Treatment of Tinea Capitis with Terbinafine and Griseofulvin

Introduction to Species-Directed Treatment

• The British Journal of Dermatology recommends using terbinafine for Trichophyton species infections and griseofulvin for Microsporum species infections, with specific weight-based dosing protocols for each 1, 2

Weight-Based Dosing for Trichophyton Species

• For patients weighing less than 20 kg, the recommended dose of terbinafine is 62.5 mg per day for 2-4 weeks 1, 2, 3
• For patients weighing 20-40 kg, the recommended dose of terbinafine is 125 mg per day for 2-4 weeks 1, 2, 3
• For patients weighing more than 40 kg, the recommended dose of terbinafine is 250 mg per day for 2-4 weeks 1, 2, 3

Weight-Based Dosing for Microsporum Species

• For patients weighing less than 50 kg, the recommended dose of griseofulvin is 15-20 mg/kg per day for 6-8 weeks 1, 2, 3
• For patients weighing more than 50 kg, the recommended dose of griseofulvin is 1 g per day for 6-8 weeks 1, 2, 3

Critical Dosing Considerations

• Higher doses of griseofulvin (20-25 mg/kg/day) may be required for Trichophyton infections, with treatment extended to 12-18 weeks in resistant cases 4, 5
• Griseofulvin should be administered with fatty food to increase absorption and improve bioavailability 5, 6
• Griseofulvin remains the only licensed treatment for tinea capitis in children in the UK, though terbinafine is widely used off-label 1, 2

Efficacy Patterns

• Terbinafine achieves significantly higher cure rates than griseofulvin for Trichophyton species 1, 4, 7
• For Microsporum canis, griseofulvin is significantly more effective than terbinafine because terbinafine cannot be incorporated into hair shafts in prepubertal children and doesn't reach the scalp surface where Microsporum arthroconidia are located 1, 4, 7

Treatment Duration

• Do not extend terbinafine treatment beyond 4 weeks, as prolonging treatment does not improve efficacy 1, 4
• For griseofulvin, ensure full 6-8 week course for Microsporum species to achieve adequate cure rates 1, 6

Species-Specific Mistakes

• Do not use terbinafine as first-line for Microsporum canis, as it has poor efficacy due to pharmacokinetic limitations in prepubertal children 1, 4, 7, 8
• Obtain fungal culture before treatment when possible to guide species-directed therapy, though empiric treatment is reasonable with clinical signs (scale, lymphadenopathy, alopecia) 2, 3

Safety Profile

• Terbinafine is well tolerated with gastrointestinal disturbances and rashes in less than 8% of patients 1, 4
• Griseofulvin is contraindicated in lupus erythematosus, porphyria, and severe liver disease 1, 2, 7

Treatment Failure Management

• If no clinical improvement after initial treatment course, consider lack of compliance, suboptimal drug absorption, or organism insensitivity 2, 3, 7
• If clinical improvement but ongoing positive mycology, continue current therapy for additional 2-4 weeks 2, 3
• If no initial clinical improvement, switch to second-line therapy with itraconazole (5 mg/kg per day for 2-4 weeks) 2, 3, 7