<p>Due to the pharmacological effects and mechanism of action of memantine suggests that the effects of L-dopa, dopaminergic agonists, and anticholinergics may be enhanced by concomitant treatment with NMDA-antagonists such as memantine. The effects of barbiturates and neuroleptics may be reduced. Concomitant administration of mematine with the antispasmodic agents, dantrolene or baclofen, can modify their effects and a dosage adjustment may be necessary. Memantine should not be used with amantadine, ketamine, dextromethorphan, phenytoin, cimetidine, ranitidine, procainamide, quinidine, quinidine, quinine &amp; nicotine.</p>