Usage
- Fusidic acid is primarily prescribed for bacterial skin infections, including impetigo, folliculitis, and infected eczema or dermatitis. It can also be used for other staphylococcal infections like osteomyelitis, pneumonia, septicemia, wound infections, endocarditis, and superinfected cystic fibrosis. For ophthalmic use, it treats bacterial conjunctivitis, blepharitis, stye, and keratitis.
- Pharmacological Classification: Antibiotic.
- Mechanism of Action: Fusidic acid inhibits bacterial protein synthesis by preventing the translocation of the elongation factor G (EF-G) on the ribosome, thus stopping the growth and multiplication of bacteria.
Alternate Names
- Sodium Fusidate (the sodium salt of fusidic acid).
- Brand Names: Fucidin, Fucithalmic.
How It Works
- Pharmacodynamics: Fusidic acid is primarily bacteriostatic, meaning it inhibits bacterial growth rather than directly killing bacteria. It is highly effective against Gram-positive bacteria, particularly Staphylococcus aureus.
- Pharmacokinetics:
- Absorption: Topical application results in minimal systemic absorption. Oral absorption is variable. Intravenous administration achieves high serum concentrations.
- Metabolism: Primarily hepatic. Metabolites include dicarboxylic ester/acid, 3-keto fusidic acid, hydroxy fusidic acid, and glucuronide fusidic acid.
- Elimination: Primarily biliary excretion with a small amount in urine. Not significantly dialyzed.
- Mode of Action: Fusidic acid binds to EF-G, preventing its translocation along the mRNA during protein synthesis. This halts elongation and effectively blocks the production of new proteins essential for bacterial survival.
- Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: Primarily inhibits EF-G, a key factor in protein synthesis.
Dosage
Standard Dosage
Adults:
- Topical: Apply a thin layer to the affected skin 3-4 times daily. Less frequent application may suffice for covered lesions.
- Ophthalmic: Instill 1 drop into the conjunctival sac twice daily.
- Oral (Sodium Fusidate):
- Skin infections: 250 mg twice daily.
- Systemic infections: 500 mg three times daily.
- Severe infections: Dose may be doubled, or combination therapy considered.
- IV (Sodium Fusidate): Patients <50 kg: 6-7 mg/kg three times daily. Patients ≥50 kg: 500 mg three times daily. Administer over 2 hours through a central line or at least 6 hours through a peripheral vein.
Children:
- Topical/Ophthalmic: As per adult dosage.
- Oral (Fusidic acid suspension):
- <1 year: 50 mg/kg/day divided into three doses.
- 1-5 years: 250 mg (5 mL) three times daily.
- 5-12 years: 500 mg (10 mL) three times daily.
-
12 years: As per adult dosage.
- IV (Sodium Fusidate): Up to 12 years: 20 mg/kg/day divided into three doses, infused over at least 2 hours.
Special Cases:
- Elderly Patients: No dose adjustment typically required.
- Patients with Renal Impairment: No dose adjustment usually needed.
- Patients with Hepatic Dysfunction: No dose adjustment generally required.
- Patients with Comorbid Conditions: Consider individual patient factors.
Clinical Use Cases
Dosage guidelines for specific clinical situations are generally the same as the standard dosages mentioned above. It is important to note that intravenous fusidic acid may be preferred in cases where absorption from the gastrointestinal tract is unpredictable or when rapid attainment of high serum concentrations is required.
Dosage Adjustments
Dose modifications are generally not required for renal or hepatic impairment. However, always consider patient-specific factors and consult local guidelines.
Side Effects
Common Side Effects
- Topical/Ophthalmic: Skin irritation, burning, itching, redness, contact dermatitis, conjunctival irritation.
- Oral/IV: Gastrointestinal discomfort, nausea, diarrhea, jaundice, liver dysfunction (rare), hypersensitivity reactions (rash, urticaria, angioedema).
Rare but Serious Side Effects
- Drug reaction with eosinophilia and systemic symptoms (DRESS), toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome (SJS), rhabdomyolysis (especially with statins), thrombophlebitis (IV), acute generalized exanthematous pustulosis, angioedema.
Long-Term Effects
- Potential for antibiotic resistance with prolonged or repeated use.
- Risk of secondary infections (e.g., fungal infections) with prolonged use.
Adverse Drug Reactions (ADR)
Severe hypersensitivity reactions, DRESS syndrome, SJS/TEN, rhabdomyolysis require immediate medical attention.
Contraindications
- Hypersensitivity to fusidic acid or any component of the formulation.
- Concomitant use with statins (HMG-CoA reductase inhibitors) due to increased risk of rhabdomyolysis.
Drug Interactions
- Statins: Increased risk of rhabdomyolysis.
- Warfarin and other coumarin anticoagulants: Fusidic acid may potentiate their effects.
- HIV protease inhibitors (e.g., ritonavir, saquinavir): Increased plasma concentrations of both drugs, potentially leading to hepatotoxicity.
- Oral contraceptives: Reduced efficacy of hormonal contraceptives.
Pregnancy and Breastfeeding
- Pregnancy: Topical application generally considered safe. Limited systemic absorption minimizes fetal risk. Systemic administration should be used cautiously, weighing the potential benefits against possible risks.
- Breastfeeding: Topical use is generally safe. Avoid applying to the nipple area or wash it off thoroughly before breastfeeding. Systemic administration may lead to drug excretion in breast milk, though levels appear low.
Drug Profile Summary
- Mechanism of Action: Inhibits bacterial protein synthesis.
- Side Effects: Skin irritation (topical), gastrointestinal discomfort (oral/IV), rare but serious reactions like rhabdomyolysis and hypersensitivity.
- Contraindications: Hypersensitivity, concomitant use with statins.
- Drug Interactions: Statins, warfarin, HIV protease inhibitors, oral contraceptives.
- Pregnancy & Breastfeeding: Topical use generally safe; systemic use with caution.
- Dosage: See detailed dosage section above.
- Monitoring Parameters: Liver function tests (with systemic use), monitor for signs of rhabdomyolysis (especially with statins).
Popular Combinations
- Topical combination with betamethasone valerate (Fucicort) for inflammatory skin infections.
Precautions
- General Precautions: Pre-screening for allergies.
- Specific Populations: See above sections on pregnancy, breastfeeding, and children.
- Lifestyle Considerations: No specific lifestyle restrictions usually required with topical or ophthalmic use. For systemic administration, consider the potential for gastrointestinal upset and other side effects.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Fusidic Acid?
A: See detailed dosage section above.
Q2: What are the common side effects of topical Fusidic Acid?
A: Skin irritation, burning, itching, contact dermatitis.
Q3: Can Fusidic Acid be used during pregnancy?
A: Topical application generally considered safe. Systemic use with caution, considering benefits versus risks.
Q4: What are the contraindications for Fusidic Acid use?
A: Hypersensitivity to fusidic acid or its components. Concomitant use with statins.
Q5: How does Fusidic Acid interact with Warfarin?
A: May potentiate the anticoagulant effect of warfarin. Close monitoring of INR is recommended.
Q6: Is Fusidic acid effective against all types of bacteria?
A: No. Primarily effective against Gram-positive bacteria, particularly Staphylococcus aureus. Gram-negative bacteria, including Pseudomonas, are often resistant.
Q7: Can Fusidic Acid be used for eye infections?
A: Yes, fusidic acid eye drops/ointment are available for bacterial eye infections like conjunctivitis.
Q8: Can I use Fusidic Acid if I am breastfeeding?
A: Topical use is generally safe. Avoid applying to the nipple area or cleanse thoroughly before breastfeeding. Discuss systemic use with your doctor.
Q9: How long should a course of Fusidic Acid treatment typically last?
A: Treatment duration varies depending on the infection and its severity. Topical treatment typically lasts for a few days to a week. Systemic treatment may be longer. Follow your doctor’s instructions.
