CLINICAL-STUDY OF RECOVERY AND HALF-LIFE OF VAPOR-HEATED FACTOR-VII CONCENTRATE

Background: The in vivo recovery and half-life of intermediate-purity, vapor-heated factor VII (FVII) concentrate were determined in patient s having a congenital deficiency for FVII according to the 1991 guidel ines of the International Society for Thrombosis and Haemostasis. Stud y Design and Methods: A total of 11 patients received a single infusio n of the FVII concentrate. Blood was drawn before infusion and 15 and 30 minutes and 1,2, 4, 8, 12, and 24 hours after. Recoveries were calc ulated from the highest FVII activity of the first four blood samples drawn after infusion. The two-phase linear regres- sion method was use d to estimate the half-life according to the two-compartment model. In addition, a noncompartmental approach was applied. Results: The mean recovery value obtained for FVII concentrate, 110.53 percent (SD, +/- 26.37), indicates rapid and efficient incorporation into the blood str eam. Equivalent results were obtained with both pharmacokinetics metho ds and indicate a very short half-life for FVII. A half-life of 6.49 h ours (SD, +/- 2.42) with the compartmental method and a half-life of 5 .25 hours noncompartmental method. Conclusion: The half-life and recov ery reported here, along with the specificity of the replacement thera py, the earlier anecdotal cases of clinical efficacy, and the clinical safety of the concentrate with regard to viral infections, recommend vapor-heated FVII concentrate for the treatment of patients with hered itary FVII deficiency.