Rapid antidepressant activity of melanocyte-inhibiting factor: A clinical trial

Melanocyte-inhibiting factor prolylleucyl-glycinamide) is a naturally occurring peptide which has been synthesized and studied in preclinical models of depression and clinical trials with depressed patients. Animal studies indicate that melanocyte-inhibiting factor, or MIF, mimics tricyclic antidepressants in the dopa potentiation test (Plotnikoff et al., 1971), and like an augmenter of dopaminergic activity abolishes oxotremorine-induced tremors (Plotnikoff and Kastin, 1976). The drug is active in hypophysectomized animals, suggesting an involvement outside of the pituitary (Plotnikoff et al., 1974). The results of animal studies have led to trials of MIF in Parkinson's disease and depression. A double-blind clinical trial of MIF compared to placebo suggested efficacy in severe depression (Ehrensing and Kastin, 1974). However, the number of patients studied was relatively small. Patients showed greater improvement of 60 mg/day of MIF than 150 mg/day or placebo. Of particular interest was the fact that the drug was administered for only 6 days, suggesting a relatively rapid onset of action for MIF. This possibility led to the present study: a comparison of MIF with a dose of a tricyclic antidepressant that is typically used in the first week of treatment. Should MIF be found to have a very rapid onset of action it would be the drug of choice for patients with suicidal ideation or severe anorexia, who require a rapid treatment response.