What other kinds of combinations are doctors testing and thinking about?
Researchers are already testing a double protease inhibitor combination: ritonavir + saquinavir. Results so far show that these two drugs do a good job of attacking HIV together. Four different dose combinations are being studied, but the safest and most effective dosing schedule isn’t known yet. However, it is known that saquinavir may be taken twice a day with ritonavir rather than three times a day-the schedule used when saquinavir is given in combination with nucleosides. The new version of saquinavir is being studied with the protease inhibitor nelfinavir. Researchers are also testing the combination of ddI and hydroxyurea, an anticancer drug. Some early results show that the combination lowers the level of virus in blood better than ddI alone. More recent studies of ddI + d4T + hydroxyurea show decreases in levels of virus but little effect on CD4 counts. Hydroxyurea must be used with caution because it can quickly lower levels of white blood cells (which include CD4 cells) and o
