A method was developed for varying the pH of the medium during dissolution rate studies of timed-release tahlets with the aid of compressed, totally soluble, alkaline powder mixtures. Commercial as well as experimental timed-release capsules or tablets were used as models, and dissolution rates were determined at pH 1.1, 2.4, and 7.4. The system can be applied to other pH values or other variations of the dissolution medium ( e g . , ionic strength) to: ( a ) correlate in uitro release rates with bioavailability data, ( b ) discriminate between alternative formulations during dosage form development, o r ( c ) serve as a selective control procedure for a series of sustainedrelease dosage forms.
Keyphrases Dissolution rate-timed-release tablets, continuous determination as a function of pH Dosage forms-timed-release tablets, dissolution rate, continuous determination as a function of pH Tromethamine-buffer system for dissolution rate studies of timed-release tablets as a function of pH LJltrapure grade, 99.9%; Aldrirh Chemiral Co., Milwaukee, Wis. Sentry, LJnion Carhide Corp., New York, N.Y. Carver laboratory press model C, Fred S. Carver, Inc., Monomonee Falls,