Treatment of Tinea Corporis After Failure of Ketoconazole and Terbinafine

Initial Assessment and Treatment

• The British Journal of Dermatology recommends assessing compliance with previous medication regimens, as poor adherence is a common cause of apparent treatment failure, and considering suboptimal drug absorption, particularly if medications were not taken with food when indicated 2, 3
• The American Academy of Dermatology, as referenced in Praxis Medical Insights, suggests obtaining mycological confirmation via KOH preparation and culture to identify the causative organism and confirm the diagnosis 1

Second-Line Oral Therapy: Itraconazole

• The British Journal of Dermatology recommends itraconazole as a second-line agent because it has broad-spectrum activity against both Trichophyton and Microsporum species, with a dosing regimen of 100 mg daily for 15 days, or alternatively 50-100 mg daily for 4 weeks 2, 1, 3
• The American College of Dermatology, as referenced in Praxis Medical Insights, notes that itraconazole achieves an 87% mycological cure rate in tinea corporis, superior to griseofulvin's 57% 1

Important Drug Interactions to Monitor

• The British Journal of Dermatology warns of significant drug interactions with itraconazole, including enhanced toxicity with warfarin, certain antihistamines, antipsychotics, midazolam, digoxin, cisapride, ciclosporin, and simvastatin, and decreased efficacy with concomitant H2 blockers, phenytoin, and rifampicin 2

Critical Adjunctive Measures to Prevent Recurrence

• The American Academy of Dermatology, as referenced in Praxis Medical Insights, recommends environmental decontamination and contact screening to prevent reinfection, including cleaning all fomites with disinfectant or 2% sodium hypochlorite solution, and screening and treating household contacts 1, 4

Monitoring and Treatment Endpoints

• The American College of Dermatology, as referenced in Praxis Medical Insights, states that mycological cure, not just clinical improvement, is the definitive treatment endpoint, and recommends repeat mycology sampling until mycological clearance is documented 5, 1
• The British Journal of Dermatology suggests continuing current therapy for an additional 2-4 weeks if clinical improvement occurs but mycology remains positive 2, 3