Twice-Weekly Squaric Acid Clears 67% of Warts – Brief Article – Statistical Data Included
SAN FRANCISCO — Twice-weekly applications of squaric acid dibutylester cleared recurrent warts in 67% of 568 adults and children in a retrospective study, Dr. Giuseppe Micali and his associates reported in a poster at the annual meeting of the American Academy of Dermatology.
Among 443 patients who completed 10 weeks of twice-weekly applications of squaric acid dibutylester (SADBE), 382 (86%) completely cleared their warts and 61 (14%) were nonresponders. The remaining 125 patients either stopped the drug due to a strong eczematous reaction (13 patients) or did not complete 10 weeks of therapy for other reasons (112 patients).
Only one patient whose warts cleared on therapy developed a relapse within 2 years of follow-up, although five patients with common warts grew new warts at sites other than those treated in the study.
“The application of SADBE is quick and simple and does not interfere with work activity or affect social life,” said Dr. Micali of the University of Catania (Italy).
Participants included 404 adults and 164 children older than 2 years of age who either refused surgical or destructive treatments for warts or who had multiple and resistant warts of various kinds: common, flat, plantar, or mosaic warts. Of the 382 patients whose warts cleared, 281 were adults (with a mean age of 28 years) and 101 were children (mean age 10 years).
The drug did not appear to cause any systemic side effects and generally was well tolerated. Some erythema (usually mild), desquamation, edema, itching, burning, and pain were considered part of the response to therapy and gradually disappeared if the treatment was stopped.
Previous data on contact immunotherapy using SADBE for treating warts consisted of small case series that suggested effectiveness but did not include follow-up, he noted. The treatment has not been approved by the Food and Drug Administration, but the drug is available in the United States if mixed by a pharmacist.
The Italian investigators used a particularly potent form of the drug created with the help of a filtering machine to esterify the squaric acid. This created an almost an-hydrous, more stable compound, he said.
The first sensitization was carried out by topical application of 3% SADBE in acetone. Subsequently clinical staff applied a 0.03% solution of SADBE initially progressively switching to more concentrated solutions (0.3% -3%) if warts persisted.
The anatomical location of the warts seemed to affect the speed and rate of clearance, Dr. Micali reported.
Plantar warts in 86 patients cleared fastest after a mean 6 weeks of treatment. The therapy worked in each of these patients, and none interrupted therapy due to side effects, perhaps because the thickness of the sole decreased sensitivity, compared with other sites, he said.
Among 269 patients with multiple common warts, 226 cleared their warts after a mean 6 weeks; 43 did not respond.
Flat warts in 62 patients needed a mean 8 weeks of treatment to clear. Ten of these patients developed strong local eczematous reactions and stopped therapy; another 13 did not respond.
The 26 patients with periungual or subungual warts needed a mean 10 weeks to clear; SADBE did not work in five patients.
Two patients in the study had warts on the backs of their hands that cleared after SADBE was applied solely to the scalp for the treatment of alopecia areata, supporting the idea that SADBE may have a remote immunomodulating effect, he commented.
Five of the 61 nonresponders were undergoing immunosuppressive or immunomodulating therapy; another non-responder had HIV. Immunosuppression may have contributed to SADBE’s failure to dear warts, Dr. Micali said.
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