THE EFFECTS OF FENPIVERINIUM AND OTHER ANTIMUSCARINICS MAY BE ENHANCED BY THE CONCOMITANT ADMINISTRATION OF OTHER DRUGS SUCH AS AMANTADINE, SOME ANTIHISTAMINES, PHENOTHIAZINE, ANTIPSYCHOTICS, AND TRICYCLIC ANTIDEPRESSANTS. INHIBITION OF DRUG-METABOLISING ENZYMES BY MAOIS MAY POSSIBLY ENHANCE THE EFFECTS OF ANTIMUSCARINICS.