To Prevent Clotting

Hematologists have long sought ways to prevent the formation of dangerous and possibly fatal blood clots. First there was heparin, extracted from the livers and lungs of beef cattle. Then came coumarins, made from rotted sweet clover. Now some British researchers believe they have found what they want in the venom of a Malayan pit viper, close kin to American rattlesnakes.

The trouble with heparin and some other anticoagulants is that they not only prevent clotting, but may overshoot the mark and make a patient liable to hemorrhage. Doctors in Malaya, treating victims of pit viper bites, noticed that they never seemed to have trouble with clots, and neither did they bleed excessively. Years of research to purify the active part of the venom yielded a substance named Arvin by London's Twyford Laboratories. Now, reports in the Lancet testify to the potential of Arvin, given intravenously.

At Oxford's United Hospitals, 19 patients with a variety of clotting problems, including deep-Vein thromboses in the legs and some involving the lungs, have been treated. In at least ten, the result is cautiously reported as "satisfactory." In others, it was equivocal, but all these patients had other complicating problems. From London's Royal Postgraduate Medical School comes a report of nine patients treated, eight successfully. Most important, the Lancet notes editorially, is that Arvin may not only prevent clotting but actually help to dissolve some clots already formed.

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