Tenoretic is a combination of two rugs prescribed for hypertension - atenolol and chlorthalidone. Atenolol is a cardio-selective beta-blocker. Chlorthalidone is a diuretic. Tenoretic is not indicated for the initial treatment of hypertension but combines two effective drugs in a convenient once-a-day dosage for individuals who have been prescribed atenolol and chlorthalidone.