<p><strong>Atenolol&nbsp;</strong>is a beta1-selective (cardio selective) beta-adrenergic receptor blocking agentwithout membrane stabilizing or intrinsic sympathomimetic (partial agonist) activities.This preferential effect is not absolute, however, and at higher doses, Atenolol inhibitsbeta-2-adrenoreceptors, chiefly located in the bronchial and vascular musculature.Chlorthalidone<br />
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<strong>Chlorthalidone&nbsp;</strong>is a monosulfonamyl double ring system which differs chemically fromthiazide diuretics in that a double ring system is incorporated in its&#39; structure. It is an oraldiuretic with prolonged action and low toxicity. The diuretic of the drug occurs within 2 hours of an oral dose. It produces diuresis with greatly increased excretion of sodium andchloride. At maximal therapeutic dosage, Chlorthalidone is approximately equal in itsdiuretic effect to comparable maximal therapeutic doses of benzothiadiazine diuretics.The site of action appears to be the cortical diluting segment of the ascending limb of Henle&#39;s loop of the nephron.</p>