More data to support simplification of anti-retroviral treatment was wheeled out at ECCMID (the Tenth European Congress on Clinical Microbiology and Infectious Diseases) this week in Stockholm.
Twelve week data from the BEST study of the ritonavir/indinavir combination showed equivalence between indinavir three times daily and twice daily ritonavir/indinavir (100mg/800mg), with 88% of the RTV/IDV group and 89% of the indinavir group below 500 copies/ml by this point. This data comes from 219 patients, and all those who discontinued due to side-effects are included as treatment failures in this analysis.
The ritonavir/indinavir combination was less well tolerated due to the use of ritonavir liquid, say researchers. Thirteen per cent of the RTV/IDV group reported nausea, vomiting, diarrhoea or abdominal pains, compared with 4% of the indinavir group.
However, the incidence of nephrolithiasis (kidney stones, lower back pain and a build up of indinavir crystals in the kidney) was also higher in the ritonavir/indinavir group, at 13% compared to 5% in the indinavir group. Discontinuation rates due to this problem were the same in both arms, suggesting that the condition can be managed by prompt advice and intervention, but it clearly raises concerns about the way in which individuals are advised about the need for adequate water intake when starting this experimental combination.
Twenty-four week results from this study will be presented at the Thirteenth World Conference in Durban next month.
Further analysis of Du Pont's 006 study was also reported, showing that efavirenz appears to be equivalent to three times daily indinavir in people with advanced immune system damage. The 006 study compared AZT/3TC/efavirenz with AZT/3TC/indinavir or indinavir/efavirenz. The latest analysis of 006 shows that in people with baseline CD4 counts below 100 cells, 69.8% of the efavirenz group had viral load below 400 copies at week 48, compared with 50% of the indinavir group, a nonsignificant difference given the small number of patients involved. Anyone who switched treatment due to intolerance was counted as a viral load 'failure' in this analysis. Differences in CD4 increase were also similar: the efavirenz group had an average increase of 175 cells after 48 weeks, compared to 120 cells in the indinavir arm.