Atenolol and chlorthalidone have been used singly and concomitantly for the treatment of hypertension. Studies have shown that there is no interference with bioavailability when these agents are given together in the single combination tablet. Therefore, this combination provides a convenient formulation for the concomitant administration of these two drugs.

Atenolol is a beta1-selective (cardioselective) beta-adrenergic receptor blocking agent that provides-

• reduction in resting and exercise heart rates and cardiac output
• reduction of systolic and diastolic blood pressure at rest and on exercise
• reduction in reflex orthostatic tachycardia.

Chlorthalidone is a monosulfonamyl diuretic with prolonged action and low toxicity. It produces diuresis with greatly increased excretion of sodium and chloride at distal convoluted tubule of the nephron.

This combination is indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure lowers the risk of fatal and non-fatal cardiovascular events, primarily strokes and myocardial infarctions.

The initial dose is Atenolol 50 mg and Chlorthalidone 25 mg once a day. If an optimal response is not achieved, another antihypertensive agent may be added gradually beginning with 50 percent of the usual recommended starting dose to avoid an excessive fall in blood pressure. Atenolol is excreted via kidneys and therefore dosage should be adjusted in cases of severe impairment of renal function.

Use in elderly: Clinical studies of Atenolol & Chlorthalidone combination did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects.

Atenolol and Chlorthalidone combination is contraindicated in hypersensitivity to this product or to sulfonamide-derived drugs. It is also contraindicated in patients with sinus bradycardia, heart block greater than first degree, cardiogenic shock, overt cardiac failure and anuria.

The adverse effects observed for this combination are essentially the same as those seen with the individual components. Atenolol: Bradycardia, Cold Extremities, Postural Hypotension, Leg Pain, Dizziness, Vertigo, Light Headedness, Tiredness, Fatigue, Lethargy, Drowsiness, Depression, Dreaming, Diarrhea, Nausea, Wheeziness, Dyspnea, Chlorthalidone Orthostatic hypotension, anorexia, gastric irritation, vomiting, cramping, constipation, vertigo, purpura, photosensitivity, rash, urticaria, hyperglycemia, glycosuria, hyperuricemia, muscle spasm, weakness, restlessness.

Overdose Effects

No specific information is available with regard to overdosage of this combination in humans. Treatment should be symptomatic and supportive and directed to the removal of any unabsorbed drug by induced emesis, or administration of activated charcoal. Atenolol can be removed from the general circulation by hemodialysis. Further consideration should be given to dehydration, electrolyte imbalance and hypotension by established procedures.

This combination may aggravate peripheral arterial circulatory disorders. Periodic determination of serum electrolytes to detect possible electrolyte imbalance should be performed at appropriate intervals.

Pregnancy & Lactation

Pregnancy Category D. Caution should be exercised when this drug is administered to a woman who is breastfeeding.