Trial Information

A Double-Blind, Randomized, Placebo-Controlled Trial of Eutectic Lidocaine/Prilocaine Cream 5% (EMLA) for Analgesia Prior to Cryotherapy of Verrucae Plantaris in Adults

Methodology:

The study is a single-centre, double-blind, randomized, placebo-controlled, parallel-group
trial with one visit. The investigators planned to include at least 64 patients in 4 months.
Adult patients (at least 21 years old) diagnosed with plantar warts are potential subjects
for the study.

Once a potential subject is identified, the field investigator will assess him/her for
eligibility to enter the study. Then, the potential subject will be provided with full and
adequate verbal and written information about the nature, purpose, possible risks and
benefits of the study. If the subject agrees to enroll into the study, a signed informed
consent will be obtained from him/her.

All patients are randomly assigned by computer-generated randomization sequence to receive
either eutectic lidocaine/prilocaine cream (EMLA)® 5% or placebo 60 mins prior to
application of cryotherapy. The plantar warts are pared with shape blade before applying
EMLA®or placebo cream. Based on the randomization, an designated dermatology laboratory
technician will apply either the EMLA® cream 5% or placebo cream to the wart lesions. The
cream is applied as a thick layer to the wart and to the surrounding 1 to 2 mm and left on
for 60 minutes under occlusion of Tegaderm dressing. The cream is then removed, and liquid
cryotherapy applied using cryospray. The lesions are treated with double freeze-thaw cycle.
The end point of each freeze is a complete ice-ball covering the lesion with 1-2mm
peripheral extension. The study involved only one treatment with either placebo or EMLA®
cream 5% followed by cryotherapy as described. No other analgesic other than the EMLA® cream
5% or placebo is allowed at least 2 hours prior to or during cryotherapy.

A 100 mm visual analogue pain scale (VAS) is used to denote pain severity ranging from "no
pain" (0 mm) to the "worst possible pain" (100 mm). The patient will choose a distance from
the "no pain" anchor closest to the pain experienced during cryotherapy for wart removal.
Pain is evaluated in each participant using a self-administered VAS immediately after
cryotherapy treatment.

Potential Benefits:

The potential benefits are:

1. The patients may experience less pain during application cryotherapy.

2. The application of local anesthetic cream may possibly increase the effectiveness of
cryotherapy.

Potential Risks:

EMLA cream® is known to be relatively safe with minimal side effects. The commonest side
effect would be local irritation to the skin e.g. redness, itchiness which is reversible
after removal of the cream. Very rarely (<1000), severe allergic reaction can occur with
application of EMLA cream® (AstraZeneca information brochure).