Timolol eent
Name: Timolol eent
Interactions for Timolol
Appears to be metabolized partly by CYP2D6.104 105 106 107 c
Drugs Affecting Hepatic Microsomal Enzymes
CYP2D6 inhibitors: Potential pharmacodynamic (increased β-adrenergic blockade) and pharmacokinetic interaction (increased plasma timolol concentrations).104 105 106 107 c
Specific Drugs
| Drug | Interaction | Comments |
|---|---|---|
| β-Adrenergic blocking agents, systemic | Additive systemic and ocular effects104 105 106 107 108 | |
| Calcium-channel blocking agents | Potential hypotension, AV conduction disturbances, and left ventricular failure101 102 104 105 106 107 | Caution advised104 105 106 107 Avoid concomitant use in patients with impaired cardiac function104 105 106 107 |
| Cimetidine | Possible additive reductions in resting heart rate and IOPc | |
| Digitalis | Possible additive effect in prolonging AV conduction time when used concomitantly with calcium-channel blocking agents (diltiazem, verapamil)104 105 106 107 | |
| Catecholamine-depleting drugs (e.g., reserpine) | Possible additive effects104 105 106 107 | Observe closely for evidence of marked bradycardia or hypotension (may be manifested as vertigo, syncope, or postural hypotension)104 105 106 107 |
| Clonidine | Oral β-adrenergic blocking agents may exacerbate rebound hypertension following discontinuance of clonidine104 105 106 107 | Not reported with ophthalmic use of timolol104 105 106 107 |
| Epinephrine | Mydriasis possible following concomitant ocular administration104 105 106 107 Atopic individuals and those with a history of severe anaphylactic reactions may not respond to usual doses of epinephrine used in the treatment of anaphylactic reactions104 105 106 107 | |
| Ocular hypotensive agents | Additive IOP-lowering effects104 105 106 107 108 | Used to therapeutic advantage104 105 106 107 108 If more than one topical ophthalmic drug is used, administer at least 10 minutes apart104 106 |
| Quinidine | Potential increase in plasma timolol concentrations and in β-blockade (bradycardia)103 104 105 106 107 |
Preparations
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.
| Routes | Dosage Forms | Strengths | Brand Names | Manufacturer |
|---|---|---|---|---|
| Ophthalmic | Solution | 0.25% (of anhydrous timolol) | Betimol (with benzalkonium chloride) | Vistakon |
| 0.5% (of anhydrous timolol) | Betimol (with benzalkonium chloride) | Vistakon |
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
| Routes | Dosage Forms | Strengths | Brand Names | Manufacturer |
|---|---|---|---|---|
| Ophthalmic | Solution | 0.25% (of timolol)* | Timolol Maleate Ophthalmic Solution | Apotex, Bausch & Lomb, Falcon |
| Timoptic Ocumeter Plus (with benzalkonium chloride) | Merck | |||
| Timoptic Ocudose (preservative-free) | Merck | |||
| 0.5% (of timolol)* | Timolol Maleate Ophthalmic Solution | Apotex, Bausch & Lomb, Falcon | ||
| Timoptic Ocumeter Plus (with benzalkonium chloride) | Merck | |||
| Timoptic Ocudose (preservative-free) | Merck | |||
| Solution, gel-forming | 0.25% (of timolol)* | Timolol GFS (with benzalkonium chloride) | Falcon | |
| Timoptic-XE Ocumeter (with benzododecinium bromide) | Merck | |||
| 0.5% (of timolol)* | Timolol GFS (with benzalkonium chloride) | Falcon | ||
| Timoptic-XE Ocumeter (with benzododecinium bromide) | Merck |
| Routes | Dosage Forms | Strengths | Brand Names | Manufacturer |
|---|---|---|---|---|
| Ophthalmic | Solution | 0.5% (of timolol) with Dorzolamide Hydrochloride 2% (of dorzolamide) | Cosopt Ocumeter Plus (with benzalkonium chloride) | Merck |
Usual Pediatric Dose for Glaucoma (Open Angle)
<18 years:
Solution:
Initial dose: Instill 1 drop (0.25% solution) in the affected eye(s) twice daily.
Maintenance dose: If response is unsatisfactory, may change to 0.5% solution. If satisfactory response is maintained, may decrease dose to once daily.
Renal Dose Adjustments
Data not available
Liver Dose Adjustments
Data not available