Local Anesthetic
PREGNANCY RECOMMENDATION: Limited Human Data—Probably Compatible
BREASTFEEDING RECOMMENDATION: No Human Data—Probably Compatible
PREGNANCY SUMMARY
Only one source has described the use of benzocaine in human pregnancy and there are no animal reproduction studies. Systemic absorption may occur from mucous membranes or from damaged skin with the amount absorbed dependent on the administered dose. There are about 50 over-the-counter (OTC) products that contain benzocaine, a number suggesting wide use of this anesthetic. There is no evidence that topical use of this drug class is associated with any aspect of developmental toxicity. Nevertheless, the best course is to avoid use of benzocaine on mucous membranes or damaged skin during pregnancy.
FETAL RISK SUMMARY
Benzocaine (ethyl aminobenzoate) is a topical local anesthetic that is indicated for various purposes such as pruritic dermatoses, pruritus, minor burns, insect bites, toothache, and minor sore throat pain. Systemic absorption is poor from intact skin but it is well absorbed from mucous membranes and traumatized skin. It is metabolized, primarily by cholinesterase in plasma, to inactive metabolites. The agent is available OTC in formulations for oral and topical sprays, solutions, lozenges, creams, and gels (1).
Reproduction studies in animals have not been conducted.
It is not known if benzocaine crosses the human placenta. The molecular weight (about 165) is low enough that exposure of the embryo or fetus, if absorption has occurred, should be expected. However, appropriate clinical use should minimize any exposure.
The Collaborative Perinatal Project monitored 50,282 mother–child pairs, 47 of whom had exposure to benzocaine during the 1st trimester (2, pp. 357–363). No evidence of an association with large classes of malformations was found. For use anytime during pregnancy, 238 exposures were recorded (2, p. 440). From these data, no evidence of an association with large categories of major or minor malformations or to individual defects was found. These results were also cited in a 1988 review of anesthetic agents (3).
BREASTFEEDING SUMMARY
No reports describing the use of benzocaine during breastfeeding have been located. Although the molecular weight (about 165) is low enough for excretion into breast milk, systemic absorption is poor from intact skin. However, the anesthetic is well absorbed from mucous membranes and traumatized skin and use of agent on these surfaces should be avoided or kept to minimum during breastfeeding.
References
1.Product information. Benzocaine. Merck Manual Professional, 2007. Available at http://www.merck.com/mmpe/print/lexicomp/benzocaine.html. Accessed January 27, 2011.
2.Heinonen OP, Slone D, Shapiro S. Birth Defects and Drugs in Pregnancy. Littleton, MA: Publishing Sciences Group, 1977.
3.Friedman JM. Teratogen update: anesthetic agents. Teratology 1988;37:69–77.