CARISOPRODOL

Fetal Risk Summary

Carisoprodol is a centrally acting muscle relaxant. The reproductive effect of this drug in animals has not been studied. No published studies describing the use of this agent in human pregnancy, other than the one shown below, have been located.

The Collaborative Perinatal Project monitored 50,282 mother-child pairs, 14 of whom were exposed in the 1st trimester to carisoprodol (1). No association of the drug with large classes of malformations or to individual defects was found.

In a surveillance study of Michigan Medicaid recipients involving 229,101 completed pregnancies conducted between 1985 and 1992, 326 newborns had been exposed to carisoprodol during the 1st trimester (F. Rosa, personal communication, FDA, 1993). Twenty (6.1%) major birth defects were observed (14 expected), including (observed/expected) 3/3 cardiovascular defects, 2/0.5 oral clefts, and 1/1 hypospadias. No anomalies were observed in three other categories of defects (spina bifida, polydactyly, and limb reduction defects) for which data were available. Only with the two cases of oral clefts is there a suggestion of a possible association, but other factors, including the mother's disease, concurrent drug use, and chance, may be involved.

Breast Feeding Summary

Carisoprodol is concentrated into human milk with concentrations two to four times those in the maternal plasma (2). The American Academy of Pediatrics considers two other centrally acting skeletal muscle relaxants (e.g., Baclofen, Methocarbamol) to be compatible with breast feeding (3), because neither agent is concentrated in milk. Because of the high concentrations that appear in milk and the absence of reports describing the use of this drug during lactation, carisoprodol should be used cautiously, if at all, during lactation. Women taking this drug and who elect to nurse should closely monitor their infants for sedation and other changes in behavior or functions.

References

1. Heinonen OP, Slone D, Shapiro S. Birth Defects and Drugs in Pregnancy. Littleton, MA:Publishing Sciences Group, 1977:357–65.
2. Product information. Soma. Wallace Laboratories, 1994.
3. Committee on Drugs, American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 1994;93:137–50.