Ritonavir (ABT 538) is an inhibitor of HIV protease used to treat HIV infection and AIDS. Ritonavir is also a SARS-CoV 3CL^pro inhibitor with an IC₅₀ of 1.61 μM. Ritonavir (ABT 538) can penetrate the blood brain barrier (BBB)^{[1][2][3][4][5][6][7]}.

Ritonavir (ABT 538) is an inhibitor of CYP3A4 mediated testosterone 6β-hydroxylation with mean K_i of 19 nM and also inhibits tolbutamide hydroxylation with IC₅₀ of 4.2 μM^[1].
Ritonavir (ABT 538) is found to be a potent inhibitor of CYP3A-mediated biotransformations (nifedipine oxidation with IC₅₀ of 0.07 mM, 17alpha-ethynylestradiol 2-hydroxylation with IC₅₀ of 2 mM; terfenadine hydroxylation with IC₅₀ of 0.14 mM). Ritonavir is also an inhibitor of the reactions mediated by CYP2D6 (IC₅₀=2.5 mM) and CYP2C9/10 (IC₅₀=8.0 mM)^[2].
Ritonavir results in an increase in cell viability in uninfected human PBMC cultures. Ritonavir markedly decreases the susceptibility of PBMCs to apoptosis correlated with lower levels of caspase-1 expression, decreases in annexin V staining, and reduces caspase-3 activity in uninfected human PBMC cultures. Ritonavir inhibits induction of tumor necrosis factor (TNF) production by PBMCs and monocytes in a time- and dose-dependent manner at nontoxic concentrations^[3].
Ritonavir inhibits p-glycoprotein-mediated extrusion of saquinavir with an IC₅₀ of 0.2 μM, indicating a high affinity of ritonavir for p-glycoprotein^[4].
Ritonavir inhibits human liver microsomal metabolism of ABT-378 potently with K_i of 13 nM. Ritonavir combined with ABT-378 (at 3:1 and 29:1 ratios) inhibits CYP3A (IC₅₀=1.1 and 4.6 μM), albeit less potently than Ritonavir (IC₅₀=0.14 μM)^[5].

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.

* Please refer to the solubility information to select the appropriate solvent. Once prepared, please aliquot and store the solution to prevent product inactivation from repeated freeze-thaw cycles.
Storage method and period of stock solution: -80°C, 2 years; -20°C, 1 year. When stored at -80°C, please use it within 2 years. When stored at -20°C, please use it within 1 year.

• [1]. Eagling VA, et al. Differential inhibition of cytochrome P450 isoforms by the protease inhibitors, ritonavir, saquinavir and indinavir. Br J Clin Pharmacol. 1997 Aug;44(2):190-4.  [Content Brief]

  [2]. Kumar GN, et al. Cytochrome P450-mediated metabolism of the HIV-1 protease inhibitor ritonavir (ABT-538) in human liver microsomes. J Pharmacol Exp Ther. 1996 Apr;277(1):423-31.  [Content Brief]

  [3]. Weichold FF, et al. HIV-1 protease inhibitor ritonavir modulates susceptibility to apoptosis of uninfected T cells. J Hum Virol. 1999 Sep-Oct;2(5):261-9.  [Content Brief]

  [4]. Drewe J, et al. HIV protease inhibitor ritonavir: a more potent inhibitor of P-glycoprotein than the cyclosporine analog SDZ PSC 833. Biochem Pharmacol. 1999 May 15;57(10):1147-52.  [Content Brief]

  [5]. Kumar GN, et al. Potent inhibition of the cytochrome P-450 3A-mediated human liver microsomal metabolism of a novel HIV protease inhibitor by ritonavir: A positive drug-drug interaction. Drug Metab Dispos. 1999 Aug;27(8):902-8.  [Content Brief]

  [6]. Qi Sun, et al. Bardoxolone and bardoxolone methyl, two Nrf2 activators in clinical trials, inhibit SARS-CoV-2 replication and its 3C-like protease. Signal Transduct Target Ther. 2021 May 29;6(1):212.  [Content Brief]

  [7]. C Anthonypillai, et al. The distribution of the HIV protease inhibitor, ritonavir, to the brain, cerebrospinal fluid, and choroid plexuses of the guinea pig. J Pharmacol Exp Ther.2004 Mar;308(3):912-20.  [Content Brief]