Adimolol, a long acting beta-adrenoceptor blocker in man

Area of Science:

• Pharmacology
• Cardiovascular Physiology

Background:

• Beta-adrenoceptor antagonists (beta-blockers) are crucial in managing cardiovascular conditions.
• Understanding the duration and mechanism of action of novel beta-blockers is essential for clinical application.

Purpose of the Study:

• To compare the effects of single oral doses of adimolol and propranolol on blood pressure, heart rate, and beta-adrenoceptor function in healthy males.
• To investigate the duration of adimolol's beta-adrenoceptor antagonist activity and its potential mechanisms.

Main Methods:

• A randomized, placebo-controlled study involving eight healthy males.
• Administration of single oral doses of adimolol (600 mg), propranolol (240 mg), and placebo.
• Measurements included blood pressure, heart rate, exercise and isoprenaline-induced heart rate changes, and lymphocyte beta-adrenoceptor binding.

Main Results:

• Both adimolol and propranolol significantly reduced blood pressure and heart rate, with effects lasting up to 7 days for adimolol.
• Adimolol and propranolol attenuated heart rate responses to exercise and isoprenaline.
• Adimolol significantly reduced beta-adrenoceptor number and affinity, with prolonged functional antagonism lasting up to 7 days.
• Adimolol's elimination half-life was 14 hours, significantly longer than propranolol's 3 hours.

Conclusions:

• Adimolol exhibits prolonged beta-adrenoceptor antagonist activity, sustained for up to 7 days after a single dose.
• The prolonged effect of adimolol may be attributed to non-competitive antagonism and a reduction in beta-adrenoceptor number, in addition to competitive antagonism.
• Adimolol demonstrates a longer duration of action compared to propranolol, suggesting potential advantages in certain clinical settings.