Abstract
ALTHOUGH urinary excretion studies (Campbell, Nelson & Chapman, 1959; Chapman, Shenoy & Campbell, 1959; Shenoy, Chapman & Campbell, 1959) have been used as a technique to evaluate prolonged-release dosage forms of amphetamine, the significance of the results is in doubt because of the use of non-specific assay methods and the failure to control urinary pH. The use of radioactive material has indicated the similarity between a dose of 5 mg amphetamine three times a day and a 15 mg prolonged release preparation (Rosen, Tannenbaum, Ellison, Free & Crosley, 1965).