HYPERTENSION
The initial dose is 50 mg daily either alone or added to diuretic therapy. If an optimal response is not achieved, the dosage should be increased to 100 mg daily. Increasing the dosage beyond 100 mg a day is unlikely to produce any further benefit..
ANGINA PECTORIS.
As for hypertension. Some patients may require a dosage of 200 mg once a day for optimal effect.

POSTMYOCARDIAL INFARCTION..
100 mg daily in single or divided doses

2. THERAPEUTIC / DIAGNOSTIC CLAIMS

Atenolol is indicated in the treatment of hypertension, angina pectoris and post-myocardial infarction.

3. DESCRIPTION OF DOSAGE FORM
Atenolol is a cardiovascular beta-adrenergic receptor blocking agent. It specifically competes with beta-adrenergic receptor stimulating agents for available receptor sites. The mechanism of antihypertensive effect of atenolol has been attributed to the reduction in cardiac output or to circulatory adjustments to a chronically reduced cardiac output. The beneficial effect of Atenolol in angina pectoris is derived from its ability to decrease heart rate and myocardial contractibility. By attenuating the cardiac response to sympathetic stimulation, beta blockade reduces myocardial oxygen demand and thereby delays the onset of ischaemic pain.

Warnings And Precautions :
DRUG INTERACTIONS.
Reserpine: Concomitant administration of atenolol with reserpine may increase the incidence of hypotension and bradycardia as compared with atenolol alone because of reserpine's catecholamine depleting activity.

Clonidine: Beta blockers may exacerbate the rebound hypertension which can follow the withdrawal of clonidine. If the two drugs are coadministered, the beta blocker should be withdrawn several days before the gradual withdrawal of clonidine. If clonidine is replaced by beta blocker therapy, the introduction of beta blockers should be delayed for several days after clonidine administration has stopped.
PREGNANCY
Atenolol can cause fetal harm when administered to a pregnant woman. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of potential hazard to the foetus.
NURSING MOTHERS
The extent of atenolol distribution in breast milk has not been established.

IN IMPAIRED RENAL FUNCTION.
Atenolol is excreted by the kidneys. Hence the drug should be used with caution in patients with impaired renal function.
OTHERS
Patients with bronchospastic diseases: These patients should in general not receive beta blockers. Because of its relative b1 selectivity, however, atenolol may be used with caution in patients with bronchospastic disease who do not respond to, or cannot tolerate, other antihypertensive treatment. Since b1 selectivity is not absolute, the lowest possible dose of atenolol should be used (initiated at 25 mg) with concurrent administration of b2 agonists.
CESSATION OF THERAPY.
Severe exacerbation of angina and the occurrence of myocardial infarction and ventricular arrhythmias have been reported in angina patients following the abrupt discontinuation of therapy with beta blockers. Hence, patients with coronary artery disease, who are being treated with atenolol, should be advised against abrupt discontinuation of therapy.

4. CONTRAINDICATIONS

Sinus bradycardia, second or third degree AV block, cardiogenic shock, overt cardiac failure and hypersensitivity to atenolol.

5. SIDE EFFECTS

In therapeutic doses, atenolol is well tolerated. Side effects include bradycardia, hypotension, headache, dizziness, depression, second or third degree block, precipitation of CCF, fatigue, diarrhoea, nausea and coldness of extremities.

6. TOXIC EFFECTS

Mutagenicity, Carcinogenecity and Teratogenecity
Atenolol has no mutagenic potential in standard tests. Carcinogenicity tests in rats given 300 mg.kg-1 daily for 24 months and in mice given the same dose for 18 months showed no carcinogenic effect. Carcinogenic effects of atenolol have been sought in mice and rats and teratogenic effects in rats and rabbits: none of these animal studies has shown any significant toxic, teratogenic or carcinogenic effects. In rat teratology studies at dose upto 200 mg.kg-1 per day there was a significant decrease in the number of live fetuses but no increase in malformations.
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