HIV-1 protease inhibitor [2]
HIV-1 protease inhibitor [4]
Matrix metalloproteinase (MMP) expression and activity inhibitor (Specifically MMP-2 and MMP-9) [4]

Saquinavir is a protease inhibitor. Proteases are enzymes that break protein molecules into smaller fragments. HIV protease is crucial for intracellular viral replication and the release of mature viral particles from infected cells. Saquinavir binds to the active site of the viral protease and blocks cleavage of the viral polyprotein, hence preventing viral maturation. Saquinavir inhibits both HIV-1 and HIV-2 proteases. Research has also looked at saquinavir as a promising anti-cancer medication.

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At a concentration of 10 µM, saquinavir significantly inhibited the invasion of human primary cervical intraepithelial neoplasia (CIN) cells (CIN612-7E and CIN612-9E) promoted by epidermal growth factor (EGF, 20 ng/ml). In CIN612-7E cells, inhibition was approximately -82% (P = 0.03). [4]
Treatment with 10 µM saquinavir for 96 hours down-regulated the expression of MMP-9 and MMP-2 genes in CIN cells. In CIN612-7E cells, it reduced MMP-9 RNA levels by approximately -58% (P = 0.01) and MMP-2 RNA levels by approximately -55% (P = 0.01). [4]
Treatment with 10 µM saquinavir for 96 hours reduced the gelatinolytic activity of MMP-9 and MMP-2 released by CIN cells. In CIN612-7E cells, it reduced MMP-9 proteolytic activity by approximately -74% and MMP-2 activity by approximately -41%. [4]
Treatment with 10 µM saquinavir for 5 days reduced the growth rate (cytostatic effect) of primary CIN cells, but did not affect the growth rate of cervical carcinoma-derived cell lines (SiHa, CaSki). [4]
Treatment with 10 µM saquinavir did not significantly inhibit the invasion of highly progressed cervical carcinoma cell lines (SiHa and CaSki), nor did it affect MMP-2 expression or activity in these cells. However, it reduced MMP-9 expression by -44% (P = 0.02) and activity by -71% (P = 0.04) in CaSki cells. [4]

In a 48-week, multicenter, open-label, non-inferiority clinical trial (Gemini study), treatment-naive HIV-1-infected adults receiving saquinavir boosted with ritonavir (SQV/r 1000/100 mg twice daily) in combination with emtricitabine/tenofovir (FTC/TDF) demonstrated similar virologic efficacy to those receiving lopinavir/ritonavir (LPV/r). At week 48, 64.7% of participants in the SQV/r arm (n=167) achieved HIV-1 RNA <50 copies/mL, compared to 63.5% in the LPV/r arm (n=170), meeting the non-inferiority criterion. [2]
The median increase in CD4 cell count from baseline at week 48 was 178 cells/mm³ in the SQV/r arm. [2]
The proportion of participants with virologic failure (VF) was 7% (11/167) in the SQV/r arm. Among these, only one participant developed new major protease inhibitor (PI)-associated resistance mutations (G48V, V82A, I84V) at the time of failure, and this participant was also documented as poorly adherent. [2]

Zymography for MMP Activity: Total proteins from conditioned media of cells treated with or without 10 µM saquinavir for 96 hours were separated by non-reducing SDS-PAGE co-polymerized with gelatin. Gels were incubated overnight at 37°C to allow enzymatic degradation of gelatin. After staining, the decrease in staining intensity (cleared bands) corresponding to MMP-2 (72 kD) and MMP-9 (92 kD) activity was quantified by densitometry. [4]

Cell Invasion Assay (Boyden Chamber): Primary CIN cells (CIN612-7E, CIN612-9E) or cervical carcinoma cell lines (SiHa, CaSki) were cultured for 96 hours in the absence or presence of 10 µM saquinavir. Cells were then harvested and seeded into the upper chamber of a Boyden chamber apparatus with a reconstituted basement membrane. The lower chamber contained 20 ng/ml human recombinant epidermal growth factor (EGF) as a chemoattractant. After incubation, cells that invaded through the membrane to the lower side were counted. [4]
Cell Growth Assay: CIN cells (seeded at 1.5 x 10^4 cells/well) or cervical carcinoma cells (seeded at 0.5 x 10^4 cells/well) were cultured for 5 days in the absence or presence of 10 µM saquinavir. The number of viable cells was counted at the end of the culture period. [4]
Cell Toxicity Assay (XTT Assay): CIN612-7E cell sensitivity to saquinavir was evaluated using an XTT-based in vitro toxicology assay. Cells were cultured for 48 hours with 10 µM saquinavir. The assay measures the reduction of XTT tetrazolium to a water-soluble orange formazan derivative by mitochondrial dehydrogenases in living cells. Absorbance was measured spectrophotometrically, and cell survival rate was calculated relative to untreated controls. [4]
Western Blot Analysis: CIN612-7E cells were cultured in the absence or presence of 10 µM saquinavir for the indicated time. Cells were lysed, proteins were separated by SDS-PAGE, transferred to a membrane, and probed with a monoclonal antibody against p53. Blots were re-probed with anti-β-actin antibody for loading control. Band intensity was quantified by densitometry. [4]
Real-Time Polymerase Chain Reaction (RT-PCR): Total RNA was extracted from cells treated with or without 10 µM saquinavir for 96 hours. cDNA was synthesized and amplified using specific primers for MMP-2 and MMP-9. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as a housekeeping gene for normalization. RT-PCR was performed using a SYBR Green PCR kit. [4]

Absorption, Distribution and Excretion
The absolute bioavailability of saquinavir via oral administration is only about 4%, which is believed to be due to incomplete absorption and extensive first-pass metabolism. To significantly increase serum concentrations of saquinavir and thus improve its therapeutic effect, it is often used in combination with ritonavir. Ritonavir is another protease inhibitor and a potent inhibitor of enzymes involved in the first-pass metabolism of saquinavir. After twice-daily administration of 1000 mg saquinavir and 100 mg ritonavir, the steady-state AUC24h was 39026 ng·h/mL. The primary elimination pathway of saquinavir appears to be extensive hepatic metabolism, followed by excretion of the parent drug and its metabolites in the feces. Following oral or intravenous administration of radiolabeled saquinavir, approximately 81-88% of the radioactive material is excreted in the feces within 5 days of administration, while only 1-3% is excreted in the urine. Mass balance studies showed that after oral administration, only 13% of the radioactive material in plasma originated from unmetabolized parent drug, with the remainder originating from hepatic metabolites of saquinavir. In contrast, after intravenous administration, approximately 66% of the radioactivity in circulating plasma was attributed to unmetabolized parent drug, indicating a higher degree of first-pass metabolism after oral administration. The steady-state volume of distribution of saquinavir is approximately 700 L, indicating its widespread distribution in tissues. The systemic clearance of saquinavir after intravenous administration is approximately 1.14 L/h/kg. The mean steady-state AUC at 3 weeks after administration of 1200 mg saquinavir liquid capsules three times daily was 7249 nGh/mL, while the AUC after administration of 600 mg saquinavir hard capsules three times daily was 866 nGh/mL. Although the AUC of saquinavir in adults taking liquid-filled capsules was lower in weeks 61–69 than in week 3, the AUC in HIV-infected adults taking hard gelatin capsules (600 mg, three times daily) was higher in weeks 61–69 than at the same time point. It is estimated that the relative oral bioavailability of saquinavir in liquid-filled (soft gelatin) capsules is approximately 331% (range: 207–530%) of that in hard gelatin capsules at a single 600 mg dose. Based on the average absolute bioavailability of 4% for hard capsules, the average oral bioavailability of liquid-filled capsules is approximately 13%. However, these are calculated estimates and not based on actual measurements of oral bioavailability of liquid capsules. Saquinavir and its metabolites are primarily excreted via the biliary system and feces (over 95% of the drug), with very little excretion in urine (less than 3% of the administered dose). Due to limited absorption and extensive first-pass metabolism, the oral bioavailability of saquinavir hard capsules (saquinavir mesylate, Invirase) is only 4%, with significant inter-patient variability. …Concomitant administration with high-calorie, high-fat foods can enhance saquinavir absorption. Furthermore, the increase in saquinavir exposure is greater than the dose-proportional increase. For example, a three-fold increase in the oral dose of saquinavir leads to an eight-fold increase in exposure. For more complete data on the absorption, distribution, and excretion of saquinavir (10 items in total), please visit the HSDB record page. Metabolism/Metabolites Following oral administration, saquinavir is primarily metabolized in the liver. In vitro studies have shown that over 90% of its biotransformation is mediated by the CYP3A4 isoenzyme. Saquinavir is rapidly metabolized into a variety of inactive monohydroxylated and dihydroxylated compounds. In vitro studies have demonstrated that saquinavir is rapidly metabolized in the liver into a variety of inactive monohydroxylated and dihydroxylated metabolites. Saquinavir metabolism is mediated by cytochrome P450; CYP3A4 isoenzymes are involved in over 90% of the metabolism. Significant changes appear to occur after oral administration of saquinavir following first-pass metabolism in the liver. Saquinavir is primarily metabolized by hepatic CYP3A4. Saquinavir metabolites are inactive against HIV-1. Known human metabolites of saquinavir include: (2S)-N-[(2S,3R)-4-[(3S,4aS,8aS)-3-(tert-butylcarbamoyl)-7-hydroxy-decahydroisoquinoline-2-yl]-3-hydroxy-1-phenylbut-2-yl]-2-[(quinoline-2-yl)carbamoyl]butyramide, (2S)-N-[(2S,3R)-4-[(3S,4aS,8aS)-3-[(1-hydroxy-2-yl)carbamoyl]butyramide, and (2S)-N-[(2S,3R)-4-[(3S,4aS,8aS)-3-[(1-hydroxy-2-yl)carbamoyl]butyramide. [Methylpropyl-2-yl]carbamoyl]-decahydroisoquinoline-2-yl]-3-hydroxy-1-phenylbut-2-yl]-2-[(quinoline-2-yl)carbamoyl]succinamide and (2S)-N-[(2S,3R)-4-[(3S,4aR,8aS)-3-(tert-butylcarbamoyl)-6-hydroxy-decahydroisoquinoline-2-yl]-3-hydroxy-1-phenylbut-2-yl]-2-[(quinoline-2-yl)carbamoyl]succinamide. This study employed a ritonavir enhancement regimen (saquinavir/ritonavir, SQV/r) to improve the pharmacokinetic characteristics of saquinavir. However, specific pharmacokinetic parameters of saquinavir (e.g., Cmax, Tmax, AUC, half-life, bioavailability) are not reported in this paper. [2] The article points out that the development of a new 500 mg film-coated tablet formulation (Invirase) reduces the burden of medication and makes saquinavir more suitable as a first-line treatment. [2]

Interactions
Saquinavir co-administration with terfenadine may result in elevated terfenadine plasma concentrations. Saquinavir competes with astemizole, cisapride, ergot Derivative, midazolam, or triazolam for the cytochrome P450 enzyme CYP3A, potentially inhibiting the metabolism of these drugs and leading to serious and/or life-threatening arrhythmias or persistent sedation. Therefore, co-administration of any of these drugs with saquinavir mesylate capsules or saquinavir soft capsules is not recommended. Saquinavir mesylate capsules co-administered with calcium channel blockers, clindamycin, dapsone, or quinidine (these drugs are substrates of the cytochrome P450 enzyme system CYP3A4 isoenzyme) may result in elevated plasma concentrations of these drugs; patients should be monitored for toxicities associated with these drugs. Ethanol intake reduces the bioavailability of oral saquinavir (SQV), whether taken alone or in combination with ritonavir (RTV).
Concomitant use of rifabutin or rifampin with saquinavir mesylate capsules can reduce the steady-state AUC and peak plasma concentration of saquinavir by approximately 80% and 40%, respectively; carbamazepine, dexamethasone, phenobarbital, phenytoin sodium, or other CYP3A4 inducers may also reduce the plasma concentration of saquinavir; if a patient is taking any of the preparations of saquinavir, alternative medications should be considered.
For more complete data on drug interactions of saquinavir (17 in total), please visit the HSDB record page.

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In the Gemini study, 3% (5/167) of subjects in the SQV/r group discontinued treatment due to adverse events (AEs). [2]
The most frequently reported drug-related adverse events in the SQV/r group were gastrointestinal disorders (17%, 27/167). Specific adverse events reported in the SQV/r group included bronchitis (6%), diarrhea (7%), nausea (6%), and upper respiratory tract infection (2%). [2]
The incidence of renal adverse events was low in the SQV/r group (4%, 7 subjects). Two of these were serious adverse events (kidney stones; and hypokalemia with atrial tachycardia and tuberculous pleurisy). No subjects withdrew from the study due to renal-related adverse events. [2]
Regarding changes in plasma lipids, SQV/r treatment resulted in elevated levels of fasting total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) from baseline. However, compared to the LPV/r group, the median increase in TG levels at weeks 24 and 48 was significantly lower in the SQV/r group. [2]
Six of the 167 subjects in the SQV/r group (3.6%) started lipid-lowering therapy (all receiving statins). [2]
Three subjects died in the SQV/r group. One death (a crime victim) was considered by the researchers to be unrelated to the study drug. [2]
After treating CIN612-7E cells with 10 µM saquinavir for 48 hours, XTT assay showed very little cell death. Its toxicity was significantly lower than that of the apoptotic anticancer drug astrococcus used as a positive control. [4]
After treating CIN cells with 10 µM saquinavir, the intracellular protein level of the tumor suppressor p53 did not change, indicating that at this therapeutic concentration, saquinavir does not significantly impair the cellular proteasome function associated with p53 degradation. [4]

[1]. In vitro and in vivo anticancer action of Saquinavir-NO, a novel nitric oxide-derivative of the protease inhibitor saquinavir, on hormone resistant prostate cancer cells. Cell cycle. 2011, 1.

[2]. Gemini: A Noninferiority Study of Saquinavir/Ritonavir Versus Lopinavir/Ritonavir as Initial HIV-1 Therapy in Adults. JAIDS Journal of Acquired Immune Deficiency Syndromes. 2009,50 (4) :367-374.

[3]. Saquinavir.

[4]. Ritonavir or saquinavir impairs the invasion of cervical intraepithelial neoplasia cells via a reduction of MMP expression and activity. AIDS. 2012, 26 (8): 909-919.

[5]. Saquinavir Inhibits Early Events Associated with Establishment of HIV-1 Infection: Potential Role for Protease Inhibitors in Prevention. Antimicrob. Agents Chemother. 2012, 56 (8): 4381-4390.

[6]. 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
Saquinavir is indicated for the treatment of HIV infection or AIDS when used in combination with other antiretroviral drugs. Saquinavir softgels (Fortovase) are the preferred dosage form, as recommended by the U.S. Food and Drug Administration (FDA). /U.S. product label contains/
Saquinavir was not detected in cord blood. Saquinavir softgels were well tolerated during pregnancy and were not associated with birth abnormalities in this small study. Mother-to-child transmission of HIV was successfully prevented in all cases. Low levels of saquinavir exposure were observed in the mothers. However, this did not appear to affect the virological efficacy of the combination therapy. Cord blood samples showed extremely low fetal exposure to saquinavir.
Drug Warnings Major adverse reactions associated with saquinavir treatment involve the gastrointestinal tract. In HIV-infected adults receiving saquinavir liquid or hard capsules in combination with other antiretroviral agents (e.g., 2-dideoxynucleoside reverse transcriptase inhibitors), the incidence of diarrhea was 15.6%–19.9%, abdominal discomfort 8.6%–13.3%, abdominal pain 2.3%–7.8%, nausea 10.6%–17.8%, dyspepsia 8.4%–8.9%, abdominal distension 5.7%–12.2%, vomiting 2.9%–4.4%, taste disturbances 4.4%, and constipation 3.3%. Adverse gastrointestinal reactions occurring in less than 2% of patients receiving saquinavir hard or liquid capsules as monotherapy or in combination with other antiretroviral agents included anorexia, abdominal distension, buccal mucosal ulceration, oral ulceration, cheilitis, and dryness. Oral symptoms, dysphagia, abdominal cramps, esophageal ulcers, esophagitis, belching, hematochezia or abnormal stool color, increased bowel movements, fecal incontinence, stomach pain, gastritis, gastroesophageal reflux, gastrointestinal ulcers, gastrointestinal inflammation, intestinal obstruction, gingivitis, glossitis, hemorrhoids, infectious diarrhea, melena, painful defecation, parotid gland disease, anal itching, /SRP: heartburn/, stomach discomfort, pelvic pain, rectal bleeding, salivary gland disease, stomatitis, taste disturbances, toothache, and dental disease.
In HIV-infected adults receiving saquinavir liquid capsules in combination with other antiretroviral drugs, headache occurred in 58.9% of cases. Among patients receiving saquinavir liquid capsules in combination with other antiretroviral therapies, the reported rates of depression were 2.7%, insomnia 5.6%, and anxiety or sexual dysfunction 2.2%. In patients receiving saquinavir hard capsules or liquid capsules (alone or in combination with other antiretroviral drugs), adverse neurological reactions reported in less than 2% of cases include ataxia, cerebral hemorrhage, confusion, seizures, dizziness, dysarthria, paresthesia, facial numbness, facial pain, limb numbness, hyperesthesia, hyperreflexia, hyporeflexia, dizziness, polyradiculoneuritis, paresthesia, peripheral neuropathy, tingling, hemiparesis, poliomyelitis, progressive multifocal leukoencephalopathy, spasticity, tremor, and loss of consciousness. Adverse psychological reactions reported in less than 2% of patients receiving this drug include agitation, amnesia, anxiety, behavioral disorders, vivid dreams, euphoria, hallucinations, irritability, somnolence, overdose, mental disorders, psychosis, intellectual decline, drowsiness, and speech disorders. Rarely reported serious neurological adverse reactions (considered at least possibly related to the study drug) in clinical studies of patients receiving saquinavir monotherapy or in combination with other antiretroviral agents include suicide attempts, confusion, ataxia, asthenia, and headache. For more complete data on saquinavir (23 total), please visit the HSDB records page. Pharmacodynamics: Saquinavir exerts its antiviral activity by inhibiting a key enzyme in the HIV-1 viral life cycle. As with other protease inhibitors, saquinavir is prone to drug interactions—caution should be exercised when using saquinavir in patients taking other medications due to the prevalence of pharmacodynamic and pharmacokinetic interactions. Saquinavir is known to prolong the QTc interval in healthy individuals; therefore, caution should be exercised when using saquinavir in patients taking other medications that prolong the QTc interval, or in patients where QTc interval prolongation may have serious consequences (e.g., patients with a history of heart disease). Careful and regular blood tests are recommended for patients, as saquinavir is associated with the development of metabolic complications such as diabetes and hyperlipidemia, as well as the exacerbation of pre-existing liver disease.

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Saquinavir is a well-established HIV-1 protease inhibitor. [2]
The Gemini study showed that in treatment-naïve patients, the saquinavir-enhanced ritonavir (SQV/r) regimen was non-inferior to the lopinavir/ritonavir (LPV/r) regimen over 48 weeks, supporting its use as a preferred first-line treatment. [2]
This study highlights that saquinavir-enhanced ritonavir has a superior triglyceride profile compared to the lopinavir/ritonavir regimen, which may be a factor to consider for patients at risk of metabolic complications. [2]
The incidence of major protease inhibitor resistance mutations was low in patients who failed virology in the SQV/r group, supporting the use of enhanced protease inhibitors in initial treatment. [2]
Saquinavir is an HIV protease inhibitor used in highly active antiretroviral therapy (HAART). [4] In addition to its antiviral activity, saquinavir has also shown direct antitumor and antiangiogenic properties in HIV-free preclinical models. [4] This study provides a mechanistic explanation for the clinical benefits observed with highly active antiretroviral therapy (HAART, which includes protease inhibitors such as saquinavir) in reducing the occurrence and progression of cervical intraepithelial neoplasia (CIN) in HIV-infected women. [4] The data suggest that saquinavir, at therapeutic concentrations, effectively inhibits the invasion of precancerous CIN cells by downregulating key matrix metalloproteinases (MMP-2 and MMP-9), but may lack efficacy against highly advanced cervical cancer cells. [4]
These findings support the repurposing of saquinavir for the prevention of progression or recurrence of cervical intraepithelial neoplasia (CIN), providing a potential non-surgical treatment option. [4]

C38H50N6O5

670.85

670.384

127779-20-8

Saquinavir mesylate;149845-06-7;Saquinavir-d9;1356355-11-7

441243

White to off-white solid powder

1.3±0.1 g/cm3

1015ºC at 760 mmHg

91.5ºC

567.7ºC

0mmHg at 25°C

1.646

6.4

5

7

13

49

1140

6

CC(C)(C)NC(=O)[C@@H]1C[C@@H]2CCCC[C@@H]2CN1C[C@H]([C@H](CC3=CC=CC=C3)NC(=O)[C@H](CC(=O)N)NC(=O)C4=NC5=CC=CC=C5C=C4)O

QWAXKHKRTORLEM-UGJKXSETSA-N

InChI=1S/C38H50N6O5/c1-38(2,3)43-37(49)32-20-26-14-7-8-15-27(26)22-44(32)23-33(45)30(19-24-11-5-4-6-12-24)41-36(48)31(21-34(39)46)42-35(47)29-18-17-25-13-9-10-16-28(25)40-29/h4-6,9-13,16-18,26-27,30-33,45H,7-8,14-15,19-23H2,1-3H3,(H2,39,46)(H,41,48)(H,42,47)(H,43,49)/t26-,27+,30-,31-,32-,33+/m0/s1

(2S)-N-[(2S,3R)-4-[(3S,4aS,8aS)-3-(tert-butylcarbamoyl)-3,4,4a,5,6,7,8,8a-octahydro-1H-isoquinolin-2-yl]-3-hydroxy-1-phenylbutan-2-yl]-2-(quinoline-2-carbonylamino)butanediamide

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)

DMSO : ~100 mg/mL (~149.07 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (3.73 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 (3.73 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 (3.73 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.)