Increased risk of hypotension, bradycardia or heart failure w/ Ca antagonists. Increased effectiveness & increased risk of heart failure w/ dihydropyridine derivatives. Concomitant use w/ digitalis glycosides or medicinal products that have a stabilizing effect on heart rhythm (eg, disopyramide & quinidine) can have an effect on the heart. Use of clonidine should only be stopped a few days after atenolol is stopped. Reduced effect w/ medicinal products that have a stimulating effect on the nervous system eg, adrenaline; certain analgesics, antipyretics & anti-inflammatory eg, ibuprofen & indomethacin. Increased effect of oral antidiabetics & insulin. Increased BP-lowering effect w/ other BP-lowering medicines. Potential interaction w/ inhalation anaesth.