Inhibition of platelet monoamine oxidase in depressed subjects treated with phenelzine.

The authors treated 19 depressive inpatients double-blind with a mean dose of 78 mg/day of phenelzine for 3 weeks to determine the possible relationship between monoamine oxidase (MAO) inhibition and the effectiveness of phenelzine. Clinical ratings made on the Hamilton Depression Rating Scale, the Beck Depression Inventory, and the SCL-90 indicated a minimum of 60% MAO inhibition had to be achieved for the drug to be consistently beneficial.