TETRACYCLINE, A BACTERIOSTATIC ANTIBIOTIC, MAY ANTAGONIZE THE BACTERICIDAL EFFECT OF PENICILLIN.
NAFCILLIN IN HIGH DOSAGE, I.E., 2 GRAMS EVERY 4 HOURS, HAS BEEN REPORTED TO DECREASE THE EFFECTS OF WARFARIN. THIS EFFECT MAY PERSIST FOR UP TO 30 DAYS AFTER NAFCILLIN HAS BEEN DISCONTINUED.
NAFCILLIN WHEN ADMINISTERED WITH CYCLOSPORINE HAS BEEN REPORTED TO RESULT IN SUBTHERAPEUTIC CYCLOSPORINE LEVELS.