Pronunciation: TI-moe-lahl MAL-ee-ate
Class: Beta-adrenergic blocking agent

Trade Names

Betimol
- Solution 0.25%
- Solution 0.5%

Blocadren
- Tablets 5 mg
- Tablets 10 mg
- Tablets 20 mg

Istalol
- Solution 0.5%

Timoptic
- Solution 0.25%
- Solution 0.5%

Timoptic Ocudose
- Solution 0.25%
- Solution 0.5%

Timoptic-XE
- Solution, gel-forming 0.25%
- Solution, gel-forming 0.5%

Apo-Timol (Canada)
Apo-Timop (Canada)
Gen-Timolol (Canada)
PMS-Timolol (Canada)
Sandoz Timolol (Canada)

Pharmacology

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

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Pharmacokinetics

Absorption

Timolol is rapidly and about 90% absorbed following oral administration. T _max is approximately 1 to 2 h.

Distribution

Timolol is not extensively bound to plasma proteins.

Metabolism

Timolol undergoes approximately 50% first-pass metabolism.

Elimination

Timolol t _½ is approximately 4 h.

Indications and Usage

Treatment of hypertension, alone or in combination with other agents; reduction of risk of reinfarction post-MI; migraine prophylaxis; treatment of elevated IOP in chronic open-angle glaucoma, ocular hypertension, aphakic glaucoma patients, patients with secondary glaucoma, and in patients with elevated IOP who need ocular pressure lowering.

Contraindications

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

Dosage and Administration

Hypertension
Adults

PO 10 mg twice daily, titrate to response every 7 days (max, 60 mg/day).

MI Prophylaxis
Adults

PO 10 mg twice daily.

Migraine Prophylaxis
Adults

PO 10 mg twice daily (max, 30 mg/day); if no response in 6 wk then discontinue.

Glaucoma
Adults

Ophthalmic 1 drop 0.25% to 0.5% solution in affected eye(s) twice daily.

Storage/Stability

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.

Drug 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 derivatives

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.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Hypotension; heart palpitations; bradycardia; heart failure, edema.

CNS

Dizziness; depression; lethargy; headache; insomnia; anxiety; tremor; paresthesia.

Dermatologic

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.

Genitourinary

Impotence; sexual dysfunction; decreased libido; dysuria; urinary retention or frequency; nocturia; increased BUN.

Hematologic

Decreased Hgb, Hct.

Metabolic

Alteration of glucose metabolism; masking of hypoglycemia; increased triglycerides, uric acid, potassium.

Respiratory

Wheezing; cough; breathing difficulties, especially in asthmatics or patients with COPD.

Miscellaneous

Joint pain; muscle cramps.

Precautions

Warnings Abrupt withdrawal In patients with angina pectoris or CAD, may cause exacerbation of angina, occurrence of MI, and ventricular arrhythmias. Monitor patients closely. Because CAD is common and unrecognized it may be prudent not to discontinue beta-blocker therapy abruptly in patients treated only for hypertension.

Pregnancy

Category C .

Lactation

Excreted in breast milk.

Children

Safety and efficacy not established.

Renal Function

Dosage reduction may be required.

Hepatic Function

Dosage reduction may be required.

Abrupt withdrawal

Has been associated with increased angina and MI; gradually decrease dose over 1 to 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 health care provider 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.

Thyrotoxicosis

Drug may mask clinical signs (eg, tachycardia) of developing or continuing hyperthyroidism. Abrupt withdrawal may exacerbate symptoms of hyperthyroidism, including thyroid storm.

Overdosage

Symptoms

Severe bradycardia, severe hypotension, bronchospasm, acute cardiac failure.

Patient Information

• Explain that eye drops commonly produce transient stinging or discomfort and to notify health care provider 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 to 2 min and apply gentle pressure over bridge of nose. Do not rub eye.
• Explain that if using eye drops, health care provider may need to monitor eye pressure at regular intervals and at different times of day.
• Tell patient to consult health care provider 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 health care provider immediately of shortness of breath (especially if lying down), feet swelling, night cough, and slow pulse rate.
• Tell patient to notify health care provider 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 health care provider quickly if nausea, vomiting, or diarrhea develop. Dehydration may occur and may lower BP severely. Health care provider 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, health care provider should be informed that this drug is being used (even as eye drops). Health care provider may wish to discontinue drugs temporarily.
• Explain to patient that abrupt withdrawal of the drug is dangerous and dose is generally tapered according to health care provider'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 health care provider.

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