The Haemodynamics of β-Blockers During Antihypertensive Therapy
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The Haemodynamics of During Antihypertensive Therapy The main effects seem to occur during exercise, but peripheral resistance changes little The haemodynamic effects of j3-blockers were assessed during chronic antihypertensive treatment. 89 previously untreated males with mild to moderate essential hypertension received j3-blocker therapy for 1 year: alprenolol 400-800mg daily (10 patients); atenolol 100-200mg daily (13 patients); bunitrolol 10-60mg daily (11 patients); metoprolol 50-250mg daily (12 patients); penbutolol 20-80mg daily (13 patients); pindolol 5-15mg daily (14 patients); and timolol 10-30mg daily (16 patients). Doses were initially adjusted to provide a BP of 140/90mm Hg or less without side effects. Assessments were conducted before and after 1 year's treatment and in 17 patients (7 alprenolol and 10 atenolol) also after 3-5 years' treatment. Heart rate decreased in all patients at rest and during exercise. The mean reduction at the highest (150-W) workload ranged from 27-45 beats/min. The reduction in heart rate was less on l3-blockers with strong intrinsic sympathomimetic activity (pindolol 11% reduction at rest, and bunitrolol 13%) than on j3-blockers without (atenolol 24%; metoprolol 21 % and timolol 26%). Both pindolol and bunitrolol did however, produce considerable heart rate reductions at 150-W exercise (36 and 32 beats/min, respectively). All is-blockers induced significant reductions in systolic, diastolic and mean arterial pressure at rest and during the 3 exercise levels (50-W, 100-W, 150-W). The relative BP reductions during rest and exercise were generally similar on each drug. A significant feduction occurred in cardiac index (CI) with all j3-blockers at rest and during exercise. During exercise, the mean.CI values were reduced by 10-25%, with timolol producing the greatest reduction. Stroke index (SI) was relatively unchanged at rest, but tended to increase during 100-Wand 150-W exercise, with significant increases of about 13% seen with atenolol and pindolol. With timolol, no increase in SI was seen and thus CI was decreased to the same extent as heart rate. Total peripheral resistance index (TPRI) did not fall significantly below pre-drug levels in any of the groups. Only 10 patients demonstrated a decrease in TPRI of 10% or more at rest and during 2 workloads. Oxygen consumption was not significantly reduced by any of the j3-blockers. The reduction in mean arterial pressure was less than 10mm Hg during rest in 17 patients (5 each on alprenolol and metoprolol, 3 on bunitrolol and 1 each on atenolol, timolol, penbutolol and pindolol) compared with 10 patients during exercise (4 on metoprolol, 3 on alprenolol, 2 on bunitrolol and 1 on timolol). Side effects usually disappeared after 4-8 weeks and included muscular fatigue, dizziness, sleeping problems and cold feet. Thus, the j3-blockers used in this study reduced BP, heart rate and cardiac index particularly during exercise, but had little effect on total peripheral resistance. Significant reductions in peripheral resistance have only been obtained in hypertensive patients who received an a-blocker (prazosin) in combination with j3-blocker therapy, or a j3-blocker with partial a-blocking properties (Iabetalol) or vasodilating properties (prizidolol). Lund-Johansen. P.: European Heart Journal 4 (Suppl. 0) : 1 (1983) 14 INPHARMA ® 18 Feb 1984 0156-2703/ 84/0218-0014/0$01.00/0 © AOIS Press
Transcript of The Haemodynamics of β-Blockers During Antihypertensive Therapy
The Haemodynamics of ~-Blockers During Antihypertensive Therapy
The main effects seem to occur during exercise, but peripheral resistance changes little The haemodynamic effects of j3-blockers were assessed during chronic antihypertensive treatment. 89
previously untreated males with mild to moderate essential hypertension received j3-blocker therapy for 1 year: alprenolol 400-800mg daily (10 patients); atenolol 100-200mg daily (13 patients); bunitrolol 10-60mg daily (11 patients); metoprolol 50-250mg daily (12 patients); penbutolol 20-80mg daily (13 patients); pindolol 5-15mg daily (14 patients); and timolol 10-30mg daily (16 patients). Doses were initially adjusted to provide a BP of 140/90mm Hg or less without side effects. Assessments were conducted before and after 1 year's treatment and in 17 patients (7 alprenolol and 10 atenolol) also after 3-5 years' treatment.
Heart rate decreased in all patients at rest and during exercise. The mean reduction at the highest (150-W) workload ranged from 27-45 beats/min. The reduction in heart rate was less on l3-blockers with strong intrinsic sympathomimetic activity (pindolol 11% reduction at rest, and bunitrolol 13%) than on j3-blockers without (atenolol 24%; metoprolol 21 % and timolol 26%). Both pindolol and bunitrolol did however, produce considerable heart rate reductions at 150-W exercise (36 and 32 beats/min, respectively).
All is-blockers induced significant reductions in systolic, diastolic and mean arterial pressure at rest and during the 3 exercise levels (50-W, 100-W, 150-W). The relative BP reductions during rest and exercise were generally similar on each drug.
A significant feduction occurred in cardiac index (CI) with all j3-blockers at rest and during exercise. During exercise, the mean.CI values were reduced by 10-25%, with timolol producing the greatest reduction. Stroke index (SI) was relatively unchanged at rest, but tended to increase during 100-Wand 150-W exercise, with significant increases of about 13% seen with atenolol and pindolol. With timolol, no increase in SI was seen and thus CI was decreased to the same extent as heart rate. Total peripheral resistance index (TPRI) did not fall significantly below pre-drug levels in any of the groups. Only 10 patients demonstrated a decrease in TPRI of 10% or more at rest and during 2 workloads. Oxygen consumption was not significantly reduced by any of the j3-blockers.
The reduction in mean arterial pressure was less than 10mm Hg during rest in 17 patients (5 each on alprenolol and metoprolol, 3 on bunitrolol and 1 each on atenolol, timolol, penbutolol and pindolol) compared with 10 patients during exercise (4 on metoprolol, 3 on alprenolol, 2 on bunitrolol and 1 on timolol). Side effects usually disappeared after 4-8 weeks and included muscular fatigue, dizziness, sleeping problems and cold feet. Thus, the j3-blockers used in this study reduced BP, heart rate and cardiac index particularly during exercise, but had little effect on total peripheral resistance.
Significant reductions in peripheral resistance have only been obtained in hypertensive patients who received an a-blocker (prazosin) in combination with j3-blocker therapy, or a j3-blocker with partial a-blocking properties (Iabetalol) or vasodilating properties (prizidolol). Lund-Johansen. P.: European Heart Journal 4 (Suppl. 0): 1 (1983)
14 INPHARMA® 18 Feb 1984 0156-2703/ 84/0218-0014/0$01.00/0 © AOIS Press
