Ro 11-2465 (cyan-imipramine), citalopram and their N-desmethyl metabolites: effects on the uptake of 5-hydroxytryptamine and noradrenaline in vivo and related pharmacological activities

Ro 11-2465 (cianopramine, cyan-imipramine) and citalopram (CIT), putative antidepressant drugs, are very potent and selective 5-hydroxytryptamine (5-HT) uptake inhibitors in vitro. This study investigated the effects of these drugs and their desmethyl metabolites, Ro 12-5419 (desmethylcianopramine, cyan-desipramine) and desmethylcitalopram (DCIT), respectively, on the uptake of 5-HT and noradrenaline (NA) in vivo [protection against H 77/77 (4, alpha-dimethyl-metatyramine)-induced displacement of 5-HT and NA] and on related pharmacological activities. All the investigated drugs antagonized H 77/77-induced displacement of 5-HT in the rat brain, though the effects of the metabolites were considerably weaker than those of the parent compounds. The H 77/77-induced displacement of brain NA in rats and mice was antagonized only by Ro 12-5419 and Ro 11-2465. All the drugs potentiated the pressor response to 5-HT in pithed rats; however, Ro 12-5419 and particularly Ro 11-2465 could also block the response when used in higher doses (greater than or equal to 0.1 mg/kg). Only Ro 12-5419 and Ro 11-2465 were able to potentiate the pressor response to NA. Ro 12-5419 also potentiated thyrotropin releasing hormone (TRH) hyperthermia and antagonized reserpine hypothermia in mice; Ro 11-2465 potentiated the TRH hyperthermia only. CIT and DCIT were inactive in both these tests. Of all the four drugs only CIT and Ro 12-5419 considerably stimulated the hind limb flexor reflex in spinal rats.(ABSTRACT TRUNCATED AT 250 WORDS)