Haemophilia 2002: emerging risks of treatment

Intravenous Hemostats: Foundation, Targeting, and Controlled-Release

Uncontrollable blood loss is the greatest cause of mortality in prehospital patients and the main source of disability and death in hospital care. Compared with external hemostats, intravenous hemostats are more appropriate for preventing and treating uncontrolled bleeding in vivo and large bleeding on the body surface. This Review initially establishes intravenous hemostats' response basis, including the coagulation mechanism, fibrinolytic pathway, and protein corona. Second, the study of advancement of intravenous hemostat targeting was expanded from two perspectives, cellular hemostatic agents and synthetic hemostatic agents. Meanwhile, after discussing the progress of controlled-release intravenous hemostats with platelets as the stimuli, this Review offers insight into the possibility of controlled-release intravenous hemostats with microenvironment as the stimuli, combining the studies of controlled-release targeted thrombolysis.

Biomaterials and Advanced Technologies for Hemostatic Management of Bleeding

Bleeding complications arising from trauma, surgery, and as congenital, disease-associated, or drug-induced blood disorders can cause significant morbidities and mortalities in civilian and military populations. Therefore, stoppage of bleeding (hemostasis) is of paramount clinical significance in prophylactic, surgical, and emergency scenarios. For externally accessible injuries, a variety of natural and synthetic biomaterials have undergone robust research, leading to hemostatic technologies including glues, bandages, tamponades, tourniquets, dressings, and procoagulant powders. In contrast, treatment of internal noncompressible hemorrhage still heavily depends on transfusion of whole blood or blood's hemostatic components (platelets, fibrinogen, and coagulation factors). Transfusion of platelets poses significant challenges of limited availability, high cost, contamination risks, short shelf-life, low portability, performance variability, and immunological side effects, while use of fibrinogen or coagulation factors provides only partial mechanisms for hemostasis. With such considerations, significant interdisciplinary research endeavors have been focused on developing materials and technologies that can be manufactured conveniently, sterilized to minimize contamination and enhance shelf-life, and administered intravenously to mimic, leverage, and amplify physiological hemostatic mechanisms. Here, a comprehensive review regarding the various topical, intracavitary, and intravenous hemostatic technologies in terms of materials, mechanisms, and state-of-art is provided, and challenges and opportunities to help advancement of the field are discussed.

Replacement therapy with recombinant factor IX. A multicentre evaluation of current dosing practices in Italy

BACKGROUND

The in vivo recovery of recombinant factor IX (rFIX) is reported to be lower than that of plasma-derived products, with potential clinical implications for dosing. In clinical practice, a conversion (augmentation) factor is suggested to calculate the necessary doses of rFIX. The aim of this study was to assess the range of values for the conversion factor in usual clinical practice in Italy.

MATERIALS AND METHODS

The study was questionnaire-based and proposed to all Italian Haemophilia centres treating patients with haemophilia B. Age, weight, dosage used in the last effective infusion, treatment regimen (prophylaxis versus on-demand), human immunodeficiency virus (HIV) and hepatitis C virus (HCV) status, and years of previous therapy with rFIX were recorded for patients with severe haemophilia B treated with rFIX. Mean, standard deviation, median and range were calculated for demographic and treatment data for the overall population and for subgroups. The conversion factor for the theoretical dosage of 40 IU/Kg was calculated.

RESULTS

Among 207 patients with severe haemophilia B being followed in 24 centres, 138 (66.7%) were being treated with rFIX. The sample of 207 patients represents 83.1% of the population of Italian patients with severe haemophilia B. The age range of the studied patients was 0-72 years (mean, 24 years) and the weight range was 3-108 kg (mean, 60 kg). Nineteen patients (14.4%) were positive for HIV and 51 (42.9%) were positive for HCV. The mean dosage of rFIX was 44 IU/Kg, with no significant difference between those receiving the product as prophylaxis or on-demand. A reduction in dosage was observed with increasing age (0.23 IU/kg/year). The mean value for the conversion factor was 1.10 ± 0.36 (median 1.00, range 0.51-2.08), when estimated for the whole population. No effect of HIV and HCV status was found on the dose prescribed. No evident correlation was found with the underlying genetic mutation.

DISCUSSION

We found that dosing of rFIX in clinical practice is very close to that of plasma-derived FIX concentrates. As a consequence, dosing in the non-surgical setting should be started using the same criteria as those for plasma-derived FIX and treatment effectiveness verified on a clinical basis rather than relying on in vivo recovery assessments.

Hepatitis C: serological and molecular diagnosis and genotype in haemophilic patients at the Regional Hemocenter of Maringá, Maringá PR Brazil

Prior to the process of viral inactivation in the 1980s most haemophilic patients were infected with hepatitis C virus, currently one of the disease's main causes. The prevalence of infection by hepatitis C virus in haemophilic patients enrolled in the Hemocenter of the Regional University Hospital maintained by the State University of Maringá is evaluated from social and epidemiologic data and from serum and molecular tests. Possible association between haemophilia's type and severity, type of treatment, data of start of treatment and hepatic enzyme rates of Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST) was verified. Sixty-nine haemophilic patients, 82.6% with haemophilia A and 17.4% with haemophilia B, in the 1 - 67 years age bracket, average age 22 years, were investigated. Whereas anti-HCV was investigated with third generation immunoenzymatic test and confirmed by HCV-RNA, LiPA technique determined genotypes. HCV-prevalence infection reached 37.7% and 21.7% respectively when antibody anti-HCV and HCV-RNA detection and associated significantly (p<0.05) with type of treatment, date of start of treatment and ALT and AST hepatic enzyme rates are taken into account. HCV genotype 1 predominated (53.3%) followed by genotype 3 (40.0%) and genotype 2 (6.7%). HCV predominance is high in haemophilic patients although infection has not been reported in patients under the age of 17.

Darunavir: a second-generation protease inhibitor

PURPOSE

The pharmacology, pharmacokinetics, drug interactions, clinical efficacy, adverse events, dosage and administration, and place in therapy of darunavir are reviewed.

SUMMARY

Darunavir is the most recent protease inhibitor (PI) to receive approved labeling from the Food and Drug Administration for the treatment of human immunodeficiency virus (HIV). Darunavir is unique among currently available PIs because it maintains antiretroviral activity against a variety of multidrug-resistant HIV strains. Darunavir is well absorbed, and the bioavailability of darunavir increases by 30% when given with food. Darunavir is approximately 95% bound to plasma proteins. Darunavir is metabolized by and inhibits cytochrome P-450 (CYP) isoenzyme 3A4; therefore, darunavir is prone to CYP3A4-mediated drug-drug interactions. Two trials have demonstrated the clinical efficacy of darunavir in HIV-positive patients previously treated with antiretrovirals. One trial demonstrated a 2 log(10) decrease in plasma HIV RNA levels, compared with a decrease of <1 log(10) in the control group. Average increases in CD4+ T-cell counts for darunavir and control groups were 124 and 20 cells/mm(3), respectively. Adverse events reported from preliminary safety data indicate that darunavir has a similar safety profile to other currently available PIs. The recommended adult dosage of darunavir is 600 mg (two tablets) combined with ritonavir 100 mg every 12 hours with food. Darunavir should be used with caution in patients with hepatic dysfunction. No dosage adjustment is necessary for patients with mild or moderate renal dysfunction.

CONCLUSION

Darunavir is a new HIV PI that retains virological activity in the presence of multiple protease mutations. As such, darunavir appears to be a useful component of optimized combination antiretroviral therapy for HIV-infected patients previously treated with antiretrovirals.

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.

Should hemophilia treaters switch to albumin-free recombinant factor VIII concentrates

PURPOSE OF REVIEW

To discuss the advantages and disadvantages of the albumin-free recombinant factor VIII concentrates in the treatment of hemophilia A.

RECENT FINDINGS

The third-generation recombinant factor VIII product Advate has been found to be safe and effective in treating bleeding associated with hemophilia A.

SUMMARY

Multiple issues must be considered when selecting a factor VIII concentrate for patients with hemophilia A including efficacy, availability, risk of transmission of infectious agents, risk of inhibitor development and cost. Third-generation recombinant factor VIII concentrates have been shown to be safe and effective. A theoretical improvement in risk of infectious agent transmission has been achieved by production of the products without human or animal plasma proteins. Controversy exists, however, with regard to a higher risk of inhibitor development with recombinant products. The higher cost of Advate can also potentially play a role in product choice. Overall every patient and their family must be presented with the advantages and disadvantages of all factor VIII concentrates, and be allowed to make an informed decision about which product to use for treatment.

Blood safety and the choice of anti-hemophilic factor concentrate

Hemophilia is a congenital disorder due to the deficiency of the activity of factor VIII (classical hemophilia A) or IX (Christmas disease or hemophilia B). Bleeding is common and may result in long-term complications or even death. Bleeding may be treated or prevented by infusion of factor concentrates however these drugs are not without risk. Clinicians often feel ill prepared to provide accurate and impartial information regarding these drugs. This review will provide the reader with an historical yet up to date perspective on blood safety as it relates to the choice of concentrates to treat hemophilia.

A Patient’s Perspective on Hemophilia

People with hemophilia play a central role in partnering with their physicians to achieve the best possible clinical and economic outcomes. To make informed choices regarding a hemophilia therapy, patients and their caregivers must assess four basic areas: safety, purity, cost, and convenience--where safety is the number one concern. Access to information, including informed consent on issues affecting choice of therapy, treater, regimen, and point of service, ancillary, and comprehensive care services, is of fundamental importance when choosing a therapy. Hemophilia treaters are often the primary source for information and also play a large part in therapy decisions based on possible inhibitor formation, patients' lifetime insurance caps, and therapy availability. In order to help optimize a patient's outcomes, hemophilia treaters must also periodically re-evaluate and modify disease management techniques. Given the devastation of the hemophilia community during the worst years of the acquired immune deficiency syndrome (AIDS) epidemic, physicians, government agencies, and industry must complement policy decisions with medical ethics, psychosocial, and quality-of-life considerations--and patients must remain vigilant about the safety of their therapy. It is imperative that standards of care ensure access to the safest therapies available and enable those with hemophilia to live a life only minimally disrupted by their disease.

Haemophilias A and B

The haemophilias are inherited disorders in which one of the coagulation factors is deficient. Although deficiencies of factor VIII (haemophilia A) and factor IX (haemophilia B) are well recognised, von Willebrand's disease is much more common. Rare defects can occur in any of the coagulation factors. In the past, men with haemophilia were likely to die in their youth. With advances in diagnosis, and especially with development of safe and effective treatment, affected individuals can now look forward to a normal life expectancy. Complications of the disorder, particularly the development of antibodies that make treatment ineffective, and of treatment, such as transfusion-transmitted infections, have taken a severe toll on these patients. The future holds the realistic possibility of gene therapy. However, we must not forget that haemophilia is a worldwide disorder that requires significant economic resources not available for the majority.

Adverse events in the prophylaxis of haemophilia

Whilst prophylaxis undoubtedly offers many advantages, the potential for adverse effects must also be borne in mind. Modern plasma-derived products have an extremely good safety record with regard to transmission of pathogens, although continuous vigilance is required as new pathogens continue to emerge, eg new variant Creutzfeldt-Jakob disease. There is no evidence that prophylactic treatment is associated with an increased incidence of inhibitors, and it is now recognized that genetic factors are the most significant in conferring susceptibility. Although subtle immunological abnormalities have also been observed in patients with haemophilia, there is no evidence that these are of any clinical significance. There has been a growing trend to use indwelling venous catheters for prophylaxis. The risk of infection has been appreciated for some time, although it has only recently been possible to quantify this with more precision. The risk of catheter-associated thrombosis is now recognized to be higher than hitherto appreciated. Whilst sporting activities are to be encouraged, there is a potential for significant trauma in children with prophylaxis, as plasma coagulation factor levels remain far below normal with the usual regimens.