What is safer for a lactating mother, amitriptyline or cimetidine?

Safety of Amitriptyline vs Cimetidine During Lactation

Cimetidine is safer than amitriptyline for lactating mothers due to its lower risk profile and minimal transfer into breast milk. 1

Medication Transfer into Breast Milk

Amitriptyline

• Amitriptyline is excreted into breast milk, with reported levels of 135-151 ng/mL in breast milk when maternal serum levels were 83-141 ng/mL 2
• While one study reported no detectable levels in infant serum, the FDA label warns of "potential for serious adverse reactions in nursing infants from amitriptyline" 2
• The FDA recommends considering discontinuation of either nursing or the medication, based on the importance of the drug to the mother 2

Cimetidine

• Cimetidine is secreted in human milk but in amounts that pose minimal risk to the infant 1
• The drug has been studied extensively in pregnancy with no evidence of harm to the fetus at doses up to 40 times the normal human dose 1
• While the FDA label includes a general statement that "nursing should not be undertaken while patient is on a drug," this is a standard precautionary statement rather than specific evidence of harm 1

Safety Considerations

Amitriptyline Concerns

• Amitriptyline has significant anticholinergic effects that could potentially affect the infant 2
• It has a longer half-life and active metabolites that could accumulate in the infant 3
• Potential adverse effects include sedation, cardiovascular effects, and CNS effects 2
• Tricyclic antidepressants like amitriptyline have been reported to produce arrhythmias, sinus tachycardia, and prolongation of conduction time 2

Cimetidine Advantages

• Has been extensively studied with no evidence of impaired fertility or harm to the fetus 1
• Has a better-established safety profile during lactation compared to amitriptyline 1, 4
• Lower risk of sedation or CNS effects in the infant 1

Clinical Approach

When Prescribing for Lactating Mothers:

• Select medications with the lowest risk to the infant 5
• Consider timing medication doses to be taken just after breastfeeding or before the infant's longest sleep period 4
• For mental health conditions, effective treatment of the mother should be prioritized, but with medications that have established safety profiles during lactation 5

Monitoring Recommendations

• If amitriptyline must be used, monitor the infant for signs of:

  • Sedation
  • Poor feeding
  • Anticholinergic effects (dry mouth, constipation)
  • Cardiovascular changes 2, 3

• If cimetidine is used, standard infant monitoring is sufficient as adverse effects are rare 1, 4

Important Caveats

• The decision regarding medication use during breastfeeding should consider:
  • The necessity of the medication for the mother
  • The potential impact on the infant
  • The benefits of continued breastfeeding 4
• In most cases, the advantages of breastfeeding outweigh the very low risk of adverse effects from medication exposure 6
• Whenever possible, consult updated resources like LactMed for current safety information 5