Dr Rubab Khalid: Breastfeeding and Drugs

This post is about one of an important topic Breastfeeding and Drugs. The choice of safe drugs during pregnancy and breastfeeding is paramount for an obstetrician. The safety profile for mother as well as infant is to be kept in mind. This post covers analgesics, antibiotics, antidepressants and drugs used for complex medical conditions. The points have been extracted from a TOG article which was published in April 2021. I have compiled the information in a tabulated form which will be helpful in quick revision for the exam.

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Introduction

Most drugs can be take safely by lactating mothers
Medications use during breastfeeding shortens the duration of breastfeeding mainly due to maternal fear of harming the baby

Common drugs used in lactation period

Analgesics

In postnatal period — analgesia is needed routinely most often after CS, AVB & perineal tear repair

Analgesics	Pharmacokinetics	Drug levels — in mother / infant	Effects on infant	Effect on lactation & breast milk
Paracetamol	• Non-opioid • No anti-inflammatory action • Oral absorption rates depend on gastric emptying	• Peak in breast milk 1-2 hr after • Infants exposed to 1%-3.5% of maternal-adjusted dose	No adverse affects
Ibuprofen	• NSAID 2 arylpropionic acid (2-APA) class • Oral - rapid & complete absorption • Short half-life • Low risk of accumulation	• Undetectable in breast milk	No adverse affects
Codeine	• Very weak analgesic activity • Analgesic activity provided by its metabolites Metabolised to • Morphine, norcodeine & codein-6-glucuronide via CYP2D6 • Morphine-6-glucuronide via UGT2B7	• 1% of maternal-adjusted dose received by fully breastfed infant • Plasma clearance prolonged in newborn infants • Morphine:codeine ratio higher in infant serum	Contraindicated by MHRA to used during lactation	Increased serum prolactin — does not affect ability to breastfeed in established lactation
Aspirin	Rapidly metabolised to salicylic acid	Excreted into breast milk at high levels	• Metabolic acidosis may occur • Thrombocytopenia, fever & petechia	No effect
Tramadol	• Centrally acting • Structurally related to codeine & morphine • Agonist at mu opioid receptors • Inhibits re-uptake of serotonin & noradrenaline	Low excretion into breast milk	Limited	Increased serum prolactin — does not affect ability to breastfeed in established lactation
Morphine	• Metabolised to inactive morphine-3-gluoronide (60%) & active morphine-6-glucoronide (10%) within 15-20 min of IM or SC & within 30-90 min or oral • Much lower peak levels after oral use	• Prolonged plasma clearance in very young infants • Clearance approach adult level at 2 months of age	Unlikely to be harmful	Delayed lactogenesis

Antibiotics

Antibiotics	Pharmacokinetics	Drug levels — in mother / infant	Effects on infant	Effect on lactation & breast milk
Co-amoxiclave	Β-lactam inhibits peptidoglycan synthesis	0.25 - 0.5% of standard infant dose	• Side effects uncommon • Restlessness, diarrhoea, rash	Not significant
Flucloxacillin	Β-lactam specially for G+ve organisms	Low	Ocasional diarrea & thrush	Safe to use
Metronidazole	• Bactericidal • Inhibits nucleic acid synthesis in bacterial cells • Well absorbed orally • >90% bioavailability • Absorption unaffected by infection	• After topical — plasma levels 1% of that after 250 mg oral dose • Use only water or gel-based for breast • Well distributed in breast milk • Infants exposed to less than standard paediatric doses • Well tolerated	Candida infections & diarrhoea	• Altered taste of breast milk • No negative impact on ability to breastfeed
Ciprofloxacin	• Fluoroquinolone • Inhibits DNA gyros & topoisomerase IV	• Negligible risk after topic use • After oral infant would receive max of 0.57 mg daily	No effect
Tetracyclines	• Protein synthesis inhibitor • Biostatic • Inhibit translation by binding to 30S ribosomal subunit	Avg peak & trough levels approx 6% of maternal weight-adjusted dose	Short-term use unlikely to be harmful
Nitrofurantoin	• Contraindicated <1 month or in G6PD deficiency	Low	• Do not use <8 days after delivery or in G6PD deficiency
Vancomycine & Teicoplanin	• Mainstay t/m for MRSA • Poorly absorbed orally	Unlikely to reach infant

Anxiety & Depression

Antidepressants during breastfeeding depend on the drugs used antenatally
Abrupt cessation or change of drugs not recommended
If antidepressants taken
All through pregnancy — 37% less likely to breastfeed
From 3rd trimester — 75% less likely to breastfeed
Must support & reassure the patient

Drugs	Drug levels — in mother / infant	Effect on lactation & breast milk
SSRI	Sertaline — SSRI of choice • Low levels in breast mil • Not detected in infant serum	If SSRI used during pregnancy & lactation, mother may struggle with breastfeeding
SSRI	Fluoxetine — higher average level in breast milk • Can cause colic & drowsiness • No long term adverse developmental outcomes • Do not stop if needed by mother • Monitor infants
TCA	• Low levels in breast milk • May cause drowsiness & sedation
Others	Venlafaxine — relatively higher dose transferred to infants

High Blood Pressure

VTE and Breastfeeding

Drugs	Drug levels — in mother / infant
Warfarin	• Very low levels in breast milk • No effect on vitamin K-dependent clotting factors • No special precautions required
LMWH	• Not excreted into breast milk or absorbed by an infant
Direct oral anticoagulants	• Not recommended as first-line t/m in pregnancy / lactation • Paucity of safety data

Complex Medical Problems

Condition/ Drugs	Mother / Infant
Asthma	Beta-2 Agonists & Steroid Inhalers —Safe Montelukast — low levels excreted & can be used in children as young as 6 months High-dose Steroids — can continue breastfeeding with short courses
Steroids	Prednisolone — safe up to 40 mg/day • Poorly excreted into breast milk
Monoclonal antibodies	• Paucity of safety data • Excretion into breast milk minimal • Absorption minimal Adalimumab / Inflximab — no adverse effects, be cautious
Antiepileptic drugs	• Some drugs (e.g. phenytoin, carbamazepine) enhance metabolism of other drugs, whereas other (e.g. valproic acid) slow metabolism Levetiracetam — low levels excreted in breast milk, safe to use, may reduce breast milk supply in some Lamotrigine — encourage to breast feed. Need to monitor serum levels in infant & adjust the dose Sodium valproate — reassuring safety profile, can be used