Drug information of nafcillin


Drug group:

A semi-synthetic antibiotic related to penicillin, Naficillin is a narrow-spectrum beta-lactam antibiotic drug. It is a beta-lactamase-resistant penicillin that is indicated for the treatment of Staphylococcal infections caused by strains that are resistant to other penicillins, except those caused by MRSA. It may be used as a first-line therapy in Methicillin-Sensitive Staphylococcus aureus infections

Mechanism of effect

Like other penicillins, nafcillin exerts a bactericidal action against penicillin-susceptible microorganisms during the state of active multiplication in the bacterial cell wall synthesis. It inhibits the biosynthesis of the bacterial cell wall by forming covalent bonds with penicillin-binding proteins that play a critical role in the final transpeptidation process. Binding to penicillin-binding proteins inhibits the transpeptidase and carboxypeptidase activities conferred by these proteins and prevents the formation of the crosslinks


Nafcillin is a semisynthetic antibiotic substance derived from 6-amino-penicillanic acid. The drugs in this class are highly resistant to inactivation by staphylococcal penicillinase and are active against penicillinase-producing and non penicillinase-producing strains of Staphylococcus species


absorption: Following intravenous administration of 500mg nafcillin, the mean plasma concentration was approximately 30 µg/mL. This value was reached after 5 minutes of injection
Volume of distribution:Nafcillin is reported to be widely distributed in various body fluids, including bile, pleural, amniotic and synovial fluids
protein binding:The degree of nafcillin binding to serum proteins is 89.9 ± 1.5%, where it is mainly bound to albumin
metabolism:Hepatic metabolism accounts for less than 30% of the biotransformation of most penicillins
Route of elimination:Nafcillin is primarily eliminated by non-renal routes, namely hepatic inactivation and excretion in the bile
half-life: The serum half-life of nafcillin administered by the intravenous route ranged from 33 to 61 minutes as measured in three separate studies.

Drug indications


Susceptible InfectionsStaphylococcal EndocarditisBursitis septic


Susceptible Infections
500 mg IV/IM q4-6hr
Severe Infections
1 g IV/IM q4hr
Staphylococcal Endocarditis
2 g IV q4hr for 4-6 weeks; may be longer and may add rifampin and gentamicin if prosthetics present
Bursitis septic
2 g IV q4hr

Drug contraindications

A history of a hypersensitivity (anaphylactic) reaction to any penicillin

Solutions containing dextrose in patients with known allergy to corn or corn products

Side effects

Hypersensitivity , Hypocalcemia




Interstitial nephritis

Possible hypokalemia


Neurotoxicity (high doses)

Pseudomembranous colitis

Phlebitis (oxacillin preferred in peds)

  • cariprazine
  • cobimetinib
  • dienogest/estradiol valerate
  • doravirine
  • elvitegravir/cobicistat/emtricitabine/tenofovir DF
  • lorlatinib
  • lumacaftor/ivacaftor
  • lumefantrine
  • naloxegol
  • ombitasvir/paritaprevir/ritonavir & dasabuvir
  • panobinostat
  • praziquantel
  • regorafenib
  • roflumilast
  • vandetanib


Evaluate renal, hepatic, hematologic systems periodically during prolonged treatment
Serious and occasionally fatal hypersensitivity (anaphylactic) reactions reported; reactions are more likely to occur in individuals with history of penicillin hypersensitivity and/or a history of sensitivity to multiple allergens; inquire about previous hypersensitivity reactions to penicillins, cephalosporins, or other allergens before initiating therapy; if allergic reaction occurs, discontinue treatment and institute appropriate therapy

Points of recommendation

A history of a hypersensitivity (anaphylactic) reaction to any penicillin

Solutions containing dextrose in patients with known allergy to corn or corn products

Pregnancy level

Pregnancy Category: B
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk

Breast feeding warning

Lactation: Excreted into breast milk; use caution

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