Is itraconazole (ITR) administered once daily (OD) or twice daily (BD) in the treatment of tinea corporis?

Itraconazole Dosing for Tinea Corporis: Once Daily (OD)

For tinea corporis, itraconazole should be administered at 100 mg once daily (OD) for 15 days, not twice daily. 1, 2

Evidence-Based Dosing Regimen

The standard treatment protocol for tinea corporis is straightforward:

• Itraconazole 100 mg once daily for 15 days 3, 4, 5
• Clinical and mycological cure rates of 80-88% are achieved with this regimen 4, 5
• Treatment effects continue for 2-4 weeks after discontinuation due to itraconazole's persistence in keratinized tissues 3, 6

Why Once Daily Dosing Works

The pharmacokinetic profile of itraconazole supports once-daily dosing for superficial dermatophytoses:

• Tissue concentrations in skin are 2-4 times higher than plasma levels, with exceptional affinity for keratinous tissues 7
• Therapeutic concentrations persist in the epidermis for up to 4 weeks after stopping treatment, even when plasma levels become undetectable after one week 6
• Peak plasma concentrations are reached within 2.5 hours, with steady-state achieved in approximately 15 days 7

When Twice Daily Dosing IS Indicated

Twice daily dosing (200 mg BD) is reserved for more severe or invasive infections, not tinea corporis:

• Osteoarticular sporotrichosis: 200 mg twice daily for at least 12 months 1
• Pulmonary sporotrichosis: 200 mg twice daily for at least 12 months 1
• Treatment failures in cutaneous sporotrichosis: escalate to 200 mg twice daily 1

Comparative Efficacy Data

Multiple double-blind trials demonstrate superiority of once-daily itraconazole over griseofulvin:

• Itraconazole 100 mg OD achieved 81% mycological cure vs. 65% with griseofulvin 500 mg daily in tinea corporis/cruris 5
• Clinical response rates of 88% vs. 69% favoring itraconazole at 2 weeks post-therapy 5
• Faster clinical improvement observed with 100 mg daily compared to 50 mg daily dosing 8

Administration Considerations

Capsule formulation should be taken with food for optimal absorption 2, 7

• The oral solution formulation is better absorbed on an empty stomach, but capsules require food 2, 7
• Avoid concomitant use of H2 blockers, proton pump inhibitors, phenytoin, or rifampicin, which decrease itraconazole efficacy 1, 2

Common Pitfalls to Avoid

• Do not use twice-daily dosing for uncomplicated tinea corporis - this is unnecessary and increases cost without improving outcomes for superficial infections 3, 4
• Do not stop treatment early if clinical improvement occurs before 15 days - complete the full 15-day course to ensure mycological cure 3, 4
• Monitor for drug interactions, particularly with warfarin, certain antihistamines (terfenadine, astemizole), statins, and digoxin 1, 2
• Serum level monitoring is not routinely needed for tinea corporis, but should be considered if treatment response is suboptimal after 2 weeks 2

Treatment Failure Management

If no clinical improvement occurs after completing the 15-day course:

• First, assess compliance and rule out reinfection 1
• Consider escalating to 200 mg once daily (not twice daily initially) 1
• Alternative agents include terbinafine 250 mg daily or topical terbinafine 1% cream 1, 2