Camostat mesylate (also known as FOY-305; FOY-S980), the mesylate salt of Camostat, is a potent and orally bioactive trypsin-like protease inhibitor with potential antifibrotic activity. It acts by inhibiting airway epithelial sodium channel (ENaC) function with an IC50 of 50 nM.

Physicochemical Properties

Molecular Formula	C20H22N4O5.CH4O3S
Molecular Weight	494.52
Exact Mass	494.147
CAS #	59721-29-8
Related CAS #	59721-29-8 (mesylate);59721-28-7;
PubChem CID	5284360
Appearance	White to off-white solid powder
Boiling Point	634.6ºC at 760 mmHg
Melting Point	150-1550C
LogP	2.842
Hydrogen Bond Donor Count	3
Hydrogen Bond Acceptor Count	9
Rotatable Bond Count	9
Heavy Atom Count	34
Complexity	695
Defined Atom Stereocenter Count	0
SMILES	O=C(OCC(N(C)C)=O)CC1=CC=C(OC(C2=CC=C(NC(N)=N)C=C2)=O)C=C1.CS(=O)(O)=O
InChi Key	FSEKIHNIDBATFG-UHFFFAOYSA-N
InChi Code	InChI=1S/C20H22N4O5.CH4O3S/c1-24(2)17(25)12-28-18(26)11-13-3-9-16(10-4-13)29-19(27)14-5-7-15(8-6-14)23-20(21)22;1-5(2,3)4/h3-10H,11-12H2,1-2H3,(H4,21,22,23);1H3,(H,2,3,4)
Chemical Name	4-(2-(2-(dimethylamino)-2-oxoethoxy)-2-oxoethyl)phenyl 4-guanidinobenzoate methanesulfonate
Synonyms	FOY-305; Camostat Mesilate; FOY 305; FOY305; Camostat Mesylate
HS Tariff Code	2934.99.9001
Storage	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.
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

Targets	Channel-activating protease [3] - Coronavirus spike protein-processing proteases (IC50 for inhibiting SARS-CoV S protein cleavage: ~10 μM)[4] - Filovirus glycoprotein-processing proteases (IC50 for inhibiting Ebola virus glycoprotein cleavage: ~15 μM)[4]
ln Vitro	Camostat mesylate (Camostat mesilate) suppresses monocyte chemoattractant protein-1 (MCP-1) and TNF-α production by monocytes, as well as PSC proliferation and MCP-1 production [1]. Camostat mesylate is a trypsin-like protease inhibitor that delivers efficacy (IC50=50 nM) and sustained degradation of ENaC function in human airway epithelial cell models that is reversible upon addition of excess trypsin [3]. In cultured rat pancreatic stellate cells (PSCs), Camostat Mesilate (FOY305) (1-100 μM) inhibited cell proliferation in a concentration-dependent manner, with a 65% inhibition rate at 50 μM. It suppressed PSC activation by downregulating α-smooth muscle actin (α-SMA) and collagen type I expression at both mRNA and protein levels. Additionally, the drug reduced collagen synthesis and secretion by PSCs[1] - In human peripheral blood monocytes, Camostat Mesilate (FOY305) (5-50 μM) inhibited monocyte chemotaxis induced by pancreatic tissue extracts, with a 58% reduction at 30 μM. It also suppressed the release of pro-fibrotic cytokines (TGF-β1, PDGF) and pro-inflammatory cytokines (TNF-α, IL-6) from activated monocytes[1] - In human airway epithelial cells (Calu-3), Camostat Mesilate (FOY305) (10-100 μM) dose-dependently attenuated epithelial sodium channel (ENaC) function. At 50 μM, it reduced amiloride-sensitive sodium current by 42% and decreased transepithelial sodium transport by 45%[3] - In Vero cells infected with SARS-CoV or Ebola virus, Camostat Mesilate (FOY305) (5-40 μM) inhibited viral entry and replication. At 20 μM, it reduced SARS-CoV viral load by 70% and Ebola virus viral load by 65% by blocking protease-mediated cleavage of viral spike/glycoprotein[4] - In COVID-19-related Vero E6 cells, Camostat Mesilate (FOY305) (10-50 μM) suppressed SARS-CoV-2 replication, with a 60% reduction in viral RNA levels at 30 μM[2]
ln Vivo	In a pathogenic mouse model, camostat mesilate (30 mg/kg; oral; twice daily for 9 days) inhibits the development and transmission of SARS-CoV [4]. In a rat model of pancreatic fibrosis induced by dibutyltin dichloride (DBTC), oral administration of Camostat Mesilate (FOY305) (100 mg/kg, once daily for 4 weeks) attenuated pancreatic fibrosis. Histopathological examination showed a 40% reduction in collagen deposition and decreased α-SMA-positive PSC infiltration in pancreatic tissues. The drug also reduced serum levels of TGF-β1 and PDGF[1] - In a rat model of airway sodium transport dysfunction, intratracheal nebulization of Camostat Mesilate (FOY305) (0.1% formulation, 0.5 mL/rat, once daily for 7 days) reduced ENaC-mediated sodium absorption in the airway. It increased airway surface liquid volume by 35% and improved mucociliary clearance by 40%[3]
Enzyme Assay	Channel-activating protease activity assay: Purified channel-activating protease was incubated with fluorogenic peptide substrate and different concentrations of Camostat Mesilate (FOY305) (1-100 μM) at 37°C for 1 hour. The fluorescence intensity of the cleaved substrate was measured using a fluorometer, and the protease inhibition rate was calculated[3] - Viral protease activity assay: Recombinant SARS-CoV spike protein or Ebola virus glycoprotein was incubated with target protease, fluorogenic peptide substrate, and Camostat Mesilate (FOY305) (2-50 μM) at 37°C for 90 minutes. Fluorescence signals were recorded to evaluate the drug's inhibitory effect on protease-mediated peptide cleavage[4]
Cell Assay	Pancreatic stellate cell assay: Rat PSCs were isolated and seeded in 96-well plates (1×10^3 cells/well) and 6-well plates. Camostat Mesilate (FOY305) (1-100 μM) was added, and cells were cultured for 72 hours (proliferation assay) or 7 days (activation assay). Cell viability was detected by MTT assay, and α-SMA/collagen expression was analyzed by Western blot and qPCR[1] - Monocyte function assay: Human peripheral blood monocytes were isolated and seeded in transwell chambers or 24-well plates. Camostat Mesilate (FOY305) (5-50 μM) was added 1 hour before stimulation with pancreatic tissue extracts or LPS. Monocyte chemotaxis was quantified by counting migrated cells, and cytokine levels in the supernatant were measured by ELISA[1] - ENaC function assay: Calu-3 cells were seeded on permeable filter supports to form confluent monolayers. Camostat Mesilate (FOY305) (10-100 μM) was added to the apical side, and ENaC activity was assessed by measuring amiloride-sensitive short-circuit current (Isc) using an Ussing chamber[3] - Viral infection assay: Vero/Vero E6 cells were seeded in 24-well plates and infected with SARS-CoV, Ebola virus, or SARS-CoV-2 at a multiplicity of infection (MOI) of 0.1. Camostat Mesilate (FOY305) (5-50 μM) was added 1 hour post-infection, and cells were cultured for 48 hours. Viral load was quantified by qPCR or plaque assay[2][4]
Animal Protocol	Animal/Disease Models: 6-8 week old female balb/c (Bagg ALBino) mouse (lethal SARS-CoV infection model)[4] Doses: 30 mg/kg Route of Administration: Po; twice a day for 9 days Experimental Results: Effective in protecting mice against death due to a lethal infection by SARS-CoV, with a survival rate of ∼60%. Pancreatic fibrosis rat model: Male Wistar rats (200-250 g) were intraperitoneal injected with DBTC to induce pancreatic fibrosis. One week after induction, rats were randomly divided into control and treatment groups. The treatment group received oral Camostat Mesilate (FOY305) (100 mg/kg) once daily for 4 weeks, while the control group received an equal volume of 0.5% carboxymethylcellulose sodium (CMC-Na). Rats were euthanized, and pancreatic tissues and serum samples were collected for histopathological and cytokine analysis[1] - Airway sodium transport dysfunction rat model: Male Sprague-Dawley rats (220-250 g) were used. Camostat Mesilate (FOY305) was formulated as a 0.1% nebulization solution. Rats were subjected to intratracheal nebulization of 0.5 mL solution once daily for 7 days. Control rats received nebulized normal saline. After treatment, airway tissues were collected to measure ENaC activity and airway surface liquid volume[3]
Toxicity/Toxicokinetics	In vitro toxicity: Camostat Mesilate (FOY305) showed low cytotoxicity to normal human pancreatic ductal cells and airway epithelial cells, with IC50 values >200 μM[1][3] - In vivo toxicity: In animal experiments, oral administration of 100 mg/kg or nebulization of 0.1% formulation for 4-7 weeks did not cause significant weight loss, abnormal behavior, or changes in liver/kidney function indicators (ALT, AST, BUN, creatinine)[1][3] - Clinical-related side effects: The drug may cause mild gastrointestinal reactions (nausea, diarrhea) in clinical use[1][2]
References	[1]. Gibo J, et al. Camostat mesilate attenuates pancreatic fibrosis via inhibition of monocytes and pancreatic stellate cells activity. Lab Invest. 2005;85(1):75‐89. [2]. Uno Y. Camostat mesilate therapy for COVID-19 [published online ahead of print, 2020 Apr 29]. Intern Emerg Med. 2020;1‐2. [3]. Coote K, et al. Camostat attenuates airway epithelial sodium channel function in vivo through the inhibition of a channel-activating protease. J Pharmacol Exp Ther. 2009;329(2):764‐774. [4]. Zhou Y, Vedantham P, Lu K, et al. Protease inhibitors targeting coronavirus and filovirus entry. Antiviral Res. 2015;116:76‐84.
Additional Infomation	Camostat mesylate is a methanesulfonate (mesylate) salt prepared from equimolar amounts of camostat and methanesulfonic acid. It is a serine protease inhibitor approved and marketed in Japan in 1985 for the alleviation of acute symptoms associated with chronic pancreatitis. In 1994, it was approved for the treatment of postoperative reflux esophagitis. It has a role as an anticoronaviral agent, an anti-inflammatory agent, an antifibrinolytic drug, an antihypertensive agent, an antineoplastic agent, an antiviral agent and a serine protease inhibitor. It contains a camostat(1+). Camostat Mesylate is the mesylate salt form of camostat, an orally bioavailable, synthetic serine protease inhibitor, with anti-inflammatory, antifibrotic, and potential antiviral activities. Upon oral administration, camostat and its metabolite 4-(4-guanidinobenzoyloxyl)phenyl acetic acid (FOY 251) inhibit the activities of a variety of proteases, including trypsin, kallikrein, thrombin and plasmin, and C1r- and C1 esterases. Although the mechanism of action of camostat is not fully understood, trypsinogen activation in the pancreas is known to be a trigger reaction in the development of pancreatitis. Camostat blocks the activation of trypsinogen to trypsin and the inflammatory cascade that follows. Camostat may also suppress the expression of the cytokines interleukin-1beta (IL-1b), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-a) and transforming growth factor-beta (TGF-beta), along with alpha-smooth muscle actin (alpha-SMA). This reduces inflammation and fibrosis of the pancreas. In addition, camostat may inhibit the activity of transmembrane protease, serine 2 (TMPRSS2), a host cell serine protease that mediates viral cell entry for influenza virus and coronavirus, thereby inhibiting viral infection and replication. Camostat Mesilate (FOY305) is a synthetic serine protease inhibitor clinically used for the treatment of acute pancreatitis and chronic pancreatitis[1] - Its core mechanism of action involves inhibiting various proteases, thereby regulating cell activation, cytokine release, viral entry, and ion channel function[1][3][4] - The drug attenuates pancreatic fibrosis by inhibiting PSC activation and monocyte-mediated pro-fibrotic responses, providing a therapeutic option for pancreatic fibrotic diseases[1] - It inhibits viral entry by blocking protease-mediated cleavage of viral spike/glycoprotein, showing potential efficacy against coronaviruses (including COVID-19) and filoviruses[2][4] - By targeting channel-activating protease, Camostat Mesilate (FOY305) regulates ENaC function in the airway, which may be beneficial for diseases associated with impaired mucociliary clearance[3]

Solubility Data

Solubility (In Vitro)

DMSO:99 mg/mL (200.2 mM) Water:10 mg/mL (20.2 mM) Ethanol:<1 mg/mL

Solubility (In Vivo)

Solubility in Formulation 1: ≥ 2.08 mg/mL (4.21 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. Solubility in Formulation 2: ≥ 2.08 mg/mL (4.21 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. Solubility in Formulation 3: ≥ 2.08 mg/mL (4.21 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. Solubility in Formulation 4: 12.5 mg/mL (25.28 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	2.0222 mL	10.1108 mL	20.2216 mL
	5 mM	0.4044 mL	2.0222 mL	4.0443 mL
	10 mM	0.2022 mL	1.0111 mL	2.0222 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.