Atropine

It is an antimuscarinic alkaloid with antispasmodic action on smooth muscle, reduces salivary and bronchial secretions and perspiration, depresses the vagus nerve and increases heart rate. It is used parenterally in bradycardia and asystole in acute cardiopulmonary resuscitation, as anesthetic premedication, as an antispasmodic in gastrointestinal disorders, to treat or prevent bronchospasm and in poisoning by muscarinic fungi or by organophosphate pesticides. It is used topically in ophthalmology as a mydriatic and cycloplegic. ^(Martindale)

Since the last update we have not found published data on its excretion in breastmilk.

Its low percentage of protein binding and low molecular weight facilitate the passage into breast milk, while its very large volume of distribution makes excretion in breast milk difficult.

Theoretically, the maximum concentration that atropine would reach in breast milk would be 11 micrograms/L of milk, which would mean a theoretical dose for the infant of 0.0017 milligrams/kg/day, an amount 12 times lower than that used in a single preanesthetic dose. (Hale 1999)

Although antimuscarinics are thought to decrease prolactin production ^{(Müller 1983)}, atropine and prolactin-oxytocin relationships are little and poorly studied, with conflicting results in humans ^{(Kamimori 2009, Satar 2004, Casanueva 1984, De Martino 1980)}. Once lactation is established, milk production depends more on the repeated stimulation of suckling than on prolactin levels. There is no proven relationship between atropine and breast milk production.

Expert authors consider that, in isolated doses or used as eye drops, atropine is probably safe during lactation^{(Hale, LactMed, Briggs 2015, Hagemann 1998)}. American Academy of Pediatrics: Maternal Medication Usually Compatible With Breastfeeding. ^{(AAP 2001)}. Recommendations for Drugs in the Eleventh WHO Model List of Essential Drugs: compatible with breastfeeding. ^{(WHO-UNICEF 2002)}

OPHTHALMIC USE:

Systemic absorption should be minimized by pressing the tear duct (inner corner of the eye) with the finger for 1 to 2 minutes and administering the dose immediately after breastfeeding. ^{(Belkin 2020, Blumen 2020, Méndez 2012)}

The small dose and poor plasma absorption of most topical ophthalmological preparations make it unlikely that significant amounts will transfer into breastmilk. Topical use of Atropine in the form of eye drops is compatible with breastfeeding.