Efficacy and Safety of Brivudine in the Treatment of Herpes Zoster

Inclusion Criteria: 1. Age ≥18 years, regardless of gender; 2. Signed Informed Consent Form; 3. Female subjects must not plan for pregnancy or oocyte donation from screening until 1 week after the last dose and must voluntarily adopt highly effective physical contraception; male subjects must not plan for fertility or sperm donation during the same period and must voluntarily adopt highly effective physical contraception. Methods include: * Barrier methods: Condom or barrier cap (diaphragm or cervical cap); * Intrauterine device (IUD) or intrauterine system (IUS); * Surgical sterilization (bilateral oophorectomy with/without hysterectomy, total hysterectomy, bilateral tubal ligation, or vasectomy) performed ≥6 months prior to the first dose in the subject or their partner; * Other investigator-confirmed highly effective physical contraception. Exclusion Criteria: 1. Allergy to brivudine, famciclovir, or penciclovir; 2. Current use of fluorouracil agents (e.g., 5-fluorouracil, capecitabine, tegafur, flucytosine); 3. Cancer patients currently undergoing chemotherapy; 4. Pregnant or lactating women; 5. Parkinson's disease; 6. Any condition deemed inappropriate for study participation by the investigator.