Outcomes after isolated mirtazapine (Remeron) supratherapeutic ingestions

Mirtazapine (Remeron) is a newly approved medication for the treatment of depression. It is an alpha(2)-adrenergic antagonist that causes increased levels of neuronal norepinephrine and serotonin. It is also believed to be an antagonist at the serotonin receptors 5-HT(2) and 5-HT(3). Little is known about isolated mirtazapine ingestions. We conducted a retrospective chart review of mirtazapine ingestions reported to our Poison Center during 2004. A standardized data sheet was completed collecting information regarding standard demographic data along with co-ingestants, neurologic and cardiovascular symptoms, and disposition. Data collection was reviewed by a second investigator, and a kappa score was calculated. Of 71 patients identified with mirtazapine ingestions, there were 33 isolated exposures that were further reviewed. A kappa score for inter-reviewer reliability was calculated and at 0.61, 95% confidence interval 56-70. The average age of these patients was 27 years (range 6-82 years), with the mean ingestion of 343 mg (range 15-1500 mg). The most common neurologic symptom was drowsiness seen in 8/23 patients, 1 patient became agitated, and 14 patients had no abnormal neurologic findings. Cardiovascular effects were recorded in 4/23 patients, with 3 patients exhibiting tachycardia and 1 patient with bradycardia and hypotension. Seven of 23 patients required admission; there were no deaths. Mirtazapine overdoses are generally very well tolerated, with the most common symptoms being drowsiness and lethargy. This study is limited by being a retrospective chart review.