Combining the anti-HIV drugs Viread and Videx can cause a drop in CD4-cell count even if HIV replication is controlled, researchers reported in the July 1 edition of the journal AIDS. Among 95 HIV patients taking regimens containing the two medications, 37 of them'nearly 40%'had CD4 counts that dropped by 50 during the year-and-a-half study window. The researchers say dosage of Videx at a level of 5.5 milligrams per kilogram of patient weight and long duration of Videx therapy were most strongly linked to CD4 decreases.
The researchers theorize that falling CD4 levels could be caused by Viread preventing a key cellular enzyme from clearing Videx-related toxicity within the cells, causing them to eventually self-destruct when toxin levels become too high. They recommend that physicians with patients taking both drugs pay close attention to CD4 counts as well as renal function tests to gauge whether drug toxicity might be affecting CD4 levels. Lowering the dosage of Videx, they suggest, might also help prevent cell loss.
