RT Journal A1 Nicholson JP, Resnick LM, Laragh JH T1 HYdrochlorothiazide is not additive to verapamil in treating essential hypertension JF Archives of Internal Medicine JO Archives of Internal Medicine YR 1989 FD January 1 VO 149 IS 1 SP 125 OP 128 DO 10.1001/archinte.1989.00390010119015 UL http://dx.doi.org/10.1001/archinte.1989.00390010119015 AB • Calcium channel blockers, a newer class of antihypertensive medications, have gained considerable acceptance as monotherapeutic agents, particularly in low renin hypertension where diuretics are also most effective. To study whether thiazide diuretics exert an additional antihypertensive effect in the setting of calcium channel blockade, we gave verapamil hydrochloride (360 mg/d) or hydrochlorothiazide (25 mg/d) alone and in combination in an open study to 13 hypertensive patients with mild to moderate essential hypertension. Both verapamil and hydrochlorothiazide lowered blood pressure (170±17/109±6 mm Hg pretreatment to 150±25/95±8 mm Hg with verapamil; 170±5/109±2 mm Hg pretreatment to 164±25/103±10 mm Hg with hydrochlorothiazide), but addition of hydrochlorothiazide to verapamil resulted in no added benefit (150±25/95±8 mm Hg vs 150±20/95±6 mm Hg). Furthermore, while hydrochlorothiazide lowered serum potassium values (4.2±0.25 mmol/L to 3.7±0.35 mmol/L) and stimulated plasma renin activity (1.5±1.3 ng/mL/h pretreatment to 3.3 ±2.7 ng/mL/h with verapamil), verapamil only modestly elevated renin activity (1.5 ± 1.3 ng/mL/h pretreatment to 2.7 ±2.5 ng/mL/h with verapamil) and did not lower potassium values. Altogether, the data suggest that in essential hypertension, at least for verapamil, concurrent diuretic therapy may not be helpful or warranted.(Arch Intern Med 1989;149:125-128)