Bioavailability of Different Oral Dosage Forms of Cimetidine in Dogs. The bioavailability of cimetidine (200 mg) after oral administration to awake dogs was increased significantly by using tablets containing alginate. In addition the timespan was prolonged during which therapeutic plasma concentrations were maintained. Release and absorption of cimetidine were retarded from tablets containing methacrylic acid-copolymers, but the bioavailability was decreased from this dosage form and therapeutic plasma concentrations were not reached.