Ketoconazole Shampoo
Ketoconazole shampoo
Generic Name
Ketoconazole shampoo
Mechanism
- Ketoconazole disrupts fungal cell membrane synthesis by inhibiting lanosterol 14‑α‑demethylase, a cytochrome P450 enzyme that converts lanosterol to ergosterol.
- Reduced ergosterol content compromises membrane integrity, leading to leakage of cellular contents and fungal cell death.
- The drug also exhibits anti‑inflammatory properties, decreasing sebaceous gland activity and reducing erythema associated with seborrheic dermatitis.
Pharmacokinetics
| Parameter | Details | Clinical Implication |
| Absorption | Minimal systemic absorption (<1 % of applied dose) | Low systemic toxicity, but may be relevant in heavily damaged skin |
| Distribution | Primarily remains in the stratum corneum of the scalp | Local action; negligible plasma concentrations |
| Metabolism | Little systemic metabolism; mainly excreted unchanged via feces | No significant drug‑drug interaction risk |
| Elimination | Rapid clearance; trough levels negligible | No need for dose adjustment based on renal/hepatic function |
Indications
- Seborrheic dermatitis of the scalp and associated dandruff (most common indication in the U.S.).
- Contact dermatitis secondary to onychomycosis or other superficial fungal infections when topical azoles are indicated.
- Tinea capitis (outside U.S.) as an adjunct to systemic therapy.
Contraindications
- Contraindicated in individuals with known hypersensitivity to ketoconazole or other azoles.
- Eye irritation: avoid contact with the eyes; rinse thoroughly if accidental exposure occurs.
- Pregnancy/Lactation: topical use is generally considered low risk, but use only if benefits outweigh potential unknowns.
- Infants: use only under physician supervision; caution in infants under 6 months.
- Chronic liver disease: minimal risk, but avoid due to potential systemic absorption in extensive skin damage.
Dosing
- 2 % Ketoconazole shampoo
- Apply to wet scalp.
- Massage 30–60 s.
- Leave on scalp for 5 min.
- Rinse thoroughly.
- Frequency: 3 × per week.
- 4 % Ketoconazole shampoo – same regimen, reserved for severe or refractory cases.
- Duration: Usually 2–4 weeks; assess response after 2 weeks.
- Adjunctive: Use a trivial, pH‑balanced shampoo between ketoconazole treatments to prevent dryness.
Adverse Effects
Common:
• Scalp itching, burning, or erythema (transient).
• Dryness or flaking of scalp skin.
Serious (rare):
• Contact dermatitis hypersensitivity reaction.
• Systemic absorption leading to hepatic enzyme elevations (rare in topical use).
• Ocular irritation if shampoo enters eyes.
Monitoring
- Observe for signs of contact dermatitis during the first 1–2 weeks.
- In patients with extensive scalp disease, consider periodic liver function tests if prolonged use (>4 weeks).
- Patient should immediately report severe head‑ache, visual changes, or systemic symptoms.
Clinical Pearls
- Leave it on: A 5‑minute dwell time improves efficacy; omitting this step can reduce clearance of seborrheic exudate.
- Use 4% for resistance: For patients unresponsive to 2 % shampoo, upgrading to 4 % can be a cost‑effective alternative to systemic azoles.
- Combine with keratolytics: Adding a mild keratolytic (e.g., salicylic acid‑based shampoo) can enhance desquamation in severe dandruff.
- Avoid eye contact: Because ketoconazole can cause ocular irritation, instruct patients to give a slurry of water to dilate eyes before rinsing.
- Allergy testing: For patients who develop contact dermatitis, consider patch testing to rule out ketoconazole hypersensitivity.
- Adjunctive therapy: In persistent cases, a short course of oral terbinafine or fluconazole is sometimes used; however, topical ketoconazole remains first‑line for scalp involvement in most settings.
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• Key pharmacology terms: ketoconazole shampoo, antifungal, lanosterol 14‑α‑demethylase, seborrheic dermatitis, dandruff, dosing, systemic absorption, adverse effects, monitoring.