Timolol concentrations in breast milk of a woman treated for glaucoma: calculation of neonatal exposure.
A 32-year-old lactating woman with open-angle glaucoma used timolol maleate 0.5% eye drops twice daily to her right eye for 6 months. Four milk samples were collected over a span of 6 days. Timolol maleate milk levels were examined by liquid chromatography tandem mass spectrometry and found to be at a mean of 0.12 ng/mL (range, 0 to 0.37 ng/mL). At this level, the theoretical maximum relative infant dose expressed as a percentage of the weight-adjusted maternal dose was 0.012%. As most glaucoma patients administer drops to both eyes, the dosage was duplicated to reflect the more pertinent calculated theoretical relative infant dose of 0.024%. This dose of timolol is unlikely to cause systemic side effects to the healthy breastfed infant.
Madadi
Parvaz
P
Department of Physiology and Pharmacology, University of Western Ontario, Ontario, Canada. pmadadi@uwo.ca
Koren
Gideon
G
Freeman
David J
DJ
Oertel
Reinhard
R
Campbell
Robert J
RJ
Trope
Graham E
GE
D000328:Adult; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001942:Breast Feeding; D004359:Drug Therapy, Combination; D005260:Female; D005902:Glaucoma, Open-Angle / Q000188:drug therapy* / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D018811:Maternal Exposure; D008895:Milk, Human / Q000378:metabolism*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D013999:Timolol / Q000008:administration & dosage / Q000493:pharmacokinetics*
D000959:Antihypertensive Agents; D013999:Timolol