Rolipram, in contrast to the tricyclic antidepressants amitriptyline and imipramine or the acetylcholine receptor antagonist atropine, failed to antagonize the salivation, hypothermia, or tremor caused in mice by the muscarinic receptor agonists pilocarpine or oxotremorine. The absence of anticholinergic activity, the extremely low therapeutic dose, and the novel mechanism of antidepressant action suggest that rolipram may also be a well tolerable antidepressant suitable for the treatment of problematic subpopulations of depressives such as elderly patients.

No abstract