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August 22, 1990

The Effects of Thiazides Plus Calcium Channel Blockers

Author Affiliations

St George's Hospital Medical School London, England

St George's Hospital Medical School London, England

JAMA. 1990;264(8):971-972. doi:10.1001/jama.1990.03450080057023

To the Editor.—  In our view the article by Burris and coworkers1 adds to the confusion surrounding the merits of adding a thiazide diuretic to a calcium antagonist. Despite the study being large and well designed, there are three major problems with the interpretation of the results that have not been addressed by the authors.First, all of the current calcium antagonists have peak and trough effects. It is therefore vital that, in studies where potentially additive combinations are being looked at, the timing of the blood pressure measurement following the last dose is carefully controlled and stated in the article. The efficacy of the calcium antagonists either alone or in combination will depend on when the blood pressure was measured. In the article Burris et al state that the blood pressure was measured 12 ± 2 hours after a dose: assuming that this is an SD, blood pressure