Effect of docusate sodium on drug release from a controlled-release dosage form

This study was designed to determine the effect of a clinically used surfactant, docusate sodium, on the release of chlorpheniramine from a controlled-release dosage form (encapsulated coated pellets). In vivo treatments consisted of the controlled-release capsule alone or with 200 mg of docusate sodium. Plasma chlorpheniramine levels were determined, and the AUC was calculated. No significant difference in AUC values was observed between the two treatments. At a concentration below the CMC, docusate sodium enhanced the in vitro drug release rate. The surfactant exerted a greater effect on the release of the first one-third of the drug contained in nonwax-coated pellets. At the CMC, 0.02% (w/v), docusate sodium rapidly entrapped chlorpheniramine in micelles. The overall enhanced dissolution rate in vivo may have been offset by micellar drug entrapment.