TIMOLOL MALEATE Drug Interactions
Also known as: Timolol Maleate
Timolol Maleate is an eye drop medication used to treat high pressure inside the eye. It works by helping to reduce the amount of fluid your eye produces, which in turn lowers the pressure. This medication is primarily prescribed for conditions like ocular hypertension and open-angle glaucoma to help protect your vision.TIMOLOL MALEATE has 7 documented drug interactions in our database, including 0 contraindicated, 3 major, 2 moderate, and 2 minor interactions.
0
Contraindicated
3
Major
2
Moderate
2
Minor
The co-administration of timolol, a beta-blocker primarily metabolized by CYP2D6, with fluoxetine, a potent CYP2D6 inhibitor, can significantly increase timolol plasma concentrations. This interaction can lead to exaggerated beta-blockade effects, including severe bradycardia, hypotension, and heart block, particularly given timolol's systemic absorption even when administered topically.
Mechanism
Fluoxetine is a potent inhibitor of the cytochrome P450 2D6 (CYP2D6) enzyme. Timolol is primarily metabolized by CYP2D6, so fluoxetine inhibits the metabolism of timolol, leading to decreased clearance and increased systemic exposure of timolol.
Clinical Management
Avoid concurrent use if possible. If co-administration is necessary, closely monitor the patient for signs and symptoms of excessive beta-blockade (e.g., bradycardia, hypotension, dizziness, fatigue). Consider using an alternative antidepressant with minimal CYP2D6 inhibition (e.g., sertraline, escitalopram) or a beta-blocker primarily cleared renally (e.g., atenolol, bisoprolol, nadolol) or with less CYP2D6 involvement.
The combination of timolol and fluoxetine can lead to significantly increased plasma concentrations of timolol, potentially causing severe bradycardia, hypotension, and heart block. This interaction is particularly concerning given timolol's non-selective beta-blocking effects and systemic absorption even with ophthalmic administration.
Mechanism
Fluoxetine is a potent inhibitor of the cytochrome P450 2D6 (CYP2D6) enzyme. Timolol is primarily metabolized by CYP2D6, so fluoxetine inhibits its metabolism, leading to reduced clearance and increased systemic exposure to timolol.
Clinical Management
Close monitoring for signs and symptoms of beta-blockade toxicity (e.g., bradycardia, hypotension, dizziness, fatigue) is essential. A lower starting dose of timolol or an alternative beta-blocker not metabolized by CYP2D6 (e.g., atenolol, bisoprolol, nadolol) should be considered. If the combination is necessary, dose adjustments for timolol may be required, and ECG monitoring is advisable.
Paroxetine, a potent CYP2D6 inhibitor, can significantly increase systemic exposure to timolol, a beta-blocker primarily metabolized by CYP2D6. This interaction can lead to enhanced beta-blockade, manifesting as severe bradycardia, hypotension, and potentially heart block.
Mechanism
Paroxetine inhibits the cytochrome P450 2D6 (CYP2D6) enzyme, which is a primary metabolic pathway for timolol. This pharmacokinetic inhibition reduces timolol's clearance, leading to elevated plasma concentrations and prolonged pharmacological effects.
Clinical Management
Concomitant use should be approached with caution. If co-administration is necessary, consider using an alternative antidepressant with minimal CYP2D6 inhibitory effects (e.g., sertraline, escitalopram) or an alternative beta-blocker not significantly metabolized by CYP2D6 (e.g., atenolol, bisoprolol). If the combination is unavoidable, monitor the patient closely for signs of excessive beta-blockade such as bradycardia, hypotension, and dizziness, and be prepared to reduce the timolol dose.
Citalopram can inhibit the metabolism of timolol, potentially increasing timolol plasma concentrations and enhancing its beta-blocking effects. This can lead to an increased risk of bradycardia, hypotension, and other systemic beta-blocker adverse effects, especially given timolol's systemic absorption even from ophthalmic administration.
Mechanism
Citalopram is a moderate inhibitor of CYP2D6, which is involved in the metabolism of timolol. Inhibition of timolol's metabolism by citalopram can lead to elevated plasma levels of timolol. Additionally, both drugs can independently cause bradycardia, leading to an additive pharmacodynamic effect.
Clinical Management
Monitor patients closely for signs and symptoms of excessive beta-blockade, such as bradycardia, hypotension, and fatigue. Consider using a beta-blocker less dependent on CYP2D6 metabolism (e.g., atenolol, bisoprolol) or an antidepressant with less CYP2D6 inhibition (e.g., sertraline, escitalopram) if an interaction is suspected or clinical concerns arise. Dose reduction of timolol may be necessary.
Coadministration of fluvoxamine with timolol may increase timolol plasma concentrations, potentially leading to enhanced beta-blockade effects such as bradycardia and hypotension. This interaction is primarily due to fluvoxamine's inhibition of CYP1A2, which is involved in timolol metabolism.
Mechanism
Fluvoxamine is a potent inhibitor of CYP1A2. Timolol is metabolized by CYP2D6 and to a lesser extent by CYP1A2. Inhibition of CYP1A2 by fluvoxamine can reduce timolol clearance, leading to elevated systemic levels.
Clinical Management
Monitor patients for signs and symptoms of increased beta-blockade, including bradycardia, hypotension, and fatigue. Consider using a lower dose of timolol or an alternative antidepressant with less CYP1A2 inhibitory activity if adverse effects occur. If timolol is used topically, remind patients about systemic absorption and potential for interaction.
The interaction between timolol and sertraline is generally considered minor due to sertraline's minimal CYP2D6 inhibition. While both drugs can independently cause bradycardia, the risk of a significant pharmacokinetic interaction leading to increased timolol levels is low.
Mechanism
Timolol is metabolized by CYP2D6, but sertraline is a weak inhibitor of this enzyme. Therefore, significant inhibition of timolol metabolism by sertraline is unlikely, though additive pharmacodynamic effects on heart rate are theoretically possible.
Clinical Management
No specific dose adjustments are typically required. Monitor patients for signs of excessive beta-blockade, such as bradycardia or hypotension, especially if they are sensitive to beta-blockers or have underlying cardiac conditions. If such symptoms occur, consider reducing the timolol dose.
There is generally no significant pharmacokinetic interaction between timolol and escitalopram. Both drugs can independently cause bradycardia, so an additive pharmacodynamic effect resulting in a slight increase in bradycardia risk is theoretically possible, but clinically unlikely to be significant.
Mechanism
Escitalopram is a weak inhibitor of CYP2D6, the primary enzyme metabolizing many beta-blockers. However, timolol is primarily metabolized by CYP2D6 and CYP2C19, and escitalopram's weak inhibition of these enzymes is not expected to significantly alter timolol's plasma levels. Both agents can cause bradycardia through different mechanisms, leading to a theoretical additive pharmacodynamic effect.
Clinical Management
No specific dose adjustments are typically required when co-administering timolol and escitalopram. Monitor patients for signs of excessive bradycardia, especially if they are sensitive to beta-blockers or have underlying cardiac conditions, although this is generally not a common concern with this combination.
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