Comparison of clenbuterol enantiomers using four psychopharmacological tests sensitive to beta-agonists

The effects of the enantiomers of clenbuterol were compared in four psychopharmacological tests in which beta-adrenergic agonists are known to be active. In mice (+/-)-clenbuterol 0.06 mg/kg decreased motor activity and antagonized the hypothermia induced by 16 mg/kg of apomorphine; at 0.5 mg/kg it increased head-twitches and tremors induced by 1-5-hydroxytryptophan (4 mg/kg) and decreased the number of bites of a food pellet by mice which had been maintained on a water only diet for 24-27 h ('Tantale' test). The present results show that the (-) form is responsible for this activity and that the (+) form has no effect per se and does not antagonize the (-) enantiomer.