Comparison of dissolution behavior of scopolamine butylbromide between ethical and over-the-counter drugs

Abstract

Marketing authorization holders do not disclose any information on the pharmaceutical properties of overthecounter drugs (OTC).When a drug is switched from a prescription drug to OTC, pharmacists can acquire that information from the corresponding ethical drug (ED) through the package insert, interview form, and so on. However, the pharmaceutical equivalence between ED and OTC is unclear. In this study, we examined the drug dissolution behavior of both ED and OTCs containing scopolamine butylbromide. Dissolution tests were performed by the paddle method using Japanese Pharmacopeia (JP) XV test fluids at pH 1.2, 4.0 and 6.8 and water based on the guidelines for bioequivalence studies of generic products. The dissolution profiles of OTCs diŠered significantly from ED showing a similarity factor (f2) value ranging from 8.9 to 42.9. Time until 85dissolution ranged from 23 to 95 min and from 17 to 174 min at pH 1.2 and pH 6.8, respectively. Then JP XV disintegration tests were conducted to investigate diŠerences in the disintegration process. The disintegration time of preparations showing delayed dissolution was prolonged compared to that of others, suggesting that the disintegration of the tablet or capsule is one of the important factors aŠecting the drug dissolution. These diŠerences in the disintegration and drug dissolution might cause diŠerences in the bioavailability of the drug. For patient safety, more detailed product information of OTCs should be supplied by the manufacturer, and not be assumed from that of corresponding ED. © 2011 The Pharmaceutical Society of Japan.