From the Journals

Pot peaks in breast milk 1 hour after smoking


Key clinical point: Cannabinoid levels peak in breast milk 1 hour after smoking.

Major finding: Breastfeeding infants ingest around 2.5% of the maternal dose in breast milk.

Study details: A pilot pharmacokinetic study in eight women.

Disclosures: No conflicts of interest were declared.

Source: Baker T et al. Obstet Gynecol. 2018;131:783-8.



The levels of delta-9-tetrahydrocannabinol in breast milk peak around 1 hour after smoking, according to a pilot pharmacokinetic study.

Eight mothers who were either occasional or chronic cannabis smokers, and who exclusively breastfed their infants, were directed to smoke a preweighed, standardized amount of “Prezidential Kush” from a preselected Denver dispensary after initially discontinuing for 24 hours. Researchers collected breast milk samples from just before smoking, and at 20 minutes, 1 hour, 2 hours, and 4 hours after smoking, according to a paper published in the May issue of Obstetrics & Gynecology.

Marijuana leaves Smithore
The mean concentration of delta-9-tetrahydrocannabinol in the breast milk peaked at 94 ng/mL at 1 hour after smoking, and the average concentration over the whole period was 53.5 ng/mL.

This translated to an estimated relative infant dose of 2.5% of the maternal dose, or 8 mcg per kilogram per day.

“It remains unclear what exposure to cannabis products during this critical neurobehavioral development period will mean for the infant,” wrote Teresa Baker, MD, of Texas Tech University Health Sciences Center, and her coauthors. “These questions will require an enormous effort to determine.”

Concentrations of delta-9-tetrahydrocannabinol metabolites 11-OH-delta-9-tetrahydrocannabinol and 11-Nor-9-carboxy-delta-9-tetrahydrocannabinol were too low to be detected.

The authors noted that these metabolites are known to be more water soluble and polar than delta-9-tetrahydrocannabinol itself, which may make it more difficult for them to enter the breast milk compartment.

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