FLUPENTHIXOL

Fetal Risk Summary

Flupenthixol crosses the placenta with cord blood levels averaging 24% of maternal serum levels (1). Amniotic fluid concentrations are similar to those in cord blood. Flupenthixol 1 mg daily was used throughout the 2nd and 3rd trimesters in one patient with borderline psychotic depression (2). None of the infants in the above studies was apparently affected by the exposure to flupenthixol.

Breast Feeding Summary

Flupenthixol is excreted into breast milk (1,2). In one study, concentrations were about 30% higher than those in maternal serum (1). In a second study, a mother received flupenthixol 1 mg daily throughout the 2nd and 3rd trimesters (2). The dose was increased to 4 mg daily on the 1st postpartum day, then tapered to 2 mg daily over the next 7 weeks. The mother was also receiving nortriptyline. While receiving the 4-mg daily dose, milk concentrations, measured 2–4.5 hours after a dose on postpartum days 6 (four samples) and 20 (two samples), ranged from 2.0–6.8 ng/mL, with a mean of 3.2 ng/mL. The milk:serum ratios for these samples ranged from 0.50–1.62, with a mean of 0.85. No effects of the drug exposure were observed in the nursing infant, who had normal motor development for the first 4 months (2). The significance of chronic exposure of the nursing infant to this drug is unknown, but concern has been expressed about the effects of long-term exposure on the infant's neurobehavioral mechanisms (2).

References

1. Kirk L, Jorgensen A. Concentrations of cis(z)-flupenthixol in maternal serum, amniotic fluid, umbilical cord serum, and milk. Psychopharmacology (Berlin) 1980;72:107–8.
2. Matheson I, Skjaeraasen J. Milk concentrations of flupenthixol, nortriptyline and zuclopenthixol and between-breast differences in two patients. Eur J Clin Pharmacol 1988;35:217–20.