DrugindexOnline^{2nd edition}

Pronouncation: (ox-uh-SILL-in SO-dee-uhm)
Class: Penicillinase-resistant penicillin

Trade Names:
Oxacillin Sodium
- Powder for oral solution 250 mg/5 mL
- Powder for injection 500 mg
- Powder for injection 1 g
- Powder for injection 2 g
- Powder for injection 10 g

Mechanism of Action

Pharmacology

Inhibits mucopeptide synthesis in bacterial cell wall.

Pharmacokinetics

Absorption

30% to 35% of the oral dose is absorbed from the GI tract. The T _max is 5 min (IV), 30 min (IM), and 30 min to 2 hr (oral). The C _max is 43 mcg/mL (IV), 2.6 to 3.9 mcg (oral), and 5.3 to 10.9 mcg/mL (IM). Food decreases the rate and extent of absorption.

Distribution

Varies. Concentrations are found in CSF and aqueous humor, pleural, bile, and amniotic fluids. Protein binding is approximately 94.2%, mainly albumin. Crosses the placenta and distributes into milk.

Metabolism

Metabolized to active and inactive metabolites.

Elimination

Rapidly excreted primarily as unchanged drug in urine. The t _½ for elimination is 30 min. The t _½ for serum is 20 to 30 min.

Indications and Usage

Treatment of infections caused by penicillinase-producing staphylococci; initial therapy of suspected staphylococcal infection.

Contraindications

Hypersensitivity to penicillins. Do not treat severe pneumonia, empyema, bacteremia, pericarditis, meningitis and purulent or septic arthritis with oral oxacillin during acute state.

Dosage and Administration

Adults

PO / IV / IM 250 mg to 1 g q 4 to 6 hr.

Children (less than 40 kg)

PO / IV / IM 50 to 100 mg/kg/day in divided doses q 4 to 6 hr.

Premature/Neonates

IV / IM 25 mg/kg/day.

General Advice

• Administer oral doses on empty stomach at least 1 hr before or 2 hr after meals.
• Reconstitute IM preparation to dilution of 250 mg/1.5 mL. Use deep, slow injection. Rotate sites to prevent tissue irritation.
• Reconstitute IV preparation with sterile water for injection or sodium chloride for injection. Administer slowly over approximately 10 min to prevent vein irritation.

Storage/Stability

IM solution is stable for up to 3 days at room temperature or 7 days under refrigeration. IV solutions are stable for at least 6 hr at room temperature. Reconstituted oral solution is stable for 14 days if refrigerated.

Drug Interactions

Contraceptives, oral

Reduced efficacy of oral contraceptives.

Probenecid

Increased oxacillin levels.

Tetracyclines

Impaired bactericidal effects of oxacillin.

Incompatibility

Aminoglycosides.

Laboratory Test Interactions

Antiglobulin ( Coombs' ) test

Drug may cause false-positive results.

Urine and serum protein determinations

Drug may cause false-positive reactions with sulfosalicylic acid and boiling test, acetic acid test, biuret reaction, and nitric acid test but not with bromphenol blue test ( Multi-Stix ).

Urine glucose test

May cause false-positive urine glucose test result with Benedict solution, Fehling solution, or Clinitest tablets but not with enzyme-based tests (eg, Clinistix , Tes-tape ).

Adverse Reactions

CNS

Neurotoxicity (eg, lethargy, neuromuscular irritability, hallucinations, convulsions and seizures); dizziness; fatigue; insomnia; reversible hyperactivity; prolonged muscle relaxation.

Dermatologic

Ecchymosis.

EENT

Itchy eyes; abnormal taste perception.

GI

Glossitis; stomatitis; gastritis; sore mouth or tongue; dry mouth; furry tongue; black “hairy” tongue; nausea; anorexia; vomiting; abdominal pain or cramp; diarrhea or bloody diarrhea; rectal bleeding; flatulence; enterocolitis; pseudomembranous colitis; anorexia.

Genitourinary

Interstitial nephritis (eg, oliguria, proteinuria, hematuria, hyaline casts, pyuria); nephropathy; increased creatinine and BUN; vaginitis.

Hematologic

Deep vein thrombosis; hematomas; phlebitis; anemias; thrombocytopenia; eosinophilia; leukopenia; granulocytopenia; neutropenia; bone marrow depression; agranulocytosis; reduced Hgb or Hct; prolongation of bleeding and prothrombin time.

Hepatic

Transient hepatitis; cholestatic jaundice; increased LFT results.

Metabolic

Elevated serum alkaline phosphatase, AST, ALT, bilirubin, and LDH; hypernatremia; hypokalemia; reduced albumin, total proteins, and uric acid.

Miscellaneous

Hypersensitivity reactions that may lead to death; hyperthermia; pain at site of injection; hyperthermia; sciatic neuritis.

Precautions

Pregnancy

Category B .

Lactation

Excreted in breast milk.

Hypersensitivity

Reactions range from mild to life-threatening. Administer cautiously to cephalosporin-sensitive or imipenem-sensitive patients because of possible crossreactivity.

Superinfection

May result in bacterial or fungal overgrowth of nonsusceptible organisms.

Pseudomembranous colitis

Consider pseudomembranous colitis in patients who develop diarrhea.

Sodium content

Contains 2.5 to 3.1 mEq sodium/g.

Overdosage

Symptoms

Neuromuscular hyperexcitability, stupor, agitation, confusion, asterixis, hallucinations, coma, multifocal myoclonus, seizures, encephalopathy.

Patient Information

• Advise patient to complete full course of therapy, even if symptoms abate, to prevent reoccurrence of infection.
• Instruct patient to discard any liquid forms of medication after 7 days if stored at room temperature; after 14 days if refrigerated.
• Instruct patient to notify health care provider if symptoms of infection do not improve.
• Advise patient to report pruritus and rash immediately.
• Instruct patient to report the following signs of superinfection: black, “furry” tongue, loose or foul-smelling stools, vaginal itching, discharge.