Milk levels of amitriptyline and its metabolites are low. Immediate side effects have not been reported and a limited amount of follow-up has found no adverse effects on infant growth and development.Amitriptylineuse during breastfeeding would usually not be expected to cause any adverse effects in breastfed infants, especially if the infant is older than 2 months. Other agents with fewer active metabolites may be preferred when large doses are required or while nursing a newborn or preterm infant.
Amitriptylineis metabolized to nortriptyline which has antidepressant activity equal to amitriptyline 's.
A mother who had been taking amitriptyline 100 mg daily for 6 weeks postpartum had breastmilk levels of amitriptyline and nortriptyline of 151 and 59 mcg/L, respectively, 16 hours after a dose. Eleven days later, breastmilk levels of amitriptyline and nortriptyline were 135 and 52 mcg/L, respectively, 14 hours after the dose. The amounts in milk represent an infant dosage of about 1.8% of the maternal weight-adjusted dosage.
Amitriptylineand nortriptyline were measured in breastmilk in a mother who was taking amitriptyline 75 mg daily. Her milk amitriptyline levels were 104 and 72 mcg/L and her nortriptyline levels were 75 and 63 mcg/L at 2 and 10 weeks, respectively, after starting treatment (time after dose not specified). After 19 weeks of therapy, an amitriptyline dose of 25 mg daily produced milk amitriptyline levels of 30 mcg/L; nortriptyline levels were not detectable (<30 mcg/L). The authors estimated that this infant would receive 1% of the maternal weight-adjusted dosage.
Another mother who was taking amitriptyline 175 mg daily had amitriptyline and nortriptyline milk levels of 13 and 15 mcg/L each on the morning and evening of the first day of therapy. On days 2 to 26 of therapy, milk amitriptyline ranged from 23 to 38 mcg/L. On day 26 milk nortriptyline was about 64 mcg/L. E-10-hydroxynortriptyline was found in milk in levels averaging 89 mcg/L over this 26-day time period.
A 2-week postpartum mother of a preterm infant had been taking amitriptyline 100 mg daily for 4 days when milk was analyzed. Milk amitriptyline levels were highest at 1.5 and 6 hours after the dose at 103 and 100 mcg/L, respectively. They fell to 29 mcg/L 24 hours after the dose. Milk nortriptyline levels were highest at 18 hours after the dose at 58 mcg/L. Using the peak milk level data from this study, an exclusively breastfed infant would receive an estimated maximum of 0.9% of the maternal weight-adjusted dosage.
Two mothers who were taking amitriptyline had milk samples taken 12 to 15 hours after their daily dose. The mother taking 100 mg daily had a foremilk level of 30 mcg/L and a hindmilk level of 113 mcg/L. The mother taking 175 mg daily had a hindmilk level of 197 mcg/L. Using the hindmilk data from this study, an exclusively breastfed infant would receive an estimated maximum of 1% of the maternal weight-adjusted dosage
A mother who had been taking amitriptyline 150 mg daily for 3 weeks was nursing her infant (extent not stated).Amitriptylineand nortriptyline were undetectable (<28 mcg/L) in the infant's serum.
A mother who had been taking amitriptyline 100 mg daily for 7.5 weeks postpartum was nursing her infant.Amitriptylineand nortriptyline were undetectable (<10 mcg/L) 14 hours after a dose.
A 3-week-old breastfed had undetectable serum amitriptyline (<5 mcg/L) and nortriptyline (<15 mcg/L) during maternal amitriptyline use of 75 mg daily.
After 26 days of breastfeeding (4 of 6 daily feedings; 500 to 600 mL daily) during maternal use of amitriptyline 175 mg daily, amitriptyline and its metabolites were undetectable in the serum of one infant.
One infant whose mother was taking amitriptyline 100 mg daily, had a plasma level of 7.5 mcg/L at an unspecified time after the maternal dosage.
Effects in Breastfed Infants:
At least 23 infants have been reported to have been exposed to amitriptyline in breastmilk with no reports of adverse reactions with maternal dosages from 75 to 175 mg daily.
Follow-up for 1 to 3 years in a group of 20 breastfed infants whose mothers were taking a tricyclic antidepressant found no adverse effects on growth and development. One of the mothers whose infant was followed up at 18 months of age was taking amitriptyline 150 mg daily. Two small controlled studies indicate that other tricyclic antidepressants have no adverse effect on infant development. In one of the studies, 2 mothers were taking amitriptyine 100 and 175 mg daily. One of the infants tested in the low normal range from birth and on repeat testing.
In another study, 25 infants whose mothers took a tricyclic antidepressant during pregnancy and lactation were tested formally between 15 to 71 months and found to have normal growth and development. Some of the mothers were taking amitriptyline .
Possible Effects on Lactation:
Amitriptylinehas caused increased prolactin levels in nonpregnant, nonnursing patients. The clinical relevance of these findings in nursing mothers is not known. The prolactin level in a mother with established lactation may not affect her ability to breastfeed.
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