A Multicentre, Randomised Clinical Trial to Compare a Topical Nitrizinc(®) Complex Solution Versus Cryotherapy for the Treatment of Anogenital Warts

INTRODUCTION: Anogenital warts (AGW) are a relevant clinical issue in the field of sexually transmitted disease, and to date no treatment provides a satisfactory clearance rate. Treatment can be both medical and surgical, and be provided by a healthcare provider or by the patient. Cryotherapy (CRYO) is among the most common treatments for AGW. Nitrizinc® Complex solution (NZCS) is a solution containing organic acids, nitric acid and zinc and copper salts that is applied topically to warts, producing mummification of the damaged tissue. It is considered to be an effective and well-tolerated treatment for genital and common warts. The aim of our study was to compare NZCS to CRYO in the treatment of AGW. METHODS: We performed a prospective, multicentre, single-blind, randomised, superiority clinical study involving 120 patients, aged 18–55 years, diagnosed with a first episode of AGW, with each patient having from three to ten AGW. The patients were treated either with NZCS or CRYO for a maximum of four treatments. Primary endpoints were: (1) comparison of the clinical efficacy of CRYO and NZCS, based on response to treatment (clearance of AGW) within four treatment sessions; and (2) tolerability, assessed via a short questionnaire at the end of each treatment session. Secondary endpoints were: (1) number of treatments needed for clearance; and (2) recurrence at 1 and 3e months after confirmed clearance. The results were analysed on an intention-to-treat basis. RESULTS: A complete response was achieved in 89.7% of the NZCS group and in 75.4% of the CRYO group (p = 0.0443). NZCS was found to be better tolerated. There was no difference between the NZCS and CRYO treatment arms in the number of sessions needed to clear the lesions. Recurrence occurred after 1 month in 18.4% of the NZCS group and 38.1% of the CRYO group (p = 0.0356), and after 3 months in 25 and 40.6% of these groups, respectively (p = 0.1479). CONCLUSIONS: Nitrizinc® Complex solution can be considered to be as effective as CRYO for the treatment of small (< 5 mm) external AGW, with a better tolerability profile and lower rate of recurrence. TRIAL REGISTRATION: ISRCTN identifier, ISRCTN36102369.