PXR; HIV protease (IC50 = 14.6 ng/mL)

Amprenavir has an enzyme inhibition constant (Ki = 0.6 nM) that is within the other protease inhibitors' Ki range. The in vitro 50% inhibitory concentration (IC50) of amprenavir against clinical HIV isolates of wild type is 14.6 +/- 12.5 ng/mL (mean +/- SD) [1]. By preventing MMP proteolytic activation, amprenavir directly inhibited the invasion of Huh-7 hepatocarcinoma cell lines [2].

Amprenavir was able to encourage the remission of hepatocarcinoma growth in vivo through anti-angiogenetic and general anti-tumor activities, through independent pathways related to PI3K/AKT, which is currently one of the more plausible theories to explain the anti-tumor effects of the various protease inhibitors[2]. PXR was effectively activated and PXR target gene expression was induced both in vitro and in vivo by amprenavir. In mice of the wild type, but not in mice lacking PXR, a brief exposure to amprenavir markedly raised the levels of atherogenic low-density lipoprotein cholesterol and plasma total cholesterol [3]. The recommended dosage of amprenavir for adults and children is 1200 mg twice daily for adults, 20 mg/kg twice daily for children under the age of 13, or 15 mg/kg three times daily for adolescents under the weight of 50 kg[1].

Amprenavir induced the expression of the PXR target gene in LS180 intestinal cells and HepaRG hepatoma cells.

Absorption, Distribution and Excretion
Rapidly absorbed after oral administration in HIV-1-infected patients with a time to peak concentration (Tmax) typically between 1 and 2 hours after a single oral dose. The absolute oral bioavailability of amprenavir in humans has not been established.
Amprenavir is absorbed rapidly after oral administration. Taking amprenavir with a standard meal reduces the plasma AUC by only about 13%, but high-fat meals may have greater effects and should be avoided.
Only minimal amounts of amprenavir are eliminated unchanged in urine or feces; less than 3% of a dose is eliminated unchanged in urine. Following a single oral dose of radiolabeled amprenavir, approximately 14% of the dose is eliminated in urine and 75% is eliminated in feces; 2 metabolites account for more than 90% of radioactivity in feces.
Distribution of amprenavir into body tissues and fluids has not been fully characterized. Studies in rats indicate that amprenavir is distributed to a variety of tissues following oral administration. The apparent volume of distribution of amprenavir in healthy adults is approximately 430 L.
It is not known whether amprenavir crosses the human placenta; however, the drug crosses the placenta in rats. Information from an ex vivo human placental model for transplacental passage indicates that amprenavir crosses the human placenta. Although it is not known whether amprenavir is distributed in human milk, the drug is distributed into milk in rats.
In patients with hepatic impairment, the peak plasma concentration and AUC of amprenavir may be increased. In adults with moderate cirrhosis who received a single 600-mg oral dose of amprenavir given as liquid-filled capsules, the AUC (0-4 hours) of the drug averaged 25.76 ug hour/mL compared with 12 ug hour/ml in healthy adults. In adults with severe cirrhosis who received the same dose, peak plasma concentrations averaged 9.43 ug/ml and the AUC (0-4 hours) averaged 38.66 ug hour/ml compared with 4.9 ug/ml or 12 ug hour/ml, respectively, in healthy adults.

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Metabolism / Metabolites
Hepatic. Amprenavir is metabolized in the liver by the cytochrome P450 3A4 (CYP3A4) enzyme system. The 2 major metabolites result from oxidation of the tetrahydrofuran and aniline moieties. Glucuronide conjugates of oxidized metabolites have been identified as minor metabolites in urine and feces.
The metabolic fate of amprenavir has not been fully determined, but the drug is metabolized in the liver. Amprenavir is metabolized principally by the cytochrome P450 (CYP) isoenzyme 3A4. The 2 major metabolites of the drug result from oxidation of the tetrahydrofuran and aniline moieties; glucuronide conjugates of oxidized metabolites have been identified as minor metabolites in urine and feces.
Hepatic. Amprenavir is metabolized in the liver by the cytochrome P450 3A4 (CYP3A4) enzyme system. The 2 major metabolites result from oxidation of the tetrahydrofuran and aniline moieties. Glucuronide conjugates of oxidized metabolites have been identified as minor metabolites in urine and feces.
Half Life: 7.1-10.6 hours

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Biological Half-Life
7.1-10.6 hours
The plasma elimination half-life of amprenavir in HIV-infected adults with normal renal and hepatic function ranges from 7.1-10.6 hours.

Toxicity Summary
Amprenavir inhibits the HIV viral proteinase enzyme which prevents cleavage of the gag-pol polyprotein, resulting in noninfectious, immature viral particles.

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Protein Binding
Very high (90%). Amprenavir has the highest affinity for alpha(1)-acid glycoprotein.

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Interactions
Because amprenavir oral solution contains a large amount of propylene glycol, concurrent use /with alcohol, disulfiram, or metronidazole/ is not recommended.
Although these medications /alprazolam, clorazepate, diazepam, or flurazepam/ have not been specifically studied with amprenavir, amprenavir may increase the serum concentrations of these medications.
Although these medications /amiodarone, lidocaine (systemic), tricyclic antidepressants, or quinidine/ have not been specifically studied with amprenavir, amprenavir may interfere in the metabolism of these medications and cause serious or life threatening adverse events; monitoring of serum concentrations for these medications is recommended if amprenavir is used concurrently.
Although antacids have not been specifically studied with amprenavir, based on data from other protease inhibitors, antacids (and didanosine due to the antacid content present in didanosine formulations) may interfere with the absorption of amprenavir; it is recommended that antacid and didanosine administration be separated from amprenavir administration by at least one hour.
For more Interactions (Complete) data for AMPRENAVIR (21 total), please visit the HSDB record page.

[1]. Clinical pharmacology and pharmacokinetics of amprenavir. Ann Pharmacother. 2002 Jan;36(1):102-18.

[2]. Amprenavir inhibits the migration in human hepatocarcinoma cell and the growth of xenografts. J Cell Physiol. 2013 Mar;228(3):640-5.

[3]. Pregnane X Receptor Mediates Dyslipidemia Induced by the HIV Protease Inhibitor Amprenavir in Mice. Mol Pharmacol. 2013 Jun;83(6):1190-9.

[4]. 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.

Therapeutic Uses
Amprenavir is indicated in combination with other antiretroviral agents in the treatment of HIV-1 infection. /Included in US product labeling/
Amprenavir is a human immunodeficiency virus (HIV)-protease inhibitor. The use of amprenavir for the treatment of human immunodeficiency virus type 1 (HIV-1) infection in combination with other antiretrovirals is based on analyses of plasma HIV-RNA levels and CD4 cell counts in controlled studies of up to 24 weeks duration. Results from controlled trials evaluating the long-term suppression of HIV-RNA or disease progression with amprenavir have not yet been obtained.
Amprenavir is a viral protease inhibitor with specificity for the HIV protease enzyme. The resistance profile of amprenavir appears to differ from that of other protease inhibitors such as saquinavir and indinavir. Twelve hours after single-dose administration of amprenavir 1200 mg to HIV-infected individuals, the mean plasma concentration of the drug was more than 10-fold greater than the 50% inhibitory concentration for HIV-1IIIB in peripheral blood lymphocytes. In a small nonblind study, amprenavir monotherapy increased CD4+ cell count and decreased viral load in 37 patients with HIV infection and no previous exposure to protease inhibitor therapy. Combination therapy comprising amprenavir and other antiretroviral agents (abacavir, zidovudine, lamivudine, indinavir, saquinavir or nelfinavir) decreased viral load and increased CD4+ cell counts in patients with HIV infection. Antiviral efficacy was maintained during up to 24 weeks' follow-up.

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Drug Warnings
The usually recommended dosage of amprenavir oral solution (22.5 mg/kg twice daily) provides a propylene glycol intake of 1650 mg/kg daily; however, an acceptable intake of propylene glycol used as an excipient in pharmaceuticals has not been established to date. Propylene glycol is metabolized in the liver by the alcohol and aldehyde dehydrogenase enzyme pathway, and the possibility exists that young infants, patients with renal or hepatic impairment, and certain patient groups (females, Asians, Native Alaskans, Native Americans) may be at increased risk of propylene glycol-associated adverse effects if they receive amprenavir oral solution because of diminished ability to metabolize propylene glycol. Therefore, amprenavir oral solution is contraindicated during pregnancy; in infants younger than 4 years of age; in patients with renal or hepatic failure; and in patients receiving disulfiram or metronidazole. In addition, although metabolism of propylene glycol has not been specifically studied in these patient groups, the possibility that females may have lower concentrations of alcohol dehydrogenase compared with males and that certain ethnic populations (Asians, Native Alaskans, Native Americans) may have alcohol dehydrogenase polymorphism should be considered.
Because amprenavir oral solution contains large amounts of propylene glycol and because young infants may be at increased risk of propylene glycol-associated adverse effects, the oral solution is contraindicated in pediatric patients younger than 4 years of age. Propylene glycol is metabolized in the liver by the alcohol and aldehyde dehydrogenase enzyme pathway. Although alcohol dehydrogenase is present in human fetal liver at 2 months of gestational age, this represent only about 3% of the activity reported in adults. Limited data indicate that alcohol dehydrogenase activity in infants 12-30 months of age is equal to or greater than that reported in adults. Oral or IV administration of various drugs (e.g., multivitamins) containing high concentrations of propylene glycol in pediatric patients has resulted in various propylene glycol-associated adverse effects, including hyperosmolality, lactic acidosis, respiratory depression, and seizures.
Patients being treated with amprenavir oral solution should be closely monitored for propylene glycol associated side effects including hemolysis, hyperosmolality, lactic acidosis, renal toxicity, seizures, stupor, and tachycardia.
The pharmacokinetics of amprenavir do not differ between females and males or between Blacks and non-Blacks. However, amprenavir oral solution contains a large amount of propylene glycol and because Asians, Eskimos, Native Americans, and women have a decreased ability to metabolize this compound, they may have an increased risk of developing propylene glycol-associated side effects.
For more Drug Warnings (Complete) data for AMPRENAVIR (18 total), please visit the HSDB record page.

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Pharmacodynamics
Amprenavir is a protease inhibitor with activity against Human Immunodeficiency Virus Type 1 (HIV-1). Protease inhibitors block the part of HIV called protease. HIV-1 protease is an enzyme required for the proteolytic cleavage of the viral polyprotein precursors into the individual functional proteins found in infectious HIV-1. Amprenavir binds to the protease active site and inhibits the activity of the enzyme. This inhibition prevents cleavage of the viral polyproteins resulting in the formation of immature non-infectious viral particles. Protease inhibitors are almost always used in combination with at least two other anti-HIV drugs.

C25H35N3O6S

505.63

505.224

C, 59.39; H, 6.98; N, 8.31; O, 18.99; S, 6.34

161814-49-9

Amprenavir-d4;1217661-20-5;Amprenavir-d4-1;2738376-78-6

65016

White to off-white solid powder

1.3±0.1 g/cm3

722.5±70.0 °C at 760 mmHg

72-74ºC

390.8±35.7 °C

0.0±2.5 mmHg at 25°C

1.602

4.68

3

8

12

35

745

3

S(C1C([H])=C([H])C(=C([H])C=1[H])N([H])[H])(N(C([H])([H])C([H])(C([H])([H])[H])C([H])([H])[H])C([H])([H])[C@]([H])([C@]([H])(C([H])([H])C1C([H])=C([H])C([H])=C([H])C=1[H])N([H])C(=O)O[C@]1([H])C([H])([H])OC([H])([H])C1([H])[H])O[H])(=O)=O

YMARZQAQMVYCKC-OEMFJLHTSA-N

InChI=1S/C25H35N3O6S/c1-18(2)15-28(35(31,32)22-10-8-20(26)9-11-22)16-24(29)23(14-19-6-4-3-5-7-19)27-25(30)34-21-12-13-33-17-21/h3-11,18,21,23-24,29H,12-17,26H2,1-2H3,(H,27,30)/t21-,23-,24+/m0/s1

[(3S)-oxolan-3-yl] N-[(2S,3R)-4-[(4-aminophenyl)sulfonyl-(2-methylpropyl)amino]-3-hydroxy-1-phenylbutan-2-yl]carbamate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (4.94 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (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 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (4.94 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (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 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.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (4.94 mM) (saturation unknown) 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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 (Please use freshly prepared in vivo formulations for optimal results.)