PMID: 2990158Mar 1, 1985

Steric aspects of agonism and antagonism at beta-adrenoceptors: experiments with the enantiomers of clenbuterol

Acta Pharmacologica Et Toxicologica
B Waldeck, E Widmark

Abstract

The enantiomers of clenbuterol, a beta 2-selective adrenoceptor agonist with partial agonistic activity, were examined with respect to their ability to react in vitro on adrenoceptors in the trachea (mostly beta 2), the soleus muscle (beta 2) and in the papillary muscle of the left ventricle (beta 1) from the guinea-pig. (-)-Clenbuterol relaxed the carbachol contracted trachea and depressed the subtetanic contractions of the soleus muscle in a concentration-dependent manner. (+)-Clenbuterol was at least 1,000 times less potent in this respect. Both isomers inhibited competitively the effect of isoprenaline on the trachea, the (-)-isomer being about 100 times more active than the (+)-isomer. None of the isomers showed any detectable positive inotropic effect on the papillary muscle but both inhibited competitively the response to isoprenaline. Also in this respect (-)-clenbuterol was more potent than (+)-clenbuterol. It is concluded that the beta 2-agonistic as well as the beta 1-antagonistic effect of clenbuterol resides in the (-)-isomer and that the (+)-isomer does not seem to contribute to the pharmacological effects displayed by racemic clenbuterol.

References

Sep 1, 1977·The Journal of Pharmacy and Pharmacology·B Waldeck
Jul 1, 1977·Clinical and Experimental Pharmacology & Physiology·K Bohmer, S R O'Donnell
Nov 1, 1972·Journal of Medicinal Chemistry·K Wetterlin
Aug 1, 1981·British Journal of Clinical Pharmacology·T L WhitsettM F Wilson
Feb 1, 1980·Acta Pharmacologica Et Toxicologica·E Holmberg, B Waldeck
Mar 1, 1959·British Journal of Pharmacology and Chemotherapy·O ARUNLAKSHANA, H O SCHILD

Citations

Jul 5, 2005·Expert Opinion on Investigational Drugs·D A Handley, J Morley
Dec 11, 2013·Biopharmaceutics & Drug Disposition·Iori HirosawaKen-Ichi Miyamoto
Oct 1, 1992·Pharmacology & Toxicology·A B JeppssonB Waldeck
Oct 4, 2016·Food Additives & Contaminants. Part A, Chemistry, Analysis, Control, Exposure & Risk Assessment·Maria Kristina ParrSaskia S Sterk
Jan 1, 1995·Pharmacology & Toxicology·B Waldeck
Nov 1, 1989·Pharmacology & Toxicology·D F Smith
Dec 1, 1987·British Journal of Pharmacology·M BeerS M Stahl
Mar 29, 2002·The Annals of Pharmacotherapy·Majid VakilyDion Brocks

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