TIMOPTIC-XE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TIMOPTIC-XE (TIMOPTIC-XE).
Timolol is a nonselective beta-adrenergic receptor antagonist that blocks beta-1 and beta-2 adrenergic receptors. In the eye, it reduces aqueous humor production by inhibiting beta-2 receptors in the ciliary epithelium, thereby lowering intraocular pressure.
| Metabolism | Timolol is metabolized in the liver primarily by CYP2D6 to inactive metabolites. It undergoes first-pass metabolism with systemic bioavailability of about 25-50% after ocular administration. |
| Excretion | Renal: 20% unchanged; remainder as metabolites via urine. Minor biliary/fecal elimination. |
| Half-life | Plasma: 4-6 hours; prolonged in renal impairment. Systemic half-life after ocular dosing: 4-5 hours. |
| Protein binding | ~60% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | 1.3-1.7 L/kg; distributes widely into tissues including eye. |
| Bioavailability | Ocular: systemic absorption ~20% via nasolacrimal duct; oral: ~50% (not used). |
| Onset of Action | Ocular: 0.5-1 hour (IOP reduction). |
| Duration of Action | Ocular: up to 24 hours (IOP lowering); maximal effect at 4-8 hours postdose. |
Instill one drop of 0.25% or 0.5% solution in the affected eye(s) once daily in the morning.
| Dosage form | SOLUTION, GEL FORMING/DROPS |
| Renal impairment | No dose adjustment required for renal impairment; however, systemic absorption may be increased in severe renal impairment (CrCl <30 mL/min) due to decreased clearance of timolol. Use with caution in such patients. |
| Liver impairment | No specific dose adjustment recommended; caution in severe hepatic impairment due to potential for decreased metabolism. Monitor for systemic effects. |
| Pediatric use | Safety and efficacy in pediatric patients have not been established. Use is not recommended in children <2 years; for ages 2-17 years, initiate with 0.25% solution once daily, may increase to 0.5% if adequate response not achieved. Use beta-blocker with caution and monitor for adverse effects. |
| Geriatric use | Start with 0.25% solution once daily. Lower doses may be effective due to increased systemic absorption and higher risk of adverse effects (e.g., bradycardia, hypotension). Monitor intraocular pressure and systemic side effects closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TIMOPTIC-XE (TIMOPTIC-XE).
| Breastfeeding | Timolol is excreted in human milk following oral administration. The M/P ratio is not established for ophthalmic use. Systemic absorption after ophthalmic administration is low, but theoretical risk of infant bradycardia and hypoglycemia exists. Use with caution in nursing mothers; monitor infant for signs of beta-blockade. |
| Teratogenic Risk | Timolol (Timoptic-XE) is a non-selective beta-blocker. In animal studies, timolol was not teratogenic in rats or rabbits at doses up to 50 mg/kg/day (approximately 6000 times the human ophthalmic dose). There are no adequate and well-controlled studies in pregnant women. Beta-blockers, including timolol, may cause fetal bradycardia, growth restriction, and hypoglycemia when administered during the second and third trimesters. The risk of adverse effects is lower with ophthalmic administration due to minimal systemic absorption. |
■ FDA Black Box Warning
No FDA black box warning specific to TIMOPTIC-XE; however, beta blockers have a boxed warning for abrupt cessation in patients with coronary artery disease causing exacerbation of angina and myocardial infarction.
| Serious Effects |
["Bronchial asthma or history of asthma","Chronic obstructive pulmonary disease (COPD) with bronchospastic component","Sinus bradycardia","Second or third degree atrioventricular block","Overt cardiac failure","Cardiogenic shock","Hypersensitivity to any component of the product"]
| Precautions | ["May cause bronchospasm in patients with asthma or COPD; use with caution.","Can cause cardiac depression, bradycardia, and heart failure in susceptible patients.","May mask signs of hypoglycemia in diabetic patients.","May mask signs of hyperthyroidism.","Abrupt withdrawal may exacerbate angina or precipitate myocardial infarction in patients with coronary artery disease.","Anaphylactic reactions may be more severe in patients on beta blockers.","May cause muscle weakness in myasthenia gravis.","Use with caution in patients with history of severe anaphylactic reactions to allergens."] |
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| Fetal Monitoring | Monitor maternal heart rate and blood pressure for signs of systemic beta-blockade. Monitor fetal heart rate and growth during second and third trimesters. Assess newborn for bradycardia, hypoglycemia, and respiratory depression at delivery. |
| Fertility Effects | No human data on fertility effects. Animal studies (rats) showed no adverse effects on fertility at oral doses up to 50 mg/kg/day (6000 times ophthalmic dose). |