Purpose: Entacapone, a catechol-O-methyltransferase inhibitor, is poorly water soluble (BCS class IV). The dissolution profile of pure Entacapone is improved in the presence of an alkaline buffer and after addition of a surfactant by facilitating the drug release process at the solid/liquid interface. Rationale: According to USP the best dissolution medium for Entacapone is phosphate buffer 5.8 in type II paddle-type apparatus with a paddle speed of 50 rpm. Materials and Methods: In this article an effect of various parameters (buffer, surfactant, and RPM) on the dissolution profile of Entacapone is studied by applying factorial design 33 (phosphate buffer- 5.3, 5.8, and 6.8; sodium lauryl sulfate- 0.5%, 1.0%, and 1.5%; rotation speed of paddle- 50, 75, and 100). Pure Entacapone pellets were formed using a hydraulic press. Conclusion: The release profile data revealed that the dissolution profile of Entacapone is remarkably improved in the alkaline medium (6.8), addition of surfactant does not affect the release profile, whereas increasing RPM of the paddle reduces the dissolution profile; hence it can be stated that Entacapone dissolution is pH dependent, showing maximum dissolution and pH 6.8 which is contradictory to the conditions specified in USP 2010.
Key words: Dissolution rate, entacapone, sodium lauryl sulfate, solubility