ANDA IN VIVO BIOEQUIVALENCE TESTING: PILOT STUDIES MAY BE USEFUL

Executive Summary

ANDA IN VIVO BIOEQUIVALENCE TESTING: PILOT STUDIES MAY BE USEFUL in determining the appropriate assay, sampling times and duration of study in post-1962 drugs unfamiliar to investigators, FDA Div. of Bioequivalence Branch Chief Charles Ise, PhD, suggested at an August 7 Regulatory Affairs Professionals Society workshop in Morristown, N.J. "With the number of post-62 drugs avaiIable for ANDA, it is not always possible to prepare proper guidance, for all the drugs," Ise stated. "In the case where the FDA has no guidance, a pilot study may be extremely useful." Ise pointed out that a pilot study "with four-to-six subjects" will indicate "whether a particular assay is useful in assaying blood samples from an in vivo bioequivalence study." He also noted that sampling times and duration of the study "can readily be assessed from a pilot study," as well as the number of subjects required for the study "with the proper power." Since November 1984, Ise noted, FDA's Bioequivalence Div. has prepared guidelines for bioequivalence testing of 13 drugs. The list includes guidelines for amiloride, carbamazepine, clonidine, lorazepam, propoxyphene napsylate/acetaminophen, and tolazamide. More recent1y, the division has published bioequivalence testing guidelines for allopurinol, disopyramide, doxepin, indomethacin, metoclopramide, and verapamil. Ise also noted that the bioequivalence testing guide for diazepam has recently been revised. Asked about the bioequivalence requirements for a post-1962/0TC combo Ise responded: "This would have to be submitted in the form of a petition first and a decision would be made whether it would be accepted [for ANDA filing] first and if it were acceptable, we would then make that decision of what the requirements would be." Ise also urged companies to submit dissolution data and in vivo bioequivalence study results concurrently. Ise explained that while the agency has reviewed dissolution data prior to receiving in vivo bioequivalence study results, this approach "resulted in confusion for both the drug firms and the Division of Bioequivalence in tracking down whether all bioequivalence requirements had been met by the firm."