

Rectal suppositories with 0.10 g/2.0 g Papaverine hydrochloride content were made with 12 different vehicles. The membrane diffusion method was used to study the factors influencing the in vitro drug liberation. The Polysorbate 20 and 61 tenside pair, the optimal concentration of which was 5% each, was found to influence diffusion favourably. Neutral oils softening the consistency (Miglyol 812 and Estasan), similarly in 5%, also had a favourable effect on the in vitro diffusion by increasing the spreading properties. As to the lipophil suppository masses with high and low hydroxyl numbers, only the latter could be used favourably. The 6-month-long storage resulted in drug retention in several experimental series. Correlation was found in several cases between the physical parameters of the suppositories and their in vitro drug liberation. Finally, with the help of linear regression calculation and in view of the in vitro relative bioavailability values the optimal vehicle is suggested for the formulation of suppositories containing Papaverine hydrochloride. The triglyceride type Estaram 299 was found to be the most suitable in every respect, either in itself or combined with 5% neutral oil.