Rapid cycling in manic-depressives induced by tricyclic antidepressants.

Maintenance tricyclic antidepressants induced rapid cycling between mania and depression in five female bipolar (manic-depressive) patients. Lithium carbonate did not prevent the tricyclic-induced rapid cycling, although two patients subsequently responded well to lithium carbonate alone. In these patients, the action of tricyclics can be conceptualized as accelerating rather than counteracting the natural, cyclic course of the illness in all of its phases. In this respect, tricyclics are analogous to several other drugs that are capable of modulating the frequency of oscillatory biological processes.