timolol/dorzolamide (Rx)

Brand and Other Names:Cosopt, Cosopt PF
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

timolol/dorzolamide

ophthalmic solution

  • 0.5%/2%

Open-Angle Glaucoma or Ocular Hypertension

Instill 1 gtt in affected eye(s) q12hr

Dosage Forms & Strengths

timolol/dorzolamide

ophthalmic solution

  • 0.5%/2%

Open-Angle Glaucoma or Ocular Hypertension

<2 years

  • Contraindicated

>2 years

  • Instill 1 gtt in affected eye(s) q12hr
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Interactions

Interaction Checker

and timolol/dorzolamide

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              Serious - Use Alternative (34)

              • acebutolol

                acebutolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • artemether/lumefantrine

                artemether/lumefantrine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

              • atenolol

                atenolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • betaxolol

                betaxolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • bisoprolol

                bisoprolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • carvedilol

                carvedilol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • celiprolol

                celiprolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • clonidine

                clonidine, timolol. Either increases toxicity of the other by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

              • dacomitinib

                dacomitinib will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid use with CYP2D6 substrates where minimal increases in concentration of the CYP2D6 substrate may lead to serious or life-threatening toxicities.

              • digoxin

                digoxin, timolol. Either increases toxicity of the other by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

              • diltiazem

                diltiazem, timolol. Either increases toxicity of the other by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

              • epinephrine

                timolol increases effects of epinephrine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypertension and bradycardia. Consider selective beta 1 blocker (e.g., metoprolol).

              • epinephrine racemic

                timolol increases effects of epinephrine racemic by pharmacodynamic synergism. Avoid or Use Alternate Drug. Risk of hypertension and bradycardia. Consider selective beta 1 blocker (e.g., metoprolol).

              • esmolol

                esmolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • fexinidazole

                fexinidazole, timolol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration of fexinidazole with drugs known to induce bradycardia. .

              • fluoxetine

                fluoxetine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

              • givosiran

                givosiran will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug. Avoid coadministration of sensitive CYP2D6 substrates with givosiran. If unavoidable, decrease the CYP2D6 substrate dosage in accordance with approved product labeling.

              • iobenguane I 131

                timolol will decrease the level or effect of iobenguane I 131 by Other (see comment). Avoid or Use Alternate Drug. Based on the mechanism of action of iobenguane, drugs that reduce catecholamine uptake or that deplete catecholamine stores may interfere with iobenguane uptake into cells, and thus, reduce iobenguane efficacy. Discontinue interfering drugs for at least 5 half-lives before administration of either the dosimetry or an iobenguane dose. Do not administer these drugs until at least 7 days after each iobenguane dose.

              • labetalol

                labetalol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • lofexidine

                lofexidine, timolol. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid coadministration with other drugs that decrease pulse or blood pressure to mitigate risk of excessive bradycardia and hypotension.

              • lumefantrine

                lumefantrine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

              • metoprolol

                metoprolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • nadolol

                nadolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • nebivolol

                nebivolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • paroxetine

                paroxetine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

              • penbutolol

                penbutolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • pindolol

                pindolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • propranolol

                propranolol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • quinidine

                quinidine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Avoid or Use Alternate Drug.

              • rivastigmine

                timolol increases toxicity of rivastigmine by pharmacodynamic synergism. Avoid or Use Alternate Drug. Additive bradycardia effect may result in syncope.

              • sotalol

                sotalol and timolol both increase anti-hypertensive channel blocking. Avoid or Use Alternate Drug.

              • umeclidinium bromide/vilanterol inhaled

                timolol, umeclidinium bromide/vilanterol inhaled. pharmacodynamic antagonism. Avoid or Use Alternate Drug. If a beta-blocker must be used in patients with COPD taking a beta-agonist, consider using a beta-blocker that is beta-1 selective .

              • verapamil

                verapamil, timolol. Either increases toxicity of the other by unspecified interaction mechanism. Avoid or Use Alternate Drug. Can increase risk of bradycardia.

              • vilanterol/fluticasone furoate inhaled

                timolol, vilanterol/fluticasone furoate inhaled. pharmacodynamic antagonism. Avoid or Use Alternate Drug. If a beta-blocker must be used in patients with COPD taking a beta-agonist, consider using a beta-blocker that is beta-1 selective .

              Monitor Closely (131)

              • acebutolol

                acebutolol and timolol both increase serum potassium. Use Caution/Monitor.

              • aceclofenac

                timolol and aceclofenac both increase serum potassium. Use Caution/Monitor.

                aceclofenac decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • acemetacin

                timolol and acemetacin both increase serum potassium. Use Caution/Monitor.

                acemetacin decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • albuterol

                timolol increases and albuterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

                timolol decreases effects of albuterol by pharmacodynamic antagonism. Use Caution/Monitor.

              • aldesleukin

                aldesleukin increases effects of timolol by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

              • alfuzosin

                alfuzosin and timolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • aluminum hydroxide

                aluminum hydroxide decreases levels of timolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • amantadine

                dorzolamide will decrease the level or effect of amantadine by Other (see comment). Modify Therapy/Monitor Closely. Excretion rate of amantadine increases rapidly when urine is acidic, administration of urine acidifying drugs may increase elimination of amantadine from the body. Monitor for efficacy of amantadine.

              • amifostine

                amifostine, timolol. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Coadministration with blood pressure lowering agents may increase the risk and severity of hypotension associated with amifostine. When amifostine is used at chemotherapeutic doses, withhold blood pressure lowering medications for 24 hr prior to amifostine; if blood pressure lowering medication cannot be withheld, do not administer amifostine.

              • amiloride

                timolol and amiloride both increase serum potassium. Modify Therapy/Monitor Closely.

              • amiodarone

                amiodarone will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

                amiodarone, timolol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of cardiotoxicity with bradycardia.

              • amlodipine

                timolol and amlodipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • amobarbital

                amobarbital decreases levels of timolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of amobarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

              • arformoterol

                timolol increases and arformoterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

                timolol decreases effects of arformoterol by pharmacodynamic antagonism. Use Caution/Monitor.

              • articaine

                timolol, articaine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Increased effects of epinephrine in anesthetic; risk of hypertension and bradycardia. Do NOT D/C chronic beta blocker Tx prior to anesthetic administration. Consider selective beta 1 blocker (e.g., metoprolol).

              • asenapine

                asenapine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

                asenapine and timolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • aspirin

                timolol and aspirin both increase serum potassium. Use Caution/Monitor.

                aspirin decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • aspirin rectal

                timolol and aspirin rectal both increase serum potassium. Use Caution/Monitor.

                aspirin rectal decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • aspirin/citric acid/sodium bicarbonate

                aspirin/citric acid/sodium bicarbonate decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

                timolol and aspirin/citric acid/sodium bicarbonate both increase serum potassium. Use Caution/Monitor.

              • atazanavir

                atazanavir increases effects of timolol by pharmacodynamic synergism. Use Caution/Monitor. Increased risk of hypotension, bradycardia, AV block, and prolonged PR interval. Consider lowering beta blocker dose.

              • atenolol

                atenolol and timolol both increase serum potassium. Use Caution/Monitor.

              • avanafil

                avanafil increases effects of timolol by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

              • bendroflumethiazide

                timolol increases and bendroflumethiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • betaxolol

                betaxolol and timolol both increase serum potassium. Use Caution/Monitor.

              • bismuth subsalicylate

                bismuth subsalicylate, timolol. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Blockage of renal prostaglandin synthesis; may cause severe hypertension.

              • bisoprolol

                bisoprolol and timolol both increase serum potassium. Use Caution/Monitor.

              • bretylium

                timolol, bretylium. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Each drug may cause hypotension.

              • bumetanide

                timolol increases and bumetanide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • bupivacaine

                timolol, bupivacaine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Use extreme caution during concomitant use of bupivacaine and antihypertensive agents.

              • bupropion

                bupropion will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              • butabarbital

                butabarbital decreases levels of timolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of butabarbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

              • butalbital

                butalbital decreases levels of timolol by increasing metabolism. Use Caution/Monitor. Consider a higher beta-blocker dose during coadministration of butalbital. Atenolol, sotalol, nadolol less likely to be affected than other beta blockers.

              • calcium acetate

                calcium acetate decreases effects of timolol by unspecified interaction mechanism. Use Caution/Monitor.

              • calcium carbonate

                calcium carbonate decreases effects of timolol by unspecified interaction mechanism. Use Caution/Monitor.

                calcium carbonate decreases levels of timolol by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • calcium chloride

                calcium chloride decreases effects of timolol by unspecified interaction mechanism. Use Caution/Monitor.

              • calcium citrate

                calcium citrate decreases effects of timolol by unspecified interaction mechanism. Use Caution/Monitor.

              • calcium gluconate

                calcium gluconate decreases effects of timolol by unspecified interaction mechanism. Use Caution/Monitor.

              • candesartan

                candesartan and timolol both increase serum potassium. Use Caution/Monitor.

                timolol, candesartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

              • carbenoxolone

                timolol increases and carbenoxolone decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • carbidopa

                carbidopa increases effects of timolol by pharmacodynamic synergism. Use Caution/Monitor. Therapy with carbidopa, given with or without levodopa or carbidopa-levodopa combination products, is started, dosage adjustment of the antihypertensive drug may be required.

              • carvedilol

                carvedilol and timolol both increase serum potassium. Use Caution/Monitor.

              • celecoxib

                celecoxib will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

                timolol and celecoxib both increase serum potassium. Use Caution/Monitor.

                celecoxib decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • celiprolol

                celiprolol and timolol both increase serum potassium. Use Caution/Monitor.

              • chloroprocaine

                timolol, chloroprocaine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Increased effects of epinephrine in anesthetic; risk of hypertension and bradycardia. Do NOT D/C chronic beta blocker Tx prior to anesthetic administration. Consider selective beta 1 blocker (e.g., metoprolol).

              • chloroquine

                chloroquine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              • chlorothiazide

                timolol increases and chlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • chlorpropamide

                timolol decreases effects of chlorpropamide by pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers may also mask the symptoms of hypoglycemia.

              • chlorthalidone

                timolol increases and chlorthalidone decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • choline magnesium trisalicylate

                timolol and choline magnesium trisalicylate both increase serum potassium. Use Caution/Monitor.

                choline magnesium trisalicylate decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • cimetidine

                cimetidine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              • citalopram

                citalopram increases levels of timolol by decreasing metabolism. Use Caution/Monitor.

              • clevidipine

                timolol and clevidipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • clonidine

                timolol, clonidine. Mechanism: pharmacodynamic synergism. Modify Therapy/Monitor Closely. Non selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.

              • cobicistat

                cobicistat will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              • cyclopenthiazide

                timolol increases and cyclopenthiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • darifenacin

                darifenacin will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              • dasiglucagon

                timolol decreases effects of dasiglucagon by unknown mechanism. Use Caution/Monitor. Dasiglucagon may stimulate catecholamine release; whereas beta blockers may inhibit catecholamines released in response to dasiglucagon. Coadministration may also transiently increase pulse and BP.

              • desflurane

                desflurane, timolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

              • desvenlafaxine

                desvenlafaxine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Desvenlafaxine inhibits CYP2D6; with higher desvenlafaxine doses (ie, 400 mg) decrease the CYP2D6 substrate dose by up to 50%; no dosage adjustment needed with desvenlafaxine doses <100 mg

              • diclofenac

                timolol and diclofenac both increase serum potassium. Use Caution/Monitor.

                diclofenac decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • diflunisal

                timolol and diflunisal both increase serum potassium. Use Caution/Monitor.

                diflunisal decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • digoxin

                timolol and digoxin both increase serum potassium. Use Caution/Monitor.

                timolol increases effects of digoxin by pharmacodynamic synergism. Use Caution/Monitor. Enhanced bradycardia.

              • diltiazem

                timolol and diltiazem both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • diphenhydramine

                diphenhydramine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              • dobutamine

                timolol increases and dobutamine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

                timolol decreases effects of dobutamine by pharmacodynamic antagonism. Use Caution/Monitor.

              • dopexamine

                timolol increases and dopexamine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

                timolol decreases effects of dopexamine by pharmacodynamic antagonism. Use Caution/Monitor.

              • doxazosin

                doxazosin and timolol both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • dronedarone

                dronedarone will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              • drospirenone

                timolol and drospirenone both increase serum potassium. Modify Therapy/Monitor Closely.

              • duloxetine

                duloxetine will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              • eliglustat

                eliglustat increases levels of timolol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Monitor therapeutic drug concentrations, as indicated, or consider reducing the dosage of the concomitant drug and titrate to clinical effect.

              • elvitegravir/cobicistat/emtricitabine/tenofovir DF

                elvitegravir/cobicistat/emtricitabine/tenofovir DF increases levels of timolol by affecting hepatic enzyme CYP2D6 metabolism. Modify Therapy/Monitor Closely. Cobicistat is a CYP2D6 inhibitor; caution with CYP2D6 substrates for which elevated plasma concentrations are associated with serious and/or life-threatening events.

              • ephedrine

                timolol increases and ephedrine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

                timolol decreases effects of ephedrine by pharmacodynamic antagonism. Use Caution/Monitor.

              • epinephrine

                timolol increases and epinephrine decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

                timolol decreases effects of epinephrine by pharmacodynamic antagonism. Use Caution/Monitor.

              • epinephrine inhaled

                timolol decreases effects of epinephrine inhaled by pharmacodynamic antagonism. Use Caution/Monitor. Beta2-adrenergic blockers may may inhibit bronchodilatory effects of epinephrine.

              • epinephrine racemic

                timolol increases and epinephrine racemic decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

                timolol decreases effects of epinephrine racemic by pharmacodynamic antagonism. Use Caution/Monitor.

              • eprosartan

                eprosartan and timolol both increase serum potassium. Use Caution/Monitor.

                timolol, eprosartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

              • esmolol

                esmolol and timolol both increase serum potassium. Use Caution/Monitor.

              • ethacrynic acid

                timolol increases and ethacrynic acid decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • ether

                timolol, ether. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Both beta blockers and ether depress the myocardium; consider lowering beta blocker dose if ether used for anesthesia.

              • etodolac

                timolol and etodolac both increase serum potassium. Use Caution/Monitor.

                etodolac decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • etomidate

                etomidate, timolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

              • fedratinib

                fedratinib will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Adjust dose of drugs that are CYP2D6 substrates as necessary.

              • felodipine

                timolol and felodipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • fenbufen

                timolol and fenbufen both increase serum potassium. Use Caution/Monitor.

              • fenoprofen

                timolol and fenoprofen both increase serum potassium. Use Caution/Monitor.

                fenoprofen decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • fingolimod

                timolol increases effects of fingolimod by pharmacodynamic synergism. Use Caution/Monitor. Both medications decrease heart rate. Monitor patients on concomitant therapy, particularly in the first 6 hours after fingolimod is initiated or after a treatment interruption of at least two weeks, for bradycardia and atrioventricular block. To identify underlying risk factors of bradycardia and AV block, obtain a new or recent ECG in patients using beta-blockers prior to starting fingolimod.

              • flurbiprofen

                timolol and flurbiprofen both increase serum potassium. Use Caution/Monitor.

                flurbiprofen decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • formoterol

                timolol increases and formoterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

                timolol decreases effects of formoterol by pharmacodynamic antagonism. Use Caution/Monitor.

              • furosemide

                timolol increases and furosemide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • gentamicin

                timolol increases and gentamicin decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • glimepiride

                timolol decreases effects of glimepiride by pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers may also mask the symptoms of hypoglycemia.

              • glipizide

                timolol decreases effects of glipizide by pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers may also mask the symptoms of hypoglycemia.

              • glucagon

                glucagon decreases toxicity of timolol by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Coadministration of glucagon with beta-blockers may have transiently increased pulse and blood pressure.

              • glucagon intranasal

                glucagon intranasal decreases toxicity of timolol by sympathetic (adrenergic) effects, including increased blood pressure and heart rate. Use Caution/Monitor. Coadministration of glucagon with beta-blockers may have transiently increased pulse and blood pressure.

              • glyburide

                timolol decreases effects of glyburide by pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers may also mask the symptoms of hypoglycemia.

              • guanfacine

                timolol, guanfacine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Non selective beta blocker administration during withdrawal from centrally acting alpha agonists may result in rebound hypertension.

              • haloperidol

                haloperidol will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              • hydralazine

                hydralazine increases effects of timolol by pharmacodynamic synergism. Use Caution/Monitor. Additive hypotensive effects.

              • hydrochlorothiazide

                timolol increases and hydrochlorothiazide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • ibuprofen

                timolol and ibuprofen both increase serum potassium. Use Caution/Monitor.

                ibuprofen decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • ibuprofen IV

                ibuprofen IV decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

                timolol and ibuprofen IV both increase serum potassium. Use Caution/Monitor.

              • imatinib

                imatinib will increase the level or effect of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor.

              • indacaterol, inhaled

                indacaterol, inhaled, timolol. Other (see comment). Use Caution/Monitor. Comment: Beta-blockers and indacaterol may interfere with the effect of each other when administered concurrently. Beta-blockers may produce severe bronchospasm in COPD patients. Therefore, patients with COPD should not normally be treated with beta-blockers. However, under certain circumstances, e.g. as prophylaxis after myocardial infarction, there may be no acceptable alternatives to the use of beta-blockers in patients with COPD. In this setting, cardioselective beta-blockers could be considered, although they should be administered with caution.

              • indapamide

                timolol increases and indapamide decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • indomethacin

                timolol and indomethacin both increase serum potassium. Use Caution/Monitor.

                indomethacin decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • insulin aspart

                timolol, insulin aspart. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers delay recovery of normoglycemia after insulin induced hypoglycemia; however, they also inhibit insulin secretion, so long term beta blocker Tx may result in reduced glucose tolerance. Insulin induced hypoglycemia may induce hypertension during non selective beta blocker Tx.

              • insulin degludec

                timolol, insulin degludec. Other (see comment). Modify Therapy/Monitor Closely. Comment: Beta-blockers may either increase or decrease the blood glucose lowering effect of insulin; beta-blockers can prolong hypoglycemia (interference with glycogenolysis) or cause hyperglycemia (insulin secretion inhibited).

              • insulin degludec/insulin aspart

                timolol, insulin degludec/insulin aspart. Other (see comment). Modify Therapy/Monitor Closely. Comment: Beta-blockers may either increase or decrease the blood glucose lowering effect of insulin; beta-blockers can prolong hypoglycemia (interference with glycogenolysis) or cause hyperglycemia (insulin secretion inhibited).

              • insulin detemir

                timolol, insulin detemir. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers delay recovery of normoglycemia after insulin induced hypoglycemia; however, they also inhibit insulin secretion, so long term beta blocker Tx may result in reduced glucose tolerance. Insulin induced hypoglycemia may induce hypertension during non selective beta blocker Tx.

              • insulin glargine

                timolol, insulin glargine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers delay recovery of normoglycemia after insulin induced hypoglycemia; however, they also inhibit insulin secretion, so long term beta blocker Tx may result in reduced glucose tolerance. Insulin induced hypoglycemia may induce hypertension during non selective beta blocker Tx.

              • insulin glulisine

                timolol, insulin glulisine. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers delay recovery of normoglycemia after insulin induced hypoglycemia; however, they also inhibit insulin secretion, so long term beta blocker Tx may result in reduced glucose tolerance. Insulin induced hypoglycemia may induce hypertension during non selective beta blocker Tx.

              • insulin inhaled

                timolol, insulin inhaled. Other (see comment). Modify Therapy/Monitor Closely. Comment: Beta-blockers may either increase or decrease the blood glucose lowering effect of insulin; beta-blockers can prolong hypoglycemia (interference with glycogenolysis) or cause hyperglycemia (insulin secretion inhibited).

              • insulin lispro

                timolol, insulin lispro. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers delay recovery of normoglycemia after insulin induced hypoglycemia; however, they also inhibit insulin secretion, so long term beta blocker Tx may result in reduced glucose tolerance. Insulin induced hypoglycemia may induce hypertension during non selective beta blocker Tx.

              • insulin NPH

                timolol, insulin NPH. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers delay recovery of normoglycemia after insulin induced hypoglycemia; however, they also inhibit insulin secretion, so long term beta blocker Tx may result in reduced glucose tolerance. Insulin induced hypoglycemia may induce hypertension during non selective beta blocker Tx.

              • insulin regular human

                timolol, insulin regular human. Mechanism: pharmacodynamic antagonism. Use Caution/Monitor. Non selective beta blockers delay recovery of normoglycemia after insulin induced hypoglycemia; however, they also inhibit insulin secretion, so long term beta blocker Tx may result in reduced glucose tolerance. Insulin induced hypoglycemia may induce hypertension during non selective beta blocker Tx.

              • irbesartan

                irbesartan and timolol both increase serum potassium. Use Caution/Monitor.

                timolol, irbesartan. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Risk of fetal compromise if given during pregnancy.

              • isoproterenol

                timolol increases and isoproterenol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

                timolol decreases effects of isoproterenol by pharmacodynamic antagonism. Use Caution/Monitor.

              • isradipine

                timolol and isradipine both increase anti-hypertensive channel blocking. Modify Therapy/Monitor Closely.

              • ivabradine

                ivabradine, timolol. Either increases effects of the other by pharmacodynamic synergism. Modify Therapy/Monitor Closely. Most patients receiving ivabradine will also be treated with a beta-blocker. The risk of bradycardia increases with coadministration of drugs that slow heart rate (eg, digoxin, amiodarone, beta-blockers). Monitor heart rate in patients taking ivabradine with other negative chronotropes.

              • ketamine

                ketamine, timolol. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Risk of hypotension.

              • ketoprofen

                timolol and ketoprofen both increase serum potassium. Use Caution/Monitor.

                ketoprofen decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • ketorolac

                timolol and ketorolac both increase serum potassium. Use Caution/Monitor.

                ketorolac decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • ketorolac intranasal

                timolol and ketorolac intranasal both increase serum potassium. Use Caution/Monitor.

                ketorolac intranasal decreases effects of timolol by pharmacodynamic antagonism. Use Caution/Monitor. Long term (>1 wk) NSAID use. NSAIDs decrease prostaglandin synthesis.

              • labetalol

                labetalol and timolol both increase serum potassium. Use Caution/Monitor.

              • lasmiditan

                timolol increases effects of lasmiditan by pharmacodynamic synergism. Use Caution/Monitor. Lasmiditan has been associated with a lowering of heart rate (HR). In a drug interaction study, addition of a single 200-mg dose of lasmiditan to propranolol decreased HR by an additional 5 bpm compared to propranolol alone, for a mean maximum of 19 bpm.

              • levalbuterol

                timolol increases and levalbuterol decreases serum potassium. Effect of interaction is not clear, use caution. Use Caution/Monitor.

                timolol decreases effects of levalbuterol by pharmacodynamic antagonism. Use Caution/Monitor.

              • levodopa

                levodopa increases effects of timolol by pharmacodynamic synergism. Use Caution/Monitor. Consider decreasing dosage of antihypertensive agent.

              • lidocaine

                timolol, lidocaine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Increased effects of epinephrine in anesthetic; risk of hypertension and bradycardia. Do NOT D/C chronic beta blocker Tx prior to anesthetic administration. Consider selective beta 1 blocker (e.g., metoprolol).

                timolol increases levels of lidocaine by decreasing elimination. Use Caution/Monitor. Risk of hypertension and bradycardia. Consider selective beta 1 blocker (e.g., metoprolol).

              • lisdexamfetamine

                dorzolamide will increase the level or effect of lisdexamfetamine by passive renal tubular reabsorption - basic urine. Use Caution/Monitor.

              • lopinavir

                lopinavir increases levels of timolol by affecting hepatic enzyme CYP2D6 metabolism. Use Caution/Monitor. Potential for increased toxicity. Increased risk of PR prolongation and cardiac arrhythmias. .

              Minor (28)

              • adenosine

                timolol, adenosine. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Bradycardia.

              • agrimony

                agrimony increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • brimonidine

                brimonidine increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • cevimeline

                cevimeline increases effects of timolol by unspecified interaction mechanism. Minor/Significance Unknown.

              • ciprofloxacin

                ciprofloxacin increases levels of timolol by decreasing metabolism. Minor/Significance Unknown. May also rarely decrease beta blocker levels.

              • cocaine

                timolol increases effects of cocaine by pharmacodynamic synergism. Minor/Significance Unknown. Risk of angina.

              • cornsilk

                cornsilk increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • dihydroergotamine

                dihydroergotamine, timolol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive vasospasm.

              • dihydroergotamine intranasal

                dihydroergotamine intranasal, timolol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Additive vasospasm.

              • dipyridamole

                dipyridamole, timolol. Mechanism: pharmacodynamic synergism. Minor/Significance Unknown. Risk of bradycardia.

              • escitalopram

                escitalopram increases levels of timolol by decreasing metabolism. Minor/Significance Unknown.

              • fenoldopam

                fenoldopam increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown. Additive hypotensive effects.

              • forskolin

                forskolin increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • imaging agents (gadolinium)

                timolol, imaging agents (gadolinium). Mechanism: unknown. Minor/Significance Unknown. Increased risk of anaphylaxis from contrast media.

              • levobetaxolol

                levobetaxolol increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • maitake

                maitake increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • melatonin

                melatonin decreases toxicity of timolol by pharmacodynamic antagonism. Minor/Significance Unknown. Melatonin may correct beta blocker induced sleep disturbances.

              • metipranolol ophthalmic

                metipranolol ophthalmic increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • neostigmine

                timolol, neostigmine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive bradycardia.

              • noni juice

                timolol and noni juice both increase serum potassium. Minor/Significance Unknown.

              • octacosanol

                octacosanol increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • physostigmine

                timolol, physostigmine. Either increases effects of the other by pharmacodynamic synergism. Minor/Significance Unknown. Additive bradycardia.

              • pilocarpine

                pilocarpine increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • reishi

                reishi increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • shepherd's purse

                shepherd's purse, timolol. Other (see comment). Minor/Significance Unknown. Comment: Theoretically, shepherd's purse may interfere with BP control.

              • tizanidine

                tizanidine increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown. Risk of hypotension.

              • treprostinil

                treprostinil increases effects of timolol by pharmacodynamic synergism. Minor/Significance Unknown.

              • yohimbe

                timolol decreases toxicity of yohimbe by pharmacodynamic antagonism. Minor/Significance Unknown.

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              Adverse Effects

              >10%

              Dorzolamide

              • Ocular burning, stinging, discomfort (33%)
              • Bitter taste (25%)
              • Superficial punctate keratitis (10-15%)
              • Ocular allergic reactions (10%)

              Frequency Not Defined

              Dorzolamide

              • Blurred vision
              • Ocular dryness
              • Photophobia
              • Ocular redness
              • Tearing
              • Stevens-Johnson syndrome
              • Toxic epidermal necrolysis

              Timolol

              • Arrythmia
              • Bradycardia
              • Syncope
              • Fatigue
              • Headache
              • Dyspnea
              • Bronchospasm
              • Chest pain
              • Edema
              • Paresthesia
              • Nausea
              • Rales
              • Depression
              • Decreased exercise tolerance
              • Raynaud's phenomenon
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              Warnings

              Contraindications

              Age <2 years

              Hypersensitivity, asthma, severe COPD, sinus bradycardia, 2nd/3rd degree AV block (except in patients with artificial pacemaker), overt CHF, cardiogenic shock

              Cautions

              Dorzolamide (a sulfonamide) and, although administered topically, is absorbed systemically; same types of adverse reactions attributable to sulfonamides may occur with topical administration, including severe skin reactions

              Bacterial keratitis associated with use of multiple-dose containers of topical ophthalmic products, inadvertently contaminated by patients who, in most cases, had concurrent corneal disease or disruption of ocular epithelial surface

              Conjunctivitis reported with chronic administration (may resolve upon discontinuation of therapy)

              Sympathetic stimulation may be essential for support of circulation in diminished myocardial contractility; its inhibition by beta-adrenergic receptor blockade may precipitate more severe failure; in patients without history of cardiac failure continued depression of myocardium with beta-blocking agents over a period of time can, in some cases, lead to cardiac failure; discontinue therapy at first sign or symptom of cardiac failure

              Not for use as monotherapy in angle-closure glaucoma

              Use caution in diabetes, heart failure, psychiatric disease (may cause or exacerbate CNS depression), peripheral vascular disease

              Not for administration to patients with chronic obstructive pulmonary disease (e.g., chronic bronchitis, emphysema) of mild or moderate severity, bronchospastic disease, or a history of bronchospastic disease (other than bronchial asthma or a history of bronchial asthma, in which timiool is contraindicated)

              Patients may be unresponsive to usual doses of epinephrine used to treat anaphylactic reactions; patients with a history of atopy or a history of severe anaphylactic reactions to a variety of allergens may be more reactive to repeated accidental, diagnostic, or therapeutic challenge with such allergens Increase muscle weakness in some patients with myasthenia gravis or myasthenic symptoms reported

              Beta-adrenergic receptor blocking agents may mask signs and symptoms of acute hypoglycemia; administer with caution in patients subject to spontaneous hypoglycemia or to diabetic patients (especially those with labile diabetes) who are receiving insulin or oral hypoglycemic agents

              Beta-adrenergic blocking agents may mask certain clinical signs (e.g., tachycardia) of hyperthyroidism; manage carefully patients suspected of developing thyrotoxicosis to avoid abrupt withdrawal of beta-adrenergic blocking agents that might precipitate thyroid storm

              Not studied in patients with severe renal impairment (CrCl <30 mL/min); not recommended; dorzolamide and its metabolite are excreted predominantly by kidney

              Use with caution in hepatic impairment; not studed

              Patients receiving beta-adrenergic receptor blocking agents have experienced protracted severe hypotension during anesthesia; difficulty in restarting and maintaining heartbeat has also reported; gradual withdrawal of beta-adrenergic receptor blocking agents recommended; the effects of beta-adrenergic blocking agents may be reversed by sufficient doses of adrenergic agonists if necessary

              There is increased potential for developing corneal edema in patients with low endothelial cell counts; use caution

              Avoid concomitant administration with systemic beta-blockers or carbonic anhydrase inhibitors

              Use caution in patients taking calcium channel blockers, cardiac glycosides, or inhaled anesthetic agents

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              Pregnancy & Lactation

              Pregnancy Category: C

              Lactation: Excreted in breast milk; not recommended

              Pregnancy Categories

              A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

              B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

              C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

              D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

              X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

              NA: Information not available.

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              Pharmacology

              Mechanism of Action

              Dorzolamide: Sulfonamide and carbonic anhydrase inhibitor; inhibition of carbonic anhydrase in ciliary processes of the eye decreases aqueous humor secretion, presumably by slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport

              Timolol: Nonselective beta-adrenergic receptor blocker; reduces IOP by reducing production of aqueous humor

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              Images

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              Patient Handout

              A Patient Handout is not currently available for this monograph.
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              Formulary

              FormularyPatient Discounts

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              Tier Description
              1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
              2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
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              Code Definition
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              Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.