Papules of molluscum contagiosum
PIC QUESTION OF THE WEEK: 5/07/07 Q: Why would cimetidine be used in the treatment of molluscum contagiosum? A: Molluscum contagiosum is a viral infection characterized by firm, painless papules that are two to five millimeters in diameter with an indentation or dot at their tip. The term molluscum contagiosum is of Latin origin and describes both the stalk-like dermal protrusions and contagious nature of the disease. This infectious disease primarily occurs in children and involves areas of the face, neck, armpits, hands, and/or arms. In adults, the lesions may be noted in the lower abdomen, inner upper thigh, buttocks, or genitals. If the papules are found on the genitals, it is considered a sexually transmitted disease. The causative virus is a member of the poxvirus family and not related to genital warts or human papilloma virus (HPV). The modes of transmission include direct person-to-person contact, sexual encounter with an infected individual, and exposure to fomites. The heat and moisture of skin folds appear to hasten the development and spread of the virus. This skin disorder is self-limiting and can resolve in six to eighteen months, but may take longer in immunocompromised individuals or in children due to their immature immune system. In immunocompromised adults, the condition can become disfiguring. Even though the disease is generally self-limited, most physicians recommend treatment. The therapeutic options for molluscum contagiosum include local removal of lesions through curettage, surgery, cryotherapy, or laser therapy or by systemic drug therapy. Treatments have included topical agents such as cantharidin, podophyllin, imiquimod, and tretinoin. Cimetidine (Tagamet ®), a histamine H2 antagonist, has been identified as a potential option for the management of molluscum contagiosum. This group of compounds has also been somewhat effective in other viral conditions including verruca (common warts). The exact mechanism by which cimetidine exerts its antiviral effects in these skin disorders has not been established. These compounds may alter cell-mediated immunity resulting in a decrease in cell proliferation and delayed hypersensitivity response. In molluscum contagiosum, cimetidine dosage has ranged from 35 to 40 mg/kg/day in divided doses with treatment extending from 2-4 months. It has been used as monotherapy and as an adjunct to other treatments. This is not an FDA labeled indication for any histamine H2 antagonist. Although these drugs have been prescribed for molluscum contagiosum, evidence-based systems such as the Cochrane Database consider their efficacy to be negligible. References: • • •
Smolinski K, Yan AC. How and when to treat molluscum contagiosum and warts in children. Pediatr Ann 2005; 34: 211-24. van der Wouden JC, Menke J, Gajadin S, et al. Interventions for cutaneous molluscum contagiosum. Cochrane Database Syst Rev 2006(2):CD004767. Mayo Clinic. Molluscum contagiosum. http://www.mayoclinic.com/health/molluscumcontagiosum/DS00672/DSECTION=3 (accessed 2007, May 2).
Kay J. Mehalko and Pamela A. Gradisek, Pharmacy Clerkship Students The PIC Question of the Week is a publication of the Pharmaceutical Information Center, Mylan School of Pharmacy, Duquesne University, Pittsburgh, PA 15282 (412.396.4600)