IN THE COURSE of evaluation for approval, a single-component drug is occasionally found to be unambiguously less effective or more dangerous than others. Such a drug may, nevertheless, be a valuable addition to the armamentarium, but it will be approved only as a second-line therapy, to be used only after others have been found to be ineffective or contraindicated. For example, bepridil is approved for the treatment of chronic stable angina, but its associated adverse drug reactions (ADRs) are sufficiently more severe than those of other approved antianginal products that bepridil is not approved as first-line therapy.
Drugs like bepridil are unusual. Most single-component products are approved as first-line therapy. Betaxolol, bisoprolol, chlorthalidone, and hydrochlorothiazide are separately approved as first-line therapy for hypertension, so some physicians may find it unremarkable that fixed-dose combinations of betaxolol and chlorthalidone and of bisoprolol and hydrochlorothiazide are also approved as first-line therapy. In fact,