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.
Vectavir (SmithKline Beecham)
1% cream in 2 g tubes
Indication: herpes labialis
Patients with shingles can be treated with famciclovir. However, the drug is a prodrug which must be metabolised to its active form, penciclovir. Treatment with oral penciclovir is not used as it has a very low bioavailability; however, topical penciclovir can be effective in the treatment of herpes infections of the lips.
To be effective, the cream must be applied every two hours, at least 6 times a day, for 4 days. Patients using penciclovir heal significantly faster than those using a placebo cream. However, in absolute terms, this means the cold sore heals up one day earlier.
There is minimal systemic absorption of penciclovir and no more local adverse reactions than placebo. The risks of phototoxity and photo allergy in the Australian environment are unknown.
As cold sores usually heal spontaneously, there is no clear indication for using this product. Although some patients with recurrent cold sores may wish to try penciclovir, the benefit is likely to be small. The safety and efficacy of penciclovir cream has not been established in children, pregnant women or immuno compromised patients.