What is the recommended dose and duration of terbinafine (Terbinafine) tablets for the treatment of tinea cruris (jock itch) in a healthy 24-year-old male?

From the Guidelines

For a rash around the groin and rectal area in a 24-year-old healthy male, oral terbinafine tablets should be prescribed at a dose of 250 mg once daily for 1 week, as this duration has shown similar efficacy to longer treatment courses in terms of mycological cure rates and faster clinical resolution. The guidelines for the treatment duration of terbinafine can be found in studies such as the one published in Pediatrics in 2017 1, which discusses the management of tinea pedis outbreaks and mentions that oral terbinafine, 250 mg, given once daily for 1 week, has similar efficacy to 4 weeks of clotrimazole 1% cream.

When treating a rash around the groin and rectal area, which is likely tinea cruris (jock itch), it's essential to confirm the diagnosis to rule out other conditions like candidiasis or contact dermatitis. Some key points to consider in the management of this condition include:

• Keeping the affected area clean and dry
• Wearing loose cotton underwear
• Considering the use of antifungal powder to prevent recurrence
• The potential use of topical antifungal creams alongside oral therapy for faster symptom relief
• Monitoring for rare but potential adverse events such as isolated neutropenia and liver failure, particularly in individuals with preexisting liver disease, as noted in the study 1.

Given the information from the study 1, a 1-week course of oral terbinafine may be sufficient for the treatment of tinea cruris, offering the advantage of a shorter treatment duration with similar efficacy to longer courses, which can improve patient compliance and reduce the risk of adverse effects. However, it's crucial to follow up with patients to assess the response to treatment and adjust the management plan as necessary.

From the Research

Treatment Guidelines for Terbinafine

• The recommended dose of terbinafine for a rash around the groin and rectal area is not explicitly stated in the provided studies, but the studies suggest the following doses:
  • 7.5 mg/kg per day 2
  • 500 mg/d orally for 7 days 3
• The treatment duration for terbinafine is not consistently stated across the studies, but the following durations are mentioned:
  • 8 weeks or until cure 2
  • 4 weeks 4
  • 7 days 3
  • 14 days and 28 days after treatment 5
• The guidelines for 4 weeks of treatment are likely based on the study by 4, which compared the efficacy of oral terbinafine versus itraconazole in the treatment of dermatophytic infection of skin and found that mycological cure was seen in 74.3% of patients in the terbinafine group after 4 weeks.

Efficacy of Terbinafine

• The efficacy of terbinafine in treating fungal skin diseases is variable across the studies, with cure rates ranging from 28% to 74.3% 2, 4
• Terbinafine combined with itraconazole may achieve better therapeutic effects in fungal skin diseases, with a 100% cure rate reported in one study 5
• A meta-analysis of randomized controlled trials found that combination therapy with terbinafine and itraconazole had a better cure rate compared to terbinafine monotherapy 6

Comparison with Other Treatments

• Terbinafine was compared to itraconazole in several studies, with itraconazole showing superior efficacy in some cases 2, 4
• Terbinafine was also compared to fluconazole, with fluconazole showing better efficacy in one study 3
• The combination of terbinafine and itraconazole was found to be more effective than monotherapy with either drug in some studies 5, 6