Category:

• Antibiotic

Description:

• Penicillinase-Resistant Penicillin

Indications:

• Mild to moderate infections caused by penicillinase-producing staphylococci

• Upper Respiratory Tract Infections

• Localized soft tissue/skin infections

• Lower Respiratory Tract Infections

• Disseminated infections

Contraindications:

• None

Precautions:

• Pregnancy category B

• Use with caution in patients with penicillin or cephalosporin allergy (5-10% chance of cross-reactivity)

• Counsel patient to finish all medication to prevent development of resistance

• Inform patient to take at even intervals, preferably around the clock

• Take on an empty stomach, 1 hour before or 2 hours after meals.  Food inhibits absorption

• Parenteral dosage form is reserved for severe infections

• Orally administered nafcillin serum levels are low and unpredictable

Adverse Reactions (Side Effects):

• Hypersensitivity

• Gastrointestinal: nausea, vomiting, diarrhea

• Vaginitis  

Dosage:

• Administered orally (capsules) and injectable

• Injectable

  • Adult and children (>40kg):

    • 500mg IM q4-6h or IV q4h

  • Infants and children (<40kg):

    • 25mg/kg IM twice daily or IV in 4-6 divided doses

  • Neonates:

    • 10mg/kg IM twice daily

• Oral

  • Adult and children (>40kg):

    • 250-500mg q4-6h (may increase to 1 gram q4-6h for severe infections)

  • Infants and children (<40kg):

    • Staphylococcal  infections:  50mg/kg/day in 4 divided doses

    • Scarlet fever and pneumonia: 25mg/kg/day in 4 divided doses

    • Streptococcal pharyngitis: 250mg tid for 10 days

  • Neonates:

    • 10mg/kg 3-4 times per day