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August 22, 1990

The Effects of Thiazides Plus Calcium Channel Blockers-Reply

JAMA. 1990;264(8):972-973. doi:10.1001/jama.1990.03450080057024

In Reply.—  We appreciate the opportunity to respond to the comments of Cappuccio et al. The measurement of blood pressure at 12 ± 2 hours after receiving a dose was not an SD but a commonly used protocol requirement that all blood pressure measurements be made within 12 ± 2 hours after dosing, and, in fact, 100% of the patients had these measurements at 10 to 14 hours after taking a dose, just before the next dose.Because these measurements were obtained at trough, the data demonstrate that the antihypertensive activity of the diltiazem sustained-release and hydrochlorothiazide formulations lasts for at least 12 hours. The diltiazem sustained-release preparation used in our study is the standard commercial preparation marketed in the United States (Cardizem SR, Marion Laboratories Inc, Kansas City, Mo). This product has been shown to have a consistent blood pressure—lowering effect throughout the dosing interval, with a duration of