Acquired Resistance to Ancrod Its Evaluation and Clinical Occurrence

Summary

A simple test for the detection and quantitation of resistance to ancrod is described. The test is based on the polymerization of fibrinogen by ancrod. The possible variables of the method such as the concentration of fibrinogen, the adsorption of ancrod onto a normal serum protein and the kinetics of the reaction between ancrod and the inactivating substance are examined. By this method, in 4 out of 19 patients who had previously received ancrod, resistance could be detected up to 15 months after therapy. In one of those patients, a second series of doses of ancrod was given. When the dose was elevated to an extent corresponding to the concentration of the inactivating substance, hypofibrinogenemia could be promptly established. The clinical importance of the test is discussed.

• References

• 1 Bell W. R, Bolton G, Pitney W. R. 1968; The effect of arvin on blood coagulation factors. British Journal of Haematology 15: 589.
• 2 Chan K. E, Rizza C. R, Henderson M. P. 1965; A study of the coagulant properties of Malayan pit viper venom. British Journal of Haematology 11: 464.
• 3 Pitney W. R, Holt P. J. L, Bray C, Bolton G. 1969; Acquired resistance to treatment with arvin. The Lancet I: 79.
• 4 Regoeczi E, Bell W. R. 1969; In vivo behaviour of the coagulant enzyme from Agkistro- don rhodostoma venom : Studies using ¹³¹I-Arvin. British Journal of Haematology 16: 573.
• 5 Regoeczi E, Gergely J, Macfarlane A. S. 1966; In vivo effects of Agkistrodon rhodostoma venom : Studies with fibrinogen ¹³¹I. Journal of Clinical Investigation 45: 1202.
• 6 Ross J. W, Bunn D. R. G, Ashford A. 1969; Antigenicity of arvin. The Lancet I: 310.
• 7 Vinazzer H. 1971; Zur Wirkung von Arvin auf die Blutgerinnung. Wiener Zeitschrift für Innere Medizin 52: 378.