A Randomized, Parallel Group, Pilot Study to Assess Efficacy and Safety of Acyclovir-penciclovir Cream Versus an Active Comparator (Abreva) in the Suppression of Herpes Simplex Virus Eruptions in Subjects With a History of Herpes Labialis

This will be a randomized, efficacy assessor-blinded, parallel group, pilot study of up to 40 subjects with documented herpes labialis.

Potential subjects will be assessed during a screening visit that must take place no greater than 2 weeks prior to the lesion induction visit. During the screening period, subjects that meet all other entry criteria will undergo ultraviolet (UV) susceptibility testing to determine their individual minimal erythemal dose (MED). UV susceptibility testing takes place over two days with exposure to UV light on specified regions on the subject's back followed by an assessment of the exposed areas 24 hours later to identify the MED. Subjects who have a measurable MED will be allowed to continue to the induction visit. Patients that do not have measurable MED response will be considered screen failures or patients may have repeat MED testing with different levels.

At the Induction Visit, subjects will undergo UV radiation at a level 3 times their MED. The exposed area of the lip will be marked with indelible ink and a baseline photo may be taken. Each subject will then be randomly assigned in a 1:1 ratio to receive either acyclovir-penciclovir cream or Comparator. Subjects will be dispensed study medication and instructed how to apply it to the exposed area. When the patient first senses the start of developing a cold sore and applies study medication will be considered Day 1. Dosing of the study product will be done five times daily, beginning at the time that a subject first senses the start of the prodromal phase (Day 1). Subjects will be given a diary card to record their pain levels, progression of lesion development and any unusual symptoms (not normally seen with their outbreaks).

Patients will be called daily by the study team after their induction visit to determine the start of prodrome. If after 7 days, the patient does not develop any prodromal senses, the patient will be considered an induction failure.

When the patient first senses signs or symptoms of a cold sore, the patient will have the Day 1 visit conducted within 24 hours. Day 1 visit may be conducted in person or as a MyChart Virtual Visit. Patient's diary card will be reviewed and if the patient have experienced a prodrome and/or lesion since the induction visit, their compliance with dosing will be checked. If the subject has noted any unusual symptoms, these will be discussed with medical personnel to determine if the symptoms represent a treatment emergent adverse event (AE). A photo will be taken of the irradiated area (as marked at the induction visit). The blinded assessor will assess the prodrome and/or lesion and take measurements.