MORE ON NETIVUDINE WITHDRAWAL

Following the announcement that Wellcome has pulled development of its antiviral netivudine (formerly 882C), the company has provided the Marketletter with more details about what went wrong with the drug.

A spokeswoman for the company said that netivudine, which had reached the late stage of Phase II clinical testing, had not met the high safety standard set by the company's blockbuster drug Zovirax (aciclovir) and follow-up Valtrex (valaciclovir). She added that netivudine had been found to have a similar drug interaction profile to Nippon Shoji Kasei's Usevir (sorivudine - also under development by Bristol-Myers Squibb as brovavir), which has been suspended in Japan following 14 deaths caused by the drug's interactions with an anticancer drug, fluorouracil (Marketletters passim).

The withdrawal is a minor blow to Wellcome, which is attempting to see off challenges from competing antivirals, ie the newly-launched Famvir (famciclovir) from SmithKline Beecham. Nevertheless, the company now has the opportunity to concentrate its resources on valaciclovir, a prodrug of aciclovir which like famciclovir offers more convenient dosing and can draw on aciclovir's unquestioned safety profile. Valtrex is due for launch in the UK shortly, with a roll-out in Europe following rapidly thereafter.