Response to Hypertensive Medications in Asian Americans

ABSTRACT & COMMENTARY

Synopsis: Medication changes, dose reductions, and the experience of side effects were significantly more frequent in Asian American patients than in caucasians.

Source: Ka Kit Hiat, Pacis J. Arch Intern Med 1997; 137:1345-1348.

The objective of this retrospective analysis of medical records was to assess the management of hypertension in Asian Americans (AA) and to compare the results with an age- and sex-matched group of caucasian patients with hypertension.

The anti-hypertensive agents selected for both Asian and caucasian patients in this university setting included monotherapy with either calcium channel blockers or angiotensin-converting enzyme inhibitors. The study population included 200 Asian and 196 caucasian patients.

Medication change, dose reductions, and the experience of side effects were all significantly more frequent in AA patients than in caucasian patients (P < 0.001, P < 0.008, and P < 0.002, respectively).

These findings are supported by previous reports on ethnic differences in drug response to anti-hypertensive agents. They point out the need for further research on the outcomes in the management of hypertension in AA and the need to be observant of unique responses to anti-hypertensive medications in all ethnic groups.

COMMENT BY RALPH R. HALL, MD, FACP

Several observations are of note regarding the patient population in this study. Both groups were roughly 45% male and 50% female. Stratification of the AA subgroup was as follows: 35% Chinese, 21% Japanese, 20% Filipino, 7% Korean, and 17% other.

Of particular note was that the average weight of the AA patients was 6.75 kg lower than the caucasian patients. Alcohol was used by 47% of the caucasians and 23% of the AA. The AA also had significantly more illnesses than the caucasians.

The reasons for medication change were vague, as probably was necessitated by retrospective chart review, and included intolerance, ineffectiveness, and, in a few, the inability to pay.

The findings in this study are consistent with published studies with the use of propranolol and diazepam. Zhou et al found that the Chinese subjects had a two-fold greater sensitivity to the beta blocking effects of propranolol than caucasians.1 Ghoneium et al found the volume of distribution of diazepam was reduced in Chinese patients and different from other Asian groups.2

Differences in response to anti-hypertensive drugs in African-Americans and caucasians have been extensively studied. There is an obvious need to extend these studies to other ethnic groups. Institutional Review Boards are now mandated to have studies include populations that are representative of their communities. This is certainly an important step toward exploring racial and ethnic differences and their responses to treatment.

An important part of the history taking of not only Asian Americans but many caucasians is to consider what herbs they are including in their diet that will potentiate or interfere with the actions of prescribed medications.

References

1. Zhou HH, et al. N Engl J Med 1989;320:565-570.

2. Ghoneium MM, et al. Clin Pharmacol Ther 1981; 29:749-756.