IDV, a protease inhibitor, has shown excellent clinical and virologic responses when combined with 2 nucleoside analogues. Although effective, the pharmacokinetics of IDV make it difficult to use in many patients. The drug has a short half-life and requires administration in high doses every 8 hours with significant dietary restrictions. Research has shown that IDV kinetics can be improved significantly by the addition of RTV, allowing for administration of IDV at lower doses every 12 hours. The half-life of IDV is prolonged 3- to 5-fold when administered with RTV. Based on these results, it is reasonable to study this combination as a twice-daily dosing regimen.