We have investigated the feasibility of continuous infusion of undiluted
factor IX (FIX) over several days using minipumps. The stabilities of
seven different reconstituted FIX products were substantially better
than those declared by the manufacturers. Several concentrates
maintained factor activities above 80% of baseline for the entire
period of 4 weeks at 4-8 degrees C as did one product at 20-23 degrees
C. At 37 degrees C the latter concentrate was stable for at least 1
week. The stability seemed to correlate with the purity of the product.
Analysis of two prothrombin complex concentrates by gel electrophoresis
demonstrated degradation of prothrombin to prethrombin-1 and fragment 1
at 37 degrees C and in one of the concentrates also at 20-23 degrees C.
In two FIX concentrates the corresponding analysis did not reveal any
degradation. Four patients were treated with continuous infusion with a
pure FIX concentrate (Mononine(TM), Armour) after surgery or for serious
haemorrhage (two each) with good haemostatic effect, an initial
progressive decrease of the FIX clearance, and no side-effects.
Continuous infusion with FIX, using a minipump and undiluted
reconstituted factor, is therefore feasible and effective, and can be
conveniently prepared for several days at a time. Pure FIX products are
more stable and probably safer for this purpose