A Randomized Exploratory Study to Investigate the Inflammatory Response During an Ultraviolet-Radiation-Induced Cold Sore Episode

INTRODUCTION: Antivirals and occlusive lip patches are key treatments for cold sores. Additional therapeutic options, and validated methods to evaluate these, are needed. METHODS: This exploratory, double-blind, single-center study aimed to evaluate a novel lip patch containing the antiviral aciclovir (ACV) using noninvasive methods for measuring cold sore-associated inflammation. Healthy subjects with ultraviolet radiation (UVR)-induced cold sores were randomized to 10 days’ treatment with a lip patch containing ACV (N = 12) or without ACV (N = 13). Outcome measures included blood flux (field laser perfusion imaging, FLPI), skin temperature (thermography), and skin redness (high-resolution color photography, HRCP). RESULTS: Mean blood flux (in perfusion units) and skin temperature (in °C/pixel) were higher for cold sores versus intrasubject control regions. For ACV versus placebo patches, skin temperature was higher for ACV with total day 1–5 mean values of 2.6 versus 0.5 (p = 0.036) and day 1–10 mean values of 3.2 versus 0.8 (p = 0.049). Conversely, mean total episode blood flux values over days 1–5 were lower for ACV versus placebo patch (flux 2227 versus 2939, p = 0.340) and remained lower over days 1–10 (flux ACV 810 versus placebo 961, p = 0.404). HRCP failed to discriminate cold sores from control regions or between treatments. Subject-reported pain/soreness, itching, and burning were generally lower with ACV patch. CONCLUSIONS: FLPI reliably measures cold sore-related inflammation and thermography heat radiating from the skin. HRCP was of little value. TRIAL REGISTRATION: NCT01653509. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13555-021-00531-x.