<p><strong>Disopyramide</strong>: Atenolol reduces the clearance of disopyramide by 20%. Additive negative inotropic effects on the heart may be produced.<br />
<br />
<strong>Ampicillin</strong>: at doses of 1 gm and above may reduce Atenolol levels.<br />
<br />
<strong>Oral antidiabetics and insulin</strong>: Beta-blockers may decrease tissue sensitivity to insulin and inhibit insulin secretion e.g. in response to oral antidiabetics. Atenolol has less potential for these actions.</p>