Argatroban

Absorption

Bioavailability is 100% (intravenous).

Toxicity

Excessive bleeding

Description

Argatroban is a new synthetic antithrombotic agent useful in maintenance anticoagulation them ischemic stroke and disseminated intravascular coagulation. In patients on hemodialysis, argatroban is su enor to heparin, generating a more stable antithrombin effect. Other potential uses include progressing ischemic stroke and disseminated intravascular coagulation.

Description

Argatroban is a reversible inhibitor of thrombin (IC₅₀s = 0.01 and 0.09 μM for the free and clot-bound forms, respectively). It is selective for thrombin over factor Xa, trypsin, plasmin, and tissue plasminogen activator (K_is = 0.0045, 53, 0.19, 25.7, and 87.7 μM, respectively). It inhibits thrombin-induced platelet aggregation in washed isolated guinea pig platelets with an IC₅₀ value of 0.077 μM. Argatroban (3.2 mg/kg, s.c.) decreases thrombus formation in a guinea pig model of iron chloride-induced arterial thrombosis. Formulations containing argatroban have been used in the prevention or treatment of thrombosis in patients with heparin-induced thrombocytopenia.

Chemical properties

White to Off-White Crystalline Solid

Originator

Mitsubishi Kasei; Daiichi (Japan)

The Uses of Argatroban

(2S,4S)-1-(2R)-Argatroban is an isomeric impurity of Argatroban (74863-84-6 #CAS), which is a synthetic thrombin inhibitor. Antithrombotic.

The Uses of Argatroban

anticoagulant;direct thrombine inhibitor

What are the applications of Application

Argatroban is a peptidomimetic small molecule anticoagulant and direct thrombin inhibitor

Background

Argatroban is a direct, selective thrombin inhibitor. The American College of Cardiologists (ACC) recommend using bivalirudin or argatroban in patients who have had, or at risk for, heparin induced thrombocytopenia (HIT) and are undergoing percutaneous coronary intervention. Argatroban is a non-heparin anticoagulant shown to both normalize platelet count in patients with HIT and prevent the formation of thrombi. Parental anticoagulants must be stopped and a baseline activated partial thromboplastin time must be obtained prior to administering argatroban.

Indications

Argatroban is indicated for prevention and treatment of thrombosis caused by heparin-induced thrombocytopenia (HIT). It is also indicated for use in patients with, or at risk for, HIT who are undergoing percutaneous coronary intervention.

Definition

ChEBI: (2R,4R)-1-[(2S)-5-(diaminomethylideneamino)-2-[(3-methyl-1,2,3,4-tetrahydroquinolin-8-yl)sulfonylamino]-1-oxopentyl]-4-methyl-2-piperidinecarboxylic acid is a peptide.

Manufacturing Process

To a stirred solution of 28.3 g of NG-nitro-N2-(tert-butoxycarbonyl)-L-arginine in 450 ml of dry tetrahydrofuran were added in turn 9.0 g of triethylamine and 12.2 g of isobutyl chloroformate while keeping the temperature at -20°C. After 10 minutes, to this was added 15.2 g of ethyl 4-methyl-2- piperidinecarboxylate and the mixture was stirred for 10 minutes at -20°C. At the end of this period, the reaction mixture was warmed to room temperature. The solvent was evaporated and the residue taken up in 400 ml of ethyl acetate, and washed successively with 200 ml of water, 100 ml of 5% sodium bicarbonate solution, 100 ml of 10% citric acid solution and 200 ml of water. The ethyl acetate solution was dried over anhydrous sodium sulfate. The solution was evaporated to give 31.5 g (75 %) of ethyl 1-[NG-nitro-N2- (tert-butoxycarbonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylate in the form of a syrup.
To a stirred solution of 30 g of ethyl 1-[NG-nitro-N2-(tert-butoxycarbonyl)-Larginyl]- 4-methyl-2-piperidinecarboxylate in 50 ml of ethyl acetate was added 80 ml of 10% dry HCl-ethyl acetate at 0°C. After 3 hours, to this solution was added 200 ml of dry ethyl ether to precipitate a viscous oily product. This was filtered and washed with dry ethyl ether to give ethyl 1-[NG-nitro-L-arginyl]-4- methyl-2-piperidinecarboxylate hydrochloride as an amorphous solid.
To a stirred solution of ethyl 1-(NG-nitro-L-arginyl)-4-methyl-2- piperidinecarboxylate hydrochloride in 200 ml of chloroform were added in turn 18.5 g of triethylamine, and 14.7 g of 3-methyl-8-quinolinesulfonyl chloride at 5°C, and stirring was continued for 3 hours at room temperature. At the end of this period, the solution was washed twice with 50 ml of water. The chloroform solution was dried over anhydrous sodium sulfate. Upon evaporation of the solvent, the residue was chromatographed on 50 g of silica gel packed in chloroform, washed with chloroform and eluted with 3% methanol-chloroform. The fraction eluted from 3% methanol-chloroform was evaporated to give 32.1 g (91%) of ethyl 1-[NG-nitro-N2-(3-methyl-8- quinolinesulfonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylate in the form of an amorphous solid.
A solution of 30 g the above product in 100 ml of ethanol and 100 ml of 1 N sodium hydroxide solution was stirred for 24 hrs at room temperature. At the end of this period, the solution was neutralized with 1 N hydrochloric acid and then concentrated to 70 ml. The solution was adjusted to pH=11 with 1 N sodium hydroxide solution, washed three times with 100 ml of ethyl acetate, acidified with 1 N hydrochloric acid and then extracted three times with 100 ml of chloroform. The combined chloroform solution was dried over anhydrous sodium sulfate and evaporated to give 28.0 g (97%) of 1-[NG-nitro-N2-(3- methyl-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2-piperidinecarboxylic acid as an amorphous solid. IR (KBr): 3,300, 1,720, 1,630 cm-1.
To a solution of 3.00 g of 1-[NG-nitro-N2-(3-methyl-8-quinolinesulfonyl)-Larginyl]- 4-methyl-2-piperidinecarboxylic acid in 50 ml of ethanol was added 0.5 g of palladium black and then the mixture was shaken under 10 kg/cm2 H2 pressure at 100°C for 8 hrs. At the end of this period, the ethanol solution was filtered to remove the catalyst and evaporated to give 2.50 g (90%) of 1- [N2-(3-methyl-1,2,3,4-tetrahydro-8-quinolinesulfonyl)-L-arginyl]-4-methyl-2- piperidinecarboxylic acid as an amorphous solid. IR (KBr): 3,400, 1,620, 1,460, 1,380 cm-1.

brand name

Novastan (Mitsubishi Chemical Corporation, Japan);Slonnon.

Therapeutic Function

Anticoagulant

Pharmacokinetics

Argatroban is a synthetic direct thrombin inhibitor derived from L-arginine indicated as an anticoagulant for prophylaxis or treatment of thrombosis in patients with heparin-induced thrombocytopenia. Argatroban is a direct thrombin inhibitor that reversibly binds to the thrombin active site. Argatroban does not require the co-factor antithrombin III for antithrombotic activity. Argatroban exerts its anticoagulant effects by inhibiting thrombin-catalyzed or -induced reactions, including fibrin formation; activation of coagulation factors V, VIII, and XIII; protein C; and platelet aggregation. Argatroban is highly selective for thrombin with an inhibitory constant (Ki) of 0.04 μM. At therapeutic concentrations, Argatroban has little or no effect on related serine proteases (trypsin, factor Xa, plasmin, and kallikrein). Argatroban is capable of inhibiting the action of both free and clot-associated thrombin.

Pharmacokinetics

Argatroban is administered subcutaneously because of the low lipophilicity of the drug. The drug is bound to plasma protein and is metabolized via CYP3A4/5 to the aromatized metabolite and the two hydroxylated metabolites. The M-1 metabolite retains 20 to 30% of the antithrombotic activity. Coadministration of argatroban with inhibitors of CYP3A4 does not appear to produce clinically significant effects. Argatroban is eliminated via biliary secretion into the feces.

Clinical Use

Argatroban has been approved for the prophylaxis and treatment of thrombosis in patients with HIT (79). Argatroban is a peptidomimetic that binds selectively to the catalytic site of thrombin as a univalent competitive DTI. Argatroban is available as a mixture of 21-R and 21-S diastereomers (64:36), with the S-isomer approximately twice as potent as the R-isomer. The drug is a reversible inhibitor of both free thrombin as well as clot-bound thrombin.

Drug interactions

Potentially hazardous interactions with other drugs
Analgesics: increased risk of haemorrhage with IV diclofenac and ketorolac - avoid.
Antiplatelets and anticoagulants: increased risk of bleeding complications.
Heparin: avoid concomitant administration.
Urokinase: may increase the risk of bleeding.
Thrombolytics: may increase risk of bleeding complications; enhance effect of argatroban.

Metabolism

Liver via hydroxylation and aromatization of the 3-methyltetrahydroquinoline ring. Age and gender do not substantially affect the pharmacodynamic or pharmacokinetic profile of argatroban.

Metabolism

The metabolism of argatroban has not yet been fully characterised. The metabolites identified (M-1, M-2, and M-3) are formed by hydroxylation and aromatisation of the 3-methyltetrahydroquinoline ring in the liver. The main metabolite (M1) exerts 40-fold weaker antithrombin effect than argatroban. Metabolites M-1, M-2 and M-3 were detected in the urine, and M-1 was detected in plasma and faeces.
Argatroban is excreted mainly in the faeces, presumably through biliary secretion. Following intravenous infusion of [14C]-argatroban 21.8±5.8% of the dose was excreted in urine and 65.4±7.1% in the faeces.

storage

Store at +4°C

References

1) Kikumoto?et al. (1984),?Selective inhibition of thrombin by (2R,4R)-4-methyl-1-[N2-[(3-methyl-1,2,3,4-tetrahydro-8-quinolinyl)sulfonyl]-l-arginyl)]-2-piperidinecarboxylic acid; Biochemistry,?23?85 2) Jang?et al. (1990),?Prevention of platelet-rich arterial thrombosis by selective thrombin inhibition; Circulation,?81?219 3) Sugawara?et al. (2009),?Thrombin inhibition by argatroban ameliorates early brain injury and improves neurological outcomes after experimental subarachnoid hemorrhage in rats; Stroke,?40?1530 4) Schulze?et al. (2008),?The thrombin inhibitor Argatroban reduces breast cancer malignancy and metastasis via osteopontin-dependent and osteopontin-independent mechanisms; Breast Cancer Res. Treat.,?112?243