INTRODUCTION
Cutaneous warts are benign growths on the skin that can affect various parts of the body, most commonly the face, hands, and feet.1 Warts affect 10% of the population and are one of the most frequent reasons for dermatology visits.2 Warts are cutaneous manifestations of infection with human papillomavirus (HPV), a double stranded DNA virus with over 200 identifiable strains.1,3 Over 20% of warts regress spontaneously in two months, with almost 80% regressing at two years.4 Clearance rates vary with number and size of lesions, as well as the immune state and age of the affected individual.4 Treatment for cutaneous warts is often destructive in nature and includes salicylic acid, cryotherapy, and cantharidin.4 While these therapies may be effective in eradicating warts in some individuals, the underlying cause of lesions, a viral infection, is not addressed meaning nonresponse and/or recurrence are frequent.5
Cidofovir is an antiviral agent FDA approved for the management of CMV retinitis in patients with AIDS.6 It has activity against various DNA viruses, including HPV. Case reports describe the use of cidofovir in the management of recalcitrant warts, however, lack of clinical trials and high cost have limited its utilization.7 Cidofovir is now available in generic form and may be a beneficial alternative for patients with recalcitrant cutaneous warts. Cidofovir is a nucleotide analog that resembles cytosine (Figure 1).8 After intracellular phosphorylation, the active metabolite cidofovir diphosphate serves as a substrate for viral DNA polymerase and is incorporated into viral DNA. Following incorporation into the growing strand, cidofovir terminates further viral DNA replication.8,9 Cidofovir has a 25-50-fold higher affinity for viral over cellular DNA polymerase, making it selective for inhibiting viral replication. Unlike other nucleoside analogs, acyclovir and ganciclovir, cidofovir does not require viral enzymes for activation, making it useful for treating viral strains with resistant tyrosine kinases.8,9 Oral bioavailability of cidofovir is poor, and it is often given intravenously; topical preparations can be compounded. We examined the literature on the use of cidofovir in the treatment of non-genital warts to further assess its safety and efficacy (Figure 1).
Cidofovir is an antiviral agent FDA approved for the management of CMV retinitis in patients with AIDS.6 It has activity against various DNA viruses, including HPV. Case reports describe the use of cidofovir in the management of recalcitrant warts, however, lack of clinical trials and high cost have limited its utilization.7 Cidofovir is now available in generic form and may be a beneficial alternative for patients with recalcitrant cutaneous warts. Cidofovir is a nucleotide analog that resembles cytosine (Figure 1).8 After intracellular phosphorylation, the active metabolite cidofovir diphosphate serves as a substrate for viral DNA polymerase and is incorporated into viral DNA. Following incorporation into the growing strand, cidofovir terminates further viral DNA replication.8,9 Cidofovir has a 25-50-fold higher affinity for viral over cellular DNA polymerase, making it selective for inhibiting viral replication. Unlike other nucleoside analogs, acyclovir and ganciclovir, cidofovir does not require viral enzymes for activation, making it useful for treating viral strains with resistant tyrosine kinases.8,9 Oral bioavailability of cidofovir is poor, and it is often given intravenously; topical preparations can be compounded. We examined the literature on the use of cidofovir in the treatment of non-genital warts to further assess its safety and efficacy (Figure 1).
There are two steps to form the active isomer of cidofovir. The first is catalyzed by pyrimidine nucleoside monophosphate kinase and the second is catalyzed by pyrimidine nucleoside diphosphate kinase.
