cytotoxicity in LoVo cells ( IC50 = 15.8 μM ); cytotoxicity in HT-29 cells ( IC50 = 5.17 μM ); Topo I
Topoisomerase I [2]

Irinotecan and Gefitinibstudies have also linked to significantly reduce MDA-MB-231 cell migration and proliferation.[2]

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Cytotoxicity of Irinotecan hydrochloride was evaluated in LoVo and HT-29 human colorectal tumor cell lines. The IC50 values were 15.8 ± 5.1 μM for LoVo cells and 5.17 ± 1.4 μM for HT-29 cells after one cell doubling time (24 h for LoVo, 40 h for HT-29) exposure. Irinotecan hydrochloride was approximately 1000-fold less cytotoxic than its metabolite SN-38 in both cell lines. [1]
No SN-38 formation could be detected after incubation of living cells with Irinotecan hydrochloride or during carboxylesterase activity determination in microsomal extracts using irinotecan as substrate, indicating that the cytotoxicity observed during growth inhibition can be attributed to irinotecan itself rather than SN-38. The limit of detection for SN-38 was 0.2 ng. [1]
Irinotecan hydrochloride induced similar amounts of cleavable complexes at its IC50 value in both cell lines. At 1×IC50, the increase in topoisomerase I-DNA complexes relative to untreated cells was 1.32 ± 0.45 in LoVo cells (no value for HT-29 at 1×IC50 reported for irinotecan). [1]
Cellular accumulation of Irinotecan hydrochloride was linearly related to the dose up to 100 μM. Accumulation was consistently twofold higher in HT-29 cells than in LoVo cells, but the kinetics of incorporation revealed a faster initial uptake in LoVo cells. After 4 h incubation at external concentrations of 1, 5, 10, 25 μM, intracellular levels were higher in HT-29 cells. [1]
The IC50 values of Irinotecan hydrochloride in breast cancer cell lines were: 34.76 μM (concentration range 0.002–150 μM) in MCF-7 (luminal A); 201.27 μM (0.1–300 μM) in MDA-MB-231 (TNBC); and 26.36 μM (0.00768–600 μM) in SK-BR-3 (HER2+), as determined by MTT assay after 72 h treatment. [2]
Combination of Irinotecan hydrochloride with gefitinib showed synergistic effects in MCF-7 and MDA-MB-231 cells. For MDA-MB-231 cells (1:4 ratio of gefitinib:irinotecan, based on IC50 values), at total doses of 10.67 μM (Fa=0.50, CI=0.44974), 134.40 μM (Fa=0.86, CI=0.79456), 268.80 μM (Fa=0.91, CI=1.07757), 537.60 μM (Fa=0.91, CI=2.15539), the combination index (CI) values varied. Synergism (CI<1) was observed at certain Fa levels. [2]
Combination of Irinotecan hydrochloride with sunitinib showed synergistic effects in all three breast cancer cell lines when Fa value was greater than 0.6. For MDA-MB-231 cells (0.41:1.23 ratio of irinotecan:sunitinib), at total doses of 3.59 μM (Fa=0.40, CI=0.68404), 14.35 μM (Fa=0.45, CI=1.85993), 67.20 μM (Fa=0.56, CI=1.49972), 134.40 μM (Fa=0.86, CI=0.79456), 268.80 μM (Fa=0.91, CI=1.07757). [2]
Wound healing assay showed that Irinotecan hydrochloride alone (32 μM for MCF-7; 128 μM for MDA-MB-231) significantly inhibited cell migration in both MCF-7 and MDA-MB-231 cell lines compared to control at 24 h. In MCF-7 cells, the migration rate of irinotecan group was significantly lower than control, but no significant difference from the combination group. In MDA-MB-231 cells, the migration rate of irinotecan group (128 μM) was significantly lower than control, and the combination of gefitinib (32 μM) plus irinotecan (128 μM) showed significantly lower migration rate than irinotecan alone. [2]

When treating TNBC subtype cells in a xenograft model, gefitinib and irinotecan work synergistically very well.[/2]

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In a cell-derived xenograft (CDX) model using MDA-MB-231 TNBC cells in female BALB/c nude mice, Irinotecan hydrochloride alone (8 mg/kg, intraperitoneal injection, administered on days 1,3,5,7,9,11,13) significantly restricted tumor growth during the first five days and maintained good tumor growth inhibition activity. On day 14, the tumour volume of the irinotecan group was significantly smaller than that of the blank control group (p<0.001), and tumour weight was also significantly lower (p<0.001). [2]
The combination of Irinotecan hydrochloride (8 mg/kg, i.p., days 1,3,5,7,9,11,13) with gefitinib (30 mg/kg, gavage, same days) showed a more marked growth-inhibitory effect than irinotecan alone. On day 14, tumour volume of the combination group was significantly lower than that of the single-agent irinotecan group (p=0.0465), and tumour weight was lower with marginal significance (p=0.0659). H&E staining of tumour tissues from the combination group showed most tumour cells necrotic with concentrated and deformed nuclei, indicating cell lysis and death. [2]

Carboxylesterase activity was evaluated in microsomal extracts of LoVo and HT-29 cells using Irinotecan hydrochloride as a substrate. Microsomes (1 mg/ml) were incubated for 30 min with 5 μM irinotecan lactone (diluted in 0.01 M citric acid) in 0.1 M Tris-HCl, pH 6.9, at 37°C (final volume 40 μl). At the end of the reaction, 50 μl of a mixture of acetonitrile and methanol (1:1 v/v) was added together with 10 μl 2.5 N HCl and 50 ng internal standard (camptothecin). After centrifugation at 10,000 g for 2 min to precipitate proteins, the amount of SN-38 formed was determined by HPLC with a mobile phase of 0.1 M potassium buffer (pH 6.8) and acetonitrile (2:1 v/v) at 1 ml/min, and fluorescence detection at excitation 228 nm and emission 540 nm. The limit of quantification was 0.005 μM of SN-38 (limit of detection 0.2 ng). No formation of SN-38 was detectable with microsomal extracts of either cell line, indicating carboxylesterase activity transforming irinotecan was <20 fmol/min per mg protein. In contrast, human liver microsomes showed activity of about 4 pmol/min per mg protein with irinotecan as substrate. [1]

In 20 cm² dishes, exponentially growing cells are seeded with the ideal number of cells for each cell line (20,000 for LoVo cells, 100,000 for HT-29 cells). They receive treatment with irinotecan or SN-38 at increasing concentrations for a single cell doubling period (24 hours for LoVo cells and 40 hours for HT-29 cells) after two days. Following a 0.15 M NaCl wash, the cells are cultured in normal medium for two more doubling times before being separated from the support using trypsin-EDTA and counted using a hemocytometer. The drug concentrations that cause a 50% inhibition in growth when compared to cells cultured without the drug are then estimated to be the IC50 values.

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Growth inhibition assays: Exponentially growing LoVo and HT-29 cells were seeded in Petri dishes (20,000 for LoVo, 100,000 for HT-29). Two days later, cells were treated with increasing concentrations of Irinotecan hydrochloride for one cell doubling time (24 h for LoVo, 40 h for HT-29). After washing with 0.15 M NaCl, cells were further grown for two doubling times in normal medium, detached with trypsin-EDTA, and counted. IC50 values were estimated as drug concentrations responsible for 50% growth inhibition compared to untreated controls. [1]
Cellular accumulation assay: Evaluation of Irinotecan hydrochloride concentrations in cells after exposure to various extracellular concentrations (1, 5, 10, 25 μM) was performed by HPLC. The drug was added to complete culture medium 16 h before incubation with cells to reach lactone-carboxylate equilibrium. After 4 h incubation, cell layers were rinsed, cells recovered by scraping and pelleted. Cell extracts were obtained in methanol/acetonitrile (50/50 v/v) containing 1% HCl. Separation on a C-18 reversed-phase column with mobile phase of acetonitrile and 0.075 M ammonium acetate buffer pH 6.0 containing 5 mM tetrabutyl ammonium phosphate, delivered isocratically at 1.5 ml/min. Fluorometric detection at excitation 355 nm and emission 515 nm. [1]
Evaluation of cleavable complexes: DNA-topoisomerase I complexes were evaluated after 30-min incubations of cells with Irinotecan hydrochloride at concentrations multiples of IC50 values (0.6×, 1×). Cells (1-10×10^6) were incubated for 30 min at 37°C, then lysed with 1 ml lysis buffer. Lysates were loaded on cesium chloride gradient and centrifuged at 100,000 g for 16 h at 20°C. Fractions (200 μl) were collected from top of gradient. An aliquot (50 μl) of each fraction was diluted with equal volume of 25 mM sodium phosphate buffer and loaded onto a nitrocellulose membrane using a slot-blot device. Topoisomerase I was revealed by immunoblotting. Signal intensities in DNA-containing slots were normalized, and results expressed as relative increase in topoisomerase I-DNA complexes in treated vs untreated cells. At 1×IC50, irinotecan induced 1.32±0.45 fold increase in LoVo cells (HT-29 value not reported for irinotecan at 1×IC50). [1]
Western blotting of topoisomerase I: Nuclear extracts (100 μg protein) from LoVo and HT-29 cells were loaded onto 8% polyacrylamide gel, migrated at 40 V for 2.5 h at 4°C, transferred to Immobilon P membrane, incubated with rabbit anti-human topoisomerase I antibody (1:2000), then with HRP-labeled secondary antibody (1:4000), and detected by chemiluminescence. Signal intensities were analyzed by densitometry. Topoisomerase I levels were similar in both cell lines (non-significant 20% higher in HT-29). [1]
Topoisomerase I catalytic activity: Nuclear extracts (5-100 ng protein) were incubated at 37°C for 30 min with 1 μg pBSKS+ phagemid in 20 μl reaction buffer. Samples (20 ng DNA) were loaded onto 1% agarose gel containing ethidium bromide (0.2 μl/ml) and electrophoresed at 80 V for 1 h to separate supercoiled and relaxed DNA. Spot intensities quantified by densitometry. Catalytic activity was 12.7±0.3 ng DNA relaxed per ng nuclear protein in LoVo and 12.9±0.2 in HT-29. [1]
Real-time RT-PCR for gene expression: RNA was extracted from 10×10^6 cells, reverse transcribed. PCR was performed with TaqMan Universal Master Mix, specific primers and fluorogenic probes for topoisomerase I, CES1, CES2, ABCG2, and GAPDH as reference. Cycling: 10 min at 95°C hot start, then 40 cycles of 15 s at 95°C and 1 min at 60°C. Threshold cycle (Ct) values were determined, and ΔCt = Ct(gene) – Ct(GAPDH). Topoisomerase I expression was 30% higher in HT-29 (ΔCt 4.48±0.93) than LoVo (6.66±0.71) but not significant. CES1 expression was higher in HT-29 (9.4±0.8) than LoVo (16.8±1.5). CES2 expression was similar and much higher than CES1 in both lines (LoVo 4.61±0.79, HT-29 5.53±2.81). ABCG2 expression was similar (LoVo 11.0±0.9, HT-29 10.5±1.5). [1]
Cell viability assay (MTT) for Irinotecan hydrochloride in breast cancer cells: MCF-7, MDA-MB-231, and SK-BR-3 cells were seeded in 96-well plates at 6×10^3 cells/well overnight, then exposed to irinotecan alone or in combination for 72 h. Then 20 μl of 5 mg/ml MTT solution was added to each well, incubated for 4 h, medium removed, 150 μl DMSO added, incubated for 10 min, and absorbance at 490 nm measured. Growth inhibition rate was determined, and IC50 calculated from fitted response curves. Ratios of drugs in combinations were determined using IC50 ratios of each drug. The combination index (CI) and fraction affected (Fa) were calculated using the median effect principle with CompuSyn software. [2]

One cycle of therapy consists of five days of 5 mg/kg of iminotecan administered intraperitoneally (IV) at a volume of 0.1 cc of the suitable solution, on two separate weeks. The administration of the medication is followed by a seven-day rest period. In an eight-week period, rats receive three cycles. Under the same intratumoral injection guidelines as group II animals, control animals receive 0.1 cc of sterile 0.9% sodium chloride solution.

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Cell-derived xenograft (CDX) model: Female BALB/c nude mice (5 weeks old) were injected with 1×10^7 MDA-MB-231 cells in 100 μl PBS into the back fat pad. When tumour diameter reached 2-3 cm, tumours were harvested, cut into 1.5 mm×1.5 mm uniform blocks, and inoculated subcutaneously into another 50 mice. When tumour volume reached 100-200 mm^3, mice were randomly divided into groups (10 mice per group). Irinotecan hydrochloride was administered alone at 8 mg/kg via intraperitoneal injection on days 1, 3, 5, 7, 9, 11, 13 (every other day). For combination group, gefitinib (30 mg/kg, gavage) was given on the same schedule. The blank control received 5% glucose solution (volume approximately equal to combination group). Active control received paclitaxel (20 mg/kg, i.p., days 1 and 8) plus gemcitabine (35 mg/kg, i.p., days 1,2,3,14). Tumour size was measured with callipers every other day for 14 days, and tumour volume calculated as 0.5 × (longest measurement) × (shortest measurement)^2. Body weight was also measured every other day. On day 14, mice were sacrificed, subcutaneous tumours harvested, weighed, photographed, and three specimens per group used for H&E staining. [2]

Absorption
When patients with solid tumors received a dose of 125 mg/m^2, the maximum plasma concentration (Cmax) was 1660 ng/mL. The AUC (0-24) was 10,200 ng·h/mL. When patients with solid tumors received a dose of 340 mg/m^2, the Cmax was 3392 ng/mL. The AUC (0-24) was 20,604 ng·h/mL.
Elimination Route
In both patients, the cumulative bile and urinary excretion of irinotecan and its metabolites (SN-38 and SN-38 glucuronide) within 48 hours after administration was approximately 25% (100 mg/m^2) to 50% (300 mg/m^2).
Volume of Distribution
When patients with solid tumors received a dose of 125 mg/m^2, the volume of distribution in the terminal elimination phase was 110 L/m^2. When administered to patients with solid tumors at a dose of 340 mg/m², the volume of distribution of the terminal elimination phase was 234 L/m².
Clearance
13.3 L/h/m² [Dose 125 mg/m², solid tumor patients]
13.9 L/h/m² [Dose 340 mg/m², solid tumor patients]

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Pharmacokinetic parameters of irinotecan and SN-38 were determined in two pediatric solid tumor trials.

Irinotecan was administered at doses of 50 mg/m² (60-minute infusion, n=48) and 125 mg/m² (90-minute infusion, n=6). Irinotecan clearance (mean ± standard deviation) was 17.3 ± 6.7 L/h/m² in the 50 mg/m² dose group and 16.2 ± 4.6 L/h/m² in the 125 mg/m² dose group, comparable to that in adults. Dosage-standardized SN-38 AUC values were also comparable between adults and children. Accumulation of irinotecan and SN-38 was extremely low in children receiving a daily dosing regimen (once daily for 5 weeks every 3 weeks; or once daily for 5 weeks every 3 weeks for 2 weeks).
The clinical pharmacokinetics of irinotecan (CPT11) can be described using a two-compartment or three-compartment model, with a mean terminal half-life of 12 hours, a steady-state volume of distribution of 168 L/m², and a systemic clearance of 15 L/m²/hr. Irinotecan binds to plasma proteins at a rate of 65%. The area under the plasma concentration-time curve (AUC) of both irinotecan and its active metabolite SN38 increases proportionally with the administered dose, but varies considerably among patients. The mean 24-hour urinary excretion of irinotecan is 17-25% of the administered dose, while the recovery rates of SN38 and its glucuronide in urine are extremely low (0.5% and 6%, respectively). The pharmacokinetics of irinotecan and SN38 are not affected by prior parent drug exposure. The AUC of irinotecan and SN38 is significantly associated with leukopenia and sometimes with the severity of diarrhea. Elevated bilirubin levels appear to affect the systemic clearance of irinotecan. PMID:9932079 Bull Cancer (12): 11-20 (1998)

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Metabolism/Metabolites
Hepatitis. The metabolism of irinotecan to the active metabolite SN-38 is mediated by carboxylesterases and occurs primarily in the liver. SN-38 is then bound primarily by UDP-glucuronyltransferase 1A1 (UGT1A1) to form the glucuronide metabolite.
The concentration of SN38 in the human body is approximately 100 times lower than the corresponding irinotecan concentration, but these concentrations are crucial because SN38 is 100 to 1000 times more cytotoxic than the parent compound. SN38 binds to plasma proteins at a rate of 95%. Plasma decay of SN38 is closely related to decay of the parent compound. Irinotecan is extensively metabolized in the liver. The bispiperidine carbonyl group of irinotecan is first removed by carboxylesterases to generate the corresponding carboxylic acid and SN38. This metabolite can be converted to SN38 glucuronide by UDP-glucuronyltransferase (1.1 isoenzyme). A recently discovered metabolite is 7-ethyl-10-[4-N-(5-aminovaleric acid)-1-piperidinyl]carbonyloxycamptothecin (APC), which is formed by the action of cytochrome P450 3A4. Many other unidentified metabolites have also been detected in bile and urine. ...PMID: 9932079 Bull Cancer (12): 11-20 (1998)
Irinotecan is a camptothecin analogue, a prodrug that requires bioactivation to form the active metabolite SN-38. SN-38 is a DNA topoisomerase I inhibitor. Irinotecan undergoes two metabolic pathways in vivo: first, CYP3A4-mediated oxidative metabolism to produce two inactive metabolites, APC or NPC; second, tissue carboxylesterase-mediated hydrolysis to generate SN-38, which is ultimately detoxified by glucuronidation via UGT1A1 to generate SN-38G. The pharmacological properties of irinotecan are also influenced by inter-individual genetic differences in irinotecan activation and inactivation enzymes (e.g., CYP3A4, CYP3A5, UGT1A1), and it competes with many concomitant drugs (e.g., anticonvulsants, St. John's wort, and ketoconazole) for elimination. Furthermore, irinotecan and its metabolites are expelled from cells via various drug transporters (e.g., Pgp, BCRP, MRP1, MRP2). This review highlights the latest research findings on irinotecan activation, transport mechanisms, glucuronidation, and CYP3A-mediated drug interactions, aiming to elucidate its complex pharmacological mechanisms and provide insights for future research on optimizing this promising drug. PMID: 12570720Ma MK, McLeod HL; Curr Med Chem 10 (1): 41-9 (2003)
Irinotecan is a water-soluble precursor of its lipophilic metabolite SN-38. SN-38 is formed by the cleavage of the carbamate bond between the camptothecin moiety and the dipiperidine side chain of irinotecan via carboxylesterase-mediated cleavage. SN-38 is a topoisomerase I inhibitor with approximately 1000 times the potency of irinotecan, and this inhibitor has been purified from human and rodent tumor cell lines. In vitro cytotoxicity assays have shown that SN-38 is 2 to 2000 times more potent than irinotecan. However, the area under the plasma concentration-time curve (AUC) of SN-38 is only 2% to 8% of that of irinotecan, and SN-38 binds to plasma proteins at a rate of 95%, while irinotecan binds to plasma proteins at a rate of approximately 50%. Therefore, the exact contribution of SN-38 to Camptosar activity remains unclear. Irinotecan and SN-38 both exist as active lactones and inactive hydroxy acid anions. A pH-dependent equilibrium exists between these two forms, with acidic pH promoting the formation of the lactone form and alkaline pH favoring the formation of the hydroxy acid anion form. (Thomson Health Care Inc.; Physicians' Desk Reference 62 ed., Montvale, NJ 2008, p. 2594)
The metabolism of irinotecan to the active metabolite SN-38 is primarily mediated by carboxylesterases and mainly occurs in the liver. SN-38 then binds primarily via UDP-glucuronyltransferase 1A1 (UGT1A1) to form glucuronide metabolites. UGT1A1 activity is reduced in individuals carrying gene polymorphisms that lead to decreased enzyme activity (e.g., the UGT1A128 polymorphism). Approximately 10% of the North American population is homozygous for the UGT1A128 allele. In a prospective study, irinotecan, administered as monotherapy every 3 weeks, showed that homozygous UGT1A128 patients had higher SN-38 exposure than patients carrying the wild-type UGT1A1 allele. In in vitro cytotoxicity assays using two cell lines, the activity of SN-38 glucuronide was 1/50 to 1/100 that of SN-38. The distribution of irinotecan in humans is not fully elucidated. Irinotecan has a urinary excretion rate of 11% to 20%; SN-38 has a urinary excretion rate of less than 1%; and SN-38 glucuronide has a urinary excretion rate of 3%. Within 48 hours of irinotecan treatment, the cumulative bile and urinary excretion of irinotecan and its metabolites (SN-38 and SN-38 glucuronide) in both patients was approximately 25% (100 mg/m²) to 50% (300 mg/m²). Thomson Health Care Inc.; Physician's Desk Reference, 62nd ed., Montville, NJ, 2008, p. 119. 2594
Irinotecan's known human metabolites include 7-ethyl-10-[4-N-(5-aminovaleric acid)-1-piperidinyl]carbonyloxycamptothecin and (2S,3S,4S,5R)-6-[[(19S)-10,19-diethyl-14,18-dioxo-7-(4-piperidin-1-ylpiperidin-1-carbonyl)oxy-17-oxa-3,13-diazapentacyclo[11.8.0.02,11.04,9.015,20]eicos-1(21),2,4(9),5,7,10,15(20)-hepten-19-yl]oxy]-3,4,5-trihydroxyoxacyclohexane-2-carboxylic acid. S73 | METXBIODB | Metabolite Reaction Database from BioTransformer | DOI:10.5281/zenodo.4056560

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Biological Half-Life
The half-life of irinotecan is approximately 6–12 hours. The terminal elimination half-life of the active metabolite SN-38 is 10–20 hours.
Following intravenous infusion of irinotecan in humans, plasma concentrations of irinotecan decrease exponentially, with a mean terminal elimination half-life of approximately 6–12 hours. The mean terminal elimination half-life of the active metabolite SN-38 is approximately 10–20 hours. The half-lives of the lactone (active) forms of irinotecan and SN-38 are similar to those of total irinotecan and SN-38 because the lactone and hydroxy acid forms are in equilibrium.

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Cellular accumulation of Irinotecan hydrochloride was linearly related to dose up to 100 μM in LoVo and HT-29 cells. Accumulation was consistently twofold higher in HT-29 cells than LoVo cells. After 4 h incubation at 50 μM, intracellular accumulation over time showed faster initial uptake in LoVo cells. [1]
No SN-38 formation was detected from irinotecan in cell culture or microsomal extracts, indicating negligible conversion to active metabolite in these cell lines. The carboxylesterase activity transforming irinotecan to SN-38 was <20 fmol/min per mg protein in both cell lines. [1]

Protein binding: 30%-68% protein bound, primarily to albumin.

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Interactions
A total of 190 patients treated with irinotecan (49 smokers, 141 non-smokers, administered intravenously every 90 minutes for 3 weeks) were evaluated for pharmacokinetics. Complete toxicity data were obtained in 134 patients treated with a fixed dose of irinotecan of 350 mg/m² or 600 mg. Compared with non-smokers, smokers had a significantly lower area under the dose-normalized plasma concentration-time curve for irinotecan (median, 28.7 vs 33.9 ng·hr/mL/mg; P = .001). Furthermore, smokers experienced a nearly 40% reduction in SN-38 exposure (median 0.54 ng xh/mL/mg vs. 0.87 ng xh/mL/mg; P < .001), and a higher relative conversion of SN-38 to SN-38G (median 6.6 vs. 4.5; P = .006). Hematologic toxicity was significantly reduced in smokers. In particular, the incidence of grade 3-4 neutropenia was 6% in smokers compared to 38% in non-smokers (odds ratio [OR] 0.10; 95% confidence interval 0.02 to 0.43; P < .001). There was no significant difference in the incidence of delayed diarrhea (6% vs. 15%; OR, 0.34; 95% CI, 0.07 to 1.57; P = .149). This study suggests that smoking significantly reduces irinotecan exposure and treatment-induced neutropenia, indicating a potential risk of treatment failure. Although the underlying mechanism is not fully understood, regulation of CYP3A and uridine diphosphate glucuronide transferase isoenzyme 1A1 may be partly responsible. Data suggest that further research is necessary to determine whether smokers have a higher risk of treatment failure. PMID:17563393 van der Bol JM et al; J Clin Oncol 25 (19): 2719-26 (2007)
In the treatment of human immunodeficiency virus-associated malignancies, the combined use of protease inhibitors and anticancer drugs may lead to potential drug interactions. This study investigated the effect of lopinavir/ritonavir (LPV/RTV) on the pharmacokinetics of irinotecan (CPT11) in 7 patients with Kaposi's sarcoma. The results showed that the LPV/RTV combination reduced the clearance of CPT11 by 47% (11.3±3.5 vs 21.3±6.3 l/h/m², P=0.0008). This effect was associated with an 81% decrease in the AUC of the oxidative metabolite APC (7-ethyl-10-[4-N-(5-aminovaleric acid)-1-piperidinyl]-carbonyloxycamptothecin) (P=0.02). LPV/RTV treatment also inhibited the production of SN38 glucuronide (SN38G), with a 36% decrease in the SN38G/SN38 AUC ratio (5.9±1.6 vs 9.2±2.6, P=0.002), consistent with the inhibitory effect of LPV/RTV on UGT1A1. This dual effect resulted in CPT11 being used for the conversion of SN38 and reducing its inactivation of SN38, thereby increasing the AUC of SN38 by 204% in the presence of LPV/RTV (P=0.0001). The clinical consequences of these significant pharmacokinetic changes should be investigated. PMID: 17713471

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In the CDX mouse model, Irinotecan hydrochloride alone (8 mg/kg, i.p., every other day for 7 doses) was well tolerated. Body weight of mice in the irinotecan group remained stable during the 14-day treatment period, and no deaths were observed. In contrast, the active control group (paclitaxel plus gemcitabine) showed sharp body weight decrease and four mice died by day 5, requiring cessation of gemcitabine administration on day 6. [2]

[1]. Cancer Chemother Pharmacol . 2002 Apr;49(4):329-35.

[2]. Cancers (Basel) . 2021 Jul 17;13(14):3586.

Irinotecan hydrochloride hydrate is the trihydrate form of irinotecan hydrochloride. Onivyde, used in combination with fluorouracil and leucovorin, is indicated for the treatment of patients with metastatic pancreatic adenocarcinoma whose disease has progressed after gemcitabine treatment. It is converted to its active metabolite SN-38 via carbamate bond hydrolysis, which is approximately 1000 times more active than the prodrug. It has multiple effects, including as an EC 5.99.1.2 (DNA topoisomerase) inhibitor, an antitumor drug, an apoptosis inducer, and a prodrug. It contains anhydrous irinotecan hydrochloride. Irinotecan hydrochloride is the hydrochloride salt of a semi-synthetic derivative of camptothecin, a cytotoxic quinoline alkaloid extracted from the Asian tree Camptotheca acuminata. Irinotecan is a prodrug converted by carboxylesterase to the biologically active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38). SN-38 is 1000 times more potent than its parent compound, irinotecan. It inhibits topoisomerase I activity by stabilizing the cleavable complex between topoisomerase I and DNA, leading to DNA breaks, inhibiting DNA replication, and inducing apoptosis. Because sustained DNA synthesis is essential for irinotecan to exert its cytotoxic effects, it is classified as an S-phase specific drug. A semi-synthetic camptothecin derivative, it inhibits DNA topoisomerase I, thereby preventing the synthesis of nucleic acids in the S phase. It is used as an antitumor drug to treat colorectal and pancreatic tumors. Drug Indications: In combination with 5-fluorouracil (5-FU) and leucovorin (LV), for the treatment of metastatic pancreatic adenocarcinoma in adult patients whose disease has progressed after gemcitabine treatment.

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Irinotecan hydrochloride is a prodrug that requires activation by carboxylesterases (particularly hCE2) to its active metabolite SN-38, which is a specific inhibitor of eukaryotic DNA topoisomerase I. Camptothecins stabilize DNA-topoisomerase I cleavable complexes, leading to DNA damage and cell death. The level of topoisomerase I in tumors has been considered a determinant of sensitivity to camptothecin derivatives. However, in the two colorectal cell lines studied, irinotecan cytotoxicity was likely due to the drug itself and not to SN-38, and irinotecan uptake was more predictive of cytotoxicity than topoisomerase I availability. [1]
Irinotecan hydrochloride has been used in combination with gefitinib for treating advanced fluoropyrimidine-refractory colorectal cancer (phase I-II study). In breast cancer research, it was predicted and experimentally validated as an effective agent in combination with gefitinib for triple-negative breast cancer (TNBC), showing synergistic inhibition of tumour growth and migration in vitro and in vivo, with lower toxicity than the paclitaxel-gemcitabine combination. [2]

C₃₃H₃₉CLN₄O₆

623.14

622.255

C, 63.61; H, 6.31; Cl, 5.69; N, 8.99; O, 15.40

100286-90-6

136572-09-3 (HCl trihydrate); 1329502-92-2 (Carboxylate Sodium Salt); 143490-53-3 (Lactone Impurity); 100286-90-6 (HCl); 97682-44-5 (Free base)

60837

White to yellow solid powder

257 °C

250-256°C (dec.)

482ºC

1.31E-32mmHg at 25°C

67.7 ° (C=1, H2O)

4.768

5

11

5

47

1200

1

Cl[H].O(C1C([H])=C([H])C2=C(C=1[H])C(C([H])([H])C([H])([H])[H])=C1C(C3=C([H])C4=C(C([H])([H])OC([C@@]4(C([H])([H])C([H])([H])[H])O[H])=O)C(N3C1([H])[H])=O)=N2)C(N1C([H])([H])C([H])([H])C([H])(C([H])([H])C1([H])[H])N1C([H])([H])C([H])([H])C([H])([H])C([H])([H])C1([H])[H])=O

GURKHSYORGJETM-WAQYZQTGSA-N

InChI=1S/C33H38N4O6.ClH/c1-3-22-23-16-21(43-32(40)36-14-10-20(11-15-36)35-12-6-5-7-13-35)8-9-27(23)34-29-24(22)18-37-28(29)17-26-25(30(37)38)19-42-31(39)33(26,41)4-2;/h8-9,16-17,20,41H,3-7,10-15,18-19H2,1-2H3;1H/t33-;/m0./s1

[(19S)-10,19-diethyl-19-hydroxy-14,18-dioxo-17-oxa-3,13-diazapentacyclo[11.8.0.02,11.04,9.015,20]henicosa-1(21),2,4(9),5,7,10,15(20)-heptaen-7-yl] 4-piperidin-1-ylpiperidine-1-carboxylate;hydrochloride

CPT-11 hydrochloride; Irinotecan hydrochloride; 100286-90-6; Irinotecan Hcl; Topotecin; Campto; Camptothecin 11; CPT-11; Camptothecin 11 hydrochloride

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

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

DMSO: 100~125 mg/mL (160.5~200.6 mM)
H2O: ~3.3 mg/mL (~5.3 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (3.34 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 20.8 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: ≥ 2.08 mg/mL (3.34 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 20.8 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: ≥ 2.08 mg/mL (3.34 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 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 5%DMSO+ 40%PEG300+ 5%Tween 80+ 50%ddH2O: 5.0mg/ml (8.02mM)

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Solubility in Formulation 5: 10 mg/mL (16.05 mM) in 50% PEG300 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.

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Solubility in Formulation 6: 10 mg/mL (16.05 mM) in 0.5% CMC-Na/saline water (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.

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 (Please use freshly prepared in vivo formulations for optimal results.)