Nafcillin

Indications

INDICATIONS AND USAGE Nafcillin is indicated in the treatment of infections caused by penicillinase-producing staphylococci which have demonstrated susceptibility to the drug. Culture and susceptibility tests should be performed initially to determine the causative organism and its susceptibility to the drug (see CLINICAL PHARMACOLOGY - Susceptibility Test Methods ). Nafcillin should not be used in infections caused by organisms susceptible to penicillin G. If the susceptibility tests indicate that the infection is due to a methicillin-resistant Staphylococcus sp., therapy with Nafcillin for Injection, USP should be discontinued and alternative therapy provided. To reduce the development of drug-resistant bacteria and maintain the effectiveness of Nafcillin for Injection, USP and other antibacterial drugs, Nafcillin for Injection, USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria.

Dosage and administration (summary)

DOSAGE AND ADMINISTRATION The intent of the pharmacy bulk package for this product is for preparation of solutions for IV infusion only. Nafcillin for Injection is available for intravenous use. The usual I.V. dosage for adults is 500 mg every 4 hours. For severe infections, 1 gram every 4 hours is recommended. Administer slowly over at least 30 to 60 minutes to minimize the risk of vein irritation and extravasation. Bacteriologic studies to determine the causative organisms and their susceptibility to nafcillin should always be performed. Duration of therapy varies with the type and severity of infection as well as the overall condition of the patient.

Contraindications

CONTRAINDICATIONS A history of a hypersensitivity (anaphylactic) reaction to any penicillin is a contraindication.

Warnings and precautions

WARNINGS Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients on penicillin therapy. These reactions are more likely to occur in individuals with a history of penicillin hypersensitivity and/or a history of sensitivity to multiple allergens. Before initiating therapy with Nafcillin, careful inquiry should be made concerning previous hypersensitivity reactions to penicillins, cephalosporins, or other allergens. If an allergic reaction occurs, Nafcillin should be discontinued and appropriate therapy instituted.

Pregnancy

Pregnancy Teratogenic Effects Reproduction studies have been performed in the mouse with oral doses up to 20 times the human dose and orally in the rat at doses up to 40 times the human dose and have revealed no evidence of impaired fertility or harm to the rodent fetus due to nafcillin.

Storage and supply

HOW SUPPLIED Each Nafcillin for Injection, USP Pharmacy Bulk Package bottle contains nafcillin sodium equivalent to 10 grams of nafcillin. Nafcillin for Injection, USP is a sterile, white to yellowish-white powder supplied in Pharmacy Bulk Package bottles as follows: Nafcillin for Injection USP, 10 g Pharmacy Bulk Package bottles in a Box of 1 NDC …

Source: Nafcillin Sodium (Nafcillin) — US FDA prescribing information, 2025-08-12, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.