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Ritonavir (ABT-538; Norvir)

Alias: ABT-538; A 84538; Norvir; ABT538; Norvir; ABT-538; A-84538; Abbott 84538; ABBOTT-84538; Empetus; A-84538; Norvir Sec; 538, ABT; Ritonavir; ABT 538;
Cat No.:V0729 Purity: ≥98%
Ritonavir (previously known as ABT-538; A-84538; RTV; ABT538, trade name: Norvir) is a L-valine derivative and potent inhibitor of HIV-1 protease used to treat HIV infection and AIDS. It is widely used as a booster for other protease inhibitors/PIs such as lopinavir, and makes them work better.
Ritonavir (ABT-538; Norvir)
Ritonavir (ABT-538; Norvir) Chemical Structure CAS No.: 155213-67-5
Product category: HIV Protease
This product is for research use only, not for human use. We do not sell to patients.
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Other Forms of Ritonavir (ABT-538; Norvir):

  • Ritonavir-d6 (ABT 538-d6; RTV-d6)
  • rel-Ritonavir-d6 (ritonavir-d6; rel-ABT 538-d6; rel-RTV-d6)
  • Ritonavir metabolite
Official Supplier of:
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Top Publications Citing lnvivochem Products
Purity & Quality Control Documentation

Purity: ≥98%

Product Description

Ritonavir (previously known as ABT-538; A-84538; RTV; ABT538, trade name: Norvir) is a potent inhibitor of HIV-1 protease and a derivative of L-valine used to treat HIV infection and AIDS. It is frequently used to improve the effectiveness of other protease inhibitors, or PIs, like lopinavir. More precisely, ritonavir is used to block CYP3A4, a specific liver enzyme that typically metabolizes protease inhibitors. Ritonavir demonstrates strong in vitro inhibitory effects against both HIV-1 and HIV-2 strains, with 50% effective concentration EC50 values of 0.022 μM and 0.16 μM, respectively.

Biological Activity I Assay Protocols (From Reference)
Targets
CYP3A4; HIV
ln Vitro
Ritonavir has a mean Ki of 19 nM, making it a very potent inhibitor of CYP3A4-mediated testosterone 6β-hydroxylation. It also has an IC50 of 4.2 μM for tolbutamide hydroxylation.[1]
Ritonavir has a mean Ki of 19 nM, making it a very potent inhibitor of CYP3A4-mediated testosterone 6β-hydroxylation. It also has an IC50 of 4.2 μM for tolbutamide hydroxylation. (Source: ) It is discovered that ritonavir is a strong inhibitor of CYP3A-mediated biotransformations (IC50 values for nifedipine oxidation and 17alpha-ethynylestradiol 2-hydroxylation are 0.07 mM, 2 mM, and 0.14 mM, respectively). The reactions mediated by CYP2D6 (IC50 = 2.5 mM) and CYP2C9/10 (IC50 = 8.0 mM) are also found to be inhibited by ritonavir.[2]
In human PBMC cultures that are not infected, ritonavir increases cell viability. In uninfected human PBMC cultures, ritonavir significantly reduces caspase-3 activity, annexin V staining, and the susceptibility of PBMCs to apoptosis, which is correlated with lower levels of caspase-1 expression. In PBMCs and monocytes, ritonavir inhibits the induction of tumor necrosis factor (TNF) production in a time- and dose-dependent manner at nontoxic concentrations.[3]
Ritonavir has a high affinity for p-glycoprotein as evidenced by its ability to inhibit p-glycoprotein-mediated extrusion of saquinavir, with an IC50 of 0.2 μM.[4] Ritonavir has a 13 nM Ki that potently inhibits the microsomal metabolism of ABT-378 in human liver. Inhibiting CYP3A (IC50 = 1.1 and 4.6 μM), Ritonavir in combination with ABT-378 (at 3:1 and 29:1 ratios) is less effective than Ritonavir (IC50 = 0.14 μM).[5]
ln Vivo
PAXLOVID™ (Co-packaging of Nirmatrelvir with ritonavir) has been approved for the treatment of Coronavirus Disease 2019 (COVID-19). The goal of the experiment was to create an accurate and straightforward analytical method using ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) to simultaneously quantify nirmatrelvir and ritonavir in rat plasma, and to investigate the pharmacokinetic profiles of these drugs in rats. After protein precipitation using acetonitrile, nirmatrelvir, ritonavir, and the internal standard (IS) lopinavir were separated using ultra performance liquid chromatography (UPLC). This separation was achieved with a mobile phase composed of acetonitrile and an aqueous solution of 0.1% formic acid, using a reversed-phase column with a binary gradient elution. Using multiple reaction monitoring (MRM) technology, the analytes were detected in the positive electrospray ionization mode. Favorable linearity was observed in the calibration range of 2.0-10000 ng/mL for nirmatrelvir and 1.0-5000 ng/mL for ritonavir, respectively, within plasma samples. The lower limits of quantification (LLOQ) attained were 2.0 ng/mL for nirmatrelvir and 1.0 ng/mL for ritonavir, respectively. Both drugs demonstrated inter-day and intra-day precision below 15%, with accuracies ranging from -7.6% to 13.2%. Analytes were extracted with recoveries higher than 90.7% and without significant matrix effects. Likewise, the stability was found to meet the requirements of the analytical method under different conditions. This UPLC-MS/MS method, characterized by enabling accurate and precise quantification of nirmatrelvir and ritonavir in plasma, was effectively utilized for in vivo pharmacokinetic studies in rats[8].
Enzyme Assay
Ritonavir (ABT 538) is an inhibitor of testosterone 6β-hydroxylation mediated by CYP3A4, with a mean Ki of 19 nM. It also has an IC50 of 4.2 μM for tolbutamide hydroxylation. It is discovered that ritonavir (ABT 538) is a strong inhibitor of CYP3A-mediated biotransformations (IC50 values for nifedipine oxidation and 17alpha-ethynylestradiol 2-hydroxylation are 0.07 mM, 2 mM, and 0.14 mM, respectively). Inhibitors of the reactions mediated by CYP2D6 (IC50=2.5 mM) and CYP2C9/10 (IC50=8.0 mM) include ritonavir.
Cell Assay
In human peripheral blood mononuclear cells that are not infected, ritonavir increases cell viability. In uninfected human PBMC cultures, ritonavir significantly lowers the susceptibility of PBMCs to apoptosis, which is correlated with lower levels of caspase-1 expression, decreases in annexin V staining, and reduces caspase-3 activity. At nontoxic concentrations, ritonavir inhibits the induction of tumor necrosis factor (TNF) production by monocytes and PBMCs in a time- and dose-dependent manner. With an IC50 of 0.2 μM, ritonavir inhibits p-glycoprotein-mediated saquinavir extrusion, suggesting a high affinity for p-glycoprotein. With a Ki of 13 nM, ritonavir potently inhibits the human liver microsomal metabolism of ABT-378. Although less potently than Ritonavir (IC50=0.14 μM), Ritonavir in combination with ABT-378 (at 3:1 and 29:1 ratios) inhibits CYP3A (IC50=1.1 and 4.6 μM).
Animal Protocol
BALB/c mice
60 mg/kg
i.p.
Animal experiments[8]
A cohort of six male Sprague-Dawley rats (in good health, and their individual weights falling within the range of 200–220 g) was used. Prior to commencing the experiment, the rats were housed in a controlled environment with clean cages for a week-long acclimation period. The ambient conditions were maintained at 25 °C and a 12-h light/dark cycle. During this time, the animals enjoyed ad libitum access to food and water. Before the day of dosing, a 12-h fasting period was performed, during which water intake remained unrestricted. Each rat was received an oral administration of a solution containing 30 mg/kg of nirmatrelvir and 10 mg/kg of ritonavir, formulated in 0.5% sodium carboxymethylcellulose. At designated time points, including pre-dose (0 h), 0.33, 0.67, 1, 1.5, 2, 3, 4, 6, 8, 12, 24 and 48 h post-dosing, approximately 0.3 mL of blood was drawn from the tail vein into heparinized centrifuge tubes. After centrifugation of these samples at 8000×g and 25 °C for 10 min, the supernatant was carefully transferred into fresh tubes and stored at −80 °C pending further analysis.

Pharmacokinetic parameters of nirmatrelvir and ritonavir in each rat, encompassing area under the concentration-time curve (AUC), time to reach peak plasma concentration (Tmax), maximum plasma concentration (Cmax), elimination half-life (t1/2), apparent clearance (CLz/F), and mean residence time (MRT), were analyzed through non-compartmental statistical models using the Drugs and Statistics (DAS 3.0) software. The data were presented as mean ± standard deviation (SD).
Drug repurposing is a promising strategy for identifying new applications for approved drugs. Here, we describe a polymer biomaterial composed of the antiretroviral drug ritonavir derivative (5-methyl-4-oxohexanoic acid ritonavir ester; RD), covalently bound to HPMA copolymer carrier via a pH-sensitive hydrazone bond (P-RD). Apart from being more potent inhibitor of P-glycoprotein in comparison to ritonavir, we found RD to have considerable cytostatic activity in six mice (IC50 ~ 2.3-17.4 μM) and six human (IC50 ~ 4.3-8.7 μM) cancer cell lines, and that RD inhibits the migration and invasiveness of cancer cells in vitro. Importantly, RD inhibits STAT3 phosphorylation in CT26 cells in vitro and in vivo, and expression of the NF-κB p65 subunit, Bcl-2 and Mcl-1 in vitro. RD also dampens chymotrypsin-like and trypsin-like proteasome activity and induces ER stress as documented by induction of PERK phosphorylation and expression of ATF4 and CHOP. P-RD nanomedicine showed powerful antitumor activity in CT26 and B16F10 tumor-bearing mice, which, moreover, synergized with IL-2-based immunotherapy. P-RD proved very promising therapeutic activity also in human FaDu xenografts and negligible toxicity predetermining these nanomedicines as side-effect free nanosystem. The therapeutic potential could be highly increased using the fine-tuned combination with other drugs, i.e. doxorubicin, attached to the same polymer system. Finally, we summarize that described polymer nanomedicines fulfilled all the requirements as potential candidates for deep preclinical investigation.[7]
ADME/Pharmacokinetics
Absorption, Distribution and Excretion
The absolute bioavailability of ritonavir has not been determined. Following oral administration, peak concentrations are reached after approximately 2 hours and 4 hours (Tmax) after dosing under fasting and non-fasting conditions, respectively. It should be noted that ritonavir capsules and tablets are not considered bioequivalent.
Ritonavir is primarily eliminated in the feces. Following oral administration of a single 600mg dose of radiolabeled ritonavir, approximately 11.3 ± 2.8% of the dose was excreted into the urine, of which 3.5 ± 1.8% was unchanged parent drug. The same study found that 86.4 ± 2.9% of the dose was excreted in the feces, of which 33.8 ± 10.8% was unchanged parent drug.
The estimated volume of distribution of ritonavir is 0.41 ± 0.25 L/kg.
The apparent oral clearance at steady-state is 8.8 ± 3.2 L/h. Renal clearance is minimal and estimated to be <0.1 L/h.
Ritonavir and its metabolites are eliminated from the body predominantly in the feces (86% of unchanged drug and metabolites), with minor urinary elimination (11%, mostly metabolites).
Absorption of ritonavir is only slightly affected by diet, and this is somewhat dependent on the formulation. The overall absorption of ritonavir from the capsule formulation may increase by 15% when taken with meals. ... There is greater than sixfold variability in drug trough concentrations among patients given 600 mg of ritonavir every 12 hours.
The extent of oral absorption is high and is not affected by food. Within the clinical concentration range, ritonavir is approximately 98 to 99% bound to plasma proteins, including albumin and alpha 1-acid glycoprotein. Cerebrospinal fluid (CSF) drug concentrations are low in relation to total plasma concentration. However, parallel decreases in the viral burden have been observed in the plasma, CSF and other tissues. ... About 34% and 3.5% of a 600 mg dose is excreted as unchanged drug in the feces and urine, respectively. The clinically relevant t1/2 beta is about 3 to 5 hours. Because of autoinduction, plasma concentrations generally reach steady state 2 weeks after the start of administration. The pharmacokinetics of ritonavir are relatively linear after multiple doses, with apparent oral clearance averaging 7 to 9 L/hr.
Ritonavir is excreted principally in the feces, both as unchanged drug and metabolites. Following oral administration of 600 mg of radiolabeled ritonavir as the oral solution, 86.4% of the dose is excreted in feces (33.8% as unchanged drug) and 11.3% of the dose is excreted in urine (3.5% as unchanged drug).
For more Absorption, Distribution and Excretion (Complete) data for RITONAVIR (6 total), please visit the HSDB record page.
Metabolism / Metabolites
Ritonavir circulates in the plasma predominantly as unchanged drug. Five metabolites have been identified. The isopropylthiazole oxidation metabolite (M-2) is the major metabolite in low plasma concentrations and retains similar antiviral activity to unchanged ritonavir. The cytochrome P450 enzymes CYP3A and CYP2D6 are the enzymes primarily involved in the metabolism of ritonavir.
... Ritonavir is primarily metabolised by cytochrome P450 (CYP) 3A isozymes and, to a lesser extent, by CYP2D6. Four major oxidative metabolites have been identified in humans, but are unlikely to contribute to the antiviral effect. ...
Five ritonavir metabolites have been identified in human urine and feces. The isopropylthiazole oxidation metabolite (M2) appears to be the major metabolite. M2 (but not other metabolites) has antiviral activity similar to that of ritonavir; however, only very low concentrations of this metabolite are present in plasma. Other metabolites identified in in vitro studies include a decarbamoylated metabolite (M1) and a product of N-dealkylation at the urea terminus (M11).
Biological Half-Life
The approximate half-life of ritonavir is 3-5 hours.
The clinically relevant t1/2 beta is about 3 to 5 hours.
Toxicity/Toxicokinetics
Hepatotoxicity
Some degree of serum aminotransferase elevations occurs in a high proportion of patients taking ritonavir containing antiretroviral regimens. Moderate-to severe elevations in serum aminotransferase levels (>5 times the upper limit of normal) are found in up to 15% of patients treated with full doses of ritonavir and are more common in patients with HIV-HCV coinfection. With low “booster” doses, ritonavir does not appear to increase the frequency or severity of serum enzyme elevations, and those that occur are usually asymptomatic and self-limited, resolving even with continuation of ritonavir. Clinically apparent liver injury from full doses of ritonavir has been reported, but hepatotoxicity from low dose ritonavir has not been clearly linked to acute liver injury. In many situations, the liver injury is difficult to attribute to ritonavir because it is used in combination with higher doses of other protease inhibitors. HIV protease inhibitors have been associated with acute liver injury arising 1 to 8 weeks after onset, with variable patterns of liver enzyme elevation, from hepatocellular to cholestatic. Immunoallergic features (rash, fever, eosinophilia) are uncommon as is autoantibody formation. Ritonavir in combination with saquinavir has also been associated with a rapid onset (1 to 4 days) acute hepatic injury in patients who are taking rifampin and perhaps other agents that affect CYP 450 activity, such as phenobarbital. Finally, initiation of ritonavir based highly active antiretroviral therapy can lead to exacerbation of an underlying chronic hepatitis B or C in coinfected individuals, typically arising 2 to 12 months after starting therapy and associated with a hepatocellular pattern of serum enzyme elevations and increases followed by falls in serum levels of hepatitis B virus (HBV) DNA or hepatitis C virus (HCV) RNA. Ritonavir therapy has not been clearly linked to lactic acidosis and acute fatty liver that is reported in association with several nucleoside analogue reverse transcriptase inhibitors.
Likelihood score: C (probable rare cause of clinically apparent liver injury).
Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Ritonavir is excreted into milk in measurable concentrations and low levels can be found in the blood of some breastfed infants. No adverse reactions in breastfed infants have been reported. Achieving and maintaining viral suppression with antiretroviral therapy decreases breastfeeding transmission risk to less than 1%, but not zero. Individuals with HIV who are on antiretroviral therapy with a sustained undetectable viral load and who choose to breastfeed should be supported in this decision. If a viral load is not suppressed, banked pasteurized donor milk or formula is recommended.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Gynecomastia has been reported among men receiving highly active antiretroviral therapy. Gynecomastia is unilateral initially, but progresses to bilateral in about half of cases. No alterations in serum prolactin were noted and spontaneous resolution usually occurred within one year, even with continuation of the regimen. Some case reports and in vitro studies have suggested that protease inhibitors might cause hyperprolactinemia and galactorrhea in some male patients, although this has been disputed. The relevance of these findings to nursing mothers is not known. The prolactin level in a mother with established lactation may not affect her ability to breastfeed.
Protein Binding
Ritonavir is highly protein-bound in plasma (~98-99%), primarily to albumin and alpha-1 acid glycoprotein over the standard concentration range.
References

[1]. Br J Clin Pharmacol . 1997 Aug;44(2):190-4.

[2]. J Pharmacol Exp Ther . 1996 Apr;277(1):423-31.

[3]. J Hum Virol . 1999 Sep-Oct;2(5):261-9.

[4]. Biochem Pharmacol . 1999 May 15;57(10):1147-52.

[5]. Drug Metab Dispos . 1999 Aug;27(8):902-8.

[6]. Nat Med . 2018 May;24(5):604-609.

[7]. J Control Release . 2021 Apr 10:332:563-580.

[8]. Heliyon . 2024 May 30;10(11):e32187.

Additional Infomation
Ritonavir is an L-valine derivative that is L-valinamide in which alpha-amino group has been acylated by a [(2-isopropyl-1,3-thiazol-4-yl)methyl]methylcarbamoyl group and in which a hydrogen of the carboxamide amino group has been replaced by a (2R,4S,5S)-4-hydroxy-1,6-diphenyl-5-{[(1,3-thiazol-5-ylmethoxy)carbonyl]amino}hexan-2-yl group. A CYP3A inhibitor and antiretroviral drug from the protease inhibitor class used to treat HIV infection and AIDS, it is often used as a fixed-dose combination with another protease inhibitor, lopinavir. Also used in combination with dasabuvir sodium hydrate, ombitasvir and paritaprevir (under the trade name Viekira Pak) for treatment of chronic hepatitis C virus genotype 1 infection as well as cirrhosis of the liver. It has a role as an antiviral drug, a HIV protease inhibitor, an environmental contaminant and a xenobiotic. It is a member of 1,3-thiazoles, a L-valine derivative, a carbamate ester, a member of ureas and a carboxamide.
Ritonavir (brand name: Norvir) is a prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of HIV infection in adults and children. Ritonavir is always used in combination with other HIV medicines.
Although ritonavir is FDA-approved for the treatment of HIV infection, it is no longer used for its activity against HIV. Instead, ritonavir (given at low doses) is currently used as a pharmacokinetic enhancer to boost the activity of other HIV medicines.
Ritonavir is an HIV protease inhibitor that interferes with the reproductive cycle of HIV. Although it was initially developed as an independent antiviral agent, it has been shown to possess advantageous properties in combination regimens with low-dose ritonavir and other protease inhibitors. It is now more commonly used as a booster of other protease inhibitors and is available in both liquid formulations and as capsules. While ritonavir is not an active antiviral agent against hepatitis C virus (HCV) infection, it is added in combination therapies indicated for the treatment of HCV infections as a booster. Ritonavir is a potent CYP3A inhibitor that increases peak and trough plasma drug concentrations of other protease inhibitors such as [DB09297] and overall drug exposure. American Association for the Study of Liver Diseases (AASLD) and the Infectious Diseases Society of America (IDSA) guidelines recommend ritonavir-boosted combination therapies as first-line therapy for HCV Genotype 1a/b and 4 treatment-naïve patients with or without cirrhosis. Ritonavir is found in a fixed-dose combination product with [DB09296], [DB09183], and [DB09297] as the FDA-approved product Viekira Pak. First approved in December 2014, Viekira Pak is indicated for the treatment of HCV genotype 1b without cirrhosis or with compensated cirrhosis, and when combined with Ribavirin for the treatment of HCV genotype 1a without cirrhosis or with compensated cirrhosis. Ritonavir is also available as a fixed-dose combination product with [DB09296] and [DB09297] as the FDA- and Health Canada-approved product Technivie. First approved in July 2015, Technivie is indicated in combination with Ribavirin for the treatment of patients with genotype 4 chronic hepatitis C virus (HCV) infection without cirrhosis or with compensated cirrhosis. In Canada, ritonavir is also available as a fixed-dose combination product with [DB09296], [DB09183], and [DB09297] as the Health Canada-approved, commercially available product Holkira Pak. First approved in January 2015, Holkira Pak is indicated for the treatment of HCV genotype 1b with or without cirrhosis, and when combined with Ribavirin for the treatment of HCV genotype 1a with or without cirrhosis. The inclusion of ritonavir can select for HIV-1 protease inhibitor resistance-associated substitutions. Any HCV/HIV-1 co-infected patients treated with ritonavir-containing combination therapies should also be on a suppressive antiretroviral drug regimen to reduce the risk of HIV-1 protease inhibitor drug resistance. Ritonavir is combined with other drugs to treat coronavirus disease 2019 (COVID-19) in patients at risk for progressing into a severe form of the disease, such as [nirmatrelvir].
Ritonavir is a Cytochrome P450 3A Inhibitor and Protease Inhibitor. The mechanism of action of ritonavir is as a HIV Protease Inhibitor and Cytochrome P450 3A Inhibitor and Cytochrome P450 2D6 Inhibitor and Cytochrome P450 2C19 Inducer and Cytochrome P450 3A Inducer and P-Glycoprotein Inhibitor and Breast Cancer Resistance Protein Inhibitor and Cytochrome P450 3A4 Inhibitor and Cytochrome P450 1A2 Inducer and Cytochrome P450 2C9 Inducer and Cytochrome P450 2B6 Inducer and UDP Glucuronosyltransferases Inducer.
Ritonavir is an antiretroviral protease inhibitor that is widely used in combination with other protease inhibitors in the therapy and prevention of human immunodeficiency virus (HIV) infection and the acquired immunodeficiency syndrome (AIDS). Ritonavir can cause transient and usually asymptomatic elevations in serum aminotransferase levels and, rarely, can lead to clinically apparent acute liver injury. In HBV or HCV coinfected patients, highly active antiretroviral therapy with ritonavir may result of an exacerbation of the underlying chronic hepatitis B or C.
Ritonavir is a peptidomimetic agent that inhibits both HIV-1 and HIV-2 proteases. Ritonavir is highly inhibited by serum proteins but boosts the effect of other HIV proteases by blocking their degradation by cytochrome P450.
An HIV protease inhibitor that works by interfering with the reproductive cycle of HIV. It also inhibits CYTOCHROME P-450 CYP3A.
See also: Ombitasvir; Paritaprevir; Ritonavir (annotation moved to).
Drug Indication
Ritonavir is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. In the US, Europe, and Canada, ritonavir, in combination with [nirmatrelvir], is indicated for the treatment of mild-to-moderate coronavirus disease 2019 (COVID-19) in adults who are at high risk for progression to severe COVID-19, including hospitalization or death. In Europe, this therapeutic indication is approved under conditional marketing authorization.
FDA Label
Ritonavir is indicated in combination with other antiretroviral agents for the treatment of HIV-1-infected patients (adults and children of two years of age and older).
Ritonavir is indicated in combination with other antiretroviral agents for the treatment of HIV 1 infected patients (adults and children of 2 years of age and older).
Mechanism of Action
Ritonavic inhibits the HIV viral proteinase enzyme that normally cleaves the structural and replicative proteins that arise from major HIV genes, such as *gag* and *pol*. *Gag* encodes proteins involved in the core and the nucleocapsid, while *pol* encodes the the HIV reverse transcriptase, ribonuclease H, integrase, and protease. The *pol*-encoded proteins are initially translated in the form of a larger precursoe polypeptide, *gag-pol*, and needs to be cleaved by HIV protease to form other complement proteins. Ritonavir prevents the cleavage of the *gag-pol* polyprotein, which results in noninfectious, immature viral particles. Ritonavir is a potent inhibitor of cytochrome P450 CYP3A4 isoenzyme present both in the intestinal tract and liver. It is a type II ligand that perfectly fits into the CYP3A4 active site cavity and irreversibly binds to the heme iron via the thiazole nitrogen, which decreases the redox potential of the protein and precludes its reduction with the redox partner, cytochrome P450 reductase. Ritonavir may also play a role in limiting cellular transport and efflux of other protease inhibitors via the P-glycoprotein and MRP efflux channels.
Unlike nucleoside antiretroviral agents, the antiviral activity of ritonavir does not depend on intracellular conversion to an active metabolite. Ritonavir and other HIV protease inhibitors (e.g., amprenavir, indinavir, lopinavir, nelfinavir, saquinavir) act at a different stage of the HIV replication cycle than nucleoside and nonnucleoside reverse transcriptase inhibitors, and results of in vitro studies indicate that the antiretroviral effects of HIV protease inhibitors and some nucleoside or nonnucleoside antiretroviral agents may be additive or synergistic.
Ritonavir is a selective, competitive, reversible inhibitor of HIV protease. HIV protease, an aspartic endopeptidase that functions as a homodimer, plays an essential role in the HIV replication cycle and the formation of infectious virus. During HIV replication, HIV protease cleaves viral polypeptide products of the gag and gag-pol genes (i.e., p55 and p160) to form structural proteins of the virion core (i.e., p17, p24, p9, and p7) and essential viral enzymes (i.e., reverse transcriptase, integrase, and protease). By interfering with the formation of these essential proteins and enzymes, ritonavir blocks maturation of the virus and causes formation of nonfunctional, immature, noninfectious virions. Ritonavir is active in both acutely and chronically infected cells since it targets the HIV replication cycle after translation and before assembly. Thus, the drug is active in chronically infected cells (e.g., monocytes and macrophages) that generally are not affected by nucleoside reverse transcriptase inhibitors (e.g., didanosine, lamivudine, stavudine, zalcitabine, zidovudine). Ritonavir does not affect early stages of the HIV replication cycle; however, the drug interferes with production of infectious HIV and limits further infectious spread of the virus.
While the complete mechanisms of antiviral activity of ritonavir have not been fully elucidated, ritonavir apparently inhibits replication of retroviruses, including human immunodeficiency virus type 1 (HIV-1) and 2 (HIV-2), by interfering with HIV protease. The drug, therefore, exerts a virustatic effect against retroviruses by acting as an HIV protease inhibitor.
These protocols are for reference only. InvivoChem does not independently validate these methods.
Physicochemical Properties
Molecular Formula
C37H48N6O5S2
Molecular Weight
720.94
Exact Mass
720.312
Elemental Analysis
C, 61.64; H, 6.71; N, 11.66; O, 11.10; S, 8.90
CAS #
155213-67-5
Related CAS #
Ritonavir-d6;1616968-73-0;rel-Ritonavir-d6;1217720-20-1;Ritonavir metabolite;176655-55-3;Ritonavir-13C,d3
PubChem CID
392622
Appearance
White to off-white solid powder
Density
1.2±0.1 g/cm3
Boiling Point
947.0±65.0 °C at 760 mmHg
Melting Point
120-122°C
Flash Point
526.6±34.3 °C
Vapour Pressure
0.0±0.3 mmHg at 25°C
Index of Refraction
1.600
LogP
5.28
Hydrogen Bond Donor Count
4
Hydrogen Bond Acceptor Count
9
Rotatable Bond Count
18
Heavy Atom Count
50
Complexity
1040
Defined Atom Stereocenter Count
4
SMILES
S1C([H])=C(C([H])([H])N(C([H])([H])[H])C(N([H])[C@]([H])(C(N([H])[C@@]([H])(C([H])([H])C2C([H])=C([H])C([H])=C([H])C=2[H])C([H])([H])[C@@]([H])([C@]([H])(C([H])([H])C2C([H])=C([H])C([H])=C([H])C=2[H])N([H])C(=O)OC([H])([H])C2=C([H])N=C([H])S2)O[H])=O)C([H])(C([H])([H])[H])C([H])([H])[H])=O)N=C1C([H])(C([H])([H])[H])C([H])([H])[H]
InChi Key
NCDNCNXCDXHOMX-XGKFQTDJSA-N
InChi Code
InChI=1S/C37H48N6O5S2/c1-24(2)33(42-36(46)43(5)20-29-22-49-35(40-29)25(3)4)34(45)39-28(16-26-12-8-6-9-13-26)18-32(44)31(17-27-14-10-7-11-15-27)41-37(47)48-21-30-19-38-23-50-30/h6-15,19,22-25,28,31-33,44H,16-18,20-21H2,1-5H3,(H,39,45)(H,41,47)(H,42,46)/t28-,31-,32-,33-/m0/s1
Chemical Name
1,3-thiazol-5-ylmethyl N-[(2S,3S,5S)-3-hydroxy-5-[[(2S)-3-methyl-2-[[methyl-[(2-propan-2-yl-1,3-thiazol-4-yl)methyl]carbamoyl]amino]butanoyl]amino]-1,6-diphenylhexan-2-yl]carbamate
Synonyms
ABT-538; A 84538; Norvir; ABT538; Norvir; ABT-538; A-84538; Abbott 84538; ABBOTT-84538; Empetus; A-84538; Norvir Sec; 538, ABT; Ritonavir; ABT 538;
HS Tariff Code
2934.99.9001
Storage

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Shipping Condition
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
Solubility Data
Solubility (In Vitro)
DMSO: ~100 mg/mL (~138.7 mM)
Water: <1 mg/mL
Ethanol: ~3 mg/mL (~4.2 mM)
Solubility (In Vivo)
Solubility in Formulation 1: 2.5 mg/mL (3.47 mM) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with sonication.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C,1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

Solubility in Formulation 2: 2.5 mg/mL (3.47 mM) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 3: 2.5 mg/mL (3.47 mM) in 5% DMSO + 40% PEG300 + 5% Tween80 + 50% Saline (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.


Solubility in Formulation 4: 2.5 mg/mL (3.47 mM) in 5% DMSO + 95% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
Preparation of 20% SBE-β-CD in Saline (4°C,1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

Solubility in Formulation 5: 0.5 mg/mL (0.69 mM) in 1% DMSO 99% Saline (add these co-solvents sequentially from left to right, and one by one), suspension solution; with ultrasonication.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

Solubility in Formulation 6: 30% PEG400+0.5% Tween80+5% propylene glycol: 30 mg/mL

 (Please use freshly prepared in vivo formulations for optimal results.)
Preparing Stock Solutions 1 mg 5 mg 10 mg
1 mM 1.3871 mL 6.9354 mL 13.8708 mL
5 mM 0.2774 mL 1.3871 mL 2.7742 mL
10 mM 0.1387 mL 0.6935 mL 1.3871 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.

Calculator

Molarity Calculator allows you to calculate the mass, volume, and/or concentration required for a solution, as detailed below:

  • Calculate the Mass of a compound required to prepare a solution of known volume and concentration
  • Calculate the Volume of solution required to dissolve a compound of known mass to a desired concentration
  • Calculate the Concentration of a solution resulting from a known mass of compound in a specific volume
An example of molarity calculation using the molarity calculator is shown below:
What is the mass of compound required to make a 10 mM stock solution in 5 ml of DMSO given that the molecular weight of the compound is 350.26 g/mol?
  • Enter 350.26 in the Molecular Weight (MW) box
  • Enter 10 in the Concentration box and choose the correct unit (mM)
  • Enter 5 in the Volume box and choose the correct unit (mL)
  • Click the “Calculate” button
  • The answer of 17.513 mg appears in the Mass box. In a similar way, you may calculate the volume and concentration.

Dilution Calculator allows you to calculate how to dilute a stock solution of known concentrations. For example, you may Enter C1, C2 & V2 to calculate V1, as detailed below:

What volume of a given 10 mM stock solution is required to make 25 ml of a 25 μM solution?
Using the equation C1V1 = C2V2, where C1=10 mM, C2=25 μM, V2=25 ml and V1 is the unknown:
  • Enter 10 into the Concentration (Start) box and choose the correct unit (mM)
  • Enter 25 into the Concentration (End) box and select the correct unit (mM)
  • Enter 25 into the Volume (End) box and choose the correct unit (mL)
  • Click the “Calculate” button
  • The answer of 62.5 μL (0.1 ml) appears in the Volume (Start) box
g/mol

Molecular Weight Calculator allows you to calculate the molar mass and elemental composition of a compound, as detailed below:

Note: Chemical formula is case sensitive: C12H18N3O4  c12h18n3o4
Instructions to calculate molar mass (molecular weight) of a chemical compound:
  • To calculate molar mass of a chemical compound, please enter the chemical/molecular formula and click the “Calculate’ button.
Definitions of molecular mass, molecular weight, molar mass and molar weight:
  • Molecular mass (or molecular weight) is the mass of one molecule of a substance and is expressed in the unified atomic mass units (u). (1 u is equal to 1/12 the mass of one atom of carbon-12)
  • Molar mass (molar weight) is the mass of one mole of a substance and is expressed in g/mol.
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Reconstitution Calculator allows you to calculate the volume of solvent required to reconstitute your vial.

  • Enter the mass of the reagent and the desired reconstitution concentration as well as the correct units
  • Click the “Calculate” button
  • The answer appears in the Volume (to add to vial) box
In vivo Formulation Calculator (Clear solution)
Step 1: Enter information below (Recommended: An additional animal to make allowance for loss during the experiment)
Step 2: Enter in vivo formulation (This is only a calculator, not the exact formulation for a specific product. Please contact us first if there is no in vivo formulation in the solubility section.)
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Calculation results

Working concentration mg/mL;

Method for preparing DMSO stock solution mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.

Method for preparing in vivo formulation:Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O,mix and clarify.

(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
             (2) Be sure to add the solvent(s) in order.

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Biological Data
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