Three trials investigated the pharmacokinetics (PK) of recombinant factor XIII (rFXIII) A-subunit. To compare the PK characteristics of rFXIII among trials and different age groups of patients. Dosing with rFXIII 35 IU kg(-1) every 4th week. Blood samples for PK assessments were collected regularly throughout the dosing interval from a total of 68 individual patients with FXIII congenital deficiency. The mean PK parameters were similar across the three age groups, and for the three trials, as well as constant over time based on results from patients participating in both mentor 1 and mentor 2 trials. The geometric mean half-life ranged from 11.6 to 15.0 days, and the trough FXIII activity levels ranged from 0.15 to 0.21 IU mL(-1) . The population PK model identified body weight as a statistically significant covariate influencing clearance (CL) and volume of distribution (Vd ), with a similar increase in both parameters with increased body weight. The half-life was not affected by body weight. Gender (females vs. males) and age category (paediatric vs. adult) did not affect CL. The PK profile of rFXIII, after dosing with 35 IU kg(-1) of rFXIII, was independent of age and comparable between trials and FXIII trough activity levels were constant. Despite rather large individual variation in the maximal FXIII activity levels, all individual mean trough activity levels were above 0.1 IU mL(-1) during the entire duration of the trials. The results support that monthly dosing with 35 IU kg(-1) of rFXIII to patients with FXIII A-subunit deficiency, regardless of age, is adequate for prophylaxis.

Pathogen reduction reduces procoagulant and anticoagulant coagulation factors as well as variability. A thrombin-generation assay showed no reduced ETP and no supraphysiological thrombin generation. None of the FFP preparations is likely to be effective for treating fibrinogen deficiency.

IntroductionSpontaneous bleeding resulting in compartment syndrome at the lower adult leg due to acquired hemophilia A is rare. There are no reports on operative management of this entity.Case presentationWe present a case of atraumatic compartment syndrome of the lower leg due to acquired factor VIII deficiency, in an 83-year-old Caucasian man of European descent. He was treated surgically with a long and complicated postoperative course after presenting to a community hospital with a 2-day history of increasing pain and swelling in his left lower leg without a previous history of trauma.ConclusionsAwareness, prompt diagnosis and effective treatment of compartment syndrome caused by a rare bleeding disorder, which is usually acquired by the elderly, is essential and may spare a patient from surgery or even limb loss, if early administration of recombinant factor VIIa is effective. The course of disease in a patient with operative management of spontaneous bleeding, compartment syndrome and acquired hemophilia A may be prolonged. However, an interdisciplinary approach with meticulous surgical treatment and bleeding management with recombinant factor VIIa as well as inhibitor eradication by immunosuppressive treatment can be successful and expensive.

N8-GP (ESPEROCT ® ; turoctocog alfa pegol; Novo Nordisk A/S, Bagsvaerd, Denmark) is an extended half-life recombinant factor VIII (FVIII) molecule. FVIII-deficient plasma spiked with N8-GP can be accurately measured using many activated partial thromboplastin time (aPTT)-based one-stage clotting assay reagents with normal human plasma calibrators. To date, there are few data on the measurement accuracy of samples from patients treated with N8-GP. Here, we measure patient samples during routine treatment monitoring. Three previously treated patients with severe hemophilia A (HA) without inhibitors (baseline FVIII activity < 0.01 IU/mL) received 50 IU/ kg N8-GP every fourth day or twice weekly over 5 years as part of the pathfinder2 trial. Patient samples were monitored using the Pathromtin ® SL aPTT reagent (Siemens Healthcare GmbH, Erlangen, Germany), a BCS ® XP System analyzer (Siemens), and Standard Human Plasma (Siemens) or productspecific calibrators. Patient age ranged from 36 to 62 years. Overall, measurements performed using product-specific or Standard Human Plasma calibrators were in good agreement , with ratios randomly distributed around 1.0. Peak ratios tended to be closer to 1.0 than trough samples. Pathromtin ® SL with Standard Human Plasma calibrator consistently and accurately measured FVIII activity in samples from severe HA patients receiving N8-GP prophylaxis.

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