A double-blind, placebo-controlled study of topical tetracaine in the treatment of herpes labialis

Background: Before the September 1996 approval of 1% penciclovir cream for the treatment of herpes labialis, no other prescription topical therapy was approved for the treatment of this recurrent viral disease affecting appro ximately 20% of the adult population of the United States. Local anesthetic s, such as tetracaine, have been used in over-the-counter topical products, but are only labeled for the relief of pain and itching associated with co ld sores and fever blisters. Objective: The purpose of this study was to determine whether a topical pre paration of a tetracaine cream is safe and effective in the treatment of re current herpes labialis in immunocompetent patients. Methods: A double-blind, placebo-controlled study was conducted to assess t he relative effectiveness and safety of 1.8% tetracaine equivalent in a cre am base versus placebo in the treatment of herpes labialis in immunocompete nt adults. In this study, patients applied medication up to 6 times daily u ntil the lesions healed (scab loss), but for no more than 12 days. The pati ents were monitored on the day of enrollment, once during the course of tre atment, and at a final visit after the lesions had healed. Patients assesse d themselves the day of scab formation and the day the scab fell off. They also graded, on a daily basis, their perception of relief from itching and pain and the overall benefit. Results: The results from 72 patients (35 = placebo; 37 = active) showed th at scab formation occurred in a mean of 2.4 +/- 0.27 days for the placebo g roup and 2.3 +/- 0.26 days for the active group. Healing time (scab loss) o ccurred in a mean 7.2 +/- 0.36 days for the placebo group and in 5.1 +/- 0. 35 days in the active group. The difference observed for healing time betwe en the placebo and the active tetracaine cream was statistically significan t (P = .0002). This represents an approximately 30% reduction in the healin g time for the active group compared with the placebo group. In addition, t he study patients ranked the benefit of their treatment on a daily basis an d graded the overall benefit of the therapy at their final visit. The ranki ng was on a 1 to 10 index scale (1 = no benefit at all; 10 = very effective treatment). At the final visit there was a statistically significant diffe rence in the benefit index for active preparation versus placebo for this s ubjective evaluation (placebo index, 5.9 +/- 0.6; active index, 7.3 +/- 0.4 8 [P = .0359]). The subjects also evaluated relief from itching and pain on a daily basis. Relief from itching was significantly greater in the active group than in the placebo group on days 2 and 3 after initiation of the tr eatment. Pain was not found to be severe in either the placebo or active tr eatment groups. At day 2 of treatment and beyond, pain scores never were gr eater than 3.2 +/- 0.28 for active on a scale in which 1.0 represented "no pain at all" and 10 represented "most severe pain imaginable." Although mea n values for pain were always less for the active therapy, lesional pain sc ores never reached statistically significant lower values for active compar ed with placebo. Conclusion: Our findings indicate that a 1.8% topical tetracaine cream, whe n applied frequently significantly reduces the healing time of recurrent he rpes labialis lesions. Additionally, it is perceived by the study subjects to reduce itching of the lesions and to have a beneficial overall effect.