ZUCLOPENTHIXOL

Fetal Risk Summary

Zuclopenthixol is a thioxanthene tranquilizer with properties similar to those of chlorpromazine. No reports of the use of zuclopenthixol in pregnancy have been located.

Breast Feeding Summary

Zuclopenthixol is excreted into human milk. In six women treated with the agent between 3 days and 10 months after delivery, the mean milk:serum ratio was 0.29 (range 0.12–0.56) (1). Maternal dosages were 72 mg (IM depot injection) every 2 weeks in one patient and 4–50 mg/day orally in the other five women (time interval between oral dosing and sampling not specified). The milk concentrations were all less than 4 ng/mL, with the highest level occurring in the woman who received the injectable form. The authors estimated that an infant consuming 600 mL/day of milk would ingest 0.5–5 µg/day of zuclopenthixol. None of the nursing infants showed signs of sedation or other adverse effects.

In a 1988 study, zuclopenthixol was also measured in the milk of a woman who was being treated for puerperal psychosis 2 weeks after delivery of her first child (2). The mother was given 24 mg/day orally for 4 days, then 14 mg/day. Milk and serum samples were obtained on days 2, 3, 6, and 8 of therapy. The mean milk concentration while the mother was receiving 24 mg/day was 20 ng/mL (milk:serum ratio 0.71–2.20); it fell to 5 ng/mL while she was receiving 14 mg/day (ratio of 0.24–0.66) (the time interval between dosing and sampling was not specified). No adverse effects were observed in the nursing infant.

Although no adverse effects were observed in the seven infants exposed via the milk to zuclopenthixol, the long-term effects of this exposure have not been studied. Caution is advised, especially during prolonged therapy, until additional studies have been conducted (2).

References

1. Aaes-Jorgensen T, Bjorndal F, Bartels U. Zuclopenthixol levels in serum and breast milk. Psychopharmacology 1986;90:417–8.
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.