Carvedilol, a novel cardiovascular agent, inhibits development of vascular and ventricular hypertrophy in spontaneously hypertensive rats

The effects of carvedilol, a novel cardiovascular agent, were evaluated in developing spontaneously hypertensive rats (SHR) for effects on hemodynamics, and the ability to effect the development of left ventricular, and vascular hypertrophy associated with chronic hypertension. Chronic oral administration of low dose carvedilol (20 mg/kg/day) was initiated when rats were 5 weeks of age, and experiments progressed until 14 weeks of age. Carvedilol-treated SHR had significantly reduced systolic blood pressures and heart rates throughout the duration of the experiment, and had significantly reduced ventricle/body weights by approximately 9.0%. Morphologic analysis of tertiary branches of the mesenteric artery revealed that carvedilol-treated SHR had significant reductions in medial cross-sectional area. Carvedilol produced concentration-dependent inhibition of basal [3H]thymidine incorporation in cultured SHR vascular smooth muscle cells, as well as by stimulation produced by PDGF (1 nM), EDGF (1 nM), thrombin (0.5 U/ml), or endothelin-1 (1 nM), indicating that carvedilol had direct anti-mitogenic activity. The present studies demonstrate that low dose carvedilol produced sustained reductions in blood pressure and heart rate in developing SHR that were accompanied by significant inhibition in the development of vascular and myocardial hypertrophy. The morphological changes induced by carvedilol may be mediated by a combination of hemodynamic effects, as well as by direct anti-mitogenic effects on vascular smooth muscle.

Newer beta blockers and the treatment of hypertension

Beta-adrenoceptor blocking agents are established as one of the principal classes of antihypertensive agents. Despite progressive refinements over the years, they still possess some unwanted effects, which limit their considerable value. In recent years a wide range of variations upon the beta-blocker theme has been developed. The full clinical advantages of the newer agents remain to be defined.

The applied pharmacology of beta-adrenoceptor antagonists (beta blockers) in relation to clinical outcomes

Despite the fact that beta blockers were introduced into clinical practice 25 years ago, new beta blockers with differing kinetic and dynamic profiles continue to be developed and marketed. This overview assesses some of the more extensively studied agents from the point of view of proof of utility and the validity of claims for therapeutic advances. The clinical data suggests that despite the expectations of improvements based on kinetic and dynamic consideration, none of the newer agents have been shown unequivocally, either in terms of efficiency or tolerability, to be an advance over the reference agents, the beta 1 antagonists atenolol and metoprolol. This may be either because such improvements will not occur or because of shortcomings in the design and duration of comparative studies. There are trends to suggest that celiprolol has lesser effects on bronchial function and that it has a lesser impact on lipoprotein profiles. Approaches are suggested that might enable clinicians to appraise for themselves the validity of claims for the improved efficiency of new beta blockers.

Safety and efficacy of once-daily carvedilol vs twice-daily labetalol in mild to moderate hypertension

A multicenter, randomized, double-blind, parallel-group trial of 8 weeks' duration was designed to compare the efficacy and safety of once-daily carvedilol with that of twice-daily labetalol in patients with essential hypertension. A total of 61 patients (13 women and 48 men) aged 26-64 years (mean +/- SEM = 49.6 +/- 1.3 years) were enrolled. All patients had mild to moderate hypertension, defined as diastolic blood pressure (DBP) of 95-114 mm Hg at the end of a 1- to 2-week single-blind placebo period. In all, 30 patients received carvedilol (25 mg once daily) and 31 received labetalol (200 mg twice daily). The initial dose could be doubled for both treatment groups at day 29 if the DBP was greater than 90 mmHg on days 28 and 29. Hemodynamic parameters, including supine and standing DBP, systolic blood pressure (SBP), and heart rate (HR), were measured and safety was evaluated at baseline and at days 14, 28, and 56 at the end of the dosing interval. In all, 3 patients on carvedilol and 4 patients on labetalol required upward dose titration after 1 month. At the end of the trial, 26 of 30 carvedilol-treated patients and 27 of 31 labetalol-treated patients (87% of each group) had a supine DBP of less than or equal to 90 mm Hg. On day 56, mean decreases in supine DBP, SBP, and HR in the carvedilol group were 18.5 and 23.4 mm Hg and 11 beats/min, respectively, from baseline values of 101.6 and 163.8 mm Hg and 80 beats/min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Safety and antihypertensive efficacy of carvedilol and atenolol alone and in combination with hydrochlorothiazide

Carvedilol has been shown to be effective and safe in patients with essential hypertension when given as monotherapy. In this double-blind, randomized, group-comparative study, 2 groups of 59 patients with mild to moderate essential hypertension [median supine systolic/diastolic blood pressure at baseline (SBP/DBP), 168/105 mmHg] were treated with either 25 mg carvedilol once daily (o.d.) or 50 mg atenolol o.d. for 4 weeks. Responders at 4 weeks (DBP, less than 90 mmHg) terminated the study. Nonresponders continued the study. Hydrochlorothiazide (HCTZ) was added at 25 mg o.d. for a further 6 weeks. The median blood pressure decreased under monotherapy with carvedilol (n = 59) from 167/105 at baseline to 155/94 mmHg after 4 weeks, and in the atenolol group (n = 59) it decreased from 168/105 to 162/97 mmHg. The patients who received carvedilol in combination with HCTZ and were evaluated for efficacy (n = 38) showed a decrease in SBP/DBP from 156/97 at the end of monotherapy to 145/88 mmHg after 10 weeks; the combination of atenolol with HCTZ (n = 44) reduced BP from 162/97 to 147/88. Both carvedilol and atenolol were safe when given either alone or in combination with HCTZ. In conclusion, after long-term administration, 25 mg carvedilol o.d. and 50 mg atenolol o.d. significantly reduced both SBP and DBP over 24 h. The addition of HCTZ led to a further increase in antihypertensive efficacy. Combined treatment with carvedilol or atenolol and HCTZ was very well tolerated, without hypotensive events or relevant changes in objective safety parameters.