Current prescription patterns and safety profile of irreversible monoamine oxidase inhibitors: a population-based cohort study of older adults.

OBJECTIVE: To determine the prescription pattern and safety profile for irreversible monoamine oxidase inhibitors (MAOIs) in older adults over the past decade.

METHOD: A population-based observational cohort study of older adults was conducted from January 1, 1997, to April 14, 2007, utilizing large administrative health care databases in Ontario, Canada. We examined the prevalence and incidence of irreversible MAOI use, as well as the frequency of coprescribing of MAOIs with contraindicated medications such as serotonergic and sympathomimetic drugs. We reviewed the most responsible diagnosis of emergency department (ED) visits and acute care admissions to assess for serious adverse events that may occur during MAOI treatment (ie, serotonin syndrome and hypertensive crisis).

RESULTS: Over a 10-year period, there were 348 new users of irreversible MAOIs. The majority of patients showed a previous treatment pattern consistent with recurrent major depressive disorder, including prior use of antidepressant treatment and electroconvulsive therapy. The yearly incidence of MAOI prescriptions remained low and decreased from a rate of 3.1/100,000 to 1.4/100,000. Concomitant exposure to at least 1 serotonergic drug occurred in 18.1% of patients treated with an MAOI. No ED visits or acute care admissions for serotonin syndrome or hypertensive crisis were identified.

CONCLUSIONS: The low prescription rate of MAOIs is not consistent with the continued recommendation of MAOIs by expert opinion leaders and consensus guidelines for use in atypical depression and treatment-refractory depression. While their use appeared safe, heightened awareness of the potential risk of concomitant use of serotonergic agents is necessary. Relative underuse of the MAOIs for a significant subgroup of depressed patients with atypical and treatment-refractory depression remains a concern.