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Hemodynamic differences between carvedilol and labetalol in the cutaneous circulation
R R Ruffolo1, C F Sauermelch, R N Willette
1Division of Pharmacology, Smith Kline Beecham, p.l.c., King of Prussia, Pennsylvania.
European Journal of Clinical Pharmacology
|January 11, 1990
Summary
Carvedilol significantly increased skin blood flow and decreased vascular resistance, while labetalol had minimal impact on these measures in rats. This highlights distinct vasodilation mechanisms between these antihypertensive drugs.
Area of Science:
- Pharmacology
- Cardiovascular Physiology
- Microcirculation Research
Background:
- Labetalol and carvedilol are commonly prescribed beta-blockers with alpha-blocking activity used for hypertension.
- Understanding their distinct effects on peripheral circulation is crucial for optimizing therapeutic strategies.
- Previous research indicates potential differences in their vasodilatory properties, but direct comparative data on cutaneous microcirculation is limited.
Purpose of the Study:
- To investigate and compare the in vivo effects of labetalol and carvedilol on local cutaneous microvascular perfusion.
- To assess the impact of these drugs on calculated local cutaneous microvascular resistance.
- To elucidate potential differences in the vasodilatory mechanisms of labetalol and carvedilol.
Main Methods:
- Anesthetized rats were administered submaximal, equipotent hypotensive doses of labetalol and carvedilol.
- Local cutaneous microvascular perfusion was measured using laser Doppler flowmetry.
- Local cutaneous microvascular resistance was calculated based on perfusion and blood pressure data.
Main Results:
- Labetalol administration resulted in a significant decrease in cutaneous perfusion (-25% +/- 3%) with no significant change in cutaneous vascular resistance (-6% +/- 3%).
- In contrast, carvedilol markedly increased cutaneous perfusion (+64% +/- 9%) and significantly reduced cutaneous vascular resistance (-57% +/- 3%).
- These findings demonstrate divergent effects of the two drugs on the cutaneous microvasculature.
Conclusions:
- Carvedilol and labetalol exhibit distinct pharmacological profiles regarding their influence on cutaneous microcirculation.
- Carvedilol promotes vasodilation in the cutaneous microvasculature, whereas labetalol does not appear to share this effect at the studied doses.
- The differing effects suggest unique mechanisms of action contributing to their overall vasodilatory and antihypertensive properties.