Atenolol / Chlorthalidone

Pronunciation: (ah-TEN-oh-lahl/klor-THAL-ih-dohn)Class: Antihypertensive combination

Trade Names:Tenoretic-50- Tablets 50 mg atenolol/25 mg chlorthalidone

Trade Names:Tenoretic-100- Tablets 100 mg atenolol/25 mg chlorthalidone

Apo-Atenidone (Canada)Tenoretic (Canada)

Pharmacology

Atenolol is a beta-adrenergic blocking agent that slows heart rate, reduces cardiac output and lowers BP. Chlorthalidone is a diuretic agent that reduces body water by increasing urine output.

Indications and Usage

Treatment of hypertension.

Contraindications

Hypersensitivity to sulfonamide-derived drugs, sinus bradycardia, heart block greater than first degree, cardiogenic shock, overt cardiac failure, anuria. Not for initial therapy of hypertension.

Dosage and Administration

Adults

PO 50 mg atenolol/25 mg chlorthalidone or 100 mg atenolol/25 mg chlorthalidone once daily.

Storage/Stability

Store at room temperature in tightly closed, light-resistant container.

Drug Interactions

Clonidine

Beta-blockers may exacerbate rebound hypertension associated with clonidine withdrawal. Atenolol/chlorthalidone should be tapered and withdrawn several days before gradual withdrawal of clonidine.

Digitalis glycosides

Diuretic-induced hypokalemia may potentiate digitalis toxicity.

Lithium

May increase therapeutic and toxic effects of lithium; avoid concomitant use.

Nondepolarizing muscle relaxants

May increase effects of these agents.

Norepinephrine

May decrease arterial responsiveness to norepinephrine.

Other antihypertensive agents

May increase antihypertensive effects.

Sulfonylureas

May decrease hypoglycemic effects.

Laboratory Test Interactions

May increase serum protein-bound iodine levels without signs of thyroid disturbances.

Adverse Reactions

Cardiovascular

Bradycardia; orthostatic hypotension; cold extremities; leg pain; CHF; slow atrioventricular (AV) conduction; intensification of AV block.

CNS

Fatigue; dizziness; vertigo; light-headedness; lethargy; drowsiness; depression; dreaming.

Dermatologic

Rash.

GI

Diarrhea; nausea.

Genitourinary

Peyronie disease; impotence; diminished libido.

Hematologic

Thrombocytopenia; agranulocytosis.

Hepatic

Elevated liver enzymes; jaundice; pancreatitis.

Metabolic

Hyperuricemia; hyponatremia; hypochloremic alkalosis; hypokalemia.

Respiratory

Bronchospasm; wheezing; dyspnea.

Miscellaneous

Development of lupus syndrome with antinuclear antibodies.

Precautions

Monitor Side effects Withhold medication and notify health care provider if the following symptoms occur: hypotension; bradycardia or dyspnea; difficulty breathing on exertion or lying down; night cough; edema of hands and feet.

Pregnancy

Category D .

Lactation

Atenolol is excreted in breast milk and may produce clinically significant effects in infants.

Children

Safety and efficacy not established.

Elderly

Dose may need to be reduced.

Renal Function

Use with caution in patients with renal disease; dose may need to be reduced.

Hepatic Function

Use with caution in patients with hepatic disease; dose may need to be reduced.

Anaphylaxis

Deaths have occurred with anaphylactic reactions to beta-blockers; aggressive therapy may be required.

Cardiac failure

Use with caution in patients with history of heart failure.

Diabetes mellitus

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

Hypertension

Fixed-dose combinations of drugs are not intended for initial therapy of hypertension but are used for convenience once patient has been stabilized.

Nonallergic bronchospastic diseases (eg, chronic bronchitis, emphysema)

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

Peripheral vascular disease

May precipitate or aggravate symptoms of arterial insufficiency.

Thyrotoxicosis

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

Patient Information

• Explain that dosage will be tapered slowly before stopping. Warn that sudden discontinuation may cause adverse effects (eg, exacerbation of angina, precipitation of MI).
• Teach patient proper technique for taking pulse and BP, and instruct to check before taking medication.
• Advise patient not to take medication in evening to avoid prolonged diuretic effects.
• Instruct diabetic patient to monitor blood glucose level carefully.
• Counsel patient that impotence or decrease in libido are common side effects, and advise patient to contact health care provider if either symptom occurs.
• Caution 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 until individual effects can be determined.

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