Flucloxacillin

Flucloxacillin - a derivative of the basic penicillin structure which has stability to the staphylococcal penicillinase found in most Staphylococcus aureus isolates. Generally less active than benzylpenicillin against other Gram +ve organisms. Strains which express resistance are designated methicillin resistant and are known as MRSAs.

Uses
Infections due to penicillinase-producing staphylococci (except MRSA):
• cellulitis
• wound infection
• endocarditis
• adjunct in pneumonia
• osteomyelitis
• septic arthritis

Contraindications
Penicillin hypersensitivity

Administration
IV: 0.25–2 g 6 hourly, depending on the severity of infection. For endocarditis (in combination with another antibiotic), 2 g 6 hourly, increasing to 2 g 4 hourly if over 85 kg.
Reconstitute with 20 ml WFI, given over 3–5 min

Infection	Dose (g)	Interval (h)
Mild–moderate	0.25–0.5	6
Moderate–serious	1–2	6
Life-threatening	2	6

In renal impairment:
CC >10 ml/min dose as per normal renal function
CC <10 ml/min dose as in normal renal function up to a total daily dose of 4 g

How not to use flucloxacillin
Not for intrathecal use (encephalopathy)
Do not mix in the same syringe with an aminoglycoside (efficacy of aminoglycoside reduced)

Adverse effects
Hypersensitivity
Haemolytic anaemia
Transient neutropenia and thrombocytopenia
Cholestatic jaundice and hepatitis
• ↑ risk with treatment 2 weeks and increasing age
• may occur up to several weeks after stopping treatment

Cautions
Liver failure (worsening of LFTs)

Organ failure
Renal: reduce dose
Hepatic: avoid

Renal replacement therapy
No further dose modification is required during renal replacement therapy