A cross-over pharmacokinetic and thrombogenicity study of a prothrombin complex concentrate and a purified factor IX concentrate

Summary. A prospective cross-over study was carried out on 19 patients with haemophilia B, comparing the pharmacokinetics of a purified factor IX concentrate prepared by metal chelate affinity chromatography (9MC) with a conventional three-factor prothrombin complex concentrate (9A). The highly purified factor IX concentrate was shown to have a half-life comparable to the PCC; the in vivo recovery of the purified concentrate was significantly greater than that of the complex ( P < 0.01). The 20% change in the value of the International Standard for Factor IX Concentrate, introduced in 1988, might have been expected to lower the recovery values. However, the in vivo recovery for both concentrates was somewhat higher than reported previously, particularly in the older literature.
In nine patients, serial assays for fibrinopeptide A, prothrombin fragment FI+2 and thrombin-antithrombin complexes (TAT) were performed to assess the potential thrombogenicity of the two concentrates. Evidence was obtained that there was significantly less activation of coagulation following administration of purified factor IX (9MC), as compared to the activation that occurred after the PCC.     

Factor IX in Intravascular and Extravascular Blood Coagulation

1. Sera separated from intravascular clots obtained postmortem showed nofactor IX activity.

2. Evidence is presented suggesting that there are two forms of factor IX,intravascular and extravascular, and that there is an agent, named for convenience factor IX evolver (FNE) responsible for converting the former intothe latter with the evolvement of factor IX in the serum.

4. The significance of these experiments and some related problems arediscussed.

Submitted on January 22, 1962 Accepted on March 23, 1962     

Coagulation factor IX: successful surgical experience with a purified factor IX concentrate.

The use of plasma-derived coagulation factor concentrates has been marked by the transmission of viral agents. Infusions of factor IX complex concentrates have been additionally complicated by inappropriate thrombosis. Use of these concentrates in the neonate, in those with liver disease, and in surgical patients results in increased risk for this complication. Twenty patients have been infused with a purified coagulation factor IX concentrate for fall-off and recovery studies. A two-compartment model indicated an initial phase half-life of 4.06 +/- 2.86 hr and a beta phase half-life of 20.0 +/- 3.8 hr following the administration of AlphaNine, Coagulation Factor IX (Human). In vivo recovery was 62.7% +/- 13.8%, with an average factor IX coagulant level of 73% +/- 16% at 15 min after the infusion of a mean dose of 45 U/kg. Thirteen previously transfused patients with hemophilia B underwent major orthopedic or general or dental surgery using this purified factor IX. Operative outcomes were excellent in all patients. No excessive bleeding was noted. There was no laboratory or clinical evidence for a disseminated intravascular coagulopathy. The excellent surgical outcomes observed in this multitransfused group with biochemical evidence for active liver disease demonstrates the utility and safety of a purified coagulation factor IX concentrate.     

Coagulation Factor IX in Normal and Haemophilia B Plasma

S ummary . Coagulation factor IX has been isolated in a partially purified form from normal human plasma. Studies have been performed of the coagulant properties of this factor, of its activation by contact product and subsequent reaction with factor VIII. A similar chromatographic procedure with DE AE cellulose has been used to study the plasma of a patient with haemophilia B. A fraction has been isolated with similar physico-chemical properties to normal factor IX but lacking coagulant activity.     

Pharmacokinetics, thrombogenicity and safety of a double viral inactivated factor IX concentrate compared with a prothrombin complex concentrate

Therapeutic options for developing countries have to assure an optimum safety and efficacy and low-cost antihaemophilic concentrates. A single blind randomized crossover study was carried out in 12 previously treated HB patients, comparing the pharmacokinetics (PK), thrombogenicity (TG) and safety of two plasma-derived double-inactivated (solvent/detergent heating at 100 degrees C, 30 min) factor IX (FIX) concentrates, UMAN COMPLEX DI (product A) [plasma-derived prothrombin concentrates (PCC)] and a high purity FIX concentrate AIMAFIX DI (product B, HPFIX). In a non-bleeding state, they received one single intravenous dose 50 IU FIX kg(-1) of PCC or HPFIX, and after a wash-out period of 14 days, the other product. We evaluated acute tolerance and determined PK parameters based on FIX levels measured over a 50 h postinfusion period. We studied fibrinogen, platelets, antithrombin, F1 + 2, TAT, D-dimer, over a 360 min postinfusion period. Ten cases remained in on-demand treatment for 6 months, five with PCC and five with HPFIX. PK and anti-FIX inhibitors were repeated at 3 and 6 months. No inhibitors were detected. PK values (PCC vs. HPFIX): clearence (CL; mL h(-1) kg(-1)) 5.2 +/- 1.4 vs. 6.5 +/- 1.4; the volume of distribution at steady state (mL kg(-1)) 154.9 +/- 54.9 vs. 197.5 +/- 72.5; mean residence time (h) 29.7 +/- 8.1 vs. 30.7 +/- 9.2; T(1/2) (h) 22.3 +/- 7 vs. 23.5 +/- 12.3; incremental recovery (IR; U dL(-1) U(-1) kg(-1)) 0.96 +/- 0.17 vs. 0.76 +/- 0.13. HPFIX showed significant lower IR and higher CL. There were no differences in PK at 3 and 6 months. In TG, significant increments in TAT and F1 + 2 at 30 min and 6 h were found with PCC. Product B PK results agrees with reported results for other HPFIX preparations. Use of PCC product A has to consider its thrombogenic activity.     

The coagulant-active phospholipid content is a major determinant of in vivo thrombogenicity of prothrombin complex (Factor IX) concentrates in rabbits

In vitro evaluation of prothrombin complex concentrates in a thrombin generation assay, using DAPA and purified components of the prothrombinase complex, demonstrated significant levels of coagulant- active "phospholipid replacing" activity. Quantification of this activity showed a significant correlation (r = 0.8747, p less than 0.01) with thrombogenicity measured in vivo in a stasis model in rabbits. Extracted lipid material retained full phospholipid replacing activity in the vitro assay. Thin-layer chromatographic characterization confirmed the presence of phospholipids with known coagulant activity in vitro. In vivo, the extracted material was nonthrombogenic but augmented the thrombogenicity of purified factor Xa. Substitution of a synthetic coagulant-active phospholipid (phosphatidylcholine-phosphatidylserine lipid vesicles) for the extracted phospholipid produced a similar augmentation of a factor-Xa- induced thrombogenicity in vivo. It is concluded that the coagulant- active phospholipid content of prothrombin complex concentrates is a major determinant of thrombogenicity but requires the presence of activated clotting factors for its expression in vivo.     

Clinical Evaluation of Viral Safety of Coagulation Factor VIII and IX Concentrates

Virucidal methods to inactivate infectious agents are based on various methods of heating or chemically treating plasma concentrates of coagulation factors VIII and IX used in the treatment of hemophilia A and B. This clinical evaluation of the viral safety of such ‘treated’ concentrates is mainly based on the prospective study of previously untreated hemophiliacs by means of clinical and serological markers of viral infection. Although there have been a few focal episodes of human immunodeficiency virus (HIV) transmission by clotting factors, these have been traced to ineffective virucidal methods that are no longer used or to clerical errors during the manufacturing process. Viral inactivation by pasteurization, vapor heating, heating in the lyophilized state at 80°C and addition of solvent/detergent definitely decreases the risk of infection with hepatitis B and C. The current screening of plasma units for antibody to hepatitis C virus prior to inclusion in pools for concentrate production should further decrease the risk of hepatitis C infection. Other viruses, such as parvovirus and the hepatitis A virus, may still cause infections because they are quite resistant to virucidal methods. On the whole, virucidal methods have greatly reduced the risk of new HIV infections and, to a lesser degree, hepatitis.     

Coagulation Protein Function VII (Diametric Effects of Acetaldehyde on Factor VII and Factor IX Function)

The first metabolite of ethanol, acetaldehyde,has the ability to form adducts with proteins and altertheir function. It has been shown that acetaldehydereacts with various proteins of the blood coagulation pathway and, subsequently, produces aprolongation of the clotting time. This study evaluatedthe function of clotting proteins from the extrinsiccoagulation pathway (factor VII) and the intrinsiccoagulation pathway (factor IX) when preincubated withacetaldehyde as compared to a control and compared topreincubation with ethanol. Prior to use in a clottingassay, incubation times with acetaldehyde, ethanol, and the control were the same for both factorsVII and IX. An automatic fibrometer measured theclotting times. Factor VII preincubated withacetaldehyde prolonged the clotting time. However,factor IX preincubated with acetaldehyde actuallydecreased the clotting time. Of interest, both factorsVII and IX preincubated with acetaldehyde producedstatistically significant results when compared to thecontrol and ethanol. This experiment indicates thatacetaldehyde, in forming an adduct with proteins of theblood coagulation pathway, may induce a conformationalchange of factors VII and IX so as to either increase or decrease the clotting time. Therefore, it ispossible that some of the deranged coagulation inalcohol abusers may be a final net result of theinteraction of acetaldehyde and proteins of thecoagulation pathway.     

冠状病毒动物模型研究进展及2019-nCoV可能的易感小动物模型

建立高致病性冠状病毒动物模型对疫苗、抗体、药物、病毒致病机制研究意义重大。非人灵长类、雪貂、叙利亚仓鼠等动物均可用于建立冠状病毒的感染和疾病动物模型。不同动物模型能从不同层面模拟重现临床感染症状。然而,从适用性、经济性、易于获取等角度综合考虑,建立冠状病毒易感的小鼠模型,并快速提供数量充足的动物,对于冠状病毒疫情防控更有现实意义。本文简述了MERS-CoV、SARS-CoV以及新型冠状病毒(2019-nCoV)3种高致病性冠状病毒小鼠模型的研究进展。基于近日发表在Nature的研究成果,即SARS-CoV和2019-nCoV均利用hACE2受体感染宿主细胞推测,我们于2018年构建的hACE2-KI/NIFDC人源化小鼠模型有望用于2019-nCoV的相关研究。     

Thrombogenicity of Factor IX Concentrates: in vitro and in vivo (Rabbit) Studies

The reproducibility and correlation between the NAPTT, TGt50 in (vitro) tests and the Wessler (rabbit) stasis thrombus (in vivo) model have been studied using 10 different factor IX concentrates. The TGt50 test was more reproducible than the NAPTT and the overall reproducibility of the rabbit model was poor. The low reproducibility of the rabbit model appeared to be largely confined to those factor IX concentrates which showed a poor correlation between the NAPTT and TGt50 results. The TGt50 test emerged as the in vitro test which correlated most closely with the in vivo (rabbit) test. It is concluded that the NAPTT and TGt50 test are measuring different thrombogenic moieties in factor IX concentrates and that further studies are required to elucidate this phenomenon.     

In vivo recovery and half-life time of a steam-treated factor IX concentrate in hemophilia B patients

Summary Factor IX (FIX) recovery and half-life was measured in ten hemophilia B patients under standardized conditions. Each patient received a steam-treated high-purity factor IX concentrate at a dose of 19–39 U/kg body weight. FIX activity was determined using a one-stage assay, which was calibrated against the international concentrate standard (reagents from Immuno, Heidelberg). The in vivo recovery ranged from 24% to 53% (mean value 37.7%) and the half-disappearance time (HDT) from 8–30 h (mean 16.7 h). In four of the ten patients, the distribution and elimination half-lives were estimated and ranged from 0.3 h to 3.9 h (mean 1.4 h) and from 28.6 h to 39.7 h (mean 33.1 h), respectively. In six patients FIX was redetermined using a different FIX deficient plasma and a plasma standard (reagents from Merz & Dade, Munich, FRG). Recoveries and HDT based on the results obtained with this method were significantly higher (68.2% vs 39.7%; p<0.05), and longer (14.8 h vs 10.6 h; p<0.05), respectively. FIX activity was also measured by both assay systems in 100 healthy subjects (50 males, 50 females). The reagents from Immuno yielded a mean value of 0.77 U/ml, while the mean FIX activity utilizing standards and reagents from Merz & Dade was 1.11 U/ml (p<0.000001). The coefficient of correlation between the FIX activity measurements, as determined in 100 healthy subjects and 6 hemophilia B patients using the different test systems, was r=0.9 (N=159; y=0.08+1.3 * x; p<0.001). Our data suggest that recovery and HDT of factor IX concentrate strongly depend on the assay and calibration conditions and that an international FIX activity plasma standard is urgently required.     

Factor IX is activated in vivo by the tissue factor mechanism

Despite significant progress in elucidating the biochemistry of the hemostatic mechanism, the process of blood coagulation in vivo remains poorly understood. Factor IX is a vitamin K-dependent glycoprotein that can be activated by factor XIa or the factor VII-tissue factor complex in vitro. To investigate the role of these two pathways in factor IX activation in humans, we have developed a sensitive procedure for quantifying the peptide that is liberated with the generation of factor IXa. The antibody population used for the immunoassay was raised in rabbits and chromatographed on a factor IX-agarose immunoadsorbent to obtain antibody populations with minimal intrinsic reactivity toward factor IX. We determined that the mean level of the factor IX activation peptide (FIXP) in normal individuals under the age of 40 years was 203 pmol/L and that levels increased significantly with advancing age. The mean concentration of FIXP was markedly reduced to 22.7 pmol/L in nine patients with hereditary factor VII deficiency (factor VII coagulant activity less than 7%) but was not significantly different from normal controls in nine subjects with factor XI deficiency (factor XI coagulant activity less than 8%). These data indicate that factor IXa generation in vivo results mainly from the activity of the tissue factor mechanism rather than the contact system (factor XII, prekallikrein, high molecular-weight kininogen, factor XI). Our results may also help to explain the absence of a bleeding diathesis in many patients with deficiencies of the contact factors of coagulation.     

An open clinical study assessing the efficacy and safety of Factor IX Grifols®, a high‐purity Factor IX concentrate,in patients with severe haemophilia B

Summary. Factor IX Grifols^® is a new high‐purity plasma‐derived FIX concentrate with two specific pathogen elimination steps. Until this study was performed, there were no detailed reports with an adequate number of patients on the clinical evaluation of this product. To determine the efficacy and safety of Factor IX Grifols^® for replacement therapy in previously treated patients with severe haemophilia B, this open, multicentre and non‐randomized study included 25 male subjects over the age of 12 with severe haemophilia B. Patients underwent prophylaxis and treatment of bleeding episodes with Factor IX Grifols^® for 1 year. The clinical efficacy and safety of this product were assessed. Forty percent of the patients were children and adolescents (12–17 years old). During the 12 months follow‐up, 1 446 000 IU of Factor IX Grifols^® were administered in 961 infusions (range 12–83 infusions per patient): 31% for prophylaxis and 69% for bleeding episodes. Only five major bleeding events were reported in two patients. These haemorrhages were successfully treated with a mean of 2900 IU per bleed (range 1500–4000 IU), and 1–3 infusions per bleed. The average time elapsed from the first infusion to resolution of bleeding was 43 h (median). Overall, haemostasis was rated as excellent or good by the investigator in 96% of the infusions. No product‐related adverse events were reported. Factor IX Grifols^® is an effective and safe Factor IX concentrate and can be considered as a first line option for replacement therapy in haemophilia B patients.