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

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

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

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.

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.

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.

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

[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.

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.)