Timolol Maleate

A to Z Drug Facts

(TI-moe-lahl MAL-ee-ate)

Betimol, Blocadren, Timoptic-XE, Timoptic, Timoptic Ocudose,  Apo-Timol, Apo-Timop, Gen-Timolol, Novo-Timol Ophthalmic Solution, Novo-Timol Tablets, Nu-Timolol, Tim-Ak,

Class: Beta-adrenergic blocker

 Action Blocks beta-receptors, which primarily affect heart (slows rate), vascular musculature (decreases blood pressure) and lungs (reduces function). Reduces both elevated and normal IOP via decreasing production of aqueous humor or increasing flow.

 Indications Treatment of hypertension, alone or in combination with other agents; eduction of risk of reinfarction post-MI; migraine prophylaxis; treatment of elevated IOP in chronic open-angle glaucoma, ocular hypertension, aphakic glaucoma patients, some patients with secondary glaucoma, and in patients with elevated IOP who need ocular pressure lowering. Unlabeled use(s): Treatment of ventricular arrhythmias and tachycardias, essential tremors, anxiety; management of chronic stable angina pectoris.

 Contraindications Hypersensitivity to beta-blockers; greater than first-degree heart block; HF unless secondary to tachyarrhythmia treatable with beta-blockers; overt cardiac failure; sinus bradycardia; cardiogenic shock; bronchial asthma or bronchospasm, including severe COPD.

 Route/Dosage

Hypertension

ADULTS: PO 10 mg bid, titrate to response q 7 days (maximum 60 mg/day).

MI Prophylaxis

ADULTS: PO 10 mg bid.

Migraine Prophylaxis

ADULTS: PO 10 mg bid (maximum 30 mg/day); if no response in 6 weeks then discontinue.

Essential Tremor

ADULTS: PO 10 mg/day.

Glaucoma

ADULTS: Ophthalmic 1 gtt 0.25–0.5% solution in affected eye(s) bid.

 Interactions

Clonidine: May enhance or reverse antihypertensive effect; potentially life-threatening situations may occur, especially on withdrawal. Epinephrine: Initial hypertensive episode followed by bradycardia may occur. Ergot alkaloids: Peripheral ischemia, manifested by cold extremities and possible gangrene, may occur. Insulin: Prolonged hypoglycemia with masking of symptoms may occur. NSAIDs: Some agents may impair antihypertensive effect. Prazosin: Orthostatic hypotension may be increased. Theophyllines: Elimination of theophylline may be reduced. Effects of both drugs may be reduced. Verapamil: Effects of both drugs may be increased.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Hypotension; heart palpitations; bradycardia; heart failure, edema. CNS: Dizziness; depression; lethargy; headache; insomnia; anxiety; tremor; aresthesia. DERM: Increased sensitivity to cold; rash; pruritus; alopecia; sweating. EENT: Transient irritation, burning, tearing and conjunctival edema, blurred vision, light sensitivity (topical use). GI: Abdominal pain; diarrhea; nausea. GU: Impotence; sexual dysfunction; decreased libido; dysuria; urinary retention or frequency; nocturia; increased BUN. HEMA: Decreased Hgb, Hct. META: Alteration of glucose metabolism; masking of hypoglycemia; increased triglycerides, uric acid, potassium. RESP: Wheezing; cough; breathing difficulties, especially in asthmatics or patients with COPD. OTHER: Joint pain; muscle cramps.

 Precautions

Pregnancy: Category C. Lactation: Excreted in breast milk. Children: Safety and efficacy not established. Abrupt withdrawal: Has been associated with increased angina and MI; gradually decrease dose over 1–2 wk. Anaphylaxis: Deaths have occurred; aggressive therapy may be required. Bronchospasm: Oral and ophthalmic forms may precipitate bronchospasm in susceptible patients. CHF: Administer drug with caution to patients with CHF controlled by digitalis and diuretics. Notify physician at first sign or symptom of CHF or of unexplained respiratory symptoms in any patient. Diabetic patients: Drug may mask signs and symptoms of hypoglycemia, eg, tachycardia, BP changes. Drug may potentiate insulin-induced hypoglycemia. Peripheral vascular disease: Drug may precipitate or aggravate symptoms of arterial insufficiency. Renal/hepatic impairment: Dosage reduction may be required. Thyrotoxicosis: Drug may mask clinical signs, eg, tachycardia, of developing or continuing hyperthyroidism. Abrupt withdrawal may exacerbate symptoms of hyperthyroidism, including thyroid storm.

 Administration/Storage

• Administer tablets orally with meals and at bedtime. Administer ophthalmic solutions via dropper provided.
• Tablets may be crushed or swallowed whole.
• Store tablets at room temperature, away from moisture and sunlight.
• Store ophthalmic solution at room temperature away from sunlight. Do not freeze.
• Discard ophthalmic solution if brown, cloudy or if it contains particles.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Monitor and record BP, especially that of renal dialysis patients (report hypotension); pulse (report tachycardia); blood glucose of diabetic patients on regular basis (report hypoglycemia).
• Assess apical/radial pulse before administration. Notify physician of any changes.
• Assess and document muscle strength of myasthenia gravis patients, and report increased weakness.
• Contact physician immediately if patient shows signs of cardiac failure.
• Have available isoproterenol, dopamine, dobutamine or norepinephrine to reverse effects in emergency.
• Use ophthalmic solution cautiously if patient is taking oral beta-blockers, because solution may be absorbed systemically and create an additive effect.
• If drug is for migraine prevention, monitor effectiveness and consult physician if satisfactory response is not obtained after 6–8 wk of maximum daily dose.
• Monitor I&O and weight daily. Monitor hydration status.
• Assess for edema in feet and legs daily.

 Patient/Family Education

• Explain that eye drops commonly produce transient stinging or discomfort and to notify physician if symptoms are severe.
• Teach patient how to instill eye drops: Shake once before using. Wash hands; do not allow dropper to touch eye. Tilt head back, look up; pull lower eyelid down; instill prescribed number of drops. Close eye for 1–2 min and apply gentle pressure over bridge of nose. Do not rub eye.
• Explain that if using eye drops, physician may need to monitor eye pressure at regular intervals and at different times of day.
• Tell patient to consult physician before using otc cough, cold or allergy medications, including nasal decongestants.
• Encourage diabetic patient to use glucometer regularly. This drug may increase chances of hypoglycemic reactions to insulin or may mask signs and symptoms of hypoglycemia.
• Inform patient to notify physician immediately of shortness of breath (especially if lying down), feet swelling, night cough and slow pulse rate.
• Tell patient to notify physician of skin rash, fever, lightheadedness, confusion, depression, sore throat, unusual bleeding or bruising, jaundice and changes in urination.
• Explain ways to avoid sudden changes in posture, and caution against hot baths or showers, especially if dizziness is experienced.
• Tell patient to contact physician quickly if nausea, vomiting or diarrhea develop. Dehydration may occur and may lower BP severely. Physician may decrease dose during episode.
• Explain need to be cautious when driving or participating in activities needing coordination. This drug may produce drowsiness, dizziness, lightheadedness or blurred vision, especially during first days of therapy or when dose is increased.
• Tell patient that before any surgery, physician should be informed that this drug is being used (even as eye drops). Physician may wish to discontinue drugs temporarily.
• Explain to patient that abrupt withdrawal of the drug is dangerous and dose is generally tapered according to physician's instructions.
• Encourage patient to wear support hose.
• Instruct patient to avoid alcohol, smoking and sodium intake.
• Teach patient to take pulse at home and when to notify physician.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts