Monoamine oxidase inhibitors in bipolar endogenous depressives

Clinical lore suggests that monoamine oxidase inhibitors (MAOIs) are not effective in endogenous depression. A review of previous placebo-controlled trials of MAOI in patients with endogenous depression neither refutes nor confirms their utility in this patient group. We present patients in the depressive phase of bipolar illness refractory to treatment with tricyclics who have responded to MAOI. These open trials require confirmation in controlled studies. Bipolar illness may be a heterogeneous disorder. Presence or absence of X-linkage, low platelet MAO, or response to MAOI may indicate different forms of the disorder.