A controlled release papaverine tablet (Papacontin): a study in normal volunteers.

1. A controlled release tablet containing 300 mg of papaverine hydrochloride was compared with a capsule containing the same dose. 2. The in vitro release pattern showed a steady dissolution of the tablet, with release of the papaverine over 10 h, whereas the capsule release time was 40 min. 3. Plasma levels in volunteers who were given the tablet showed a rapid rise to therapeutic levels (150-300 ng/ml) within 1 h, and maintenance of these levels for 10-12 h, with no accumulation on repeated 12 hourly dosage. Administration of the capsule produced early peaking and a subsequent rapid fall in plasma levels.