Overview
Fusidic acid is a bacteriostatic antibiotic derived from the fungus Fusidium coccineum. It is primarily used topically for skin infections and systemically for serious staphylococcal infections when other antibiotics are unsuitable. It inhibits bacterial protein synthesis by binding to elongation factor G (EF-G) on the ribosome.
Mechanism of Action
Fusidic acid inhibits bacterial protein synthesis by binding to elongation factor G (EF-G) on the ribosome, preventing translocation of the peptidyl-tRNA from the A-site to the P-site. This action is bacteriostatic at low concentrations and may be bactericidal at higher concentrations against susceptible organisms.
Indications
- Topical treatment of primary and secondary skin infections caused by susceptible strains of Staphylococcus aureus, Streptococcus pyogenes, and Corynebacterium minutissimum
- Systemic treatment of serious staphylococcal infections (including MRSA) when other antibiotics are inappropriate or ineffective
- Bacterial conjunctivitis (ophthalmic preparations)
- Prophylaxis and treatment of infections in burn patients
Dosage
Topical: Apply 3-4 times daily to affected area. Systemic: Adults: 500 mg orally three times daily (higher doses may be used for severe infections). Children: 20-40 mg/kg/day in divided doses. Duration depends on infection severity and response.
Contraindications
- Hypersensitivity to fusidic acid or any component of the formulation
- For systemic use: severe hepatic impairment
- Concomitant use with statins (increased risk of rhabdomyolysis)
Side Effects
- Topical: Local irritation, pruritus, burning sensation, contact dermatitis
- Systemic: Gastrointestinal disturbances (nausea, vomiting, diarrhea), hepatotoxicity (elevated liver enzymes, jaundice), headache, dizziness, rash
- Rare: Thrombophlebitis (with IV administration), blood dyscrasias, anaphylaxis
Interactions
- Statins (atorvastatin, simvastatin, etc.): Increased risk of myopathy and rhabdomyolysis
- CYP3A4 inhibitors: May increase fusidic acid concentrations
- Other hepatotoxic drugs: Additive risk of liver damage
- Oral contraceptives: Reduced efficacy reported in some cases