Group gets to test new Merck AIDS drug in gel

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - A group working to develop a gel or cream women could use to protect themselves against the AIDS virus said on Tuesday they have permission to use an experimental new drug from Merck and Co (MRK.N: Quote, Profile, Research, Stock Buzz).

It is the sixth HIV drug to be tested by the International Partnership for Microbicides, said the group's chief executive officer, Dr. Zeda Rosenberg.

The drug is known only by its experimental name L'644. It is a member of a class of drugs known as gp41 fusion inhibitors. They stop the AIDS virus from attaching to the immune system cells it targets.

"It's a completely different mechanism of action to what we have currently under development and what the field has under development," Rosenberg told Reuters in a telephone interview.

"It's pretty early in the life cycle for HIV. Most of us feel that, for a microbicide to be really effective, it has to get at the infection in its earliest timepoints."

Microbicides are products, such as gels or creams, that could be applied vaginally or anally to prevent transmission of the human immunodeficiency virus that causes AIDS.

So far, attempts to create a microbicide have failed.

The AIDS virus has infected 33 million people globally, according to the World Health Organization. It has killed 25 million, and there is no vaccine to prevent the fatal and incurable virus.