TIMOLOL MALEATE
Clinical safety rating: safe
Other drugs that lower heart rate or blood pressure can have additive effects Can cause bronchospasm in patients with asthma.
Non-selective beta-adrenergic receptor antagonist (beta-blocker). Competitively blocks beta1 and beta2 receptors, reducing heart rate, myocardial contractility, and cardiac output. Also decreases aqueous humor production in the eye by blocking beta2 receptors on ciliary epithelium.
| Metabolism | Primarily hepatic via CYP2D6; undergoes extensive first-pass metabolism. Metabolites include 4-hydroxy-, N-desisopropyl-, and other inactive metabolites. |
| Excretion | Renal: 20% unchanged; biliary/fecal: 80% as metabolites |
| Half-life | 2-3 hours (terminal); prolonged in hepatic impairment |
| Protein binding | ~60% bound to albumin |
| Volume of Distribution | 2.0-3.5 L/kg (extensive tissue distribution) |
| Bioavailability | Oral: ~50% (first-pass metabolism); Ophthalmic: minimal systemic absorption (~0.5%) |
| Onset of Action | Oral: 1-2 hours; Ophthalmic: 20-30 minutes |
| Duration of Action | Oral: 6-12 hours; Ophthalmic: 12-24 hours (due to prolonged ocular absorption) |
Systemic: 1 drop of 0.25% or 0.5% solution in affected eye(s) twice daily. Additional indication: 0.5% gel-forming solution once daily. Oral: 10 mg twice daily, may increase to 20 mg twice daily if needed.
| Dosage form | SOLUTION |
| Renal impairment | No specific GFR-based dose adjustment required for ophthalmic use. For oral use in severe renal impairment (CrCl <30 mL/min), reduce dose or extend dosing interval; use with caution. |
| Liver impairment | No specific adjustment for ophthalmic use. For oral use in Child-Pugh B or C cirrhosis: consider dose reduction due to reduced metabolism; use with caution and monitor for bradycardia. |
| Pediatric use | Ophthalmic: 1 drop of 0.25% solution twice daily; may increase to 0.5% if needed. Not FDA-approved for pediatric glaucoma; use off-label. Oral: 0.1 mg/kg/dose once or twice daily, not to exceed 20 mg/day. |
| Geriatric use | Start with lowest concentration (0.25%) or lowest oral dose (10 mg once daily) due to increased systemic absorption from ophthalmic use and higher risk of bradycardia, bronchospasm, and hypotension. Monitor heart rate and blood pressure. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Other drugs that lower heart rate or blood pressure can have additive effects Can cause bronchospasm in patients with asthma.
| FDA category | Animal |
| Breastfeeding | Timolol is excreted into human breast milk with a milk-to-plasma ratio of approximately 0.5-0.8. At ophthalmic doses, infant exposure is minimal; however, systemic levels may be higher with oral use. Monitor infant for bradycardia, hypotension, and hypoglycemia. Consider alternative agents if high dose or prolonged therapy. |
| Teratogenic Risk |
■ FDA Black Box Warning
None
| Common Effects | hypertension |
| Serious Effects |
["Sinus bradycardia","Second- or third-degree atrioventricular block","Cardiogenic shock","Decompensated heart failure","Bronchial asthma or severe COPD","Hypersensitivity to timolol or any component","Reactive airway disease (for non-ophthalmic use)"]
| Precautions | ["Exacerbation of angina and myocardial infarction upon abrupt withdrawal","Bronchospasm in patients with asthma or COPD","Heart failure: may worsen or mask symptoms","Masking of hypoglycemic symptoms in diabetic patients","Peripheral vascular disease: may worsen symptoms","Thyrotoxicosis: may mask tachycardia","Anaphylactic reactions: more severe in beta-blocker use","Ophthalmic use: systemic absorption possible, same precautions apply"] |
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| Timolol maleate is pregnancy category C. First trimester: limited human data; animal studies show embryotoxicity and delayed ossification at high doses. Second and third trimesters: risk of fetal bradycardia, growth restriction, hypoglycemia, and bradyarrhythmia due to beta-blockade. Use only if potential benefit justifies risk. |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and signs of bronchospasm. Fetal monitoring: assess fetal heart rate, growth parameters via ultrasound, and amniotic fluid index throughout pregnancy. Postnatal: observe neonate for bradycardia, respiratory depression, and hypoglycemia for 48 hours after delivery. |
| Fertility Effects | No specific human studies on fertility. Animal studies: no adverse effects on fertility at systemic exposures similar to human doses. Theoretical risk of reduced placental perfusion due to beta-blockade may affect reproductive outcomes. |