Timolol Pregnancy and Breastfeeding Warnings
Timolol is also known as: Blocadren
Timolol Pregnancy Warnings
Timolol has been assigned to pregnancy category C by the FDA. Animal studies have failed to reveal evidence of fetal malformations at usual human doses. Delayed fetal ossification occurred after doses 40 times the maximum recommended human dose (on a per kg basis). Maternotoxicity and increased fetal resorption occurred in mice after doses 830 times the maximum recommended human dose (on a per kg basis). Increased fetal resorptions, but no maternotoxicity were observed in rabbits given 40 times the maximum recommended human dose (on a per kg basis). There are no controlled data in human pregnancy. Timolol should only be given during pregnancy when benefit outweighs risk.
One case in which timolol was administered during human pregnancy has been reported. A woman who was taking timolol ophthalmic drops, acetazolamide, and pilocarpine for glaucoma delivered at 36 weeks' gestation. The neonate suffered hyperbilirubinemia, metabolic acidosis, hypocalcemia, and hypomagnesemia. These complications were believed to be secondary to acetazolamide therapy, and were reversible after treatment. The use of some beta-blockers during human pregnancy has resulted in persistent bradycardia and other signs of beta-blockade. Close observation for signs and symptoms of beta-blockade for at least 48 hours of newborns whose mothers were taking timolol is recommended.
Timolol Breastfeeding Warnings
Data reveal average milk to maternal plasma drug level ratios of approximately 0.80. In one series of nine patients, dosages of timolol 5 mg three times a day were associated with an average milk timolol level of 15.9 ng/mL. After the dosage was increased to 10 mg three times a day in four of the nine patients, the average milk timolol level rose to 41 ng/mL. Timolol has also been measured in human milk after use of timolol eyedrops. In one case the milk timolol concentration averaged 5.6 ng/mL 1.5 hours after dosing in a woman who was receiving timolol 0.5% eye drops to one eye twice a day. In this case, even if the infant nursed 4 times daily, receiving 75 mL each time, the daily dose to the nursing infant would be below that expected to produce beta-blockade.
Timolol is excreted into human milk. No adverse reactions in nursing infants have been reported; however, the manufacturer recommends that due to the potential for serious adverse reactions in nursing infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
References for breastfeeding information
- Committee on Drugs, 1992 to 1993 "The transfer of drugs and other chemicals into human milk." Pediatrics 93 (1994): 137-50
- Fidler J, Smith V, DeSwiet M "Excretion of oxprenolol and timolol in breast milk." Br J Obstet Gynaecol 90 (1983): 961-65
- "Product Information. Blocadren (timolol)." Merck & Co, Inc, West Point, PA.
- Lustgarten J, Podos S "Topical timolol and the nursing mother." Arch Ophthalmol 101 (1983): 1381-2
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