Nafcillin 10 g/100mL Injection, Powder, For Solution
🆔 Identity & classification
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🏷️ RxNorm drug class
This medicine belongs to the Penicillin-class Antibacterial class.
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🏭 Manufacturer & labeler
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🩺 Clinical
Nafcillin injection is used to treat infections caused by certain types of bacteria. Nafcillin injection is in a class of medications called penicillins. It works by killing bacteria. Antibiotics such as nafcillin injection will not work for colds, flu, or other viral infections. Taking antibiotics when they are not needed increases your risk of getting an infection later that resists antibiotic treatment.
Read the full MedlinePlus article ↗- Nafcillin is used specifically for infections caused by staphylococci — a type of bacteria — that have become resistant to regular penicillin. These 'penicillinase-producing' staph...
- What kind of infection is nafcillin used for?
- NAFCILLIN Injection is formulated to be given directly into a vein (IV) or into a muscle (IM). This route allows the medication to get into your bloodstream quickly and reach effec...
- Why is it given as an injection instead of a pill?
Patient education
Supplement & herbal interactions
Some supplements/herbs that may interact with Nafcillin Sodium — tap one for details:
Nafcillin Sodium may be associated with lower levels of 7 nutrients — worth a chat with your pharmacist, not a cause for alarm.
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Ask a licensed pharmacist directly — free, answered by our team.
🧪 Inactive Ingredients / Excipients
Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.
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IACT rows and label-wide narrative are kept separate; availability and product-level specificity depend on the submitted label.Inactive ingredient FAQ
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💲 Pricing
A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.
| Price system | Per mL | Per package |
|---|---|---|
| Retail pharmacies payNADAC · weekly | Not in the retail survey — common for institutional, discontinued, or low-volume packs. | |
| Medicaid paysCMS SDUD · 12 mo | $110.69 | $11,069.00 / 100 ml |
| Medicare drug plans payPart D · Q2 2026 | $80.03 | $8,002.60 / 100 ml |
| Medicare Part B allowsASP · J2290 | $0.047 / J2290 unit | — |
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🧾 Billing & reimbursement
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🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| Nafcillin 10 g/100mLthis 25021-0198-99 | Sagent | 1 vial | — | AP | FDA listed | — |
| Nafcillin 10 g 44567-0223-01 | WG | 1 vial | — | AP | FDA listed | — |
| Nafcillin 10 g/100mL 55150-0124-09 | Eugia | 1 vial | — | AP | FDA listed | — |
| Nafcillin 10 g/100mL 63323-0330-60 | Fresenius | 1 vial | — | AP | FDA listed | — |
| Nafcillin 10 g/100mL 70860-0119-99 | Athenex | 1 bottle | — | AP | Discontinued | — |
| Nafcillin 10 g/100mL 72603-0567-01 | NorthStar | 1 vial | — | AP | FDA listed | — |
| Nafcillin 10 g/100mL 83634-0101-99 | Avenacy | 1 bottle | — | AP | FDA listed | — |
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⏳ Availability & generic status
This product is an FDA-approved generic. Other versions of the same drug are listed under Therapeutic equivalents, least expensive first.
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🗺️ Medicaid utilization & spend
📊 Medicare Part D spend CMS · PART D · 2026 (Q1)
🔬 Reported adverse events (FAERS)
Top reported reactions
Age at onset
Reporter sex
Serious outcomes
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📦 Packaging — all sizes for this product
| Package NDC | Description | Marketing start | Status |
|---|---|---|---|
| 25021-0198-99 You're viewing this | 1 VIAL in 1 CARTON (25021-198-99) / 100 mL in 1 VIAL | 2025-04-15 | Active |
🧭 About this NDC listing & data coverage
What data is (and isn’t) available for this NDC — tap to expand
| NDC identity (package / product / labeler codes) | ✓ Available |
| Labeler | ✓ Available |
| Product & package description | ✓ Available |
| Marketing category & status | ✓ Available |
| Active ingredient / dosage form / route | ✓ Available |
| FDA label (SPL via DailyMed) | ✓ Available |
| Package photos | ✓ Available |
| Inactive ingredients (structured) | — Not published for this NDC The labeler did not submit a structured excipient list, or no SPL is available. |
| NADAC pharmacy acquisition price (CMS) | — Not published for this NDC CMS publishes NADAC only for NDCs reported in its retail-pharmacy survey. |
| Orange Book / therapeutic-equivalence data | ✓ Available |
| HCPCS J-code billing crosswalk | ✓ Available |
| Medicaid utilization (CMS SDUD) | ✓ Available |
Questions about this listing
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📄 Full prescribing information FDA SPL
🎯 Indications and Usage ▾
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 Testing ). 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 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. When culture and susceptibility information are 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.
⏱️ Dosage and Administration ▾
DOSAGE AND ADMINISTRATION Nafcillin for Injection, in the Pharmacy Bulk Package Bottle is for intravenous injection only. The usual IV 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; therefore, it should be determined by the clinical and bacteriological response of the patient.
In severe staphylococcal infections, therapy 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.
⛔ Contraindications ▾
CONTRAINDICATIONS A history of a hypersensitivity (anaphylactic) reaction to any penicillin is a contraindication.
⚠️ Warnings ▾
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. Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including Nafcillin for Injection, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile .
C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains 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.
🤒 Adverse Reactions ▾
ADVERSE REACTIONS Body as a Whole The reported incidence of allergic reactions to penicillin ranges from 0.7 to 10 percent (see WARNINGS ). Sensitization is usually the result of treatment, but some individuals have had immediate reactions to penicillin when first treated. In such cases, it is thought that the patients may have had prior exposure to the drug via trace amounts present in milk or vaccines.
Two types of allergic reactions to penicillins are noted clinically, immediate and delayed. Immediate reactions usually occur within 20 minutes of administration and range in severity from urticaria and pruritus to angioedema, laryngospasm, bronchospasm, hypotension, vascular collapse, and death. Such immediate anaphylactic reactions are very rare (see WARNINGS ) and usually occur after parenteral therapy but have occurred in patients receiving oral therapy.
Another type of immediate reaction, an accelerated reaction, may occur between 20 minutes and 48 hours after administration and 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 or intraventricular 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 REACTIONS, contact Sagent Pharmaceuticals at 1-866-625-1618 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .
🔄 Drug Interactions ▾
Drug Interactions Tetracycline, a bacteriostatic antibiotic, may antagonize the bactericidal effect of penicillin, and concurrent use of these drugs should be avoided. Nafcillin in high dosage regimens, i.e., 2 grams every 4 hours, has been reported to decrease the effects of warfarin. When nafcillin and warfarin are used concomitantly, the prothrombin time should be closely monitored and the dose of warfarin adjusted as necessary.
This effect may persist for up to 30 days after nafcillin has been discontinued. Nafcillin when administered concomitantly with cyclosporine has been reported to result in subtherapeutic cyclosporine levels. The nafcillin-cyclosporine interaction was documented in a patient during two separate courses of therapy.
When cyclosporine and nafcillin are used concomitantly in organ transplant patients, the cyclosporine levels should be monitored.
🔄 Drug / Laboratory Test Interactions ▾
Drug/Laboratory Test Interactions Nafcillin in the urine can cause a false-positive urine reaction for protein when the sulfosalicylic acid test is used, but not with the dipstick.
🤰 Pregnancy ▾
Pregnancy Teratogenic Effects Pregnancy Category B 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. There are, however, no adequate or well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, nafcillin should be used during pregnancy only if clearly needed.
🧒 Pediatric Use ▾
Pediatric Use The liver/biliary tract is the principal route of nafcillin elimination. Because of immature hepatic and renal function in pediatric patients, nafcillin excretion may be impaired. Safety and effectiveness in pediatric patients have not been established for the use of intravenous nafcillin. Safety and effectiveness in pediatric patients have been established for the use of intramuscular nafcillin.
🧓 Geriatric Use ▾
Geriatric Use Clinical studies of Nafcillin for Injection did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
Each Pharmacy Bulk Package bottle contains nafcillin sodium, as the monohydrate equivalent to 10 grams of nafcillin. The sodium content is 65.8 mg [2.9 mEq] per gram of nafcillin. The product is buffered with 40 mg sodium citrate per gram.
At the usual recommended doses, patients would receive between 197.4 and 394.8 mg/day (8.7 and 17.4 mEq) of sodium. The geriatric population may respond with a blunted natriuresis to salt loading. This may be clinically important with regard to such diseases as congestive heart failure.
🆘 Overdosage ▾
OVERDOSAGE Neurotoxic reactions similar to those observed with penicillin G may arise with intravenous doses of nafcillin especially in patients with concomitant hepatic insufficiency and renal dysfunction (see PRECAUTIONS ). In the case of overdosage, discontinue nafcillin, treat symptomatically and institute supportive measures as required. Hemodialysis does not increase the rate of clearance of nafcillin from the blood.
🧬 Clinical Pharmacology ▾
CLINICAL PHARMACOLOGY In a study of five healthy adults administered a single 500 mg dose of nafcillin by intravenous injection over seven minutes, the mean plasma concentration of the drug was approximately 30 mcg/mL at 5 minutes after injection. The mean area under the plasma concentration-versus-time curve (AUC) for nafcillin in this study was 18.06 mcg•h/mL. The serum half-life of nafcillin administered by the intravenous route ranged from 33 to 61 minutes as measured in three separate studies.
In contrast to the other penicillinase-resistant penicillins, only about 30% of nafcillin is excreted as unchanged drug in the urine of normal volunteers, and most within the first six hours. Nafcillin is primarily eliminated by nonrenal routes, namely hepatic inactivation and excretion in the bile. Nafcillin binds to serum proteins, mainly albumin.
The degree of protein binding reported for nafcillin is 89.9 ± 1.5%. Reported values vary with the method of study and the investigator. 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. 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.
📦 How Supplied / Storage and Handling ▾
HOW SUPPLIED Nafcillin for Injection, USP in a Pharmacy Bulk Package contains nafcillin sodium equivalent to 10 grams of nafcillin and is supplied as follows: NDC Nafcillin for Injection, USP Package Factor 25021-198-99 10 grams per Pharmacy Bulk Package Bottle 1 vial per carton Storage Conditions Prior to reconstitution store sterile powder at 20º to 25ºC (68º to 77ºF). [See USP Controlled Room Temperature.] Sterile, Nonpyrogenic, Preservative-free. The container closure is not made with natural rubber latex. SAGENT ® Mfd. for: SAGENT Pharmaceuticals Schaumburg, IL 60195 (USA) Made in Italy ©2024 Sagent Pharmaceuticals May 2024 SAGENT Pharmaceuticals ®
📦 Storage and Handling ▾
Storage Conditions Prior to reconstitution store sterile powder at 20º to 25ºC (68º to 77ºF). [See USP Controlled Room Temperature.] Sterile, Nonpyrogenic, Preservative-free. The container closure is not made with natural rubber latex. SAGENT ® Mfd. for: SAGENT Pharmaceuticals Schaumburg, IL 60195 (USA) Made in Italy ©2024 Sagent Pharmaceuticals May 2024 SAGENT Pharmaceuticals ®
📋 Description ▾
DESCRIPTION Nafcillin for Injection, USP is a semisynthetic antibiotic penicillin derived from the penicillin nucleus 6-aminopenicillanic acid. It is the sodium salt in a parenteral dosage form. The chemical name is 4-Thia-1-azabicyclo [3.2.0]heptane-2-carboxylic acid, 6-[[(2-ethoxy-1-naphthalenyl)carbonyl]amino]-3,3-dimethyl-7-oxo-monosodium salt, monohydrate [2 S (2α,5α,6β)].
It is resistant to inactivation by the enzyme penicillinase (beta-lactamase). The structural formula of nafcillin sodium is as follows: C 21 H 21 N 2 NaO 5 S·H 2 O M.W. 454.47 Each Nafcillin for Injection, USP Pharmacy Bulk Package is supplied as a dry powder in bottles containing nafcillin sodium and is intended for intravenous use only.
It is soluble in water. The pH of the aqueous solution is 6.0 to 8.5. Each Pharmacy Bulk Package bottle contains nafcillin sodium, as the monohydrate equivalent to 10 grams of nafcillin.
The sodium content is 65.8 mg [2.9 mEq] per gram of nafcillin. The product is buffered with 40 mg sodium citrate per gram. A Pharmacy Bulk Package is a container of sterile dosage form which contains many single doses.
The contents are intended for use in a pharmacy admixture program and are restricted to the preparation of admixtures for intravenous infusion. FURTHER DILUTION IS REQUIRED AFTER RECONSTITUTION (see DOSAGE AND ADMINISTRATION , and DIRECTIONS FOR PROPER USE OF PHARMACY BULK PACKAGE ). NOT TO BE DISPENSED AS A UNIT.
Structural Formula of Nafcillin Sodium
💬 Information for Patients ▾
Information for Patients Patients should be counseled that antibacterial drugs including Nafcillin for Injection should only be used to treat bacterial infections. They do not treat viral infections (e.g. the common cold). When Nafcillin for Injection is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed.
Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by Nafcillin for Injection or other antibacterial drugs in the future. Diarrhea is a common problem caused by antibiotics which usually ends when the antibiotic is discontinued. Sometimes after starting treatment with antibiotics, patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as two or more months after having taken the last dose of the antibiotic.
If this occurs, patients should contact their physician as soon as possible.