Is fixed combination therapy appropriate for initial hypertension treatment?
Recent clinical trials in hypertension prove how seldom single drug therapy achieves target blood pressure (BP) and reduces cardiovascular morbidity and mortality. A natural response is the testing and marketing of fixed-dose combination products for hypertension, of which 14 have been approved in the United States since 1993. Currently, only five products are indicated by the Food and Drug Administration for initial therapy of hypertension; all include a diuretic. To achieve such an indication, studies must show not only safety and efficacy of the combination, but also BP lowering that is at least additive compared with the two agents given separately, as well as a "synergy" not present when each agent is given alone. Some advantages to initial combination therapy include greater BP reduction, improved adherence to pill taking, fewer side effects, and lower cost. The most likely candidates for initial combination therapy are patients with initial BP higher than 160/100 mm Hg, or those with a BP goal lower than the customary 140/90 mm Hg. These include patients with target organ damage, clinical cardiovascular disease, proteinuria, renal impairment, or diabetes mellitus. In many of these circumstances, an angiotensin converting enzyme inhibitor or angiotensin II receptor antagonist is frequently recommended; adding a diuretic or calcium antagonist to it is much more likely to result in achievement of the BP goal. More research is being done to explore the combination of not only two representatives from classes of conventional agents, but also other drugs that may help address the multiple manifestations of the "metabolic syndrome" that often accompanies hypertension.