Pindolol‐the pharmacology of a partial agonist

• Published in: British journal of clinical pharmacology Vol. 13; no. S2; pp. 149S - 158S
• Main Authors: Clark, BJ, Menninger, K, Bertholet, A
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-01-1982
• Subjects: Animals; Bronchi - drug effects; Heart - drug effects; Hemodynamics - drug effects; Humans; In Vitro Techniques; Muscle Contraction - drug effects; Muscle, Smooth, Vascular - drug effects; Pindolol - pharmacology; Time Factors
• ISSN: 0306-5251; 1365-2125
• DOI: 10.1111/j.1365-2125.1982.tb01904.x

1 Pindolol is a non‐selective beta‐adrenoceptor blocking agent; its affinity to adrenoceptors in guinea pig atria (beta 1) is not significantly different from that in guinea pig trachea (beta 1 + beta 2) and canine vascular smooth muscle (beta 2). 2 Pindolol displays a striking diversity of agonist activities in isolated tissues. Stimulant effects correspond to 40–50% of the maximum effects of isoprenaline in isolated kitten atria and guinea pig trachea and to only 10% in guinea pig atria. Effects in canine isolated mesenteric vessels are those of a full agonist, maximum responses equaling those of isoprenaline. These findings suggest that the stimulant effects of pindolol are exerted principally on beta 2‐adrenoceptors. 3 Cardiac stimulation produced by pindolol in the dog is sufficient to compensate for the cardiac depression resulting from blockade of beta‐adrenoceptors in the heart. Reductions in cardiac output and compensatory increases in total peripheral resistance do not occur or are much smaller than those produced by beta‐adrenoceptor blocking agents lacking sympathomimetic activity. 4 Pindolol‐induced relaxation of bronchial smooth muscle prevents or minimizes the bronchoconstrictor effects of injected spasmogens in the cat. 5 Pindolol has marked vasodilator activity, small doses reducing femoral and mesenteric vascular resistance by approximately 30%. Doses comparable to those used in hypertensive patients lower blood pressure by 20 mmHg in non‐anaesthetized dogs.