Nafcillin
NALLPEN
Pronunciation: naf-SIL-in
What it isPenicillinase-resistant penicillin; methicillin-susceptible staphylococcal infection.
Why this oneIts unusual distinction among antibiotics is enzyme induction strong enough to undermine warfarin.
What limits itPhlebitis and extravasation injury can end IV therapy; renal adjustment is unnecessary.
FDA-approved for
- staphylococcal infections (MSSA) (1964)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Staphylococcal / susceptible infection | adult | 500 mg IV q4h; 1 g q4h for severe infection | ||
| Staphylococcal / susceptible infection (IM) | adult | 500 mg IM q4–6h | ||
| Susceptible infection | infants & children <40 kg | 25 mg/kg IM BID | ||
| Susceptible infection | neonates | 10 mg/kg IM BID |
Renal No adjustment needed, including patients on hemodialysis
Hepatic Undefined
Instructions
- Administer IV slowly over at least 30–60 min to minimize vein irritation and extravasation
- Do not add supplementary medication to nafcillin
- Continue therapy ≥14 days for severe staphylococcal infections
- Inspect visually for particulate matter and discoloration before use
Available strengths
- inj 1, 2 g
Contraindications
- History of anaphylactic reaction to any penicillin
Cautions
- Serious/fatal hypersensitivity (anaphylaxis)
- Severe tissue necrosis/sloughing with extravasation; thrombophlebitis
- Interstitial nephritis
- Neurotoxicity with high doses (esp. hepatic + renal impairment)
- Pseudomembranous colitis
- Neutropenia/bone marrow depression
Adverse reactions
- Allergic reactions (urticaria, pruritus, fever)
- Injection-site pain/phlebitis/thrombophlebitis
- GI upset (nausea, vomiting, diarrhea)
- Elevated liver transaminases
- Interstitial nephritis
- Neutropenia
Pregnancy Undefined
Lactation Undefined
Cost
Nafcillin (NALLPEN)
| Strength | #/mo | generic $/unit | CostPlus | |
|---|---|---|---|---|
| 1 g | inj | per unit | not offered | |
| 2 g | inj | per unit | not offered |
NADAC is a voluntary CMS survey of what retail community pharmacies pay for the drugs they stock. Nafcillin is administered under clinical supervision and dispensed outside retail pharmacies, so it rarely appears on surveyed invoices.
Generic entryBy 2023
NO BOXED WARNINGS
Principal riskIt INDUCES CYP3A4, so warfarin fails
Classes and tags
Clinical profile
Legacy pregnancy categoryB
Defining liabilityAllergy, gastrointestinal effects and agent-specific renal, hepatic, hematologic or interaction risks.