Floxapen, Flucloxin

Reviewed by Clinical Practice Committee, Dr Lesley Voss and Elizabeth Oliphant
Jan 2018
Administration Newborn Drug Protocol Index Newborn Services Home Page


Dose and Administration


Postnatal Age
Dose Interval
Day 0-7 12
Day 8-28 8
Day 29+ 6


  1. Empirical therapy for infants with suspected coagulase negative staphylococcal sepsis but resistance is now increasingly common. May be administered in combination with amoxycillin and amikacin until culture results available.
  2. Skin and soft tissue infections.
  3. Bone and joint infections.

Contraindications and Precautions

  1. Hypersensitivity to penicillins/cephalosporins.
  2. Caution in preterm infants and those with jaundice, as flucloxacillin can displace bilirubin from albumin.
  3. Caution in infants with liver, renal or gastrointestinal disease.

Clinical Pharmacology

Semi-synthetic narrow spectrum bacteriocidal antibiotic with considerable activity against penicillinase producing coagulase negative staphylococci and Staphylococcus aureus. Has little activity against gram negative bacilli. Action through inhibition of biosynthesis of cell wall mucopeptides.

Well absorbed after oral administration, although absorption is reduced in the presence of food and unpredictable in neonates. Widely distributed at varying concentrations in human body tissues and fluids. Very little passes into the CSF unless the meninges are inflamed. Highly bound (92%) to human plasma proteins. Excreted, mainly unchanged, by the kidney. Tubular excretion is inhibited by probenecid.

Possible Adverse Effects

  1. Venous irritation, soft tissue injury at site of IV injection.
  2. Pain, soft tissue injury at site of IM injection.
  3. Gastrointestinal disturbance (nausea, vomiting, diarrhoea).
  4. Non-specific rashes and skin eruptions.
  5. Fever, pruritus, urticaria.
  6. Seizures (encephalopathy with high doses greater than 400 mg/kg/day).
  7. Hepatitis & choelstatic jaundice, possibly occurring up to several weeks after discontinuation, has been reported occasionally in adults.

Special Considerations

  1. May give concurrently with aminoglycoside therapy for synergistic effect. Administer separately as simultaneous administration may cause inactivation, and precipitation.
  2. Adjust dose in suspected significant renal dysfunction (usually by lengthening the dosing interval).
  3. Give 30-60 minutes before feeds.