In the study, atazanavir performed just as well as efavirenz, which so far has appeared to be the single most potent HIV drug in trials. At 48 weeks, 70 per cent on the atazanavir combo and 64 per cent on efavirenz had viral loads under 400; for viral loads under 50, the figures were 32 and 37 per cent respectively.
However,efavirenz-based regimes typically get 80 per cent of drug-naive patients undetectable - not 37 per cent. Was there something wrong with the figures?
The majority of patients were from developing countries. Two different viral load tests were used to cope with the fact that most patients had non-western strains of HIV, and the viral load testing may have been unreliable. Also, switching from AZT and 3TC was not allowed. So those who could not tolerate AZT dropped out of the trial and were counted as 'failures'.
However, only 18 per cent actually did discontinue their drugs, implying that some unknown factor contributed to the low success rates.
The good news is that whatever affected the success rates should apply equally to both drugs - so atazanavir probably is as strong as efavirenz.
The bad news is that these success rates may possibly be representative of what can currently be achieved in certain resource-poor settings.
There was relatively good news, too, on atazanavir resistance. If your HIV remains detectable on an atazanavir regime (i.e. continues to reproduce), it will start to become resistant, as it would on any other drug. But the first mutation (change) HIV makes to enable it to resist atazanavir actually makes it more susceptible to the other PIs. And atazanavir needs to collect more resistance mutations than any other PI other than amprenavir in order to become fully resistant.
If, however, you have HIV that's already strongly resistant to the other PIs it will most likely be resistant to atazanavir too.

page 3 of 9

1 / 2 / 3 / 4 / 5 / 6 / 7 /
8 / 9

home

contents of issue 84
back issues
the gazette
recipes
small ads
contacting us
weblinks

Barring the unexpected, atazanavir should be licensed in early-to-mid 2003, but expanded access programmes for those who need the drug are starting in some UK clinics this month.