LOREX' BETAXOLOL/CHLORTHALIDONE COMBO RECOMMENDED FOR APPROVAL

Executive Summary

LOREX' BETAXOLOL/CHLORTHALIDONE COMBO RECOMMENDED FOR APPROVAL as a treatment for mild-to-moderate hypertension by FDA's Cardiovascular and Renal Drugs Advisory Committee on Dec. 13. Once approved, Searle will market the beta blocker/diuretic combination under the brandname Kerlidex. Searle has marketed betaxolol for hypertension under the brandname Kerlone since May of this year under the Lorex joint venture with the French firm Synthelabo. Committee member Peter Kowey, MD, Lankenau Hospital in Philadelphia, commented: "I think that it would be reasonable to allow [betaxolol/chlorthalidone] to be an initial therapy. I believe we have enough evidence that it is safe and effective." However, Chairman Craig Brater, MD, said that he "would not like to see it labeled as 'initial' therapy." The advisory committee voted 7-2 not to recommend that Lorex include in labeling a requirement that physicians titrate betaxolol and chlorthalidone separately in patients in order to determine whether the dosage levels in the combination product are appropriate. FDA noted that most antihypertensive/diuretic combination products include such an admonition in labeling. FDA Cardio-Renal Drugs Division Director Ray Lipicky, MD, pointed out that if "one says 'titrate with individual compounds,' [5 mg/12.5 mg betaxolol/chlorthalidone] would never be used." He said that while fixed doses of combination products are common, "most people I talked to have some kind of bias against fixed dose combinations. I certainly can't deny that that also influenced the way in which fixed dose combinations are labeled." He added: "This is the first opportunity there is to change [that]." However, the committee voted 5-4 that Kerlidex labeling might include a suggestion to physicians to consider titrating the respective doses of betaxolol and chlorthalidone in patients when treating certain patient subgroups, such as black patients who may react differently to each compound. Salim Yusuf, MD/PhD, NIH Clinical Trials Branch/National Heart, Lung, and Blood Institute, suggested a label notation that "a reasonable alternative to initiating this combination...is to start with 12.5 or 25 [mg] of chlorthalidone in blacks and 5 or 10 [mg] of betaxolol in whites and then depending on the response," consider the combination product. Committee Chairman Brater noted that "data shows that in black patients, the same antihypertensive response that occurs with 25 mg of chlorthalidone can be attained by half that dose and 5 mg of betaxolol [in] combination. In addition, in white patients, the same antihypertensive response that can be gained with 10 mg of betaxolol can be gained by using 5 mg of betaxolol and 12.5 mg of chlorthalidone." Based on the results of five controlled clinical trials, Lorex concluded that "the safety profile of lower dosage combination therapy is at least as good as, or better than, component monotherapy in higher doses." In addition, the firm concluded that betaxolol 5 mg/chlorthalidone 12.5 mg is "safe and effective for initial antihypertensive therapy." Lorex presented five studies in support of the combination product involving a total of 1,146 patients with diastolic blood pressure above 100.