Professional Information

Atenolol

Pronunciation: (ah-TEN-oh-lahl)
Class: Beta-adrenergic blocking agent

Trade Names:
Tenormin
- Tablets 25 mg
- Tablets 50 mg
- Tablets 100 mg

APO-Atenol (Canada)
CO Atenolol (Canada)
Gen-Atenolol (Canada)
Novo-Atenol (Canada)
PMS-Atenolol (Canada)
RAN-Atenolol (Canada)
ratio-Atenolol (Canada)
Sandoz Atenolol (Canada)

Pharmacology

Blocks beta receptors, primarily affecting heart (slows rate), vascular system (decreases BP) and, to lesser extent, lungs (reduces function).

Pharmacokinetics

Absorption

Rapid and consistent but incomplete; approximately 50% is absorbed from the GI tract. T _max is 2 to 4 h.

Distribution

6% to 16% bound to plasma proteins.

Metabolism

Little or no metabolism by the liver.

Elimination

Approximately 50% is excreted unchanged in the feces. Approximately 50% is excreted in the urine within 24 h. T _½ is approximately 6 to 7 h.

Onset

1 h (oral).

Peak

2 to 4 h (oral).

Duration

24 h (oral). Duration of action is dose related.

Special Populations

Renal Function Impairment

Elimination is closely related to glomerular filtration rate. Significant accumulation occurs when CrCl falls below 35 mL/min/1.73 m ² .

Indications and Usage

Treatment of hypertension (used alone or in combination with other drugs), angina pectoris resulting from coronary atherosclerosis, acute MI.

Unlabeled Uses

Migraine prophylaxis, alcohol withdrawal syndrome, ventricular arrhythmias, supraventricular arrhythmias or tachycardias, esophageal varices rebleeding, anxiety.

Contraindications

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

Dosage and Administration

Hypertension
Adults

PO 50 to 100 mg/day.

Angina Pectoris

PO May require up to 200 mg/day.

Acute MI
Adults

PO 50 to 100 mg/day.

Storage/Stability

Store in a tightly closed container in a cool location.

Drug Interactions

Aluminum salts, ampicillin, calcium salts

Plasma levels and pharmacologic effects may be decreased.

Clonidine

May add to or reverse antihypertensive effects; potentially life-threatening situations may occur, especially on withdrawal.

Diltiazem

Pharmacologic effects of atenolol may be increased; symptomatic bradycardia may occur.

Nifedipine, verapamil

Effects of both drugs may be increased.

NSAIDs

Some agents may impair antihypertensive effect.

Prazosin

May increase orthostatic hypotension.

Quinidine

Pharmacologic effects of atenolol may be increased.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Hypotension; bradycardia; CHF; cold extremities; second- or third-degree heart block.

CNS

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

Dermatologic

Rash; hives; fever; alopecia.

EENT

Dry eyes; blurred vision; tinnitus; dry mouth; sore throat.

GI

Nausea; vomiting; diarrhea.

Genitourinary

Impotence; painful, difficult or frequent urination.

Hematologic

Agranulocytosis; thrombocytopenic purpura.

Hepatic

Elevated liver enzymes and bilirubin.

Respiratory

Bronchospasm; dyspnea; wheezing.

Miscellaneous

Weight changes; facial swelling; muscle weakness; hyperglycemia; hypoglycemia; antinuclear antibodies; hyperlipidemia.

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 D .

Lactation

Excreted in breast milk.

Children

Safety not established.

Elderly

Dosage reduction may be necessary.

Renal Function

Reduce dose.

Hepatic Function

Reduce dose.

Anaphylaxis

Deaths have occurred; aggressive therapy may be required.

CHF

Administer cautiously in patients with CHF controlled by digitalis and diuretics.

Diabetes mellitus

May mask symptoms of hypoglycemia (eg, tachycardia, BP changes).

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.

Overdosage

Symptoms

Bradycardia, hypotension, CHF, cardiogenic shock, hypertension, cardiac arrhythmias, seizures, respiratory depression, coma, pulmonary edema, bronchospasm, hypoglycemia.

Patient Information

Explain that full effectiveness of drug may not occur for up to 1 to 2 wk after initiation of therapy, and that dosage will be tapered slowly before stopping. Warn that sudden discontinuation can cause chest pain or heart attack.
Teach patient how to take pulse and instruct patient to check before taking drug. Warn patient not to take drug if pulse is less than 60 bpm, and to call health care provider.
When medication is being used for treatment of hypertension, teach patient how to take daily BP.
Advise patient that medication may cause increased sensitivity to cold.
Inform patients with diabetes to monitor blood glucose level carefully. It may be necessary to alter insulin dose while taking drug.
Instruct patient to report the following symptoms to health care provider: difficulty breathing; swelling of feet, legs, and hands; irregular heart beat; altered mood; depression.
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.