Timolol maleate is a non-selective beta-adrenergic receptor blocker. In its oral form (Blocadren), it is used to treat high blood pressure and prevent heart attacks, and occasionally to prevent migraine headaches. In its ophthalmic form (brand names Timoptol in Italy; Timoptic), it is used to treat open-angle and occasionally secondary glaucoma by reducing aqueous humour production through blockage of the beta receptors on the ciliary epithelium. The pharmacological mechanism by which it actually does this is still unknown.
The most serious possible side effects include cardiac arrhythmias
and severe bronchospasms
. Timolol can also lead to fainting
, congestive heart failure
, and impotence
- Children and Adults: Ophthalmic: Initial: 0.25% solution, instill 1 drop twice daily; increase to 0.5% solution if response not adequate; decrease to 1 drop/day if *controlled; do not exceed 1 drop twice daily of 0.5% solution Adults: Oral:
- Hypertension: Initial: 10 mg twice daily, increase gradually every 7 days, usual dosage: 20-40 mg/day in 2 divided doses; maximum: 60 mg/day
- Prevention of myocardial infarction: 10 mg twice daily initiated within 1-4 weeks after infarction
- Migraine headache: Initial: 10 mg twice daily, increase to maximum of 30 mg/day
- Gel-forming solution, ophthalmic, as maleate (Timoptic-XE): 0.25% (2.5 mL, 5 mL); 0.5% (2.5 mL, 5 mL)
- Solution, ophthalmic, as hemihydrate (Betimol): 0.25% (5 mL, 10 mL, 15 mL); 0.5% (5 mL, 10 mL, 15 mL) [contains benzalkonium chloride]
- Solution, ophthalmic, as maleate: 0.25% (5 mL, 10 mL, 15 mL); 0.5% (5 mL, 10 mL, 15 mL) [contains benzalkonium chloride]
- Timoptic: 0.25% (5 mL, 10 mL); 0.5% (5 mL, 10 mL) [contains benzalkonium chloride]
- Solution, ophthalmic, as maleate [preservative free] (Timoptic OcuDose): 0.25% (0.2 mL);0.5% (0.2 mL) [single use]
- Tablet, as maleate (Blocadren): 5 mg, 10 mg, 20 mg
For ophthalmic use, timolol is also available combined with other medications:
- In Canada: Apo-Timol, Apo-Timop, Gen-Timolol, Nu-Timolol, Phoxal-timolol, PMS-Timolol, Tim-AK, Timoptic, Timoptic-XE.
- In United States: Betimol, Blocadren, Istalol, Timoptic, Timoptic-XE, Timoptic OcuDose.