Clorazepate

Drug Levels and Effects:




Summary of Use during Lactation:


Clorazepate is excreted into breastmilk and appears to accumulate in the serum of breastfed infants. Because the half-life of clorazepate and its active metabolite are long, timing breastfeeding with respect to the dose is of little or no benefit in reducing infant exposure. Other agents may be preferred, especially while nursing a newborn or preterm infant.


Drug Levels:


Clorazepate is a prodrug of nordiazepam (desmethyldiazepam) which is the primary active metabolite of diazepam.

Maternal Levels.

After a single 20 mg intramuscular dose of clorazepate in 7 women, milk nordiazepam levels ranged from 7.5 to 15.5 mcg/L 2 days after the dose and 6 to 12 mcg/L 4 days after the dose.[1]

Infant Levels.

Nordiazepam has been found in infants' serum in levels higher than milk levels, indicating accumulation, and only slightly lower than adult therapeutic levels after diazepam use by the mother.[2][3]

After a single 20 mg intramuscular dose of clorazepate in 7 women, serum levels of their breastfed infants ranged from trace levels in 5 of the infants to 4 and 7.5 mcg/L in the others on the second day after the dose. On the fourth day after the dose, infant serum levels was a trace amounts in one and ranged from 4 to 8.5 mcg/L in the others, indicating accumulation in infant serum.[1]


Effects in Breastfed Infants:


Sedation in infants has been reported during maternal use of diazepam which has nordiazepam as its active metabolite.[3][4] Concern has also been expressed that nordiazepam may compete with bilirubin for hepatic glucuronide conjugation in the neonate.[2]


Possible Effects on Lactation:


Relevant published information was not found as of the revision date.


Alternate Drugs to Consider:


Lorazepam,Oxazepam


References:


1. Rey E, Giraux P, d'Athis P, et al. Pharmacokinetics of the placental transfer and distribution of clorazepate and its metabolite nordiazepam into the feto-placental unit and in the neonate. Eur J Clin Pharmacol. 1979;15:181-5. PMID:37090
2. Erkkola R, Kanto J. Diazepam and breast-feeding. Lancet. 1972;299:1235-6. Letter. PMID:4113217
3. Wesson DR, Camber S, Harkey M et al. Diazepam and desmethyldiazepam in breast milk. J Psychoactive Drugs. 1985;17:55-6. PMID:3920372
4. Patrick MJ, Tilstone WJ, Reavey P. Diazepam and breast-feeding. Lancet. 1972;299:542-3. Letter. PMID:4110044



Substance Identification:




Substance Name:

Clorazepate

CAS Registry Number:

57109-90-7

Drug Class:


  • Hypnotics and Sedatives

  • Anti-Anxiety Agents

  • Benzodiazepines


  • Administrative Information:




    LactMed Record Number:


    345


    Last Revision Date:


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