Mechanisms for interethnic differences in antihypertensive drug response

This symposium emphasizes the differences in the management of hypertension in specific populations. The purpose of this presentation is to discuss the specific mechanisms responsible for these differences. Differences in hypotensive drug responses are due to differences in the metabolism of individual drugs so that different individuals achieve different plasma drug concentrations following the same dose or differences in the effects in different individuals produced by similar plasma concentrations. Ethnic differences in response to the treatment of hypertension are of considerable importance. Some of these differences occur on the basis of phenotypic differences in drug metabolizing ability when the distribution of fast and slow metabolizers differs in different ethnic groups. Other differences are due to the recognized difference in the frequency of factors such as high and low renin hypertension in different ethnic groups. Finally interethnic differences in antihypertensive response may occur through mechanisms that have not yet been defined. An example of such a difference is the increased sensitivity of Chinese to beta receptor blockade. In Chinese individuals similar plasma propranolol concentrations produce greater reduction in blood pressure, heart rate and plasma renin activity than in caucasians. African Americans appear to have reduced beta receptor mediated vasodilation in comparison to caucasians. Thus an understanding of the mechanisms underlying interethnic differences in the response to antihypertensive drugs will allow better individualization of therapy.