Dopamine and mania. The effects of trans- and cis-clopenthixol in a double-blind pilot study.

Sordinol is composed of the mixture of cis-clopenthixol and trans-clopenthixol. The two isomers do not differ in several pharmacological properties, for instance anti-noradrenergic effect. However, cis-clopenthixol possesses anti-dopaminergic effects, while trans-clopenthixol does not. Sordinol-depot contains the almost pure cis-clopenthixol and appears to be less sedating than the oral and short-lasting intramuscular administration forms. In a double-blind pilot study with 10 manic patients, trans-clopenthixol was compared with cis-clopenthixol. Although not reaching statistical significance, cis-clopenthixol showed anti-manic effects, while trans-clopenthixol remained ineffective. It is concluded that the anti-dopaminergic effect of cis-clopenthixol is essential for its anti-manic effect, which is in agreement with the hypothesis of involvement of the dopaminergic system in the pathogenesis of mania.