DrugindexOnline^{2nd edition}

Pronouncation: (ass-cee-BYOO-toe-lahl HIGH-droe-KLOR-ide)
Class: Beta-adrenergic blocking agent

Trade Names:
Sectral
- Capsules 200 mg
- Capsules 400 mg

Apo-Acebutolol (Canada)
Gen-Acebutolol (Canada)
Gen-Acebutolol Type S (Canada)
Monitan (Canada)
Novo-Acebutolol (Canada)
Nu-Acebutolol (Canada)
Rhotral (Canada)

Mechanism of Action

Pharmacology

Blocks beta-receptors, primarily affecting heart (slows rate), vascular musculature (decreases BP), and lungs (reduces function).

Pharmacokinetics

Absorption

Well absorbed. T _max is 2.5 h (acebutolol) and 3.5 h (diacetolol). Bioavailability is about 40%. Food may decrease the rate of absorption and C _max slightly.

Distribution

About 26% protein bound. Hydrophilic (minimally excreted into CSF). Crosses placenta and is excreted in breast milk.

Metabolism

Extensive first-pass hepatic biotransformation. Major metabolite is diacetolol (active; equipotent to acebutolol).

Elimination

T _½ is about 3 to 4 h (acebutolol) and 8 to 13 h (diacetolol). About 30% to 40% eliminated by kidneys, 50% to 60% eliminated by nonrenal mechanisms (ie, bile, feces). Dialyzable.

Onset

1.5 h.

Peak

3 to 8 h.

Special Populations

Renal Function Impairment

Decreased elimination of diacetolol resulting in a 2- to 3-fold increase in its t _½ . Administer with caution.

Elderly

Bioavailability increased about 2-fold.

Indications and Usage

Management of hypertension and premature ventricular contractions.

Contraindications

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

Dosage and Administration

Hypertension
Adults

PO 400 mg daily initially in single or divided doses; usual response range is 200 to 1,200 mg/day.

Elderly

May require lower maintenance doses. Do not exceed 800 mg daily.

Ventricular Arrhythmia
Adults

PO 400 mg (200 mg twice daily); may be titrated up to 1,200 mg daily.

Storage/Stability

Store at room temperature.

Drug Interactions

Clonidine

May enhance or reverse acebutolol's antihypertensive effect; potentially life-threatening situations may occur, especially on withdrawal.

NSAIDs

Some agents may impair antihypertensive effect.

Prazosin

May cause increase in orthostatic hypotension.

Verapamil

Effects of both drugs may be increased.

Laboratory Test Interactions

Antinuclear antibodies may develop; usually reversible on discontinuation. Acebutolol may interfere with glucose or insulin tolerance tests. May cause changes in serum lipids.

Adverse Reactions

Cardiovascular

Hypotension; bradycardia; CHF; cold extremities; heart block.

CNS

Insomnia; fatigue; dizziness; depression; lethargy; drowsiness; forgetfulness.

Dermatologic

Rash; hives; fever; alopecia.

EENT

Dry eyes; blurred vision; tinnitus; slurred speech; sore throat.

GI

Nausea; vomiting; diarrhea; dry mouth.

Genitourinary

Impotence; painful, difficult or frequent urination.

Hematologic

Agranulocytosis; thrombocytopenia purpura.

Respiratory

Bronchospasm; dyspnea; wheezing.

Miscellaneous

Weight changes; facial swelling; muscle weakness.

Precautions

Pregnancy

Category B .

Lactation

Excreted in breast milk.

Children

Safety and efficacy not established.

Renal Function

Reduction in daily dose is advised.

Hepatic Function

Reduction in daily dose is advised.

Abrupt withdrawal

Abrupt withdrawal is associated with adverse reactions; gradually decrease dose over 1 to 2 wk.

Anaphylaxis

Serious reactions may occur; aggressive therapy may be required.

CHF

Administer cautiously in patients taking digitalis and diuretics for CHF.

Diabetes

Acebutolol may mask signs of hypoglycemia (eg, tachycardia, BP changes). May potentiate insulin-induced hypoglycemia.

Nonallergic bronchospasm (eg, chronic bronchitis, emphysema)

In general, do not give beta blockers to patients with bronchospastic disease.

Peripheral vascular disease

Acebutolol may precipitate or aggravate symptoms of arterial insufficiency.

Thyrotoxicosis

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

Patient Information

• Teach patient to take pulse every day and record. If less than 60 bpm, tell not to take medication and to notify health care provider.
• Instruct diabetic patients to monitor blood sugar level every 6 h. Drug may mask symptoms of hypoglycemia.
• Caution patient not to stop taking drug suddenly because doing so may exacerbate angina and increase possibility of MI.
• Explain that drug may cause dizziness. Advise patient to avoid sudden position changes to prevent orthostatic hypotension.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.