The goal of this observational study is to characterize the population pharmacokinetics (PPK) of terbinafine in pediatric patients with tinea capitis, evaluate its efficacy and safety, and identify covariates affecting drug disposition in Chinese children aged 2-18 years diagnosed with tinea capitis and treated with oral terbinafine. The main questions it aims to answer are:

What are the terbinafine pharmacokinetic parameters (e.g., AUC, CL, V) in children with tinea capitis, and how do they differ from adult values? Which covariates (e.g., age, body weight, CYP enzyme activity, renal function) significantly influence inter-individual variability in terbinafine PK parameters? What is the clinical efficacy (based on TSSS reduction and mycological cure rate) and safety profile of terbinafine in this pediatric population?

Participants will:

Undergo oral terbinafine treatment according to weight-based dosing (62.5-250 mg daily).

Concentration determination is carried out using the opportunistic sampling method.

Complete clinical assessments (TSSS scoring) and mycological examinations (microscopy/culture) at baseline and follow-up visits.

Undergo routine laboratory tests (liver/kidney function, hematology) to monitor safety.

Inclusion Criteria:

1. Aged 2 to 18 years;

2. Diagnosis of tinea capitis:

   • Typical clinical manifestations, dermatoscopic findings combined with Wood's lamp examination; ② Positive mycological examination, including positive fungal microscopy and/or isolation of dermatophytes by fungal culture; ③ Exclusion of scalp seborrheic dermatitis, psoriasis, alopecia areata, lupus erythematosus, lichen planopilaris, trichotillomania, suppurative perifolliculitis of scalp, syphilitic alopecia, etc.

Exclusion Criteria:

1. Concomitant topical treatment with terbinafine;
2. Conditions interfering with gastrointestinal absorption of terbinafine;
3. Documented hepatic/renal impairment or hematological disorders;
4. Receipt of radiotherapy, systemic cytostatic/immunosuppressive therapy, or antibacterial/antiviral/antiparasitic therapy currently or within 2 weeks prior to study initiation;
5. Participation in other clinical trials, or other circumstances deemed inappropriate by the investigator.

Chinese pediatric patients aged 2 to 18 years