re available, they should be considered in selecting or modifying antibacterial therapy. in the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

of c. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. cdad must be considered in all patients who present with diarrhea following antibiotic use. careful medical history is necessary since cdad has been reported to occur over two months after the administration of antibacterial agents. if cdad is suspected or confirmed, ongoing antibiotic use not directed against c. difficile may need to be discontinued. appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of c. difficile , and surgical evaluation should be instituted as clinically indicated.

erapy with nafcillin should be continued for at least 14 days. the treatment of endocarditis and osteomyelitis may require a longer duration of therapy. no dosage alterations are necessary for patients with renal dysfunction, including those on hemodialysis. hemodialysis does not accelerate nafcillin clearance from the blood. with intravenous administration, particularly in elderly patients, care should be taken because of the possibility of thrombophlebitis. parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. do not add supplementary medication to nafcillin for injection, usp.

may include urticaria, pruritus, and fever. although laryngeal edema, laryngospasm, and hypotension occasionally occur, fatality is uncommon. delayed allergic reactions to penicillin therapy usually occur after 48 hours and sometimes as late as 2 to 4 weeks after initiation of therapy. manifestations of this type of reaction include serum sickness-like symptoms (i.e., fever, malaise, urticaria, myalgia, arthralgia, abdominal pain) and various skin rashes. nausea, vomiting, diarrhea, stomatitis, black or hairy tongue, and other symptoms of gastrointestinal irritation may occur, especially during oral penicillin therapy. local reactions pain, swelling, inflammation, phlebitis, thrombophlebitis, and occasional skin sloughing at the injection site have occurred with intravenous administration of nafcillin (see dosage and administration ). severe tissue necrosis with sloughing secondary to subcutaneous extravasation of nafcillin has been reported. nervous system reactions neurotoxic reactions similar to those observed with penicillin g could occur with large intravenous doses of nafcillin especially in patients with concomitant hepatic insufficiency and renal dysfunction (see precautions ). nephrotoxicity renal tubular damage and interstitial nephritis have been associated with the administration of nafcillin. manifestations of nephrotoxicity are hematuria, proteinuria, and acute kidney injury, and may be associated with rash, fever, and eosinophilia. the majority of cases resolve upon discontinuation of nafcillin. some patients, however, may require dialysis treatment and may develop permanent renal damage. hepatic reactions elevation of liver transaminases and/or cholestasis may occur, especially with administration of high doses of nafcillin. gastrointestinal reactions pseudomembranous colitis has been reported with the use of nafcillin. the onset of pseudomembranous colitis symptoms may occur during or after antibiotic treatment (see warnings ). metabolic reactions agranulocytosis, neutropenia, and bone marrow depression have been associated with the use of nafcillin. to report suspected adverse events, contact fda at 1-800-fda-1088 or www.fda.gov .

or. the concurrent administration of probenecid with nafcillin increases and prolongs plasma concentrations of nafcillin. probenecid significantly reduces the total body clearance of nafcillin with renal clearance being decreased to a greater extent than nonrenal clearance. the penicillinase-resistant penicillins are widely distributed in various body fluids, including bile, pleural, amniotic and synovial fluids. with normal doses insignificant concentrations are found in the aqueous humor of the eye. high nafcillin csf levels have been obtained in the presence of inflamed meninges. renal failure does not appreciably affect the serum half-life of nafcillin; therefore, no modification of the usual nafcillin dosage is necessary in renal failure with or without hemodialysis. hemodialysis does not accelerate the rate of clearance of nafcillin from the blood. a study which assessed the effects of cirrhosis and extrahepatic biliary obstruction in man demonstrated that the plasma clearance of nafcillin was significantly decreased in patients with hepatic dysfunction. in these patients with cirrhosis and extrahepatic obstruction, nafcillin excretion in the urine was significantly increased from about 30 to 50% of the administered dose, suggesting that renal disease superimposed on hepatic disease could further decrease nafcillin clearance. pharmacokinetics intramuscular injections of nafcillin sodium, usp 1 gram produced peak serum levels in 0.5 to 1 hour of 7.61 mcg/ml. the degree of protein binding reported has been 89.9 +/-1.5%. with normal doses nafcillin is found in therapeutic concentrations in the pleural, bile, and amniotic fluids. insignificant concentrations are found in the cerebrospinal fluid and aqueous humor. blood concentrations may be tripled by the concurrent use of probenecid. clinical studies with nafcillin sodium in infants under three days of age and prematures have revealed higher blood levels and slower rates of urinary excretion than in older children and adults. a high concentration of nafcillin sodium is excreted via the bile. about 30% of an intramuscular dose is excreted in the urine. microbiology penicillinase-resistant penicillins exert a bactericidal action against penicillin-susceptible microorganisms during the state of active multiplication. all penicillins inhibit the biosynthesis of the bacterial cell wall. nafcillin sodium has been shown to be active against most isolates of the following microorganism, both in vitro and in clinical infections as described in the indications and usage section. gram-positive bacteria staphylococcus aureus (methicillin susceptible isolates only) susceptibility testing for specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by fda for this drug, please see: https://www.fda.gov/stic.