EFFICACY AND MODE OF ACTION OF MANIDIPINE - A NEW CALCIUM-ANTAGONIST

Clinical studies were performed on patients with mild-to-moderate essential hypertension to elucidate the efficacy and mode of action of manidipine. Augmentation of diuresis and natriuresis during the short- and long-term phases of manidipine treatment was found in essential hypertensive patients. Manidipine partly inhibited sympathetic nerve activity and suppressed the mean arterial pressure response to infused norepinephrine. This drug also inhibited aldosterone secretion. Natriuresis and suppression of pressor responses may contribute to the depressor mechanisms of this drug. After manidipine administration, increases in both urinary calcium and uric acid were observed. Both parameters were positively correlated with urinary excretion of sodium, and the inhibition of tubular reabsorption may contribute to this mechanism. The increase in plasma parathyroid hormone may also be involved in the calciuresis produced by manidipine. Patients with lower plasma renin activity or lower plasma ionized calcium levels showed a greater reduction in blood pressure after manidipine administration. Thus the hypotensive action of manidipine was more pronounced in low renin essential hypertension.