Table 1.

Plasma levels and activity comparison for protease inhibitors in the endogenous and exogenous Gag-Pol protease assays

Drug	Cmin–Cmax (μM)a	IC50b		Relative potency (IC50 end//IC50 ex ratio)c
		Endogenous (μM)	Exogenous (nM)
Darunavir	4.3–10.7	1.2 ± 0.8	13.2 +/− 5.1	91
Indinavir	0.67–10.1	3.4 ± 1.5	21.8 ± 6.4	156
Nelfinavir	2.4–6.6	5.3 ± 3.3	28 ± 18.8	189
Ritonavir	0.24–1.3	4.6 ± 1.4	24.5 +/− 6.8	188
Saquinavir	0.11–4.2	1.0 ± 0.5	18.9 ± 4.4	53
Tipranavir	0.59–30	3.2 ± 1.2	21.8d	146

^aPlasma levels for darunavir, indinavir, and saquinavir were obtained when coadministered (boosted) with ritonavir. Plasma levels for darunavir, indinavir, nelfinavir, ritonavir, saquinavir, and tipranavir were from references 23, 4, 10, 23, 1, and 5, respectively, and represent the range of C_min to C_max values.

^bIC₅₀s are expressed as the mean ± standard deviation from results of three separate experiments. The IC₅₀s shown were obtained using the sigmoidal nonvariable slope dose-response equation in Prism 4.

^cIC_{50 end}, endogenous IC₅₀; IC_{50 ex}, exogenous IC₅₀.

^dThe value for tipranavir in the exogenous assay is the averaged result from two separate experiments (IC₅₀s of 25.2 nM and 18.3 nM).