<p>Patients receiving drugs that bind to a1-acid glycoprotein should be closely monitored for increases in response to these drugs, e.g. propranolol, prazosin and quinidine. Folic acid may increase the metabolism of some antiepileptics, such as phenobartbitol, phenytoin and primidone. Pyridoxine can reduce the effect of levo-dopa. Bleomycin can be inactivated by ascorbic acid and riboflavin.</p>