Fosnetupitant (Pronetupitant) does not bind to all other proteins investigated, but it has micromolar affinity for L-type Ca2+ channels (pKi ∼ 5.7) and 5-HT6 receptors (pKi ∼ 5.2) [1].

Rats quickly and extensively convert Pronetupitant to Netupitant following an intravenous injection[1].

Absorption, Distribution and Excretion
Following single intravenous doses of Akynzeo for injection in patients (235 mg fosnetupitant and 0.25 mg palonosetron infused in 30 minutes) or fosnetupitant in healthy subjects (235 mg fosnetupitant infused in 30 minutes), maximum concentration of fosnetupitant was achieved at the end of the 30-minute infusion. Oral bioavailability in each species varied substantially between animals, with 42-105%, 34-83% and 37-62% in rats, dogs, and monkeys. The large variation is most likely due to the low numbers of animals used in the studies.
After one oral dose of [14C]­netupitant, approximately one-half of the administered radioactivity was measured in the urine and feces within 120 hours of the dose. The total of 3.95% and 70.7% of the radioactive dose was measured in the urine and feces collected over 336 hours, respectively, and the average fraction of an oral dose of netupitant excreted unchanged in urine is under 1%, implying that renal clearance is not a significant route of elimination for the netupitant-related entities. About 86.5% and 4.7% of administered radioactivity was estimated to be excreted via the feces and urine within 30 days post-dose.
The mean SD volume of distribution of fosnetupitant in healthy subjects and in patients was 124 +/- 76 L and 296 +/- 535 L, respectively.
Netupitant has a mean estimated systemic clearance of 0.3 ± 9.2 L/h (mean ± SD) after a single oral dose of Akynzeo.

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Metabolism / Metabolites
Fosnetupitant is the prodrug of [netupitant]. Netupitant is a moderate inhibitor and substrate of CYP3A4. Akynzeo should be used with caution in patients receiving concomitant medications that are primarily metabolized through CYP3A4 systems. One dose of netupitant 300 mg significantly inhibits CYP3A4 for about 6 days. It is avisable to avoid concomitant use of drugs that are CYP3A4 substrates for one week. If not possible, consider dose reduction of CYP3A4 substrates. In the human, rat, dog, minipig and marmoset liver microsomal incubations, two major metabolites, an _N-demethylation product (M1) _and an _N-oxidation product (M2)_, in addition to hydroxylation products (M3), were identified in all species. CYP3A4 was found to be responsible for the oxidation of netupitant to the same metabolites observed also in the incubations with human liver microsomes. Metabolism was extensive, with the metabolites generally achieving greater concentrations than parent drug witin 24 hours. M1 and M2 exposure was similar in rat to humans, but higher in dogs, however M3 was lower in both species than in humans.

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Biological Half-Life
Netupitant is eliminated from the body in a multi-exponential fashion, with an apparent elimination half-life in cancer patients of 80 ± 29 hours (mean ± SD).

Hepatotoxicity
In preregistration clinical trials of the fixed combination of fosnetupitant and palonosetron, serum aminotransferase elevations occurred in a similar proportion of treated patients as controls receiving cancer chemotherapy. The aminotransferase elevations were transient, mild-to-moderate in severity, and not associated with symptoms or jaundice. The elevations were more likely due to the cancer chemotherapy than the antiemetic prophylaxis. There have been no convincing cases of clinically apparent liver injury attributable to fosnetupitant with palonosetron published in the literature and thus, significant liver injury must be exceedingly rare if it occurs at all.
Likelihood score: E (unlikely cause of clinically apparent liver injury).

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Protein Binding
Netupitant is highly bound (>99%) to plasma proteins in all species.

[1]. In vitro and in vivo pharmacological characterization of Pronetupitant, a prodrug of the neurokinin 1 receptor antagonist Netupitant. Peptides. 2015 Jul;69:26-32.

In April 2018, the U.S. Food and Drug Administration (FDA) and the Swiss company Helsinn approved the intravenous formulation of AKYNZEO® (NEPA, a fixed antiemetic combination of fosnetupitant, 235mg, and palonosetron, 0.25mg) as an alternative treatment option for patients experiencing chemotherapy-induced nausea and vomiting. Fosnetupitant is the pro-drug form of netupitant. Generally, 25% to 30% of patients with a diagnosis of cancer receive chemotherapy as a treatment modality and 70% to 80% of these patients undergoing chemotherapy treatment may experience nausea and vomiting as major side effects. Considered one of the most distressing side effects of chemotherapy, nausea and vomiting has an immense impact on the quality of life of patients receiving certain antineoplastic therapies.
Fosnetupitant is an antiemetic agent that is given in combination with palonosetron and dexamethasone to prevent nausea and vomiting from cancer chemotherapy. When given in combination, fosnetupitant and palonosetron have not been associated with liver related serum enzyme elevations during therapy or to cases of clinically apparent liver injury with jaundice.
Fosnetupitant is a prodrug of netupitant, a selective neurokinin 1 receptor (NK1R; TACR1) antagonist, with potential antiemetic activity. Upon intravenous administration, fosnetupitant is converted by phosphatases to its active form netupitant. Netupitant competitively binds to and blocks the activity of NK1Rs in the central nervous system (CNS), by inhibiting binding of the endogenous tachykinin-derived neuropeptide substance P (SP) to NK1R. This prevents delayed emesis, which is associated with SP secretion. This may prevent chemotherapy-induced nausea and vomiting (CINV).

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Drug Indication
Indicated in combination palonosetron (as the drug Akynzeo) and dexamethasone in adults for the prevention of acute and delayed nausea and vomiting associated with initial and repeat courses of cancer chemotherapy, including, but not limited to, highly emetogenic chemotherapy. The following are indications listed on the EMA label: Prevention of acute and delayed nausea and vomiting associated with highly emetogenic cisplatin-based cancer chemotherapy. Prevention of acute and delayed nausea and vomiting associated with moderately emetogenic cancer chemotherapy.
FDA Label

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Mechanism of Action
The fosnetupitant in this drug combination is a selective P/neurokinin-1 (NK-1) receptor antagonist. [Netupitant], the active moiety of fosnetupitant, is a selective neurokinin 1 (NK1) receptor antagonist with antiemetic activity. Netupitant competitively binds to and blocks the activity of the human substance P/NK1 receptors in the central nervous system (CNS), inhibiting NK1-receptor binding of the endogenous tachykinin neuropeptide substance P (SP), which results in the prevention of chemotherapy-induced nausea and vomiting (CINV). Substance P is found in neurons of vagal afferent fibers innervating the brain-stem nucleus tractus solitarii and the area postrema, which contains the chemoreceptor trigger zone (CTZ), and may be present at high levels in response to chemotherapy. The NK-receptor is a G-protein receptor coupled to the inositol phosphate signal-transduction pathway and is found in both the nucleus tractus solitarii and the area postrema. Netupitant demonstrated 92.5% NK1 receptor occupancy at 6 hours, with 76% occupancy at 96 hours.

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Pharmacodynamics
In the combination drug, Akynzeo, palonosetron prevents nausea and vomiting during the acute phase and fosnetupitant prevents nausea and vomiting during both the acute and delayed phase after cancer chemotherapy. Neurokinin-1 (NK-1) inhibitor drugs, such as netupitant, possess unique anxiolytic, antidepressant, and antiemetic properties.

C31H35F6N4O5P

688.61

688.224

1703748-89-3

Fosnetupitant chloride monohydrochloride;1643757-72-5

71544786

White to off-white solid powder

1.86

1

13

8

47

1100

0

HZIYEEMJNBKMJH-UHFFFAOYSA-N

InChI=1S/C31H35F6N4O5P/c1-20-8-6-7-9-24(20)25-17-27(40-10-12-41(5,13-11-40)19-46-47(43,44)45)38-18-26(25)39(4)28(42)29(2,3)21-14-22(30(32,33)34)16-23(15-21)31(35,36)37/h6-9,14-18H,10-13,19H2,1-5H3,(H-,43,44,45)

(4-(5-(2-(3,5-bis(trifluoromethyl)phenyl)-N,2-dimethylpropanamido)-4-(o-tolyl)pyridin-2-yl)-1-methylpiperazin-1-ium-1-yl)methyl hydrogen phosphate

07PNET; 07-PNET; Fosnetupitant chloride; Akynzeo; trade name: Akynzeo

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: (1). This product requires protection from light (avoid light exposure) during transportation and storage.  (2). Please store this product in a sealed and protected environment (e.g. under nitrogen), 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)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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