Anticoagulant Activity and Pharmacokinetic Properties of a Sub-cutaneously Administered Mixed Micellar Formulation of Argatroban in Experimental Animals

Summary

We have studied the anticoagulant properties of a novel mixed micellar formulation containing 14 mg/ml argatroban administered by the sub-cutaneous (s. c.) route to rats, rabbits, dogs and primates. Blood samples were taken at various times post-treatment for the determination of the thrombin time (TT), Ecarin clotting time (ECT) and the activated partial thromboplastin time (aPTT). Plasma levels of argatroban were determined in the dog and primate.

Mixed micelles alone (0.15 M sodium glycocholate and 0.15 M egg lecithin) were without effect on the clotting parameters. The mixed micellar formulation of argatroban dose-dependently increased all three clotting parameters in the rat (1–4 mg/kg), the rabbit (1 and 2 mg/kg), the dog (1 and 2 mg/kg) and the primate (0.25 and 0.5 mg/kg). In each case the TT was the most sensitive parameter, followed by the ECT and the aPTT. The duration of action of argatroban in each species was dose dependent and varied from 3 h in the rat to 6 h in the dog. In the latter, the mixed micelle formulation had a significantly increased plasma half-life and mean residence time without affecting the overall area under the curve. The increases in the clotting time were strongly correlated with the plasma levels of argatroban and were linear across the range of concentrations obtained in the dog and the primate, although the aPTT plasma concentration response curve was very flat. Species differences were noted between the increase in clotting time for a given plasma concentration, with the primate being more sensitive than the dog (e. g. 4.7 times more so in terms of the ECT).

Thus, a mixed micellar formulation of argatroban, which markedly enhances its solubility, could be useful as a potential anticoagulant for sub-cutaneous administration.

Keywords

Argatroban mixed micelles - thrombin time - ecarin clotting time - aPTT - plasma levels

• References

• 1 Maraganore JM. Thrombin, thrombin inhibitors and the arterial thrombotic process. Thromb Haemost 1993; 70: 208-11.
• 2 Hemker HC. Thrombin generation, an essential step in haemostasis and thrombosis. In, “Haemostasis and Thrombosis”. Bloom AL, Forbes CD, Thomas DP, Tuddenham EGD. eds. Churchill Livingstone; London: 1994: 477-90.
• 3 Erikson BI, Ekman S, Kälebo P, Zachrisson BZ, Bach D, Close P. Prevention of deep-vein-thrombosis after total hip replacement: direct thrombin inhibition with recombinant hirudin, CGP 39393. Lancet 1996; 347: 635-9.
• 4 Erikson BI, Mouret P, Kälebo P, Baue M, Ekman S, Lindbrat S, Bach D, Close P. Recombinant hirudin, CGP 39393 (Revasc), is more effective than enoxaparin as prophylaxis of thromboembolic complications in patients undergoing total hip replacement. Haemostasis 1996; 26 (Suppl. 03) 624.
• 5 Okamoto S, Hijikata A, Kikumoto R, Tonomara S, Hara H, Ninomiya K, Maruyama A, Sugano M, Tamao Y. Potent inhibition of thrombin by the newly synthesized arginine derivative no. 805. The importance of stereostructure of its hydrophobic carboxamide portion. Biochem Biophys Res Commun 1981; 101: 440-6.
• 6 Kikumoto R, Tamao Y, Tezuka T, Tonomura S, Hara H, Ninomiya K, Hijikata A, Okamoto S. Selective inhibition of thrombin by (2R,4R)-4- Methyl-1-[N²-[(3-methyl-1,2,3,4-tetrahydro-8-quinolinyl)sulfonyl]-arginyl]-2-piperidinecarboxylic acid. Biochemistry 1984; 23: 85-90.
• 7 Berry CN, Girardot C, Lecoffre C, Lunven C. Effects of the synthetic thrombin inhibitor argatroban on fibrin- or clot-incorporated thrombin: Comparison with heparin and recombinant hirudin. Thromb Haemost 1994; 72: 381-6.
• 8 Lunven C, Gauffeny C, Lecoffre C, O’Brien DP, Roome NO, Berry CN. Inhibition by argatroban, a specific thrombin inhibitor, of platelet activation by fibrin clot-associated thrombin. Thromb Haemost 1996; 75: 154-60.
• 9 Fujioka K. The Effect of MD-805 on Experimental Acute Arterial Thrombosis in Relation to Vasoactive Prostanoids (TXA₂ and PGI₂). J Jap Coll Angiol 1989; 29: 57-64.
• 10 Jang IK, Gold HK, Ziskind AA, Leinbach RC, Fallon JT, Collen D. Prevention of Platelet-Rich Arterial Thrombosis by Selective Thrombin Inhibition. Circulation 1990; 81: 219-25.
• 11 Berry CN, Girard D, Lochot S, Lecoffre C. Antithrombotic actions of argatroban in rat models of venous, “mixed” and arterial thrombosis, and its effects on the tail transection bleeding time. Br J Pharmacol 1994; 113: 1209-14.
• 12 Berry CN, Girard D, Girardot C, Lochot S, Lunven C, Visconte C. Antithrombotic activity of argatroban in experimental thrombosis in the rabbit. Semin Thromb Hemost 1996; 22: 233-41.
• 13 Duval N, Lunven C, O’Brien DP, Grosset A, O’Connor SE, Berry CN. Antithrombotic actions of the thrombin inhibitor, argatroban, in a canine model of coronary cyclic flow: comparison with heparin. Br J Pharmacol 1996; 118: 727-33.
• 14 Schumacher WA, Heran CL, Steinbacher TE. Low molecular weight heparin (Fragmin) and thrombin active site inhibitor (Argatroban) compared in experimental arterial thrombosis and bleeding time. J Cardiovascular Pharmacol 1996; 28: 19-25.
• 15 Steffen H, Schmidt DUS. Patent 4158 707 Chem Abst. 1979; 91: 96642.
• 16 Rosoff M, Serajuddin ATM. Solubilization of diazepam in bile salts and in sodium cholate-lecithin-water phases. Int J Pharm 1980; 10: 6362-70.
• 17 Supersaxo A, Hein WR, Steffen H. Mixed micelles as proliposomal, lymphotrophic drug carrier. Pharm Res 1991; 08: 1286-91.
• 18 Alkan-Onyuksel H, Ramakrishnan S, Chai HB, Pezzuto JM. A mixed micellar formulation suitable for the solubilization of taxol. Pharm Res 1994; 11: 206-12.
• 19 Iida S, Komatsu T, Hirano T, Fujimura Y, Nakai H, Kitazawa K, Kumagai Y, Sato T, Hayashi K, Inokuchi K. Pharmacokinetic studies of argatroban (MD-805) in dogs and rabbits. Blood or plasma level profile, metabolism, excretion and accumulation after single or consecutive intravenous administration of argatroban. Oyo Yakuri (Pharmacometrics) 1986; 32: 1171-27.
• 20 Berry CN, Lunven C, Girardot C, Lechaire I, Girard D, Charles M-C, Ferrari P, O’Brien DP. Ecarin clotting time: a predictive coagulation assay for the antithrombotic activity of argatroban in the rat. Thromb Haemost 1998; 79: 228-33.
• 21 Peters RF, Lees CM, Mitchell KA, Tweed MF, Talbot MD, Wallis RB. The characterisation of thrombus development in an improved model of arteriovenous shunt thrombosis in the rat and the effects of recombinant desulphatohirudin (CGP 39393), heparin, and iloprost. Thromb Haemost 1991; 65: 268-74.
• 22 Nurmohamed MT, Berckmans RJ, Morrien-Salomons WM, Berends F, Hammes WD, Rijnierse JJMM, Sturk A. Monitoring anticoagulant therapy by activated partial thromboplastin time: Hirudin assessment. Thromb Haemost 1994; 72: 685-92.
• 23 Schwarz RP, Becker JCP, Brooks RL, Joffrion JL, Knappenberger GD, Kogan TP, Kogan PW, McKinney AA. The preclinical and clinical pharmacology of Novastan (argatroban): a small-molecule, direct thrombin inhibitor. Clin Appl Thrombos Hemost 1997; 03: 1-15.
• 24 Pötzsch B, Madlener K, Seelig C, Riess CF, Greinacher A, Müller-Berghaus G. Monitoring of r-hirudin anticoagulation during cardiopulmonary bypass – Assessment of the whole blood ecarin clotting time. Thromb Haemost 1997; 77: 920-5.
• 25 Kher A, Al Dieri R, Hemker HC, Beguin S. Laboratory assessment of antithrombotic therapy: what tests and if so why?. Haemost 1997; 27: 211-8.
• 26 Herrman JPR, Suryapranata H, den Heijer P, Gabriel L, Kutryk MJB, Serruys PW. Argatroban during percutaneous transluminal coronary angioplasty: results of a dose-verification study. J Thromb Thrombolys 1996; 03: 367-73.
• 27 Bergougnan L, Caplain H, Dubruc C, Cabanis MJ, Marsac J. Pharmacodynamic and pharmacokinetic profile of argatroban in healthy volunteers. Fund Clin Pharmacol 1997; 11: 157.
• 28 Callas DD, Fareed J. Comparative anticoagulant effects of various thrombin inhibitors, as determined in the ecarin clotting time method. Thromb Res 1996; 83: 463-8.