Recommended Dosage for Timolol
For ophthalmic use, timolol maleate solution should be started at 0.25% concentration with one drop in the affected eye(s) twice daily, which may be increased to 0.5% concentration if clinical response is inadequate after approximately 4 weeks of treatment. 1
Ophthalmic Timolol Dosing Guidelines
Initial Dosing
- Start with timolol maleate ophthalmic solution 0.25% - one drop in affected eye(s) twice daily 1
- Evaluate intraocular pressure after approximately 4 weeks of treatment 1
- If clinical response is inadequate, increase to 0.5% solution - one drop in affected eye(s) twice daily 1
Maintenance Dosing
- Once intraocular pressure is stabilized at satisfactory levels, dosing may be reduced to once daily 1
- Due to diurnal variations in intraocular pressure, measure pressure at different times during the day to confirm adequacy of once-daily dosing 1
- Dosages exceeding one drop of 0.5% solution twice daily generally do not produce further reduction in intraocular pressure 1
Clinical Evidence Supporting Dosing Recommendations
Research has demonstrated that both once-daily and twice-daily administration of timolol ophthalmic solution can be effective:
- A 12-month randomized controlled trial showed that once-daily timolol-LA 0.5% solution was statistically equivalent in efficacy to twice-daily timolol maleate 0.5% solution for treating glaucoma or ocular hypertension 2
- In a four-week study of patients with chronic open-angle glaucoma, both once-daily and twice-daily administration of 0.25% timolol ophthalmic solution were effective, with IOP reductions of 18-25% from baseline 3
- Long-term studies (2 years) have shown that twice-daily timolol at concentrations of 0.1% to 0.5% can maintain IOP control, though some patients may require concentration increases over time 4
Important Considerations
Timing of Administration
- When using once-daily dosing, morning administration is common, but evening dosing may provide better 24-hour pressure control with a lower range of diurnal pressure fluctuation (3.6 mm Hg vs 4.3 mm Hg) 5
Combination Therapy
- If intraocular pressure remains unsatisfactory on timolol monotherapy, concomitant therapy with other agents for lowering intraocular pressure can be instituted 1
- The concomitant use of two topical beta-adrenergic blocking agents is not recommended 1
- When added to timolol therapy, other agents like dorzolamide can provide additional IOP-lowering effects (14-15% further reduction) 6
Monitoring
- Regular monitoring of intraocular pressure is essential to ensure adequate response
- Be aware of potential systemic effects, including decreased pulse rate (approximately 12%) and modest reductions in blood pressure (3.8% systolic, 2.8% diastolic) 4
Contraindications
- Timolol is contraindicated in patients with severe bradycardia, high-grade AV block without pacemaker, cardiogenic shock, and decompensated heart failure 7
- Use with caution in patients with asthma, COPD, compensated heart failure, and diabetes 7
Remember that while this dosing information is primarily for ophthalmic use, the same principles of careful titration and monitoring apply when timolol is used for other indications.