CHLORHEXIDINE GLUCONATE BIOEQUIVALENCE TESTS FOR EACH INDICATION

CHLORHEXIDINE GLUCONATE BIOEQUIVALENCE TESTS FOR EACH INDICATION should be a condition for ANDA approval, Stuart maintained in a recent petition to FDA. The firm petitioned FDA to "require an applicant sponsoring an ANDA for topical antimicrobial products containing chlorhexidine gluconate to perform each of the bioequivalency tests set forth [by Stuart] in . . . this petition, in order to demonstrate that the applicant's new drug is bioequivalent to the referenced listed drug for every indication for which the listed drug is labelled." Stuart markets four OTC chlorhexidine gluconate topical products: Hibiclens 4% solution and sponge, Hibistat 0.5% solution, and Hibitane 0.5% tincture. Xttrium Labs received approval to market to chlorhexidine 4% products, Exidine aerosol and solution, via the full NDA process in December 1984. Stuart noted that its petition "is prompted by FDA's position that "in evaluating ANDAs for new topical drugs containing chlorhexidine gluconate, it will rely on the 'surgical scrub glove juice' test to assess whether the new drug is bioequivalent . . . to the referenced product." FDA stated its bioequivalance criteria in a September letter to Stuart denying the firm's request that chlorhexidine gluconate products not be approved through the ANDA process. Asserting that FDA's bioequivalence criteria is not adequate, Stuart said: "Results of the surgical scrub glove juice test are an appropriate measure of bioequivalency and therapeutic equivalency for use of such products as presurgical scrubs. Such results are not, however, a meaningful or valid measure of bioequivalency or therapeutic equivalency for the other uses for which chlorhexidine gluconate products are approved and labelled." The firm noted that other approved uses "include patient preoperative skin preparation, health care personnel hand wash, skin wound cleansing and injection site preparation." Stuart argued that "differences in formulations which might not cause differences in bioavailability and effectiveness (as a surgical scrub) might very well do so in other conditions." As an example the firm cited the differing directions for use of Hibiclens as a personnel hand wash and presurgical scrub. "It cannot be assumed that a new formulation that releases the active ingredient as effectively as Hibiclens during two threeminute presurgical scrubs will be equivalent to Hibiclens under the very different conditions of a personnal hand wash" for which the "label prescribes a 15-second brushless wash and rinse with 5 ml of the product." Specifically, Stuart is requesting that FDA require separate in vivo studies to establish bioequivalence of generic products as presurgical scrubs, preoperative skin preparations, injection site preparations, and health care personnel hand washes. For example, to establish equivalence as a preoperative skin preparation, Stuart recommends a study of "at least thirty normal subjects" with a baseline bacterial population of at least 10 on the abdomen and 10 in the axillae who have avoided "the use of medicated soaps, deodorants, lotions, shampoos . . . and test-site contact with solvents, detergents, acids or bases . . . for one week prior to testing." The preoperative skin study recommended by Stuart uses each subject as his/her control and takes bacteria counts at the cites of brand and generic topical application, the abdomen and axillae, at baseline, 10 minutes, three hours, and six hours following administration of the topicals.