Feasibility of Using Recombinant Factor VIIa in Continuous Infusion

Coagulopathy after severe pediatric trauma

Trauma remains the leading cause of morbidity and mortality in the United States among children aged 1 to 21 years. The most common cause of lethality in pediatric trauma is traumatic brain injury. Early coagulopathy has been commonly observed after severe trauma and is usually associated with severe hemorrhage and/or traumatic brain injury. In contrast to adult patients, massive bleeding is less common after pediatric trauma. The classical drivers of trauma-induced coagulopathy include hypothermia, acidosis, hemodilution, and consumption of coagulation factors secondary to local activation of the coagulation system after severe traumatic injury. Furthermore, there is also recent evidence for a distinct mechanism of trauma-induced coagulopathy that involves the activation of the anticoagulant protein C pathway. Whether this new mechanism of posttraumatic coagulopathy plays a role in children is still unknown. The goal of this review is to summarize the current knowledge on the incidence and potential mechanisms of coagulopathy after pediatric trauma and the role of rapid diagnostic tests for early identification of coagulopathy. Finally, we discuss different options for treating coagulopathy after severe pediatric trauma.

Recombinant Activated Factor VII in Patients at High Risk of Bleeding

Currently, recombinant activated factor VII (rFVIIa) (NovoSeven) is indicated for the treatment of spontaneous and surgical bleeding in congenital haemophilia A and B patients with inhibitors to factors VIII (FVIII) and IX (FIX) >5 Bethesda units (BU) worldwide, and in patients with acquired haemophilia, congenital FVII deficiency and Glanzmann's thrombasthenia in Europe. Until April 2003, almost three-quarters of a milion doses of rFVIIa have been administered proving its efficacy and excellent safety record. According to results from initial clinical trials and a large number of case reports, the rFVIIa may be effective not only in treating haemophilia patients but also in treatment of bleeding in patients on oral anticoagulation or heparin, patients with liver diseases, von Willebrand disease (vWD), thrombocytopenia, various platelet defects, congenital or acquired deficiency of FVII, and in subjects without any pre-existing coagulopathy with diffuse life-threatening bleeding triggered by surgery or trauma. This review will briefly summarize rFVIIa mode of action in haemostasis, the current clinical experience with rFVIIa and focus on the alternative use of rFVIIa in patients at the high risk of bleeding in both spontaneous cases and clinical trials reports.

rFVIIa administered by continuous infusion during surgery in patients with severe congenital FVII deficiency

The use of recombinant FVIIa (rFVIIa) to control bleed in individuals with FVII deficiency has been proven to be effective. The main problems associated with its use are that it requires frequent bolus injections to counteract its short half-life and high cost. Our study aimed to evaluate whether any advantage could be gained by providing rFVIIa by continuous infusion during surgery with regard to haemostatic efficacy, safety and cost. The prospective study included 10 patients with severe FVII deficiency, who underwent 25 surgical procedures (13 major and 12 minor procedures) and were treated with rFVIIa administered by continuous infusion. Tranexamic acid was given concomitantly every 8 h. Prothrombin time, FVII:C assay and thrombin generation assay were used to monitor the treatment. The mean total dose given was 10 mg during a major surgery and 4.4 mg during a minor surgery for a mean treatment duration of 7.5 and 4.0 days respectively. This corresponds to a reduction of 70-90% in drug usage and medication cost compared with bolus injections. Except for one major perioperative bleeding, excellent haemostasis was achieved in all procedures. One patient developed a transient inhibitory activity. None of these events affected the postoperative course or prolonged the hospital stay. Our study demonstrated that continuous infusion of rFVIIa during surgery is safe, effective and highly cost effective.

First 20 years with recombinant FVIIa (NovoSeven)

This review describes the background for the development of recombinant FVIIa (rFVIIa; NovoSeven) for use in haemophilic patients with inhibitors. The first proof of principle for using pharmacological doses of FVIIa as a haemostatic agent was obtained by producing small amounts of pure plasma-derived FVIIa, which showed encouraging effect in two patients with haemophilia A and inhibitors. To make pure FVIIa available for use in a larger number of patients, rFVIIa was produced that was approved for use in patients with inhibitors against coagulation factors (congenital haemophilia and acquired haemophilia) in 1996 (EU), 1999 (USA) and 2000 (Japan). The efficacy rate in severe bleedings and in major surgery including major orthopaedic surgery has been found to be around 90% in controlled studies, and no serious safety concerns have been demonstrated. The availability of rFVIIa has facilitated the performance of elective major surgery in haemophilia patients with inhibitors. Further steps along the vision of providing a treatment for inhibitor patients similar to non-inhibitor patients have been the efficacy of rFVIIa in home-treatment and recently the encouraging experience in prophylaxis. The concept of using pharmacological doses of rFVIIa as a haemostatic agent is a new one, which has caused difficulties in finding the correct dose. A step forward has been the demonstration that similar efficacy can be achieved after one single dose of 270 μg kg(-1) instead of three injections of a dose of 90 μg kg(-1). The higher clearance rate in children suggests that higher doses may be beneficial in children. The availability of rFVIIa has made advances in the understanding of coagulation processes possible. In a cell-based in vitro model, it has been shown that rFVIIa binds to preactivated platelets if present in concentrations of 30 nm or higher. By doing so, it activates FX into FXa and enhances the thrombin generation on the activated platelet surface in the absence of FVIII/FIX. Through the increased thrombin generation, a firm, well-structured fibrin haemostatic plug, which is resistant to premature lysis, is formed. By exploiting this mechanism of action, rFVIIa may also be effective in situations other than haemophilia, characterized by an impaired thrombin generation.

Elective orthopaedic surgery for haemophilia patients with inhibitors: single centre experience of 40 procedures and review of the literature

With the introduction of safe and effective factor VIII/IX-bypassing agents--recombinant activated factor VII (rFVIIa) and plasma-derived activated prothrombin complex concentrates (pd-APCC)--elective orthopaedic surgery (EOS) is a viable option for haemophilia patients with inhibitors. We report a series of patients with haemophilia and inhibitors undergoing EOS between 1997 and 2008 using bypassing agents to provide haemostatic cover. All inhibitor patients undergoing EOS and receiving rFVIIa, plasma-derived prothrombin complex concentrates (pd-PCC) or pd-APCC as haemostatic cover were included. Patients were operated on by the same surgeon and were managed by the same haemophilia treatment centre. Forty procedures (25 minor and 15 major) were conducted in 18 patients. Twenty-one minor cases were covered using rFVIIa, three with pd-PCC, and one with pd-APCC; all major cases were covered using rFVIIa. Bleeding was no greater than expected compared with a non-haemophilic population in all 25 minor procedures. In the major procedure group, there was no excessive bleeding in 40% of cases (6/15) and bleeding completely stopped in response to rFVIIa. For the remaining nine cases, bleeding response to rFVIIa was described as 'markedly decreased' or 'decreased' in 4/15 cases and 'unchanged' in 5/15 cases. Overall, efficacy of rFVIIa, based on final patient outcome, was 85%. One death occurred as a result of sepsis secondary to necrotizing fasciitis. Good control of haemostasis can be achieved with bypassing agents in haemophilia patients with inhibitors undergoing minor EOS; rFVIIa was used as an effective bypassing agent, enabling EOS in patients undergoing minor and major procedures.

Effect of X-ray radiation exposure on lyophilized recombinant activated factor VII (formulated for storage at room temperature)

OBJECTIVE

To investigate effects of air transport and X-ray radiation exposure through airport security of a new room temperature-stable rFVIIa formulation (NovoSeven/NovoSeven RT, Novo Nordisk A/S, Bagsvaerd, Denmark) lyophilized using in vitro study methodology, thus evaluating possible effects of exposure through airport security and airplane travel.

RESEARCH DESIGN AND METHODS

The effect of X-ray radiation exposure of rFVIIa and the solvent histidine at two different doses (400 microSv and 2000 microSv) was examined immediately after exposure, and post-exposure after storage at 30 degrees C for 1 month. References samples, not exposed to X-ray radiation, were used for comparison.

MAIN OUTCOME MEASURE

Stability of rFVIIa after X-ray radiation exposure.

RESULTS

All product parameters analyzed were within the acceptance criteria as well as within shelf life specification limits for the selected parameters for each product.

CONCLUSION

The product rFVIIa and solvent histidine are therefore not expected to be affected as a consequence of airplane traveling and X-ray exposure during airport security check using hand luggage scanners.

Off-label use of rFVIIa in children with excessive bleeding: a consecutive study of 153 off-label uses in 139 children

BACKGROUND

Recombinant factor VIIa is a general hemostatic agent. Randomized trials have demonstrated effectiveness in adults; however, data in children are confined to case reports and series subject to publication bias.

PROCEDURES

A consecutive cohort of children treated with rFVIIa was identified via inspection of pharmacy records. Data collected included demographic data, underlying disorders, reason for rFVIIa use, dosing, thrombotic events, and mortality. Efficacy was scored subjectively on a 3-point scale (complete, partial, or no response) and supported by a measurement of transfusion of red cells, platelets, fresh frozen plasma, and cryoprecipitate in the 3 days prior to and following use of rFVIIa. Patients with hemophilia and congenital factor VII deficiency were excluded.

RESULTS

Sixty-five percent had a complete response and 26% had a partial response. Following treatment, there was a mean reduction in transfusions of 14.2 ml/kg for red blood cells, 10.9 ml/kg for platelets, 9 ml/kg for fresh frozen plasma, and 4.6 ml/kg for cryoprecipitate. Thrombosis occurred in 4.3% of patients with the highest rate being in neonates (17.6%).

CONCLUSIONS

rFVIIa is an effective general hemostatic agent for management of excessive bleeding in children and that with the exception of neonates has excellent safety.

Use of recombinant factor VIIa in a preterm infant with coagulopathy and subdural hematoma

Activated recombinant factor VIIa was administered to a preterm infant with bleeding diasthesis and a huge subdural hematoma that could not be controlled by the blood products. The coagulation tests were normalized the following day. Recombinant factor VIIa can be a choice in selected cases with intractable bleedings unesponsive to conventional replacement therapy.

In vitro stability of lyophilized and reconstituted recombinant activated factor VII formulated for storage at room temperature

BACKGROUND

Recombinant activated factor VII (rFVIIa) is indicated to treat bleeding episodes or prevent bleeding related to surgery in patients with hemophilia A or B who have antibodies to coagulation factors VIII or IX. The first-generation rFVIIa formulation is stable when stored under refrigeration. A new formulation has been developed for storage at room temperature, which may improve patients' access to treatment during bleeding episodes.

OBJECTIVE

These in vitro experiments were conducted to evaluate the stability of the new formulation of rFVIIa, both lyophilized and reconstituted, under the expected storage conditions, as well as at higher temperatures.

METHODS

The stability of the new rFVIIa formulation when stored under various conditions before and after reconstitution was evaluated in terms of retained activity (clotting assay), rFVIIa content (high-performance liquid chromatography [HPLC]), and rFVIIa degradation products (HPLC), including aggregates (dimer/oligomer). Activity was analyzed within specific limits representing the allowable minimum/maximum for each test parameter at the end of the product's shelf-life, as adopted by the European Medicines Agency and the US Food and Drug Administration. Before reconstitution, vials from 9 lots of the new rFVIIa formulation, 3 of each size (1, 2, and 5 mg/vial), were stored at refrigerated temperature (5 degrees C) and at room temperature (25 degrees C) for 24 months, and at 30 degrees C for 12 months. To simulate short-term exposure to temperatures higher than recommended, samples were stored at 40 degrees C for 6 months, followed by storage at 25 degrees C for 12 months. To simulate the home setting, in which the product may be alternately stored in and out of the refrigerator, samples were stored at 30 degrees C for 8 hours and then at 5 degrees C for 16 hours, repeated daily for 5 days. To analyze the effect of storage at extremely elevated temperatures, samples were exposed to temperatures of 50 degrees C, 60 degrees C, and 70 degrees C for 12 hours. After reconstitution, samples were maintained at 25 degrees C for up to 6 hours or at 5 degrees C for up to 24 hours.

RESULTS

The specific activity and rFVIIa content of the new lyophilized formulation remained stable after storage for 24 months at 5 degrees C and 25 degrees C, and for 12 months at 30 degrees C; after 5 days of daily alternation between storage at 5 degrees C and 30 degrees C; and after storage for 6 months at 40 degrees C followed by 12 months at 25 degrees C. When stored at 50 degrees C and 60 degrees C for 12 hours, activity remained constant, whereas rFVIIa aggregates increased within the specified limits; after storage at 70 degrees C for 12 hours, rFVIIa activity decreased in parallel with the formation of aggregates, which exceeded the specified limit for the 5-mg product. After reconstitution, samples of all vial sizes of the new rFVIIa formulation retained their activity when stored at 25 degrees C for 6 hours and at 5 degrees C for 24 hours.

CONCLUSIONS

In these in vitro experiments, the new lyophilized formulation of rFVIIa was stable when stored for 24 months at 25 degrees C, 12 months at 30 degrees C, 6 months at 40 degrees C, and 12 hours at 50 degrees C and 60 degrees C without compromise to its activity or rFVIIa content. The reconstituted product retained activity when stored at 25 degrees C for 6 hours and at 5 degrees C for 24 hours.

Prophylactic treatment of a small child with severe factor VII deficiency using repeat dosing from a single vial of recombinant activated factor VII

We report our experience with a small child with severe factor VII deficiency and a history of frequent and spontaneous life-threatening hemorrhage. The patient has received several years of successful prophylactic treatment with an every 3-day infusion program in which she receives recombinant activated factor VII (rVIIa) using multiple doses from a single reconstituted vial over a 72-hr period. Comparison is made to prophylactic treatment in this same patient using plasma-derived factor VII (PDVII) using a prothrombin complex concentrate (PCC).

Orthopaedic surgery for inhibitor patients: a series of 27 procedures (25 patients)

We report on a series of 27 orthopaedic surgical procedures. It includes 20 radiosynoviortheses and seven major orthopaedic procedures, performed on 26 patients. The average age of patients was 36 years (range: 8-53) and the average follow-up time was 2.5 years (range:1-5). There were 23 good results and four fair. In the synoviorthesis group (20 patients, 20 synoviortheses) the average age was 13.5 years (range: 9-26) and the average follow-up was 4.5 years (range: 1-7). There were 19 good results and one fair. All synoviortheses were done with activated prothrombin complex concentrates (FEIBA), all the responses being good except in one case (which had the final fair result). The total dose of FEIBA used was 600 IU kg(-1,) except in a patient that had a haemorrhagic complication. In fact, he required a prolongation of treatment up to a total dose of 2000 IU kg(-1). In the group of major orthopaedic procedures, the average age of the six patients was 30.5 years (range: 11-53) and the average follow-up was 2.5 years (range: 1-5). There were six good results and one fair. Postoperative bleeding complications occurred in one of the seven major orthopaedic procedures performed (arterial pseudoaneurym after a total knee arthroplasty). Despite such complication, which had the final fair result, our study has shown that haemophilic patients with high inhibitor titres requiring orthopaedic surgery can undergo such procedures with a high expectation of success. In other words, orthopaedic surgery is now possible in haemophilia patients with high-titre inhibitors, leading to an improved quality of life for these patients.

Recombinant activated factor VII: current perspectives and Epworth experience

Recombinant factor VII was first developed for control and prevention of bleeding in haemophilia with antibodies to factor VIII and IX. Its efficacy in these situations is well established. Over recent years, the 'off-label' use of this substance has become more widespread in trauma, surgery and obstetric bleeding. Here we describe the mechanism of action of recombinant factor VII, review current literature of 'off-label' usage and our initial experience in surgical related cases of bleeding at Epworth Hospital.

Haemophilia therapies

In the last few decades dramatic improvements in the management of haemophilia patients have occurred. Haemophilia has moved from a fatal or disabling disease to a hereditary disorder with available treatment and much better clinical outcomes. The safety of antihaemophilic factor concentrates has been dramatically improved and, in a multidisciplinary environment including haematologists, orthopaedic surgeons, paediatrics, infectiologists, specialised nurses and physiotherapists, complications related to haemophilia are now limited, markedly improving the quality of life of haemophiliacs. One can even think that the cure of haemophilia through gene therapy might occur in the next decades. Keeping this ultimate aim in mind, efforts at present are mainly focused on bioengineered Factor VIII/Factor IX concentrates with increased efficacy or longer half-life or decreased immunogenicity. In addition, several preclinical and clinical studies are being carried out for optimising and individually tailoring the therapeutic regimens of antihaemophilic therapies using global haemostasis tests in combination with the routine coagulation assays.

Recombinant activated clotting factor VII (rFVIIa) in the treatment of surgical and spontaneous bleeding episodes in hemophilic patients

Inhibitors against replacement clotting factors occur in approximately 30%–40% of patients with hemophilia A and 1.5%–3% of patients with hemophilia B. In this group of patients, bleeding events are best treated with bypassing agents. Recombinant activated factor VII (rFVIIa) has become the first-line agent in treating surgical and non-surgical bleeding in many centres with efficacy at standard 90 μg/kg doses approaching 90%. The greater efficacy is associated with early initiation of treatment, as well as, possibly larger doses of rFVIIa. A higher concentration appears to be essential in initiating an adequate thrombin burst, which results in a stable clot. Higher dosage regimens, home therapy and continuous infusion regimens are continuously evolving as we strive to define optimal dosing strategies in hemophilia patients. rFVIIa has been a remarkably safe agent for hemophiliacs but with high dosages being advocated and older patients being given such doses outside a trial setting, thromboembolic events remain a concern.

An illustrative case and a review on the dosing of recombinant factor VIIa in congenital factor XI deficiency

Recombinant activated factor VII (rFVIIa) has been used in a very limited number of patients with severe factor XI (FXI) deficiency. The dose and duration of treatment has varied greatly between these case reports. In a few of these cases there was also evidence of thrombotic complications. We present here a report on one additional patient with congenital FXI deficiency. For two major orthopaedic procedures in this patient we used rFVIIa as a single bolus dose followed by continuous infusion at a low rate. The data from these treatment episodes, together with those from a review of the published cases, lend support to the concept of using much lower doses than in haemophilia with inhibitors. A bolus dose of 20 microg kg(-1) and thereafter maintenance of the FVII activity at approximately 3 IU mL(-1) appears effective and safe.

Case studies: orthopaedic surgery in adult patients with haemophilia A with inhibitors

Whilst orthopaedic surgery in haemophilia patients without inhibitors is now relatively common in specialized centres, until recently there have been only a few sporadic instances of surgery having been undertaken on patients with inhibitors. The availability of recombinant activated factor VII (rFVIIa) for haemostatic cover during surgery allows procedures to be performed that previously may not have been considered possible. Complications associated with thrombosis are rare in haemophilia patients with inhibitors, but bleeding complications remain a concern. Globally, experience of performing orthopaedic surgery in these patients is increasing and many successful outcomes have been reported. However, more knowledge relating to the incidence and type of bleeding complications liable to be encountered, together with further information about appropriate rescue treatment, would be valuable. Data relating to long-term follow-up after surgery would be useful, as would a comparison of outcomes between haemophilia patients with and without inhibitors. Optimal dosing regimens for rFVIIa as surgical cover are still to be determined and further information is required relating to the cost effectiveness of rFVIIa in surgery. Further study should address these issues.

Management of haemophilic patients with inhibitors in major orthopaedic surgery by immunadsorption, substitution of factor VIII and recombinant factor VIIa (NovoSevenR): a single centre experience

Inhibitors of factor VIII or FIX in haemophilic patients are a common and serious complication associated with an increased risk of life-threatening bleeding during elective surgery. Substitution therapy fails to be effective, therefore an alternative treatment is needed. We have performed six major elective orthopaedic interventions in four patients with haemophilia A and inhibitors. A preoperative immunadsorbant therapy with Therasorb to eliminate inhibitors was successful in four cases, but during FVIII substitution inhibitors increased on day 4 to day 6 after surgery, leading to decreasing FVIII levels. Therefore, therapy was changed to recombinant FVIIa (rFVIIa; NovoSeven). Two interventions had to be covered with sole rFVIIa therapy as immunadsorbant therapy failed to be effective in one case and the need for acute intervention did not allow pretreatment in the other. We did not see increased bleeding during or after surgery when compared to our experience with non-inhibitor haemophilic patients. In conclusion, a preoperative decrease of inhibitors from immunadsorbant therapy, perioperative substitution of FVIII and changing treatment to rFVIIa when inhibitors are increased, is a safe and economic therapy for guaranteeing haemostasis in major elective orthopaedic surgery. On the contrary, sole therapy with rFVIIa allows immediate surgical intervention without a long hospital stay prior to surgery and a need for laboratory monitoring of inhibitor titres and FVIII levels. Our findings support data previously published.

Recombinant factor VIIa: review of efficacy, dosing regimens and safety in patients with congenital and acquired factor VIII or IX inhibitors

Recombinant factor (rF)VIIa has been available to clinicians since 1996 and has an excellent safety record after almost three-quarters of a million doses have been administered. This paper will review the current clinical experience with rFVIIa dosing in acquired and congenital hemophilia with inhibitors and chronicle all spontaneous and clinical trial reports of thrombotic adverse events as of April 2003. Standard dosing of rFVIIa (90 micro g kg(-1)) allows binding of FVIIa to the surface of an activated platelet and can directly activate factor X in the absence of tissue factor. Experience with bolus dosing suggests that higher dosing (>200 micro g kg(-1)) may be more efficacious in treating hemophilia patients. Clinical trials are ongoing to validate this observation. Continuous infusion dosing may be efficacious for major surgery but high infusion rates (50 micro g kg(-1) h(-1)) might be needed. The relationship between dose of rFVIIa, amount of thrombin generated and measurable FVIIa level is still not known and perhaps newer testing which measures thrombin generation might be more advantageous. Relatively few thrombotic events have been associated with rFVIIa. Known factors predisposing to thrombosis were present in 20 of the 25 (80%) hemophilia patients who were reported spontaneously or who developed a thrombosis during a clinical trial. Additionally, thrombotic events have not increased despite a growing experience with higher dosing of rFVIIa.

Use of recombinant factor VIIa, Novo Seven, in the management of acute haemorrhage

PURPOSE OF REVIEW

The purpose of this paper is to propose the use of factor VIIa in treating severely bleeding patients.

RECENT FINDINGS

Recombinant factor VIIa was developed in 1988 to treat patients with haemophilia A or B and antibodies against factors VIII and IX, or patients with a spontaneous inhibitor against factors VIII and IX. Since then factor VIIa has been shown to be very effective in treating many other bleeding disorders, such as diverse thrombocytopathias, antibodies against other coagulation proteins like factor V, and bleeding as a result of oral anticoagulation.

SUMMARY

Recombinant factor VIIa may be the universal haemostatic agent, but further studies are needed to prove this.

Effects of sucrose on rFVIIa aggregation and methionine oxidation

The aim of this study was to characterize the effects of sucrose on the stability of recombinant factor VIIa (rFVIIa), with special emphasis on aggregation and methionine oxidation, as well as to investigate the impact of various environmental conditions on the rFVIIa conformation. The stability of rFVIIa was studied at pH 5. Aggregation was monitored using size exclusion high-performance liquid chromatography (SE-HPLC), whereas formation of methionine oxidation products was measured by reversed-phase high-performance liquid chromatography (RP-HPLC). Fourier transform infrared (FTIR) spectroscopy and circular dichroism (CD) spectroscopy were used to study protein conformation. Stability studies showed that increasing sucrose concentrations reduced the loss of monomeric rFVIIa, and decreased formation of dimeric/oligomeric and polymeric rFVIIa. Preferential exclusion of the sugar from the protein's surface, which shifts the protein molecular population away from expanded aggregation competent species and toward the compact native state, is thought to account for these observations. rFVIIa is sensitive to methionine oxidation; two mono-oxidized and one di-oxidized product were formed upon incubation. Unlike aggregation, methionine oxidation was found to increase in the presence of sucrose. The two methionine residues susceptible to oxidation are presumably located at the protein surface, and the chemical potential increase in the presence of sucrose may account for the increase in oxidation rate. While FTIR spectroscopy suggested that sucrose induces small conformational changes in the rFVIIa structure, CD spectroscopy did not support this finding. The secondary structure of precipitated rFVIIa was changed when compared to the native solution secondary structure. Appearance of bands characteristic of intermolecular beta-sheet structure were found coincident with a decrease in alpha-helix and intramolecular beta-sheet structure.

Elective orthopedic surgery for hemophilia patients with inhibitors: new opportunities

We report a series of 108 elective orthopedic surgical procedures in hemophilia patients with inhibitors, comprising 88 cases in which radiosynoviorthesis was performed and 20 cases in which major orthopedic procedures were carried out. Hemostatic cover was provided by recombinant factor VIIa (rFVIIa, NovoSeven(R), Novo Nordisk, Bagsvaerd, Denmark) in 17 cases, and by FVIII anti-inhibitor product (FEIBA, Baxter Corp, Toronto, Canada) in the remaining three procedures. A total of 51 patients from nine centers worldwide were included. The results of the procedures were characterized as good (82 procedures), fair (15), or poor (11). Postoperative bleeding complications requiring further surgical intervention occurred in three (15%) of the 20 major orthopedic procedures; all three procedures used rFVIIa as a hemostatic agent. Despite these complications, however, our study has shown that rFVIIa allows hemophilic patients with high inhibitor titers to undergo elective orthopedic surgery (EOS) with a greater expectation of success, leading to an improved quality of life. Thorough analysis of each case as part of a multidisciplinary team will help to identify further inhibitor patients in whom EOS can be performed both safely and effectively.

Concurrent total hip and knee replacements in a patient with haemophilia with inhibitors using recombinant factor VIIa by continuous infusion

The introduction of activated recombinant factor VIIa (rFVIIa) has allowed elective surgery to be safely performed in haemophiliacs with inhibitors. The main problems associated with its use are the short half-life, necessitating frequent intravenous injections, and its very high cost. Here we describe, for the first time, the performance of total hip and knee replacements in a haemophiliac with inhibitors at the same operation. The amount of rFVIIa concentrate used (8.57 mg) was similar to that normally used for a single joint replacement. The use of continuous infusion allowed for easier administration and further contributed to the reduction in cost as it avoids the peak levels associated with bolus injections.

Elective orthopaedic surgery for inhibitor patients

We report on a series of 108 elective orthopaedic surgical procedures. It includes 88 radiosynoviortheses and 20 major orthopaedic procedures, performed on 51 patients at nine centres worldwide. The average age of patients was 28.5 years (range 5-40 years), and the average follow-up time was 2 years (range 1-5 years). There were 82 good results, 15 fair and 11 poor. In the synoviorthesis group (41 patients, 88 synoviortheses) the average age was 14.3 years (range 5-40 years) and the average follow-up was 6.5 years (range 1-10 years). There were 66 good results, 14 fair and eight poor. There were no complications. In the group of major orthopaedic procedures, the average age of the 10 patients was 32.5 years (range 27-40 years), and the average follow-up was 2.3 years (range 1-5 years). There were 16 good results, one fair and three poor. Postoperative bleeding complications occurred in three of the 20 major orthopaedic procedures performed (15% complications rate). They occurred in three patients treated with insufficient doses of recombinant activated factor VII. Despite such complications, the study has shown that haemophilic patients with inhibitors requiring elective orthopaedic surgery (EOS) can undergo such procedures with a high expectation of success. In other words, EOS is now possible in haemophilic patients with inhibitors, leading to an improved quality of life for these patients. Thorough analysis of each case as part of a multidisciplinary team will allow us to perform elective orthopaedic procedures in patients with inhibitors.

Hemophilia and related bleeding disorders: a story of dismay and success

Known since the beginning of the first millennium, the hemophilias are among the most frequent inherited disorders of blood coagulation and definitely the most severe. In the 1970s, with the availability of concentrated preparations of the deficient coagulation factors VIII and IX and with the large-scale adoption of home treatment, hemophilia care became one of the most gratifying examples of successful secondary prevention of a chronic disease. Unfortunately, in the early 1980s it was recognized that factor concentrates prepared from plasma pooled from thousands of donors transmitted the hepatitis and the human immunodeficiency viruses. The scientific community reacted promptly to the devastation brought about by hepatitis and AIDS. The last 15 years of the second millennium have witnessed the development of methods that, when applied during concentrate manufacturing, inactivate viruses escaping the screening procedures. The adoption of these measures has reduced dramatically the risk of transmission of bloodborne infections. The production of recombinant factors and their availability for patients' treatment epitomize progress in hemophilia care through DNA technology. Methods based on the polymerase chain reaction (PCR) have unraveled an array of gene lesions associated with hemophilia, permitting improved secondary control of the disease through carrier detection in women from affected families and prenatal termination of their affected male infants. This article will review the aforementioned areas of progress and discuss unresolved problems (such as treatment of patients with antibodies, the risk of new infectious complications, and the issue of secondary tumors). Hopes and expectations for further improvement in the third millennium and particularly the prospects of hemophilia cure though gene replacement therapy will also be mentioned.

Continuous infusion

There is evidence, albeit scientifically weak, for improved cost/benefit with administration of factor concentrates by continuous infusion when high-dose replacement is necessary, as several studies have shown a reduced requirement for the concentrate. There is evidence from only one study for fewer bleeding complications with continuous infusion. There is evidence from two studies that additional therapy with tranexamic acid reduces the risk of bleeding complications in patients receiving continuous infusion. Future studies should address the question of minimum steady-state levels required for haemostasis, comparisons with bolus injection using a randomized design and investigate the risk of inhibitor formation.

A new approach to treatment of bleeding episodes in young hemophilia patients: a single bolus megadose of recombinant activated factor VII (NovoSeven)

Recombinant activated factor VII (rFVIIa, NovoSeven) represents an effective treatment for hemophilia patients with inhibitors, but no consensus as to the best dosing regimen exists. We assessed the efficacy and safety of a rFVIIa 'megadose' (300 micro g kg(-1) bolus) as treatment for bleeds in three young inhibitor patients. Of 114 bleeds, 95 responded to a single dose. Pain relief was faster and therapy duration significantly shorter than with continuous infusion (CI) regimens or standard boluses (90 micro g kg(-1) every 3 h). Rebleeding occurred in 9.6% of cases and 19/114 episodes required a second bolus injection. Although rFVIIa consumption per bleed (median: 300 micro g kg(-1)) was higher than with standard boluses (180-270 micro g kg(-1)), patients found single bolus administration more convenient than recurrent injections or CI. With two exceptions, no complications occurred within 3 h of treatment, despite high FVII:C levels (median: 27.4 U mL(-1); range: 19.8-54 U mL(-1)). Treatment of bleeds with a rFVIIa megadose in young inhibitor patients is effective and well tolerated.

Preliminary experience with the use of recombinant factor VIIa to treat coagulation disturbances in pediatric patients

OBJECTIVE

This study evaluates the efficacy of recombinant factor VII (rVIIa) in the treatment of coagulation dysfunction in pediatric patients.

METHODS

We retrospectively reviewed the records of pediatric patients who received rVIIa in the intensive care unit or operating room for treatment of coagulopathy. Case series in the literature were also reviewed.

RESULTS

Ten patients, ranging in age from 3 months to 19 years, received 22 doses of rVIIa. Seven of the 10 patients had received fresh frozen plasma and cryoprecipitate before the administration of rVIIa without effect. All 10 patients had a fibrinogen level above 100 mg/dl and platelet count above 100,000/mm3 at the time of rVIla administration. After rVIIa administration, there were significant decreases in prothrombin time, international normalized ratio, and partial thromboplastin time. No adverse effects were noted.

CONCLUSION

Recombinant factor VIIa can be used to effectively reverse coagulation disturbances in the pediatric patient even when treatment with fresh frozen plasma has failed. Given its therapeutic potential, prospective, randomized trials are warranted.

Guidelines on the selection and use of therapeutic products to treat haemophilia and other hereditary bleeding disorders

Evidence based guidelines are presented on the selection and use of therapeutic products to treat haemophilia. These guidelines offer advice based on the best published scientific and medical information. They will be reviewed regularly by UKHCDO Advisory Committee. Included are details of therapeutic products available in the UK to treat patients with haemophilia and other bleeding disorders and the background information on which the recommendations are based are presented.

Sequential treatment with bolus and continuous infusion of recombinant factor VIIa for hip arthroplasty in a patient with haemophilia A and inhibitor

We describe a total arthroplasty of the hip in a 40-year-old male patient with haemophilia A and a high-titre inhibitor to factor VIII, treated with rFVIIa. The patient received sequential therapy first as bolus in the early postoperative phase in order to obtain appropriate haemostasis and then as continuous infusion with lower doses to avoid frequent episodes of bleeding without a higher consumption of product. After an initial dose of 150 micro g kg-1 for the first five days after surgery, we used bolus doses of 120-90 micro g kg-1 every 2.5-3 h, achieving plasma FVII:C levels above 40 U mL-1. We then continued with continuous infusion at decreasing doses 15-7 micro g kg-1 h-1 for 12 days (FVII:C 19-7 U mL-1). There were no bleeding complications nor signs of clotting activity. The rehabilitation programme was continued without prophylactic treatment. The total consumption of rFVIIa was 6.3 mg kg-1, implying a saving of at least 30% of the product with respect to previous publications.

Efficacy of recombinant factor VIIa administered by continuous infusion to haemophilia patients with inhibitors

We have prospectively monitored treatment of haemophilia patients with inhibitors by recombinant factor VIIa (rFVIIa) administered by continuous infusion to obtain more insight in the underlying factors of the clinical efficacy of this administration method. At present, 43 treatment episodes of 14 different Dutch haemophilia inhibitor patients are included in the database. Analysis of the data showed a discrepancy between the efficacy of rFVIIa continuous infusion treatment of acute and surgical bleeds in the oral cavity [one (14%) effective, two (29%) partially effective, four (57%) not effective] and other parts of the body [29 (80%) effective, four (11%) partially effective, two (6%) not effective, one (3%) impossible to classify]. Patients who had acute or surgical oral cavity bleeds, uncontrolled by rFVIIa continuous infusion, reacted favourably to rFVIIa continuous infusion in other locations of the body. Acute bleeding episodes in the oral cavity, which could not be controlled by rFVIIa continuous infusion, stopped when the treatment regimen was switched to rFVIIa bolus injections. Finally, haemostatic control during dental extractions was excellent after the initial rFVIIa bolus injection preceding the continuous infusion, but rebleeds occurred in all patients within 48 h under rFVIIa continuous infusion coverage. These observations suggest that the efficacy of rFVIIa continuous infusion depends, at least in part, on the location of the body in which the bleeding occurs and that rFVIIa bolus injections are more effective than rFVIIa continuous infusion in the oral cavity. We hypothesize that the inability of rFVIIa continuous infusion treatment to sufficiently inhibit fibrinolysis is the underlying cause of the decreased efficacy of rFVIIa continuous infusion treatment in the oral cavity.

Efficacy and safety of a factor VIII-von Willebrand factor concentrate 8Y: stability, bacteriological safety, pharmacokinetic analysis and clinical experience

The present study was undertaken to evaluate stability, pharmacokinetic profile and efficacy of continuous infusion of 8Y in patients with different types of von Willebrand disease (vWD). Following reconstitution, 8Y levels of von Willebrand factor ristocetin cofactor (vWF:Rco), vWF antigen and factor VIII coagulant activity (FVIII:C) decreased to about 80% of the baseline levels; addition of low molecular weight heparin decreased the level of FVIII:C even further. Reconstituted 8Y was found to be sterile for up to 6 days postreconstitution. Ten vWD patients (four with type 2A, three with type 3, two with type 1 and one with 2N) underwent pharmacokinetic analysis. The recovery of vWF: RCo was significantly lower in patients with type 3 vWD (1.4 +/- 0.05% U(-1) kg(-1)) compared with that of the patients with types 1 (2.3 +/- 0.52% U(-1) kg(-1)) or 2A (2.0 +/- 0.06% U(-1) kg(-1)) vWD (P = 0.015). Type 3 vWD patients exhibited significantly higher vWF:RCo clearance (5.1 +/- 1.1 mL kg(-1) h(-1)) compared with that of patients with type 2A (2.8 +/- 0.7 mL kg(-1) h(-1)) and type 1 (2.6 +/- 1.0 mL kg(-1) h(-1)) vWD (P = 0.028). Accordingly, terminal half-life was lower in patients with type 3 vWD (8.0 +/- 0.6 h(-1)) compared with type 2A (12.7 +/- 5.9 h(-1)) or type 1 (14 +/- 1.2 h(-1)) vWD patients. Multimeric pattern of vWF from patients' plasma was similar to that of 8Y. In two patients treated with 8Y by continuous infusion for prevention or treatment of bleeding haemostasis was achieved. Thus, 8Y is suitable and haemostatically effective for continuous infusion treatment in patients with vWD.

Orthopaedic surgery in haemophilic patients with inhibitors: an overview

Our experience and a review of the literature on inhibitors have shown that, with the availability of recombinant factor VIIa (rFVIIa), haemophilic patients with high inhibitor titres requiring elective orthopaedic surgery can undergo such surgery with a high expectation of success. The advent of rFVIIa has made major elective orthopaedic surgery possible in haemophilic patients with high-titre inhibitors, resulting in an improved quality of life. Recombinant FVIIa appears to be an efficient haemostatic product for surgery in patients suffering from haemophilia A and B with inhibitors. The series of major elective orthopaedic surgical procedures using rFVIIa (n=53) is the largest ever reported in haemophilic patients with inhibitors, despite the long-standing presence of other treatment modalities, such as high-dose human factor VIII (FVIII), porcine FVIII (n=8), and prothrombin complex concentrates/activated prothrombin complex concentrates (n=9). Thorough analysis of each case as part of a multidisciplinary team will allow us to perform elective orthopaedic procedures in patients with inhibitors.

Continuous infusion of coagulation factor products

OBJECTIVE

To review clinical information related to the use of continuous infusion factor products in patients with hemophilia. Specifically, case reports and open-label trials are summarized involving the use of factor VIII and recombinant factor VIIa for a variety of indications including surgical prophylaxis, acute bleeding, primary prevention, and management of inhibitors. In addition, issues surrounding the use of continuous infusion of factor products such as pharmacokinetic rationale, stability/sterility, and cost are reviewed.

DATA SOURCES

Primary and review articles were identified through a MEDLINE search (1990-June 2001) and through secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All articles identified from the data sources were evaluated, and all information deemed relevant was included in this review.

DATA SYNTHESIS

Data concerning the administration of factor products are primarily detailed in open-label trials and case reports. Comparisons between intermittent bolus injections and continuous infusion of factor products are limited and primarily compare continuous infusion regimens with historical controls. The rationale behind the continuous-infusion approach is linked to the pharmacokinetics of factor products administered via this route. Pharmacokinetic data reveal that, with continuous infusion of factor products, a reduction in clearance and a maintenance of factor serum concentrations are noted.

CONCLUSIONS

Administration of factor products (factor VIII and recombinant factor VIIa) via continuous infusion has produced favorable hemostatic effects compared with intermittent bolus injections. The advantages of continuous infusion include maintenance of a constant factor concentration, thereby reducing risk of bleeding from excessively low trough concentrations, and a decrease in factor consumption related to a reduction in factor clearance with constant infusion. Manufacturers recommend using reconstituted factor products either immediately or within 1-3 hours after reconstitution; however, several studies have found the products to be stable and sterile for longer periods.

Continuous infusion of coagulation factors

Continuous infusion (CI) of coagulation factor concentrate is aimed at maintaining a steady haemostatic level of the missing factor in circulation, preventing dangerous troughs below the haemostatic level and unnecessary high peaks, which increase the safety and decrease the consumption of factor concentrate replacement therapy. This can be achieved by the administration of the coagulation factor at a rate corresponding to its elimination. CI has been used in wider extent since the early 1990s, after the resolution of basic questions such as the stability of factor concentrates after reconstitution, the risk of contamination and bacterial overgrowth in these biological materials during either preparation of infusion bags or prolonged administration, the frequent local thrombophlebitis, the knowledge of pharmacokinetics of coagulation factors in the conditions of CI and the development of adequate minipumps. The increasing clinical experience with CI used in haemophilia A and B and von Willebrand disease has proven the advantages of this mode of replacement therapy, providing improved margins of efficacy and safety in various clinical settings requiring the maintenance of haemostatic levels over prolonged periods, as well as reduction in treatment cost compared with the traditional therapy via intermittent injections of coagulation factors.

KEYWORDS

continuous infusion, factor VIII, factor IX, haemophilia, recombinant FVIIIa, von willebrand disease.

Experience with use of recombinant activated factor VII

Recombinant activated factor VII (rFVIIa) has recently been introduced for improving haemostasis in haemophiliac patients developing alloantibodies (inhibitors) to factor VIII (FVIII) or factor IX (FIX). We describe the successful management of haemorrhagia with rFVIIa in five different situations: an episode of surgical bleeding in a patient with haemophilia A and non-surgical haemorrhages in four patients with haemophilia A, acquired haemophilia, congenital severe FV defect and pseudo-acquired haemophilia, respectively. In each case, rFVIIa was effective and safe. There is no doubt that rFVIIa is useful in the therapeutic management of patients with antibodies to FVIII or FIX. However, the treatment is expensive and a cost-effectiveness analysis would be useful.

Pharmacokinetics of coagulation factors: clinical relevance for patients with haemophilia

Haemophilia is a recessively inherited coagulation disorder, in which an X-chromosome mutation causes a deficiency of either coagulation factor VIII (FVIII) in haemophilia A, or factor IX (FIX) in haemophilia B. Intravenous administration of FVIII or FIX can be used to control a bleeding episode, to provide haemostasis during surgery or for long term prophylaxis of bleeding. In special cases, activated factor VII (FVIIa) may be used instead of FVIII or FIX. The aim of this work is to review the pharmacokinetics of FVIII, FIX and FVIIa and to give an outline of the use of pharmacokinetics to optimise the treatment of patients with haemophilia. The pharmacokinetics of FVIII are well characterised. The systemic clearance (CL) of FVIII is largely determined by the plasma level of von Willebrand factor (vWF), which protects FVIII from degradation. Typical average CL in patients with normal vWF levels is 3 ml/h/kg, with an apparent volume of distribution at steady state (Vss) that slightly exceeds the plasma volume of the patient, and the average elimination half-life (t1/2) is around 14 hours. There are still some discrepancies in the literature on the pharmacokinetics of FIX. The average CL of plasma-derived FIX seems to be 4 ml/h/kg, the Vss is 3 to 4 times the plasma volume and the elimination t1/2 often exceeds 30 hours. FVIIa has a much higher CL (average of 33 ml/h/kg), and a short terminal t1/2 (at 2 to 3 hours). The Vss is 2 to 3 times the plasma volume. Since the therapeutic levels of coagulation factors are well defined in most clinical situations, applied pharmacokinetics is an excellent tool to optimise therapy. Individual tailoring of administration in prophylaxis has been shown to considerably increase the cost effectiveness of the treatment. Dosage regimens for the treatment of bleeding episodes or for haemostasis during surgery are also designed using pharmacokinetic data, and the advantages of using a constant infusion instead of repeated bolus doses have been explored. The influence of antibodies (inhibitors) on the pharmacokinetics of FVIII and FIX is in part understood, and the doses of coagulation factor needed to treat a patient can tentatively be calculated from the antibody titre. In conclusion, therapeutic monitoring of coagulation factor levels and the use of clinical pharmacokinetics to aid therapy are well established in the treatment of patients with haemophilia.

Inhibitor treatment: state of the art

The treatment of hemophilic patients with inhibitors presents many challenges. Recombinant activated factor VII (rFVIIa; NovoSeven, Novo Nordisk, Copenhagen, Denmark) is a new therapeutic option for this patient population. Optimization of dosing regimens may be achieved by considering (1) individual pharmacokinetics (especially in the pediatric population); (2) high-dose bolus regimens; (3) continuous infusion (CI) including high-dose CI; (4) early treatment with NovoSeven in the course of a bleeding event; and (5) use of NovoSeven as a prophylactic therapy. The literature involving these issues is reviewed here. Institution of early therapy has been shown to decrease total NovoSeven requirement while increasing efficacy. Pediatric patients may require a higher dose of NovoSeven due to the higher clearance rate and shorter half-life demonstrated by this population. Therefore, the patient's age and/or individual pharmacokinetics and clearance rate should be considered when calculating doses and CI rates. High-dose NovoSeven has been shown to be effective in some patient populations without increased reported adverse events. Despite its short half-life, prophylactic use of NovoSeven has been reported in a small number of patients, with an apparent decrease in bleeding episodes experienced. There has been significant interest in administration of NovoSeven by CI, particularly in patients requiring prolonged treatment, and it has been shown to be successful, although the optimal target factor VII activity has yet to be established and some authors have recommended the use of concomitant antifibrinolytics.

[Acquired hemophilia: current diagnostic and therapeutic approaches]

PURPOSE

Acquired haemophilia is a rare disease, occurring most frequently in elderly patients, caused by the development of autoantibodies against factor VIII.

CURRENT KNOWLEDGE AND KEY POINTS

The disease is characterised by spontaneous haemorrhagic complications which can be fatal in 15-20% of the patients. However spontaneous remission is possible and in fact natural evolution and aetiology are still partly unknown. Acquired haemophilia may arise in association with auto-immune diseases, lymphoproliferative malignancy, pregnancy and also as a drug reaction. The aims of the treatment are first to treat the bleeding which is the most common cause of morbidity and mortality, and second to eliminate the inhibitor by immunosuppression. However no consensus exists for these two parts of the treatment. Bleeding may be controlled by prothrombin complex concentrates, recombinant factor VIIa or porcine factor VIII. The inhibitor is abolished in up 70% of patients using prednisone and cyclophosphamide. Other combinations of prednisone with azathioprine or with cyclophosphamide and vincristine or the use of high-dose immunoglobulin or double-filtration plasmapheresis have also proven effective in some patients.

FUTURE AND PROJECTS

The rare occurrence of the disease, the associated with various diseases, and lack of consensus about treatment, require multicentric prospective studies.

Knee joint arthroplasty in a patient with haemophilia A and high inhibitor titre using recombinant factor VIIa (NovoSeven): a new case report and review of the literature

Elective orthopaedic surgery is regularly withheld from patients with haemophilia and high inhibitor titre despite the presence of severe arthropathy and urgent medical need. A knee joint arthroplasty was performed in a patient with severe haemophilia A and a high inhibitor titre using recombinant factor VIIa (rFVIIa) as the sole coagulation factor. There was no abnormal bleeding during surgery although an increased blood loss through surgical drains did occur during the first 6 h postoperatively. Rehabilitation was started on day 1 and continued for 3 months. Walking commenced on day 4. After 1 year of follow-up, the clinical outcome of surgery was considered excellent with no pain, knee mobility at 0-5-90 degrees, and an International Knee Society score of 95/100. No rFVIIa-associated side-effects or thrombotic complications were reported. In conclusion, knee joint arthroplasty is now an option for haemophilia patients with a high inhibitor titre. An international review of all available data on elective orthopaedic surgery in inhibitor patients is required so that the optimal treatment regime can be defined and the short- and long-term risk-benefit ratio of surgery compared to that of noninhibitor patients.

A comparison of FVII:C and FVIIa assays for the monitoring of recombinant factor VIIa treatment

The use of recombinant factor VIIa (rFVIIa) is on the increase, not only to treat haemophilic patients with inhibitors, but also patients with other clotting disorders. However, the most appropriate method of monitoring this treatment remains a question that has yet to be resolved. We studied 24 plasma samples from patients receiving rFVIIa treatment (three had haemophilia A with inhibitors, and three a congenital FVII deficiency) and compared the results obtained from the FVII:C and FVIIa assays. Although a good correlation between the two methods was obtained (r = 0.91), the values of the FVII:C method were 1.63 higher than those of the FVIIa method, with a relatively wide margin in the interval of the FVII:C/FVIIa ratios obtained [95% confidence interval (CI) 1.38--1.88, range 0.68--3.68]. This interval became wider when we compared values of over 6 IU mL(-1), which led us to conclude that the two methods cannot be considered equivalent. As the FVIIa method specifically measures FVIIa, and FVII:C assay is known to have a wide interlaboratory variability, we believe that the FVIIa assay would be more suitable for the monitoring of rFVIIa treatment.

Biotechnology: alternatives to human plasma-derived therapeutic proteins

Proteins derived from human plasma have become critically important therapeutic products since their introduction in the 1940s. In the last 20 years, the tools of molecular biology have provided alternatives to the administration of the natural products. Recombinant analogues of Factor VIII and Factor IX are commercially available, and recombinant forms of other plasma proteins are under development. Genetic engineering also provides the opportunity to modify a natural protein to improve the efficiency with which it can be produced in vitro, or to change its therapeutic profile. More efficient production systems, such as transgenic plants or animals, may yield less costly therapies and a wider availability of products that are now in limited supply. Finally, gene therapy offers the prospect of permanently correcting conditions arising from deficiencies in any one of several plasma proteins, freeing individuals from the need to undergo periodic treatments with exogenous proteins.