Abstract
1. The alpha- and beta-adrenoceptor antagonist activity of carvedilol, a beta-adrenoceptor antagonist with vasodilating properties, and labetalol were investigated in 10 healthy male subjects. They received infusions with serially increasing concentrations of isoprenaline and phenylephrine before and after single oral doses of carvedilol 6.25, 12.5 and 25 mg, labetalol 400 mg and placebo at weekly intervals in a double-blind randomised manner. An exercise step test was performed at the end of the infusions. 2. The dose of isoprenaline required to increase heart rate by 25 beats min-1 (I25) and the dose of phenylephrine required to increase systolic and diastolic blood pressure by 20 mm Hg (PS20 and PD20) were calculated using a quadratic fit to individual dose-response curves. Comparisons were made with placebo and P < 0.05 was considered significant. 3. The I25 was increased by carvedilol 25 mg and labetalol 400 mg (P < 0.05). The dose ratios at I25 were: carvedilol 6.25 mg 2.1 +/- 1.6, carvedilol 12.5 mg 3.1 +/- 1.9, carvedilol 25 mg 6.4 +/- 4.9 and labetalol 400 mg 8.8 +/- 4.4. 4. The PS20 was increased by labetalol 400 mg (P < 0.05). The dose ratios at PS20 were: carvedilol 6.25 mg 1.0 +/- 0.2; 12.5 mg, 1.2 +/- 0.2; 25 mg, 1.3 +/- 0.4 and labetalol 400 mg 2.2 +/- 0.8. 5. The PD20 was increased by labetalol 400 mg (P < 0.05). The dose ratios at PD20 were: carvedilol 6.25 mg 1.1 +/- 0.3; 12.5 mg, 1.3 +/- 0.3; carvedilol 25 mg 1.3 +/- 0.4 and labetalol 400 mg 2.1 +/- 0.8.(ABSTRACT TRUNCATED AT 250 WORDS)
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- Abshagen U. A new molecule with vasodilating and beta-adrenoceptor blocking properties. J Cardiovasc Pharmacol. 1987;10 (Suppl 11):S23–S32. [PubMed] [Google Scholar]
- Cubeddu L. X., Fuenmayor N., Varin F., Villagra V. G., Colindres R. E., Powell J. R. Mechanism of the vasodilatory effect of carvedilol in normal volunteers: a comparison with labetalol. J Cardiovasc Pharmacol. 1987;10 (Suppl 11):S81–S84. [PubMed] [Google Scholar]
- Giannattasio C., Cattaneo B. M., Seravalle G., Carugo S., Mangoni A. A., Grassi G., Zanchetti A., Mancia G. Alpha 1-blocking properties of carvedilol during acute and chronic administration. J Cardiovasc Pharmacol. 1992;19 (Suppl 1):S18–S22. doi: 10.1097/00005344-199219001-00005. [DOI] [PubMed] [Google Scholar]
- McDevitt D. G. The assessment of beta-adrenoceptor blocking drugs in man. Br J Clin Pharmacol. 1977 Aug;4(4):413–425. doi: 10.1111/j.1365-2125.1977.tb00756.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Neugebauer G., Akpan W., von Möllendorff E., Neubert P., Reiff K. Pharmacokinetics and disposition of carvedilol in humans. J Cardiovasc Pharmacol. 1987;10 (Suppl 11):S85–S88. [PubMed] [Google Scholar]
- Richards D. A. Pharmacological effects of labetalol in man. Br J Clin Pharmacol. 1976 Aug;3(4 Suppl 3):721–723. [PubMed] [Google Scholar]
- Richards D. A., Prichard B. N., Boakes A. J., Tuckman J., Knight E. J. Pharmacological basis for antihypertensive effects of intravenous labetalol. Br Heart J. 1977 Jan;39(1):99–106. doi: 10.1136/hrt.39.1.99. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Richards D. A., Prichard B. N. Clinical pharmacology of labetalol. Br J Clin Pharmacol. 1979;8(Suppl 2):89S–93S. [PMC free article] [PubMed] [Google Scholar]
- Ruffolo R. R., Jr, Gellai M., Hieble J. P., Willette R. N., Nichols A. J. The pharmacology of carvedilol. Eur J Clin Pharmacol. 1990;38 (Suppl 2):S82–S88. doi: 10.1007/BF01409471. [DOI] [PubMed] [Google Scholar]
- Sponer G., Strein K., Müller-Beckmann B., Bartsch W. Studies on the mode of vasodilating action of carvedilol. J Cardiovasc Pharmacol. 1987;10 (Suppl 11):S42–S48. [PubMed] [Google Scholar]
- Strein K., Sponer G., Müller-Beckmann B., Bartsch W. Pharmacological profile of carvedilol, a compound with beta-blocking and vasodilating properties. J Cardiovasc Pharmacol. 1987;10 (Suppl 11):S33–S41. [PubMed] [Google Scholar]
- Sumner D. J., Elliott H. L., Reid J. L. Analysis of the pressor dose response. Clin Pharmacol Ther. 1982 Oct;32(4):450–458. doi: 10.1038/clpt.1982.188. [DOI] [PubMed] [Google Scholar]
- Sumner D. J., Elliott H. L. The pressor dose-response in clinical cardiovascular pharmacology. Br J Clin Pharmacol. 1987 May;23(5):499–503. doi: 10.1111/j.1365-2125.1987.tb03084.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sumner D. J., Elliott H. L., Vincent J., Reid J. L. A pragmatic approach to the pressor dose-response as an index of vascular reactivity and adrenoceptor function in man. Br J Clin Pharmacol. 1987 May;23(5):505–510. doi: 10.1111/j.1365-2125.1987.tb03085.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tomlinson B., Bompart F., Graham B. R., Liu J. B., Prichard B. N. Vasodilating mechanism and response to physiological pressor stimuli of acute doses of carvedilol compared with labetalol, propranolol and hydralazine. Drugs. 1988;36 (Suppl 6):37–47. doi: 10.2165/00003495-198800366-00008. [DOI] [PubMed] [Google Scholar]
- Tomlinson B., Cronin C. J., Graham B. R., Prichard B. N. Haemodynamics of carvedilol in normal subjects compared with propranolol, pindolol, and labetalol. J Cardiovasc Pharmacol. 1987;10 (Suppl 11):S69–S75. [PubMed] [Google Scholar]