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Drugline nr 23092

Publicerat 2006-10-31

Question

Is mirtazapine compatible with breast-feeding?

Answer

Mirtazapine is an antidepressant with a bioavailability of 50% and a half-life of 20-40 hours (1).

This question has previously been answered in Drugline. At that time, there was only one published case. A maximum infant dose of 1% of the maternal weight-adjusted dose was calculated, and no adverse effects in the child were noted. The manufacturer had knowledge of two additional cases. In one of these, a nine-month-old child experienced adverse effects (nausea, diarrhoea and vomiting) six days after the mother initiated of mirtazapine (15 mg/day) (2).

In a recently published study the transfer of mirtazapine and its active metabolite, desmethylmirtazapine, in eight mother-infant pairs was investigated. The mothers had been treated with mirtazapine a median of 32 days (range 6-129 days), and were taking single daily doses of mirtazapine of a median of 38 mg (range 30-120 mg). The mean milk/plasma ratio was 1.1 for mirtazapine and 0.6 for the metabolite. The total relative infant dose for mirtazapine and desmethylmirtazapine was calculated to be in average 1.9% (range 0.7-3.1%) of the maternal weight-adjusted dose. In four of the infants, blood samples were drawn. Mirtazapine was only detected in plasma from one of the children (1.5 ug/l) and the metabolite in none. None of the infants showed any adverse effects (3).

Conclusion

Mirtazapine is excreted into breast milk. The reported total relative infant dose has varied between 0.7-3.1% of the maternal weight-adjusted dose and no adverse effects have been observed in the published cases. Based on existing data, mirtazapine seems to be compatible with breast-feeding. However, the infant should be observed for undesirable effects.

Jansson Å
Böttiger Y

References

  1. Remeron. Summary of Product Characteristics (SPC). Organon.
  2. Drugline no 21954 (year 2005)
  3. Kristensen JH, Ilett KF, Rampono J, Kohan R, Hackett LP. Transfer of the antidepressant mirtazapine into breast milk. Br J Clin Pharmacol 2006 Sep 13;

Senast ändrad 2018-09-20