Drug levels and HIV

July 2001     View PDF     En español

The ATHENA study

This study included 600 people, half of whom had not been on anti-HIV therapy before. Half received TDM in addition to standard monitoring (CD4+ cell counts, viral load, etc.) while the other half only used standard monitoring. Only results involving those who had not been on anti-HIV therapy before and started on either indinavir (Crixivan) or nelfinavir (Viracept) were reported. Results on participants starting other anti-HIV therapy and those who had used anti-HIV therapy before are forthcoming.

Fifty-five people started indinavir as their first line regimen, with about equal numbers taking standard dose indinavir (800mg every eight hours) and two different doses of indinavir + ritonavir (800mg IDV + 100mg RTV twice a day or 400mg IDV + 400mg RTV twice a day). After a year, a trend suggested that fewer people on TDM had to stop their therapy, primarily due to side effects. Also, significantly more people on TDM achieved viral loads below 500 copies/ml after twelve months.

The results for the group taking nelfinavir were slightly different. Ninety-two people took nelfinavir as first line therapy. Significantly fewer people on TDM stopped therapy compared to the non-TDM group, but this was almost entirely due to fewer people experiencing virologic failure (rebound in viral load) rather than side effects as seen among those taking indinavir. As a result, significantly more people on TDM achieved viral loads below 500 copies/ml after twelve months than those not on TDM.