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To the Editor.—
Our most recent experience with the prothrombin concentrate Konyne in factor VIII inhibitor patients has shown considerable variation in potency of various lots with respect to coagulant content as well as clinical effectiveness. Another investigator has made a similar observation (Charles Abildgaard, personal communication). We would suggest the manufacturer be contacted regarding potency of their product before employing it to control bleeding in inhibitor patients.As noted in our article (236:2061, 1976), the other commercially available prothrombin concentrate, Proplex, has undergone a change in processing and does not appear to be effective. The investigational product Auto IX continues to provide a good therapeutic response in this condition.
Penner JA, Kelly PE. Prothrombin Complex Concentrates for Inhibitor Patients. JAMA. 1977;237(13):1311–1312. doi:10.1001/jama.1977.03270400015004