1. Clinical Overview
A fixed-dose combination topical preparation containing a potent corticosteroid (Mometasone furoate) and a bacteriostatic antibiotic (Fusidic acid). It is primarily indicated for the treatment of inflammatory dermatoses with secondary or suspected bacterial infection, particularly those caused by Staphylococcus aureus, including methicillin-resistant strains (MRSA). The combination provides anti-inflammatory, anti-pruritic, and antibacterial actions.
| Onset | Duration | Bioavailability |
|---|---|---|
| Anti-pruritic effect: 3-6 hours; Anti-inflammatory effect: 24-48 hours; Antibacterial effect: Begins within hours of application. | Anti-inflammatory effects can persist for up to 24 hours after a single application, supporting once-daily dosing. | Topical bioavailability is low (<1% for mometasone, <2% for fusidic acid) when applied to intact skin. Increases significantly with application to inflamed, broken, or occluded skin, or over large surface areas. |
2. Mechanism of Action
Mometasone furoate binds to cytoplasmic glucocorticoid receptors, forming a complex that translocates to the nucleus. It modulates gene transcription, leading to the synthesis of anti-inflammatory proteins (lipocortin) and inhibition of pro-inflammatory mediators (cytokines, leukotrienes, prostaglandins). Fusidic acid inhibits bacterial protein synthesis by binding to elongation factor G (EF-G) and preventing the translocation step on the ribosome, leading to bacteriostatic action.
3. Indications & Uses
- Atopic dermatitis (eczema) with secondary bacterial infection
- Infected contact dermatitis
- Nummular dermatitis with infection
- Seborrheic dermatitis with suspected bacterial involvement
- Psoriasis (plaque type) in areas prone to infection (e.g., flexures)
4. Dosage & Administration
Adult Dosage: Apply a thin film to the affected area once daily. Duration should be limited, typically 1-2 weeks. Do not exceed 50g per week.
Administration: 1. Wash and dry hands and affected area. 2. Apply a thin layer and rub gently until it disappears. 3. Do not cover with occlusive dressings unless specifically directed by a physician. 4. Avoid contact with eyes, mouth, nose, and mucous membranes. 5. Wash hands after application unless hands are the treated area.
5. Side Effects
Common side effects may include:
- Local burning or stinging sensation (usually transient)
- Skin dryness
- Itching (paradoxical)
- Folliculitis
- Hypopigmentation at application site
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other Topical Corticosteroids | Additive risk of local and systemic side effects, including skin atrophy and HPA suppression. | Major |
| Live Vaccines (e.g., BCG, MMR, Varicella) | Systemic immunosuppression from absorbed steroid may potentiate replication of vaccine virus, leading to infection. | Major |
| CYP3A4 Inhibitors (e.g., Ketoconazole, Itraconazole, Clarithromycin) | May inhibit the metabolism of systemically absorbed mometasone, increasing the risk of systemic corticosteroid effects. | Moderate |
7. Patient Counselling
- DO use exactly as prescribed, once daily.
- DO NOT use for longer than the prescribed duration (usually 1-2 weeks).
- DO NOT apply to broken skin, open wounds, or near the eyes unless directed.
- DO NOT cover the area with airtight dressings (plastic wraps, tight bandages) unless advised.
- DO wash hands before and after application.
- DO report any lack of improvement or worsening after 3-4 days.
8. Toxicology & Storage
Overdose: Topical: Exaggeration of local side effects (severe skin atrophy, striae, ulceration). Systemic: Symptoms of hypercorticism (moon face, central obesity, hypertension, hyperglycemia, muscle weakness) and adrenal suppression (nausea, vomiting, fatigue, hypotension, hypoglycemia).
Storage: Store at room temperature (15-25°C). Protect from light and excessive heat. Do not freeze. Keep the tube tightly closed. Keep out of reach and sight of children.