Also known as (±)-Lorazepam, Ativan, Lormetazepam, Methyllorazepam, N-Methyllorazepam, O-Chlorooxazepam, O-Chloroxazepam

A benzodiazepine with anxiolytic, anti-anxiety, anticonvulsant, anti-emetic and sedative properties. Lorazepam enhances the effect of the inhibitory neurotransmitter gamma-aminobutyric acid on the GABA receptors by binding to a site that is distinct from the GABA binding site in the central nervous system. This leads to an increase in chloride channel opening events, a facilitation of chloride ion conductance, membrane hyperpolarization, and eventually inhibition of the transmission of nerve signals, thereby decreasing nervous excitation.

Originator: NCI Thesaurus | Source: The website of the National Cancer Institute (http://www.cancer.gov)

Can I take Lorazepam while breastfeeding?

Lorazepam has low levels in breastmilk, a short half-life relative to many other benzodiazepines, and is safely administered directly to infants. Evidence from nursing mothers indicates that lorazepam does not cause any adverse effects in breastfed infants with usual maternal dosages. No special precautions are required.

Drug levels

Maternal Levels. Four women were given 3.5 mg of lorazepam orally 2 hours before undergoing cesarean section. Colostrum levels of lorazepam averaged 8.5 mcg/L at 4 hours after the dose; conjugated lorazepam metabolites were not measured.[1]

Another woman taking 2.5 mg orally twice a day for the first 5 days postpartum had milk levels of free and conjugated lorazepam of 12 and 35 mcg/L, respectively, at an unspecified time on day 5.[2] Since infants can deconjugate and absorb glucuronides, the total drug level is probably more important than the free drug alone. Using the total amount excreted, an exclusively breastfed infant would receive about 7 mcg/kg daily with this maternal dosage or about 8.5% of the maternal weight-adjusted dosage.

A woman who was 4 weeks postpartum was taking lorazepam 2.5 mg 1 to 3 times daily and lormetazepam, which is partially metabolized to lorazepam, 2 mg once daily. On day 5 of therapy after taking 2 doses of lorazepam in the previous 8 hours, her lorazepam milk level was 123 mcg/L. On day 6 after having taken 3 doses in the previous 24 hours, her milk lorazepam level was 89 mcg/L. On day 7, milk levels were 55 and 40 mcg/L at 14 and 18.5 hours after her last dose, respectively.[3]

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

Effects in breastfed infants

Maternal Levels. Four women were given 3.5 mg of lorazepam orally 2 hours before undergoing cesarean section. Colostrum levels of lorazepam averaged 8.5 mcg/L at 4 hours after the dose; conjugated lorazepam metabolites were not measured.[1]

Another woman taking 2.5 mg orally twice a day for the first 5 days postpartum had milk levels of free and conjugated lorazepam of 12 and 35 mcg/L, respectively, at an unspecified time on day 5.[2] Since infants can deconjugate and absorb glucuronides, the total drug level is probably more important than the free drug alone. Using the total amount excreted, an exclusively breastfed infant would receive about 7 mcg/kg daily with this maternal dosage or about 8.5% of the maternal weight-adjusted dosage.

A woman who was 4 weeks postpartum was taking lorazepam 2.5 mg 1 to 3 times daily and lormetazepam, which is partially metabolized to lorazepam, 2 mg once daily. On day 5 of therapy after taking 2 doses of lorazepam in the previous 8 hours, her lorazepam milk level was 123 mcg/L. On day 6 after having taken 3 doses in the previous 24 hours, her milk lorazepam level was 89 mcg/L. On day 7, milk levels were 55 and 40 mcg/L at 14 and 18.5 hours after her last dose, respectively.[3]

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

Possible effects on lactation

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

Alternate drugs to consider

Midazolam, Oxazepam

References

1. Summerfield RJ, Nielsen MS. Excretion of lorazepam into breast milk. Br J Anaesth. 1985;57:1042-3. Letter. PMID: 4041315

2. Whitelaw AGL, Cummings AJ, McFadyen IR. Effect of maternal lorazepam on the neonate. Br Med J (Clin Res Ed). 1981;282:1106-8. PMID: 6113019

3. Lemmer P, Schneider S, Muhe A, Wennig R. Quantification of lorazepam and lormetazepam in human breast milk using GC-MS in the negative chemical ionization mode. J Anal Toxicol 2007;31:224-6. PMID: 17555647

4. Kelly LE, Poon S, Madadi P, Koren G. Neonatal benzodiazepines exposure during breastfeeding. J Pediatr. 2012;161:448-51. PMID: 22504099

Last Revision Date

20130907

Disclaimer:Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.

Source: LactMed – National Library of Medicine (NLM)

3D Model of the Lorazepam molecule

MolView – data visualization platform