CHLORPROTHIXENE

Fetal Risk Summary

Chlorprothixene is structurally and pharmacologically related to chlorpromazine and thiothixene. No specific data on its use in pregnancy have been located (see also Chlorpromazine).

Breast Feeding Summary

Chlorprothixene is excreted into breast milk (1). Serum and milk concentrations of chlorprothixene and its metabolite, chlorprothixene sulfoxide, were determined in two women consuming 200 mg/day. In one woman, plasma concentrations of the parent drug and the metabolite, 1.5–24 hours after the 200-mg dose, ranged from 13 to 51 nmol/L and 75 to 130 nmol/L, respectively. Simultaneously obtained milk levels ranged from 6 to 60 nmol/L and 42 to 96 nmol/L, respectively. The second patient had a single determination drawn 30 hours after a 200-mg dose with levels in the plasma and milk for the parent compound and metabolite of 38 and 98 nmol/L (plasma) and 115 and 54 nmol/L (milk), respectively. The milk:plasma ratio for chlorprothixene varied between 1.2 and 2.6, while that of the metabolite varied from 0.5 to 0.8. The test method used was able to recover 90%–100% of the drugs from the plasma but only 60%–70% from the milk. No adverse effects were noted in the nursing infants. The investigators calculated that a nursing infant consuming 800 mL of milk/day would ingest no more than 15 µmg of chlorprothixene/day. The American Academy of Pediatrics classifies chlorprothixene as an agent whose effect on the nursing infant is unknown but may be of concern (2).

References

1. Matheson I, Evang A, Fredricson Overo K, Syversen G. Presence of chlorprothixene and its metabolites in breast milk. Eur J Clin Pharmacol 1984;27:611–3.
2. Committee on Drugs, American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 1994;93:137–50.