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Researchers suggest renin test to avoid pressor response to antihypertensives
25 August 2010
MedWire News: Beta blockers and ACE inhibitors can elevate the blood pressure (BP) of hypertensive patients with low plasma renin activity (PRA), US researchers report.
These findings suggest that measuring PRA levels in patients with hypertension may serve as an ideal guide for determining the best antihypertensive drug to use in individual patients, say Michael Alderman (Albert Einstein College of Medicine, New York) and colleagues.
They explain that “without knowledge of PRA status, more patients will have an adequate BP fall with antivolume (V) drugs [ie, diuretics or calcium channel blockers] than with antirenin (R) drugs [ie, ACE inhibitors or beta blockers].
“At the same time, the data also indicate that avoiding antirenin system treatment of the lowest renin subjects, and targeting higher renin patients for antirenin drug treatment would substantially increase the likelihood of achieving BP control with monotherapy.”
The team measured the PRA levels of 945 patients with hypertension (systolic BP ≥140 mmHg) and randomly assigned them to receive a V (n=537) or R drug (n=408).
The results, published in the American Journal of Hypertension, showed that pressor responses, defined as a systolic BP rise ≥10 mmHg, occurred more often among patients taking R drugs than in patients taking V drugs, at 11% versus 5%, respectively (p=0.001).
The researchers found that among patients taking V drugs, pressor response frequencies remained similar despite PRA levels. However patients taking R drugs had a negative association between their pressor response rates and PRA levels, and higher pressor response rates compared with V drug patients, at 17% versus 6% among those in the lowest PRA tertile (p=0.003), and 10% versus 4% for those in the middle PRA tertile (p=0.02).
In addition, systolic BP increased to or remained elevated at ≥160 mmHg more frequently with R drugs than with V drugs, at 19% versus 13% (p=0.007). More patients in the lowest PRA tertile of the R drug group had a systolic BP ≥160 mmHg than did those in the same PRA tertile of the V drug group, at 35% versus 13% (p=0.001).
Conversely, V drugs lowered BP by at least 10 mmHg on average, and produced a systolic BP <130 mmHg more frequently, among patients in the lowest PRA tertile than R drugs, at 18% versus 5% (p=0.003).
Alderman et al conclude: “Pressor responses to antihypertensive drug monotherapy appear to be neither rare nor the result of chance alone.
“Also, our data indicate that patients with low PRA values are at highest risk of a pressor response when prescribed an R drug.”
They therefore advise: “Without knowledge of concurrent PRA status a more prudent course would start with a single drug, and titrating effective drugs until goal [blood] pressure is achieved.”
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