Initial dose is 15 or 30 mg, taken preferably in the evening. The maintenance dose is usually between 15 mg to 45 mg per day.
Elderly and Patients with Renal or Hepatic Impairment: The clearance of Mirtazapine is reduced in elderly patients and in patients with moderate to severe renal or hepatic impairment. Consequently, the prescriber should be aware that plasma Mirtazapine levels may be increased in these patient groups, compared to levels observed in younger adults without renal or hepatic impairment.
Switching Patients to Mirtazapine from a Monoamine Oxidase Inhibitor (MAOI): At least 14 days should elapse between discontinuation of a MAOI and initiation of therapy with Mirtazapine tablets. In addition, at least 14 days should be allowed after stopping Mirtazapine before starting a MAOI. Mirtazapine has an elimination half-life of approximately 20 to 40 hours; therefore, dose changes should not be made at intervals of less than 1 to 2 weeks in order to allow sufficient time for evaluation of the therapeutic response to a given dose.