PHENOLPHTHALEIN

Fetal Risk Summary

The mechanism of action of the laxative phenolphthalein is similar to that of the anthraquinone purgatives (i.e., cascara sagrada, casanthranol, danthron, and senna). Small amounts of the laxative are absorbed into the systemic circulation. It is not known if the drug crosses the placenta, although the molecular weight is low enough (approximately 318) for placental transfer to occur. No studies describing the use of phenolphthalein in experimental animals have been found.

Phenolphthalein was used by 236 mother-child pairs during the 1st trimester (1, pp. 384–387) and 806 anytime during pregnancy (1, pp. 442, 497) in the Collaborative Perinatal Project. No evidence was found to associate the use of this drug with major or minor malformations.

Breast Feeding Summary

Phenolphthalein that had undergone conjugation, but not unmetabolized phenolphthalein, was excreted into breast milk in concentrations up to 1.0 µg/mL after a single 200- to 800-mg dose in 22 lactating women (2). Bowel movements occurred in 16 of the women after the dose, but none of the nursing infants had diarrhea. The possibility that conjugated phenolphthalein may undergo deconjugation in the infant's bowel and, thus by implication, produce diarrhea in the infant, has concerned some investigators (3). However, no reports of adverse effects following use of this product during nursing have been located.

References

1. Heinenon OP, Slone D, Shapiro S. Birth Defects and Drugs in Pregnancy. Littleton, MA:Publishing Sciences Group, 1977.
2. Burgess DE. Constipation in obstetrics. In Jones FA, Godding EW, eds. Management of Constipation. Oxford: Blackwell Scientific Publications, 1972:176–88. As cited by Leng-Peschlow E. Risk assessment for senna during pregnancy. Pharmacology 1992;44(Suppl 1):20–2.
3. Odenthal KP, Ziegler D. In vitro effects of anthraquinones on rat intestine and uterus. Pharmacology 1988;36(Suppl 1):57–65.