Short-term Effects
Beta blockers are relatively rapidly absorbed,1 reaching peak plasma levels between two to four hours after ingestion.2-8 Immediate physiological effects of beta blockers are shown in a very short period of time. Within a few hours, even a small dose of beta blocker can lower blood pressure.3
Within one hour of administration, beta-blocking actions of carvedilol become evident.9 Decreases in peripheral resistance and blood pressure are seen within about 30 minutes of administration. A randomized, placebo-controlled trial studied carvedilol on 20 patients with mild to moderate essential hypertension.10 Significant decreases in systolic and diastolic blood pressures were recorded as soon as 45 minutes after carvedilol administration (p<0.01). When measured after two hours, systolic blood pressure decreased by 17.7% and diastolic blood pressure decreased by 15.4% (p<0.01). The placebo group’s blood pressure remained unchanged. A different study administered either 50 mg or 80 mg metoprolol to 14 female patients and observed that systolic blood pressure was significantly reduced within 15 minutes and persisted for six hours.11 The maximal effect was seen in two and four hours for 50 mg and 80 mg metoprolol, respectively. A double-blind trial randomized 34 hypertensive patients to once-daily treatment on atenolol, metoprolol, pindolol, or propranolol.12 All four treatments significantly lowered intra-arterial ambulatory blood pressure measured at 24 hours. Mean arterial pressure was lowered in atenolol throughout all 24 hours, metoprolol for 12 hours, pindolol for 15 hours, and slow-release propranolol for 22 hours. The study concluded that atenolol and slow-release propranolol were effective antihypertensive medications over 24 hours, whereas other drugs may need to be taken more frequently.
Long-term Effects
According to manufacturers of metoprolol tartrate7 and metoprolol succinate extended-release,13 maximal effects of metoprolol should be apparent after one week of treatment. A manufacturer of nebivolol states that the blood pressure lowering effect should be seen within two weeks of therapy.8 In the randomized, placebo-controlled study of carvedilol described above, a significant decrease in mean blood pressure was measured at one month of treatment (p<0.01).10 Another study assessed the short-term and long-term effects of carvedilol in patients with idiopathic dilated cardiomyopathy. It observed reduced right atrial, pulmonary artery, and pulmonary wedge pressures over a period of three months.14 When nebivolol and atenolol were compared in patients with essential hypertension for six months, both treatments significantly decreased systolic and diastolic blood pressures at the end of the treatment period (p<0.001).15
References
- Riddell JG, Harron DW, Shanks RG. Clinical pharmacokinetics of beta-adrenoceptor antagonists. An update. Clin Pharmacokinet. 1987;12(5):305-320.
- Tenormin [package insert]. Conovanas, PR: AstraZeneca Pharmaceuticals LP; 2011.
- Stafylas PC, Sarafidis PA. Carvedilol in hypertension treatment. Vasc Health Risk Manag. 2008;4(1):23-30. 2008.
- Coreg CR [package insert]. Ciales, PR: GK Pharmaceuticals Contract Manufacturing Operations; 2008.
- Frishman WH, Henderson LS, Lukas MA. Controlled-release carvedilol in the management of systemic hypertension and myocardial dysfunction. Vasc Health Risk Manag. 2008;4(6):1387-1400.
- Trandate [package insert]. Oakville, ON: Prometheus Laboratories Inc.; 2010.
- Lopressor [package insert]. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2008.
- Bystolic [package insert]. St. Louis, MO: Forest Pharmaceuticals; 2011.
- Vanderhoff BT, Ruppel HM, Amsterdam PB. Carvedilol: the new role of beta blockers in congestive heart failure. Am Fam Physician. 1998;58(7):1627-1634, 1641-1622.
- Dupont AG. Effects of carvedilol on renal function. Eur J Clin Pharmacol. 1990;38 Suppl 2:S96-100.
- Bengtsson C, Johnsson G, Regardh CG. Plasma levels and effects of metoprolol on blood pressure and heart rate in hypertensive patients after an acute dose and between two doses during long-term treatment. Clin Pharmacol Ther. 1975;17(4):400-408.
- Floras JS, Jones JV, Hassan MO, Sleight P. Ambulatory blood pressure during once-daily randomised double-blind administration of atenolol, metoprolol, pindolol, and slow-release propranolol. Br Med J. 1982;285(6352):1387-1392.
- Metoprolol succinate extended-release tablets [package insert]. Sodertalje, Sweden: AstraZeneca AB; 2006.
- Metra M, Nardi M, Giubbini R, Cas LD. Effects of short- and long-term carvedilol administration on rest and exercise hemodynamic variables, exercise capacity and clinical conditions in patients with idiopathic dilated cardiomyopathy. J Am Coll Cardiol. 1994;24(7):1678-1687.
- Badar VA, Hiware SK, Shrivastava MP, Thawani VR, Hardas MM. Comparison of nebivolol and atenolol on blood pressure, blood sugar, and lipid profile in patients of essential hypertension. Indian J Pharmacol. 2011;43(4):437-440.
