Bacterial infections:

Indications for: Nafcillin

Susceptible infections due to penicillinase-producing staphylococci.

Adult Dosage:

Give by deep IM gluteal inj or IV infusion over 30–60mins. IM: 500mg every 4–6hrs. IV: 500mg every 4hrs. Severe infections: 1g IM or IV every 4hrs; treat for at least 14 days, then continue for at least 48hrs after becoming afebrile, asymptomatic, or (–) cultures. Endocarditis or osteomyelitis: may need longer therapy; see full labeling. Switch to oral therapy as soon as clinically indicated.

Children Dosage:

Give by deep IM gluteal inj only. Neonates: 10mg/kg twice daily. Infants and children (<40kg): 25mg/kg twice daily.

Nafcillin Warnings/Precautions:

Cephalosporin allergy: not recommended. History of significant allergies. Asthma. Discontinue if superinfection occurs or if CDAD is suspected or confirmed. Obtain CBCs, BUN, urinalysis, creatinine, LFTs at baseline and periodically during therapy. Monitor renal, hepatic and hematopoietic function in prolonged use. Renal and hepatic impairment. Elderly (esp. IV route). Pregnancy. Nursing mothers.

Nafcillin Classification:

Penicillinase-resistant penicillin.

Nafcillin Interactions:

May be antagonized by tetracycline; avoid. Concomitant warfarin: monitor; adjust dose as needed. May antagonize cyclosporine; monitor. Potentiated by probenecid. May cause false (+) protein urine test with sulfosalicyclic acid.

Adverse Reactions:

Inj site reactions, thrombophlebitis, rash, serum sickness, GI upset, neurotoxicity, renal toxicity, elevated LFTs, blood dyscrasias; hypersensitivity reactions, CDAD, pseudomembranous colitis.


Formerly known under the brand names Nallpen, Unipen.

How Supplied:

Contact supplier.