Antipsychotic
PREGNANCY RECOMMENDATION: Limited Human Data—Animal Data Suggest Low Risk
BREASTFEEDING RECOMMENDATION: No Human Data—Potential Toxicity
PREGNANCY SUMMARY
Thiothixene, a phenothiazine derivative, is structurally and pharmacologically related to trifluoperazine and chlorprothixene (see Trifluoperazine). Although occasional reports have attempted to link various phenothiazines with congenital malformations, most of the evidence suggests that these drugs are low risk for the embryo–fetus.
FETAL RISK SUMMARY
No published reports, other than the one study below, describing the use of the drug in human pregnancy have been located. The drug is not teratogenic in mice, rats, rabbits, and monkeys (1–3).
It is not known if thiothixene crosses the human placenta. The molecular weight (about 444) is low enough that passage to the embryo–fetus should be expected.
In a surveillance study of Michigan Medicaid recipients involving 229,101 completed pregnancies conducted between 1985 and 1992, 38 newborns had been exposed to thiothixene during the 1st trimester (F. Rosa, personal communication, FDA, 1993). One (2.6%) major birth defect (two expected), a cardiovascular defect (0.5 expected), was observed. No anomalies were observed in five other categories of defects (oral clefts, spina bifida, polydactyly, limb reduction defects, and hypospadias) for which specific data were available.
BREASTFEEDING SUMMARY
No reports describing the use of thiothixene during lactation have been located. The molecular weight (about 444) is low enough that excretion into breast milk should be expected. The effect on a nursing infant from exposure to the drug in milk is unknown. However, other phenothiazines are present in milk and have caused toxicity (see Chlorpromazine). Sedation is a possible effect in nursing infants.
References
1.Owaki Y, Momiyama H, Yokoi Y. Teratological studies on thiothixene in mice. (Japanese) Oyo Yakuri 1969;3:315–20. As cited in Shepard TH. Catalog of Teratogenic Agents. 6th ed. Baltimore, MD: The Johns Hopkins University Press, 1989:618.
2.Owaki Y, Momiyama H, Yokoi Y. Teratological studies on thiothixene (Navane) in rabbits. (Japanese) Oyo Yakuri 1969;3:321–4. As cited in Shepard TH. Catalog of Teratogenic Agents. 6th ed. Baltimore, MD: The Johns Hopkins University Press, 1989;618.
3.Product information. Navane. Pfizer, 2000.