Time-dependent antihypertensive effect of carteolol--a beta-adrenoceptor antagonist with partial agonist activity

The antihypertensive effect of carteolol (0.5 to 60 mg daily), a beta-adrenoceptor antagonist with partial agonist activity, was studied in a double-blind parallel protocol. A 3-wk placebo period was followed by an 8-wk treatment period during which patients received 0.5, 2.5, 20, and 60 mg in an increasing (group 1) or decreasing (group 2) manner for successive 2-wk intervals, followed by a 2- to 6-wk withdrawal period. Resting supine and standing blood pressures (BP) and heart rates (HR) were measured at each visit. Isometric handgrip exercise and treadmill exercise were used to evaluate beta-blockade. Plasma carteolol concentration was measured by radioimmunoassay. Recumbent BP fell from 154 +/- 10/100 +/- 2 to 143 +/- 10/84 +/- 11 mm Hg for group 1 and from 153 +/- 10/100 +/- 3 to 138 +/- 14/78 +/- 8 mm Hg for group 2 after 8 wk of treatment. HR was unchanged. The greater reduction in BP for each dose was observed with the later administrations, but was not related to serum concentration. beta-Blockade was evident at all doses of carteolol. Carteolol is an effective antihypertensive. Duration of carteolol therapy, independent of dosage, is important in its effectiveness.