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.