If meprobamate is required by the mother, it is not necessarily a reason to discontinue breastfeeding. However, because there is little published experience with meprobamate during breastfeeding, other agents may be preferred, especially while nursing a newborn or preterm infant, or when other drugs that can cause sedation are used simultaneously.
One author reported a personal communication from the manufacturer. The manufacturer reports that 6 lactating women who were given a single 800 mg oral dose of meprobamate had peak milk meprobamate concentrations 4 hours after the dose.
The muscle relaxant carisoprodol is metabolized to meprobamate. A mother taking carisoprodol 700 mg three times daily during pregnancy and lactation had trough breastmilk levels of carisoprodol and meprobamate measured before the first morning dose on 4 consecutive days at steady-state (time postpartum not stated). Average minimum breastmilk levels were 0.9 mg/L for carisoprodol and 11.6 mg/L for meprobamate. The authors calculated that the minimum infant dose of the drug plus metabolite was 1.9 mg/kg daily or 4.1% of the maternal weight-adjusted dosage. Extrapolating these results to an average (rather than minimum) dose, the authors estimated that an exclusively breastfed infant would receive 3 mg/kg daily or 6% of the maternal weight-adjusted dosage.
A woman who was suspected to have been abusing carisoprodol had the drug and meprobamate detectable in breastmilk for 2 consecutive days after hospitalization; only meprobamate was detectable on day 3.
Relevant published information was not found as of the revision date.
Effects in Breastfed Infants:
A mother taking carisoprodol 700 mg plus propoxyphene 70 mg andacetaminophen900 mg 3 times daily and partially breastfeeding her infant noticed no unusual behavior or adverse reactions in her infant. The infant grew normally and, at 6 months of age, examination by a pediatrician found normal psychomotor development.
Possible Effects on Lactation:
One paper reported that some psychiatric patients receiving meprobamate alone or in combination with other psychotropic drugs developed galactorrhea. Further details of meprobamate use were not reported.
1. Ayd FJ. Excretion of psychotropic drugs in human breast milk. Int Drug Ther Newsl. 1973;8:33-40. 2. Nordeng H, Zahlsen K, Spigset O . Transfer of carisoprodol to breast milk. Ther Drug Monit. 2001;23:298-300. PMID:11360042 3. Bailey DN, Briggs JR. Carisoprodol: an unrecognized drug of abuse. Am J Clin Pathol. 2002;117:396-400. PMID:11888078 4. Hooper JH Jr, Welch VC, Shackelford RT. Abnormal lactation associated with tranquilizing drug therapy. JAMA. 1961;178:506-7. PMID:14448766
CAS Registry Number:
Hypnotics and Sedatives
Muscle Relaxants, Central
LactMed Record Number:
Last Revision Date:
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