Atenolol

Pronunciation: (a-TEN-oh-lol)Class: Beta-adrenergic blocking agent

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

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. Half-life 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 per 1.73 m ² .

Elderly

Total Cl is about 50% lower than in younger subjects. Half-life is markedly longer in elderly patients.

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, supraventricular arrhythmias or tachycardias, esophageal varices rebleeding, anxiety.

Contraindications

Hypersensitivity to beta-blockers; sinus bradycardia; greater than first-degree heart block; overt cardiac failure; cardiogenic shock.

Dosage and Administration

Acute MIAdults

PO 100 mg/day for 6 to 9 days or until hospital discharge.

Angina Pectoris

PO May require up to 200 mg/day.

HypertensionAdults

PO 50 to 100 mg/day.

Elderly

PO Initial dosage is 25 mg daily.

Renal Function Impairment

PO Adjust dose in severe renal impairment.

CrCl 15 to 35 mL/min per 1.73 m ²

Max dose 50 mg daily.

CrCl less than 15 mL/min per 1.73 m ²

Max dose 25 mg daily.

Hemodialysis

Give 25 to 50 mg after each dialysis session; marked falls in blood pressure can occur.

General Advice

• May be used alone or with other antihypertensive agents.
• In angina, withdraw atenolol gradually; observe patient for exacerbation of angina, MI, and arrhythmias. Advise patients to limit physical activity.

Storage/Stability

Store at 68° to 77°F 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

Cold extremities (12%); postural hypotension (4%); bradycardia (3%); Raynaud phenomenon, sick sinus syndrome (postmarketing).

CNS

Tiredness (26%); dizziness (13%); depression (12%); fatigue (6%); dreaming, lethargy, light-headedness (3%); drowsiness, vertigo (2%); hallucinations, headaches, psychoses (postmarketing).

Dermatologic

Lupus syndrome, psoriasiform rash or exacerbation of psoriasis, purpura, reversible alopecia (postmarketing).

GI

Diarrhea, nausea (3%); dry mouth (postmarketing).

Genitourinary

Impotence, Peyronie disease (postmarketing).

Respiratory

Dyspnea (6%); wheezing (3%).

Miscellaneous

Leg pain (3%); antinuclear antibodies, thrombocytopenia, visual disturbances (postmarketing).

Precautions

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

Monitor Closely monitor patients suspected of developing thyrotoxicosis from whom atenolol is to be withdrawn. Upon discontinuation, observe patients for exacerbation of angina, MI, and arrhythmias, and advise patients to limit physical activity.

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, BP changes, tachycardia).

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, bronchospasm, CHF, hypoglycemia, hypotension, lethargy, respiratory depression, sinus pause, wheezing.

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: altered mood; depression; difficulty breathing; irregular heart beat; swelling of feet, legs, and hands.
• 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.

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