LEDERLE's VERAPAMIL SR ANDA PETITION: SEARLE SEEKING DELAY

LEDERLE's VERAPAMIL SR ANDA PETITION: SEARLE SEEKING DELAY in FDA's decision on the petition. Searle plans to submit a study that will provide information on the types of testing it believes are necessary to establish bioequivalence and therapeutic equivalence of verapamil SR products. Searle asked for the stay in a petition filed with the agency Aug. 21. Searle manufactures Calan SR sustained-release verapamil. "FDA should take advantage of the full ninety-day period in which it may approve or disapprove the Lederle petition," Searle urged, "so that FDA will have the opportunity to consider" new information that will "soon be available" from a Searle study, as well as "the formal recommendations" that Searle intends to submit. Lederle's ANDA suitability petition for 120 mg sustained-release verapamil tabs was received by FDA on July 5. The petition notes that the drug differs from the listed drug, Knoll Pharmaceuticals' Isoptin SR 240 mg sustained-release verapamil tabs, only in its strength. Searle and Knoll co-developed verapamil and the sustained-release formula of verapamil. Lederle's petition states that the lower dose tablet "would provide flexibility and increased accuracy of dose titration by the physician, and greater patient compliance" for those who have an increased response to verapamil, such as the elderly or people of short stature. The petition says that "a bioavailability study (or a request for a waiver of the requirement based on a ]bioavailability/bioequivalence[ study for a 240 mg SR tablet (identical formula)) and a comparative dissolution study will be performed to support an ANDA." Searle pointed out that on April 20, Knoll submitted a petition requesting that "FDA recognize six elements of testing as essential to bioequivalence determinations" for verapamil SR products. Searle stated that its study and recommendations, as well as Knoll's recommendations, "will have a strong bearing on whether the Lederle petition should be approved or disapproved" and on "what testing FDA should specify to be necessary in any response approving the Lederle petition." Searle maintained that verapamil SR is an antihypertensive that has non-linear pharmacokinetics and pharmacodynamics, therefore "differences in dosage form, strength, and rate of absorption are especially important in determining bioequivalence and can have significant implications for safety and efficacy." Searle's study, to be completed in September, "will provide extensive pharmacokinetic and pharmacodynamic profiles of three verapamil products," the firm said. The study will try to measure pharmacokinetic differences among the products and "establish a correlation between such differences and differences in significant pharmacodynamic parameters." According to Searle, Knoll's petition suggests that the following testing be done to establish bioequivalence of verapamil SR products: measurement of the drugs' performance at steady state and evaluation of the drugs' performance under fasting and non-fasting conditions. In addition, Searle recommended testing that is based on "a crossover, replicate design to account for within and between subject variability" and testing that "accounts for the amount of L and D isomers of verapamil which will be due to different release rates from formulations." Searle announced on Aug. 31 that Calan SR has generated more than $ 200 mil. in total 1989 U.S. sales. "Calan SR continues to exceed industry projections," Searle President Joseph Curti, MD, said. U.S. sales in 1988, calculated by Pharmaceutical Data Systems, were $ 155 mil. Searle estimates that Calan SR has accounted for more than 13 mil. pharmacy-filled prescriptions since its approval less than three years ago.