Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.
Aldara (3M Pharmaceuticals)
5% cream in single-use sachets
Approved indication: genital and perianal warts
AMH Section 8.5
Podophyllotoxin has been the drug of choice for anogenital warts, but it commonly causes irritation. While podophyllotoxin has a mainly destructive action, imiquimodis thought to modify the immune response.
The cream is applied to the warts for 3 nights each week and is left on for6-10 hours. This appears to induce the production of interferon alpha and other cytokines. Imiquimod has no antiviral action.
A double-blind placebo-controlled trial randomised 51 non-immuno suppressed patients to receive imiquimod and 57 to receive placebo for up to 8 weeks. The warts of 19 patients in the treatment group disappeared and, in most of the other patients, the warts reduced in size. In the placebo group, the response was significantly less and no patient had a complete response.1 Other studies have shown similar benefits, but the recurrence rate after treatment is not significantly different from placebo. Efficacy has not been demonstrated in immuno compromised patients.
Most of the adverse effects of imiquimod are local skin reactions. The majority of patients will develop erythema. Erosion, itching and burning can also occur. Only 4 of the 327 patients in the clinical trials discontinued the drug because of skin reactions. Very little imiquimod is absorbed through the skin. As the potential systemic absorption is increased, imiquimod should not be applied to urethral, vaginal or rectal warts. Imiquimod is not teratogenic in animals, but the manufacturer does not recommend its use during pregnancy.
Although the efficacy of imiquimod is greater than placebo, its effectiveness needs to be compared with that of podophyllotoxin and other treatments such as liquid nitrogen or laser therapy. As the maximum duration of treatment allowed is 16 weeks, there is a need for information about the use of imiquimod forwarts which recur.
