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4CPS-072 Real-world experience in haemophilia B patients after switching to fix extended half-life using pharmacokinetic population software and monocompartmental model
  1. JC Juárez-Giménez1,
  2. O Benítez-Hidalgo2,
  3. JA Romero-Garrido3,
  4. C Mateos-Salillas4,
  5. S González-Piñeiro5,
  6. JB Montoro-Ronsano6
  1. 1Hospital Univeristario Vall D’hebron, Pharmacy, Barcelona, Spain
  2. 2Hospital Universitario Vall D’hebron, Faramcia, Barcelona, Spain
  3. 3Hospital Universitario la Paz, Farmacia, Madrid, Spain
  4. 4Hospital Universitario la Paz, Faramcia, Madrid, Spain
  5. 5Complejo Hospitalario Universitario A Coruña, Farmacia, A Coruña, Spain
  6. 6Hospital Univeristario Vall D’hebron, Farmacia, Barcelona, Spain


Background and Importance New strategies have been developed for the prophylactic treatment of patients with haemophilia B (HB) such as extended half-life recombinant factor IX concentrates (rFIX EHL). These products have shown favourable pharmacokinetic properties, attaining a half-life 3- to 5-fold longer in rFIX EHL compared to standard FIX concentrates

Aim and Objectives Efficiency of a pharmacokinetic-based tailored prophylaxis-dosing schedule versus standard dosing (DS) is compared, in HB, treated with two rFIX-EHL.

Material and Methods Observational, analytical, prospective, multicentre study, involving HB patients, being treated with rFIX-EHL linked to albumin (rFIX-FP) or to fragment crystallisable (rFIX-Fc). Demographic and clinical data, and DS and dosing interval (DI) and actual FIX trough levels were recorded. Pharmacokinetic characterisation was performed following both a population (WAPPS-HEMO) and a linear one-compartment (OC) approach. For each approach and rFIX preparation, an estimation of the time to the target trough (5 IU FIX/dL) was made. Statistical analysis was performed by means of the Student-Fisher t-test.

Results Fifteen patients were included, nine being treated with rFIX-FP (mean age, 33 years; weight 60 kg), and six with rFIX-Fc (49 years, 86 kg). Mean DS was 3222 UI (SD, 1716) every 11,9 days (SD, 4,4) for rFIX-FP patients; and 4333 UI (SD, 606) every 14,0 days (SD, 0,0) for rFIX-Fc patients. The individual tailored DI, for a 0,05 UI/dL trough target was: applying OC; 13,6 days (SD, 5,1), -1,8 days (SD, 5,9) vs DS, representing 240 IU/day (SD, 136,1) for rFIX-FP (p=0,40), and 8,6 days (SD, 1,2), +5,4 days (SD, 1,2) vs DS, representing 508 IU/day (SD, 65,6), for rFIX-Fc, (p<0,001). Applying WAPPS-HEMO; it was 15,0 days (SD, 5,1), -3,1 days (SD, 5,3) vs DS, 217 IU/day (SD, 114,7), for rFIX-FP (p=0,12), and 10,2 days (SD, 2,5), +3,8 days (SD, 2,5) vs DS, 449,7 UI/day (SD, 129,1), for rFIX-Fc, (p=0,012).

Conclusion and Relevance Efficiency of rFIX-EHL treatment following a pharmacokinetic-based tailored prophylaxis-dosing schedule versus DS in HB patients, is significantly better. Depending on the commercial preparation, rFIX-FP or rFIX-Fc. Daily-adjusted dose, for a 5 IU FIX/dL trough target, ranges between 217-240 IU/day for rFIX-FP, or 449-508 IU/day for rFIXFc, according to the two pharmacokinetic approaches (OC and population based).

Conflict of Interest No conflict of interest.

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