Fusidic acid

Generic Name

Fusidic acid

Also Known As

Sodium fusidate (when in salt form)

Derived from the fungus Fusidium coccineum

Brand Names

Fucidin

Fucibet (with betamethasone)

Fucithalmic

Fusidin

Fusivis

Available as topical cream, ointment, gel, eye drops (viscous solution), oral suspension, and tablets

Parenteral form (fusidate sodium injection) is available in some countries for severe infections

Drug Class

Steroid-like antibiotic

Protein synthesis inhibitor

Lipopeptide antimicrobial

Mechanism of Action

Inhibits bacterial protein synthesis by interfering with the elongation factor G (EF-G) on the ribosome

Binds to EF-G-GDP complex and prevents translocation of tRNA on the bacterial ribosome

Bacteriostatic at low concentrations but may be bactericidal at high concentrations

No effect on mammalian ribosomes

Spectrum of Activity

Narrow-spectrum antibiotic

Primarily active against Gram-positive bacteria

– Staphylococcus aureus including most methicillin-resistant strains (MRSA)

– Streptococcus spp. (less active)

– Corynebacterium spp.

– Propionibacterium acnes

Little to no activity against Gram-negative bacteria or fungi

Often used topically due to limited systemic penetration and narrow coverage

Indications

Topical Formulations

Local skin infections such as:

– Impetigo

– Infected eczema or dermatitis

– Infected wounds or abrasions

– Folliculitis

– Minor boils or abscesses (after drainage)

– Infected insect bites

Ophthalmic Form

Bacterial conjunctivitis caused by susceptible organisms

Usually as Fucithalmic 1% viscous eye drops

Systemic (Oral or IV)

Reserved for severe or resistant staphylococcal infections including:

– Osteomyelitis

– Septic arthritis

– Pneumonia

– Endocarditis (in combination therapy)

– Skin and soft tissue infections

Systemic use is typically in combination with rifampicin to reduce resistance emergence

Off-label Uses

Treatment of MRSA colonization (nasal or skin)

Use in acne vulgaris (adjunctive, short-term)

Prophylaxis in some surgical cases (topical)

Dosage and Administration

Topical Cream/Ointment

Apply a thin layer to the affected area 2–3 times daily for 7–10 days

Ointment preferred for dry lesions; cream for moist lesions

Use with caution under occlusive dressings

Topical Gel

Used for facial skin infections or acne-prone skin

Applied twice daily for short courses

Eye Drops (Fucithalmic)

Instill 1 drop into the affected eye twice daily

Treatment usually continues for 7 days

Oral Tablets

Typically 500 mg three times daily for adults

Children: 20–50 mg/kg/day in divided doses

Take after meals to reduce gastrointestinal upset

Used under specialist supervision

IV Injection (Sodium Fusidate)

500–1500 mg every 8–12 hours depending on severity

Diluted and infused slowly to avoid phlebitis

Used in hospital settings only

Pharmacokinetics

Highly protein bound (>95%)

Excellent bone and soft tissue penetration

Crosses placenta and is excreted in small amounts in breast milk

Metabolized in the liver; excreted mainly via bile

Half-life: 5–15 hours depending on the formulation and route

Contraindications

Known hypersensitivity to fusidic acid or excipients

Monotherapy with systemic fusidic acid in serious infections (due to rapid resistance)

Use of topical fusidic acid for more than 2 weeks (risk of resistance)

Avoid prolonged ocular use unless prescribed

Warnings and Precautions

Limit use to short durations to reduce resistance

Avoid contact with mucous membranes unless using ophthalmic preparation

Use with caution in patients with hepatic dysfunction (systemic use)

Do not use near eyes unless prescribed specifically for ophthalmic use

Systemic use should be monitored due to potential hepatotoxicity and blood dyscrasias

Topical formulations may contain excipients that cause irritation or allergic reactions

Adverse Effects

Topical Use

Stinging, burning, or irritation at the site of application

Allergic contact dermatitis

Urticaria

Rash or eczema exacerbation

Skin dryness or peeling

Photosensitivity (rare)

Ophthalmic Use

Blurred vision (transient)

Eye irritation or redness

Hypersensitivity reactions

Systemic Use

Nausea, vomiting, abdominal discomfort

Hepatotoxicity (transaminase elevation, cholestasis)

Jaundice

Leukopenia or thrombocytopenia (rare)

Hypersensitivity reactions including eosinophilia

Pseudomembranous colitis (rare)

Pregnancy and Lactation

Pregnancy

Topical fusidic acid is considered safe for short-term use

Systemic use in pregnancy only when clearly necessary and under medical supervision

Animal studies have shown no teratogenic effects

Lactation

Small amounts are excreted in breast milk

Topical use considered compatible with breastfeeding if not applied to breast

Oral use requires clinical assessment

Drug Interactions

Systemic (Oral/IV)

May potentiate the effect of anticoagulants such as warfarin

Monitor INR closely if used concomitantly

Avoid monotherapy due to rapid resistance emergence

Used with rifampicin to prevent resistance and achieve synergistic effect

No major interaction with oral contraceptives or insulin

Topical

Minimal systemic absorption; drug interactions unlikely

Avoid concurrent use with other topical antibiotics unless prescribed

Monitoring Parameters

Liver function tests during systemic use

CBC if used for longer durations

Symptom resolution of infection

Local skin reaction at site of application

Patient adherence and appropriate use duration

Culture and sensitivity if infection does not resolve

Counseling Points

Apply to clean, dry skin using clean hands

Do not use for more than 7–10 days unless instructed

Avoid using fusidic acid cream on broken or mucosal surfaces unless directed

Do not share topical antibiotics with others

Do not use eye drops for more than 7 days unless advised

Discard eye drops 28 days after opening

Store all forms below 25°C and away from direct sunlight

Comparative Notes

Fusidic Acid vs Mupirocin

Fusidic acid is less effective against MRSA than mupirocin

Mupirocin preferred for nasal MRSA decolonization

Fusidic acid is often used in dermatology for minor staph infections

Fusidic Acid vs Neomycin

Fusidic acid is less allergenic and better tolerated

Neomycin has broader coverage but higher sensitization risk

Fusidic Acid vs Clindamycin (topical)

Both used for acne

Clindamycin is broader spectrum but may lead to resistance

Fusidic acid is used for short-term, local infections

Legal and Regulatory Status

Available by prescription only

Topical forms available OTC in some countries for minor skin infections

Systemic forms restricted to hospital or specialist use

Included in national formularies across Europe, UK, and Middle East