Timolol


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO HTN Initial: 10 mg/day, increased every 7 or more days if needed. Maintenance: 10-40 mg/day. Max: 60 mg/day. Doses >30 mg/day should be given in 2 divided doses. Angina pectoris Initial: 5 mg bid, increased by 10 mg/day every 3 or more days if needed. Usual: 35-45 mg/day in divided doses. Max: 60 mg/day. Post MI Initial: 5 mg bid for 2 days, starting w/in 1-4 wk after MI, up to 10 mg bid if needed. Migraine prophylaxis 10 mg once daily or bid. Max: 30 mg/day in divided doses. Ophth Open-angle glaucoma; Ocular HTN As eye drop soln: Initial: Instill 1 drop of 0.25% soln to affected eye(s) bid, increase to 1 drop of 0.5% soln bid if needed. Reduce to 1 drop once daily if controlled. As 0.25% or 0.5% gel-forming eye drop: Instill 1 drop once daily.
Dosage Details
Ophthalmic
Open-angle glaucoma, Ocular hypertension
Adult: Eye drop soln: Initially, instill 1 drop of 0.25% soln bid into the affected eye(s), may increase to 1 drop of 0.5% soln bid if there is inadequate response; decrease to 1 drop once daily if controlled. Do not exceed 1 drop bid of 0.5% soln. As 0.25% or 0.5% gel-forming eye drops: Instill 1 drop into the affected eye(s) once daily.

Oral
Post-myocardial infarction
Adult: Initially, 5 mg bid for 2 days, starting w/in 1-4 wk after MI, increased to 10 mg bid if no adverse effects are observed.

Oral
Hypertension
Adult: Initially, 10 mg/day, increased according to response every 7 or more days. Maintenance: 10-40 mg/day. Max: 60 mg/day. Doses >30 mg/day should be given in 2 divided doses.

Oral
Prophylaxis of migraine
Adult: 10 mg once daily or bid. Max: 30 mg/day in divided doses.

Oral
Angina pectoris
Adult: Initially, 5 mg bid, increased by 10 mg/day every 3 or more days. Usual: 35-45 mg/day in divided doses. Max: 60 mg/day.
Renal Impairment
Oral:
Dose reduction may be needed.
Hepatic Impairment
Oral:
Dose reduction may be needed.
Administration
Should be taken with food.
Contraindications
Present or history of bronchial asthma, severe COPD, allergic bronchospasm, sinus bradycardia, sick sinus syndrome, 2nd and 3rd degree heart block, overt heart failure, cardiogenic shock, severe peripheral vascular disease, untreated phaeochromocytoma, metabolic acidosis.
Special Precautions
Patients w/ inadequate cardiac function, DM, myasthenia gravis, cerebrovascular insufficiency, history of atopy. Avoid abrupt withdrawal as it may exacerbate angina symptoms or precipitate MI in patients w/ coronary artery disease, or precipitate thyroid crisis in patients w/ thyrotoxicosis. Patients undergoing major surgery. May mask signs of hyperthyroidism and hypoglycaemia. Ophth soln should not be used as monotherapy for angle-closure glaucoma. Renal and hepatic impairment. Pregnancy and lactation.
Adverse Reactions
Burning and stinging sensation of the eyes, bradycardia, hypotension, arrhythmia and AV or SA nodal block, CHF, pulmonary oedema, Raynaud's phenomenon, headache, dizziness, fatigue, asthenia, abdominal discomfort, nausea, constipation, hypoglycaemia.
MonitoringParameters
Monitor BP, heart rate.
Overdosage
Symptoms: Symptomatic bradycardia, hypotension, bronchospasm and acute heart failure. Management: Symptomatic and supportive treatment. Stomach should be emptied immediately by gastric lavage. IV atropine sulfate may be given for symptomatic bradycardia, if it persists, admin IV isoproterenol HCl cautiously. For severe hypotension, a vasopressor (e.g. dobutamine, dopamine, norepinephrine) may be given, for bronchospasm, a β-adrenergic agonist and/or IV aminophylline. An IV cardiac glycoside, diuretic and oxygen should be used for cardiac failure. IV glucagon may also be useful.
Drug Interactions
Concomitant admin w/ reserpine may increase hypotension and bradycardia. Additive effects w/ other antihypertensives (e.g. hydralazine, methyldopa). Increased β-adrenergic blockade (e.g. decreased heart rate) w/ quinidine. Rebound HTN due to abrupt withdrawal of clonidine. Hypotensive effect may be antagonised by NSAIDs (e.g. indomethacin, ibuprofen).
Action
Description: Timolol is a non-selective β-adrenergic receptor blocker. It does not have significant intrinsic sympathomimetic activity, direct myocardial depressant activity or local anaesth activity. Exact mechanism of ocular hypotensive effect is unclear, but it is thought to be related to reduction of aqueous humour formation. β-blockade also causes lowering of BP.
Onset: Ophth: 30 min. Oral: 15-45 min.
Duration: Ophth: 24 hr. Oral: Approx 4 hr.
Pharmacokinetics:
Absorption: Oral: Almost completely absorbed from the GI tract (approx 90%). Oral bioavailability: 50%. Time to peak plasma concentration: Approx 1-2 hr. Ophth: Found in plasma at low concentrations.
Distribution: Crosses the placenta and enters breast milk. Volume of distribution: 1.7 L/kg. Plasma protein binding: 60%.
Metabolism: Extensively metabolised via CYP2D6 isoenzyme.
Excretion: Via urine (as metabolites and unchanged drug). Plasma half-life: 4 hr.
Storage
Store between 15-30°C. Avoid freezing and protect from light.
Disclaimer: This information is independently developed by MIMS based on Timolol from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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