Classifications: antibiotic, penicillin; antistaphylococcal penicillin; Therapeutic: penicillin antibiotic
Prototype: Penicillin G
Pregnancy Category: B
250 mg, 500 mg capsules; 250 mg/5 mL suspension; 250 mg, 500 mg, 1 g, 2 g, 4 g injection
Semisynthetic, acid-stable, penicillinase-resistant isoxazolyl penicillin. Oxacillin inhibits final stage of bacterial cell
wall synthesis by preferentially binding to specific penicillin-binding proteins (PBPs) located within the bacterial cell
wall. This leads to destruction of the cell wall of the organism.
It is highly active against most penicillinase-producing staphylococci, and is generally ineffective against gram-negative
bacteria and methicillin-resistant staphylococci (MRSA).
Primarily, infections caused by penicillinase-producing staphylococci and penicillin-resistant staphylococci. As with other
penicillins, serum concentrations are enhanced by concurrent use of probenecid.
Hypersensitivity to penicillins or cephalosporins.
History of or suspected atopy or allergy (hives, eczema, hay fever, asthma); history of GI disease; hepatic disease; renal
disease; premature infants, neonates, lactation (may cause infant diarrhea), pregnancy (category B).
Route & Dosage
Adult: PO 500 mg1 g q46h IM/IV 250 mg1 g q46h (max: 12 g/d)
Child: PO 50100 mg/kg/d divided q46h IM/IV 100200 mg/kg/d divided q46h (max: 12 g/d)
Neonate: IV 50100 mg/kg/d divided q612h
Note: The total sodium content (including that contributed by buffer) in each gram of oxacillin is approximately 3.1 mEq or 71
- Give with a full glass of water on an empty stomach (either 1 h before meals or 2 h after meals). Food reduces absorption.
- Reconstitute each 250 mg with 1.4 mL sterile water for injection to yield 250 mg/1.5 mL. Shake vial vigorously until drug
is completely dissolved. Discard unused portions after 3 d at room temperature or 7 d under refrigeration.
- Administer deep IM to adults by deep intragluteal injection. Follow agency policy for IM site in young children and infants.
Rotate injection sites.
Note: Verify correct IV concentration and rate of infusion/injection with physician before IV administration to neonates, infants,
PREPARE: Direct: Reconstitute each 500 mg or fraction thereof with 5 mL with sterile water for injection or NS to yield 250 mg/1.5 mL. Intermittent: Further dilute in 50100 mL of D5W, NS, D5/NS, or RL. Continuous: Further dilute in up to 1000 mL of compatible IV solutions.
ADMINISTER: Direct: Give at a rate of 1 g or fraction thereof over 10 min. Intermittent: Give over 1530 min. Continuous: Give over 6 h.
INCOMPATIBILITIES Solution: additive: Caffeine citrate, cephalothin, cytarabine, erythromycin, hyaluronidase, hydrocortisone, nitrofurantoin, pentobarbital, phenobarbital, tetracyclines, warfarin. Y-site: Sodium bicarbonate, verapamil.
Adverse Effects (≥1%)Body as a Whole:
therapy), superinfections, wheezing, sneezing, fever, anaphylaxis. GI:
Nausea, vomiting, flatulence, diarrhea,
hepatocellular dysfunction (elevated AST, ALT, hepatitis
, granulocytopenia, agranulocytosis
(reported in children). Skin:
Pruritus, rash, urticaria. Urogenital: Interstitial
nephritis, transient hematuria, albuminuria, azotemia (newborns and infants on high doses).
Diagnostic Test Interference
Oxacillin in large doses can cause false-positive urine protein tests using sulfosalicylic acid methods.
Incompletely and erratically absorbed orally. Peak:
30120 min IM; 15 min IV
4 h PO; 46 h IM. Distribution:
Distributes into CNS
with inflamed meninges; crosses placenta; distributed into breast milk, 90% protein bound. Metabolism:
Enters enterohepatic circulation. Elimination:
Primarily in urine, some in bile. Half-Life:
Assessment & Drug Effects
- Ask patient prior to first dose about hypersensitivity reactions to penicillins, cephalosporins, and other allergens.
- Lab tests: periodic liver functions, CBC with differential, platelet count, and urinalysis.
- Hepatic dysfunction (possibly a hypersensitivity reaction) has been associated with IV oxacillin; it is reversible with discontinuation
of drug. Symptoms may resemble viral hepatitis or general signs of hypersensitivity and should be reported promptly: hives,
rash, fever, nausea, vomiting, abdominal discomfort, anorexia, malaise, jaundice (with dark yellow to brown urine, light-colored
or clay-colored stools, pruritus).
- Withhold next drug dose and report the onset of hypersensitivity reactions and superinfections (see Appendix F).
Patient & Family Education
- Take oral medication around the clock; do not miss a dose. Take all of the medication prescribed even if you feel better,
unless otherwise directed by physician.