Emerging drugs for the treatment of hemophilia A and B

Introduction: Replacement therapy with clotting factor concentrates is the most appropriate and effective way to treat bleedings of Hemophilia A&B to prevent chronic arthropathy. Unfortunately, the short half-life (HL) of FVIII/IX concentrates obliges the patients to receive frequent infusions, a big concern for children. The development of inhibitors in about 30–45% of hemophilia A and in 3–5% of hemophilia B patient is the major adverse event of replacement therapy.

Areas covered: In the last few years, new rFIX have been developed with HL. New rFVIII concentrates are displaying small increase of PK characteristics. The new bio-engineering methods allowed the production of molecules fused with Fc fragment of IgG or Albumin or linked to PEG. A new approach to improve hemostasis is represented by Mab against TFPI and small RNA interfering with Antithrombin synthesis. Another innovative drug seems to be the new bi-specific antibody which mimics FVIII function in linking FXa and FX to tenase production.

Expert opinion: The emerging drugs for hemophilia treatment seem to be very promising. The extended half-life will improve the adherence of patients to therapy. Accurate post-marketing surveillance studies will be necessary to check the efficacy, safety and immunogenicity of these new molecules.     

Haemophilia B: current pharmacotherapy and future directions

Introduction: Hemophilia B is a rare hereditary hemorrhagic disorder characterized by deficiency of the clotting factor IX (FIX). Hemophilia B patients experience mild to severe bleeding complications according to the degree of FIX defect. Nowadays, the most challenging complication of individuals with hemophilia B is the development of alloantibodies, which render the standard replacement therapy with FIX concentrates ineffective, exposing them to a significantly increased morbidity and mortality.

Areas covered: This review summarizes the most important events leading to the development of the current FIX products available for the treatment of hemophilia B patients. In addition, it focuses on the more recent advances in the production of new FIX molecules aimed at improving the clinical management of such patients.

Expert opinion: Although the availability of plasma-derived FIX concentrates has greatly improved the clinical management of hemophilia B patients, the introduction of FIX products using recombinant DNA technology has represented the most significant therapeutic progress in hemophilia B therapy, ensuring an advanced level of safety. The development of rFIX products with extended half lives will further improve the therapeutic armamentarium for hemophilia B patients.     

The safety of pharmacologic options for the treatment of persons with hemophilia

ABSTRACT

Introduction: The mainstay of treatment of hemophilia A and B is the replacement of the congenitally deficient coagulation factor through the intravenous infusion of specific concentrates (factor VIII, FVIII, in hemophilia A; factor IX, FIX, in hemophilia B). Several commercial brands of FVIII or FIX products extracted from human plasma or engineered using recombinant DNA technology are available.

Areas covered: We analyze the safety aspects of plasma-derived and recombinant FVIII and FIX products licensed in Europe, focusing on their pathogen safety and inhibitor and thrombosis risks. The safety aspects of bypassing agents (i.e., activated prothrombin complex concentrates and recombinant activated factor VII) used for treatment of bleeding episodes in inhibitor patients will be also briefly discussed.

Expert opinion: The analysis of the published literature documents the high degree of safety from pathogen risk for both plasma-derived and recombinant products available for hemophilia treatment. The main threat to factor concentrate safety is represented by the development of neutralizing alloantibodies against the infused coagulation factor, which in hemophilia A seem to occur more frequently following the administration of recombinant than plasma-derived FVIII products. Great expectations are placed on newer products, particularly on those based upon mechanisms of action other than FVIII replacement.     

Safety of recombinant coagulation factors in treating hemophilia

Introduction: During the last decade, new FVIII/IX concentrates have been developed for the treatment of patients affected by hemophilia A/B. Significant progress has been achieved regarding their half-life, but the old issue of immunogenicity and new concerns about safety need to be addressed.

Areas covered: After the implementation of virucidal methods, both plasma-derived and recombinant clotting factor concentrates achieved a very safe profile. The development of anti-FVIII antibodies is the major adverse event of replacement therapy with both FVIII concentrates. Furthermore, the new extended half-life concentrates, protein fused or pegylated, raised some concerns about their side effects.

Expert Opinion: The treatment of hemophilia A with inhibitors by induction of immunotolerance and using by-passing concentrates, improved the quality of life of patients but did not allow them to have a life expectancy like that of patients without inhibitors. The new humanized monoclonal antibody (MAb) ACE910, mimicking FVIII function, seems to be able to reduce the bleedings of hemophilia A patients with inhibitors. The post-marketing surveillance will clarify if the adverse events observed during the phase III clinical trials and compassionate use were due to the association with a Prothrombin activated complex concentrate or to the prothrombotic effect of the drug itself.     

Haemophilia B: current pharmacotherapy and future directions

Introduction: Hemophilia B is a rare hereditary hemorrhagic disorder characterized by deficiency of the clotting factor IX (FIX). Hemophilia B patients experience mild to severe bleeding complications according to the degree of FIX defect. Nowadays, the most challenging complication of individuals with hemophilia B is the development of alloantibodies, which render the standard replacement therapy with FIX concentrates ineffective, exposing them to a significantly increased morbidity and mortality. Areas covered: This review summarizes the most important events leading to the development of the current FIX products available for the treatment of hemophilia B patients. In addition, it focuses on the more recent advances in the production of new FIX molecules aimed at improving the clinical management of such patients. Expert opinion: Although the availability of plasma-derived FIX concentrates has greatly improved the clinical management of hemophilia B patients, the introduction of FIX products using recombinant DNA technology has represented the most significant therapeutic progress in hemophilia B therapy, ensuring an advanced level of safety. The development of rFIX products with extended half lives will further improve the therapeutic armamentarium for hemophilia B patients.     

Healthcare costs among patients with hemophilia A treated with factor replacement or bypassing agents

Objective: To assess real-world costs for patients with hemophilia A treated with bypassing agents versus factor VIII (FVIII) replacement.

Methods: Claims data from a large US health insurer during 1 January 2006–30 September 2014 were used for analysis. Treated patients with hemophilia A were identified based on ≥1 medical claim with a diagnosis code for hemophilia A (ICD-9-CM 286.0) and ≥1 medical or pharmacy claim for bypassing therapy and/or FVIII replacement during 1 January 2007–31 August 2014. The bypassing therapy cohort comprised patients with ≥1 claim for bypassing therapy; all others were assigned to the factor replacement therapy cohort. Post-index hemophilia-related costs were computed as combined health plan plus patient paid amounts for medical claims with hemophilia A diagnosis code or hemophilia therapy procedure code (bypassing therapy, FVIII replacement therapy, desmopressin, antifibrinolytic therapy), as well as pharmacy claims for hemophilia therapy.

Results: The study sample represented 580 patients: 50 (8.6%) in the bypassing therapy cohort (mean age: 38.5?years; mean post-index period: 2.1?years) and 530 (91.4%) in the factor replacement therapy cohort (mean age: 29.3?years; mean post-index period: 2.7?years). Compared with the factor replacement therapy cohort, mean per-patient-per-month hemophilia-related total costs were 4.8-fold higher in the bypassing therapy cohort ($57,232 vs. $11,899), comprising 4.4-fold higher medical costs ($45,911 vs. $10,352) and 7.3-fold higher outpatient pharmacy costs ($11,321 vs. $1547).

Conclusions: Patients with hemophilia A treated with bypassing agents between 2007 and 2014 incurred substantially higher monthly hemophilia-related medical and pharmacy costs than patients treated only with FVIII replacement.     

Pharmacokinetic drug evaluation of recombinant factor VIII for the treatment of hemophilia A

Introduction: The prevention of bleeding by prophylactic factor replacement is the recommended approach for the treatment of severe hemophilia. Prophylaxis should be individualized to provide the best clinical benefit to each patient. Therefore, a pharmacokinetic approach is crucial.

Areas covered: This review aims to concisely describe the basic principles of pharmacokinetics of FVIII, the role of population pharmacokinetic, the available different recombinant FVIII concentrates and the new extended half-life FVIII molecules with possible improvement in hemophilia A treatment.

Expert opinion: Pharmacokinetic is a useful tool to predict the outcome of replacement therapy, even though a large inter-individual variability exists, becauseof several factors: age, weight, von Willebrand factor level, blood group, active bleed, presence of inhibitors to FVIII, FVIII concentrate. Among the different recombinant FVIII concentrates pharmacokinetic differences are minor and clinically not significant. The extended half-life FVIII products brings only moderate advances, as half life extension is limited to 1.5–1.8-fold in comparison to that of native FVIII. Thus, infusions could be done every fourth, rarely fifth day to ensure a safe through level and a significant benefit can be offered only to patients treated every other day or three times weekly.     

Efficacy of emicizumab prophylaxis versus factor VIII prophylaxis for treatment of hemophilia A without inhibitors: network meta-analysis and sub-group analyses of the intra-patient comparison of the HAVEN 3 trial

Abstract

Objectives: To compare the efficacy of emicizumab prophylaxis with that of factor VIII (FVIII) prophylaxis in patients with hemophilia A without inhibitors using two approaches: network meta-analyses (NMA) and additional sub-group analyses from the HAVEN 3 trial.

Methods: The NMA used data from trials identified using a systematic literature review and compared bleed rates in patients receiving emicizumab prophylaxis and patients receiving FVIII prophylaxis using a Bayesian, random effects generalized linear model with log link Poisson likelihood. Additional sub-groups of the HAVEN 3 trial included here were defined as patients whose dose-taking behavior met either European label or World Federation of Hemophilia guidelines. A negative binomial regression model was used to conduct an intra-patient comparison of bleed rates within the sub-groups, during treatment with FVIII prophylaxis before entering HAVEN 3 and treatment with emicizumab prophylaxis during HAVEN 3.

Results: Four studies were included in the base-case NMA. Evidence showed that the total treated bleed rate was lower with emicizumab prophylaxis compared with FVIII prophylaxis (rate ratio [RR]?=?0.36 [95% credible interval (CrI) = 0.13–0.95]). Similar associations were observed in sensitivity analyses. The additional HAVEN 3 analyses also showed lower rates of treated bleeds with emicizumab prophylaxis than with FVIII prophylaxis (RRs [95% confidence interval (CI)]?=?0.380 [0.186–0.790] and 0.472 [0.258–0.866] in two sub-groups). These results confirm the original HAVEN 3 intra-patient comparison findings.

Conclusions: Combined findings from NMA and additional sub-group analyses of HAVEN 3 support the superiority of emicizumab prophylaxis over FVIII prophylaxis in patients with hemophilia A without inhibitors.     

Treatment strategies in children with hemophilia

Hemophilia is an inherited bleeding disorder caused by quantitative or qualitative defects in the synthesis of factor VIII (FVIII) or factor IX (FIX). Clinically, it is divided into severe, moderate and mild disease depending on the levels of FVIII or FIX in the blood. The bleeding tendency is most pronounced and can start at a very young age in severe hemophilia, which is characterized by repeated hemorrhage into the joints and muscles. Without treatment, these episodes lead to severe arthropathy, and there is also a high risk of lethal cerebral hemorrhage. The treatment of bleeding symptoms requires the correction of the coagulation defect. Factor concentrates have been available for 30 years, initially with the development of cryoprecipitate, subsequently with increasingly purified plasma-derived forms, and ultimately with recombinant clotting factor concentrates. The advantage of this highly effective therapy has been subdued by the outbreak of HIV and Hepatitis C infections in patients with hemophilia treated with factor concentrates which did not have adequate viral inactivation steps in the purification process. Plasma-derived and recombinant factor concentrates are today considered to have a good safety profile, but are only available for a small group of hemophilia patients worldwide. A multidisciplinary team approach is important for early diagnosis, communication with the patient and parents, and to tailor the best treatment possible with the amount of clotting factor concentrates available. The main goal of hemophilia treatment is to prevent bleeding symptoms and allow normal integration in social life. In patients with severe hemophilia, this can best be achieved by early home treatment and primary prophylaxis. Future developments in gene therapy may transform severe hemophilia to a mild form, with no need for regular injections of clotting factor concentrates.     

Therapeutic approaches for haemophilia

The life-long episodic bleeding associated with inherited deficiencies of blood coagulation Factor VIII (FVIII) or Factor IX (FIX) can be well controlled with periodic iv. injections of FVIII or FIX concentrates. Either concentrate can be isolated from large human pools (i.e., plasma-derived FVIII or FIX concentrate) or from culture supernatants of recombinant cells engineered to secrete FVIII or FIX. The validated viral inactivation strategies used by manufacturers of FVIII and FIX concentrates have essentially eliminated the transmission of hepatitis B, hepatitis C and HIV viruses. The low yields and inherent instability of FVIII (and FVIIIa in particular) and the additional costs of viral inactivation methods make the annual cost/patient for prophylaxis and treatment of haemophilia very expensive. Several strategies have been adopted and proposed to improve yields of FVIII. These include: deletion of portions of FVIII which are not associated with function; mutations to prevent inactivation of FVIII by protease degradation; and synthesis of FVIII fragments to replace portions deleted in some FVIII deficient patients. An approach to improve FIX replacement involves the production of more coagulatively active FIX mutants. Another promising approach in both FVIII and FIX replacement is gene therapy. Two major issues that will have to be critically addressed before gene therapy for haemophilia can become widespread are whether the procedures will be well-tolerated in patients with significant liver impairment (due to previous exposure to hepatitis viruses) and whether consistent long-term delivery of the transgenes can be achieved.     

The availability of new drugs for hemophilia treatment

ABSTRACT

Introduction

A number of new FVIII/IX concentrates enriched the portfolio of products available for the treatment of hemophilia A/B patients. Due to the large inter-patient variability, accurate tailoring of the therapy became essential to improve patients’ adherence, clinical outcomes, and cost/effectiveness ratio. Recently, non-replacement therapies have taken the limelight and succeeded in decreasing the bleedings of patients.     

Efficacy and safety of a recombinant factor VIII produced from a human cell line (simoctocog alfa)

Introduction: The development of inhibitors against infused factor VIII (FVIII) has a detrimental impact on health and quality of life of patients with hemophilia A. Several observational studies and a recently published randomized trial indicate that the inhibitor risk in previously untreated patients (PUPs) is higher following the use of recombinant FVIII (rFVIII) products compared with plasma-derived FVIII concentrates. There is currently a great interest towards newer rFVIII products that adopt various technological solutions to reduce the inhibitor risk.

Areas covered: This review describes the efficacy and safety of simoctocog alfa (Nuwiq), a human cell-line derived rFVIII developed for the prevention and treatment of bleeding in hemophilia A patients. Particular relevance will be given to the safety aspects of this product, with special emphasis on the rate of inhibitor development, presenting the results of the phase II and III clinical trials on previously treated patients (PTPs) and the interim data from the phase III trial on PUPs.

Expert opinion: The final results from PTP studies and the preliminary data from the PUP study document the high efficacy and safety profile of this rFVIII product, which has the potential to reduce the inhibitor risk in PUPs with severe hemophilia A.     

The use of pharmacokinetics in dose individualization of factor VIII in the treatment of hemophilia A

Introduction: Hemophilia A is a bleeding disorder resulting from a lack of clotting factor VIII (FVIII), and treatment typically consists of prophylactic replacement of the deficient factor. However, high between subject variability precludes the development of a ‘one size fits all’ dosing strategy and necessitates an individualized approach. We sought to summarize the data on the pharmacokinetics of FVIII available as a basis for the development of population pharmacokinetic models to be used in dose tailoring.

Areas covered: We reviewed the pharmacokinetics of FVIII as used for the treatment of hemophilia A, with a focus on the variability observed between patients and the application of pharmacokinetic methods to dose individualization. We also explored the covariates affecting pharmacokinetic parameters, the differences between plasma-derived and recombinant FVIII and the development of extended half-life products.

Expert opinion: The pharmacokinetics of factor VIII in patients with hemophilia shows a high interpatient variability, and is affected by age, weight, level of von Willebrand factor, and blood group. A population approach to estimating individual pharmacokinetics is likely to provide the most successful strategy to tailor factor concentrate dosing to the individual needs and to ensure optimal patient outcomes, while also improving the cost-effectiveness of prophylactic replacement therapy.     

Maintenance plus reliever budesonide/formoterol compared with a higher maintenance dose of budesonide/formoterol plus formoterol as reliever in asthma:an efficacy and cost-effectiveness study

ABSTRACT

Objective: To evaluate efficacy and costeffectiveness of budesonide/formoterol (Symbicort) maintenance (one dose once or twice daily) plus additional doses as needed (Symbicort Maintenance And Reliever Therapy, SMART) compared with a higher fixed dose of budesonide/ formoterol with formoterol as needed in patients with persistent asthma.

Study design and methods: 6‐month, open, randomised study of 465 patients either not well controlled on an inhaled corticosteroid (ICS), or well controlled on a combination of ICS and a long-acting β₂‐agonist (LABA). Treatments: budesonide/formoterol 160/4.5?µg, one inhalation, once or twice daily maintenance plus additional doses as-needed (1 × SMART or 2 × SMART), or budesonide/formoterol 160/4.5?µg two inhalations twice daily plus formoterol 4.5?µg as needed (2 × 2 FIX + F). Children 6–11 years old used an 80/4.5?µg dose strength. Primary variables of efficacy were the changes in the Asthma Control Questionnaire (ACQ₅) and morning peak expiratory flow (PEF).

Results: Mean age of patients 40 years (range 6–82 years); 53% female. No differences between the groups were found in ACQ₅ scores or asthma exacerbation rates. Morning PEF was higher in the 2 × 2 FIX + F group vs. the 1 × SMART and 2 × SMART groups (differences 13?L/min and 9?L/min, respectively; p < 0.002). The 1 × SMART group showed a significant decrease in asthma controlled days compared with the two other groups. No difference was seen between the 2 × SMART group and the 2 × 2 FIX + F group. Treatment costs were significantly lower in the SMART groups compared with the 2 × 2 FIX + F group.

Conclusion: Compared with the 2 × 2 FIX + F treatment the use of budesonide/formoterol was 30–40% lower in the SMART groups while maintaining equal ACQ₅ scores. Daily asthma control improved equally with 2 × SMART compared to 2 × 2 FIX + F with a reduction in asthma medication cost. The one dose once daily maintenance treatment (1 × SMART) resulted in a low level of treatment failure (exacerbations) but led to more days with symptoms. Therefore, a daily dose of two inhalations seems to be the lowest appropriate dose in patients with moderate persistent asthma.     

Status and trend analysis of prophylactic usage of recombinant factor VIII in Chinese pediatric patients with hemophilia A: ReCare – a retrospective,phase IV,non-interventional study

Background: No study has reported the status and chronological trend of prophylactic recombinant factor VIII (rFVIII) use in Chinese pediatric patients with hemophilia A (HA).

Objective: We aimed to analyze the status and trend of rFVIII-containing prophylaxis in Chinese pediatric patients with HA.

Methods: ReCARE (Retrospective study in Chinese pediatric hemophilia A patients with rFVIII contained REgular prophylaxis) was a retrospective study conducted in 12 hemophilia treatment centers across China. The trend of prophylaxis was evaluated by determining the mean duration of prophylaxis, mean injection frequency (per week), mean dose of each injection (IU/kg), mean total dose injected/week (IU) and proportion of rFVIII consumption relative to factor VIII (FVIII) consumption over the study period.

Results: We analyzed 183 male pediatric patients with HA (mean age, 7.1?±?4.23 years), who received intermittent prophylaxis between 1 November 2007 and 31 May 2013. The mean duration of prophylaxis with rFVIII increased from 16.72 weeks in 2008 to 32.77 in 2012. Per injection dose of rFVIII increased significantly from 2008 to 2013 (25.89 to 28.31?IU/kg, p?Conclusion: Our data revealed an overall improvement in treatment dosage and duration with an increase in the number of patients receiving prophylaxis. The total proportion of rFVIII also increased gradually indicating the development of economy and safety awareness.

Trial Registration: The trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT02263066).     

Conformational comparability of factor IX-Fc fusion protein, factor IX, and purified Fc fragment in the absence and presence of calcium

A long lasting recombinant factor IX -Fc fusion protein (rFIX-Fc) is being developed for the treatment of hemophilia B and is currently in late stage clinical investigation. By limiting injection frequency and maintaining efficacy, rFIX-Fc shows promise as a new therapeutic option for hemophilia B patients. However, before gaining regulatory approval, rFIX-Fc must undergo rigorous analytical and biological testing, in addition to clinical trials. Included in this testing is the need to understand this protein's higher-order structure and dynamics. In this study, we investigated and compared the biophysical properties of rFIX-Fc, rFIX, and Fc using hydrogen/deuterium exchange mass spectrometry and differential scanning calorimetry. Within the limits of these techniques, our results show that structural comparability exists between rFIX and the FIX region of rFIX-Fc. In addition, changes in the structure and dynamics of both proteins, in response to calcium binding, a requirement for FIX function, are also highly comparable. In the case of Fc and Fc region of rFIX-Fc, conformational comparability is also established. These biophysical results further support the conclusion that fusing an immunoglobulin gamma 1 Fc to rFIX does not significantly alter the higher-order structure of FIX or Fc, Ca binding to FIX, or Fc functionality.     

Once-monthly injection of paliperidone palmitate in patients with recently diagnosed and chronic schizophrenia: a post-hoc comparison of efficacy and safety

Background: The use of long-acting injectable antipsychotics in recently diagnosed schizophrenia remains less explored. We evaluated the efficacy and safety of paliperidone palmitate once-monthly (PP1M) treatment in adult patients with recently diagnosed vs. chronic schizophrenia.

Research design and methods: These post-hoc analyses included two multicenter studies. Study 1 (NCT01527305) enrolled recently diagnosed (≤5 years) and chronic (>5 years) patients; Study 2 (NCT01051531) enrolled recently diagnosed patients only. Recently diagnosed patients were further sub-grouped into ≤2 years or 2–5 years. The primary efficacy endpoint was the change from baseline in Positive and Negative Syndrome Scale (PANSS) total score.

Results: In Study 1, 41.5% patients had recent diagnosis (≤2 years: 56.8%; 2–5 years: 43.2%); 58.5% had chronic schizophrenia. In Study 2, 52.8% and 47.2% patients were grouped into ≤2 years and 2–5 years, respectively. PANSS total score showed significantly greater improvement in patients with recently diagnosed vs. chronic schizophrenia. Similar results were obtained for PANSS responder rate, improvements in PANSS, and CGI-S scores.

Conclusion: PP1M was efficacious in both recently diagnosed and chronic schizophrenia, with the benefits being more pronounced in patients with recently diagnosed schizophrenia. This adds to growing evidence recommending long-acting antipsychotic interventions at early stages of schizophrenia.     

Olodaterol for the treatment of chronic obstructive pulmonary disease: a narrative review

ABSTRACT

Introduction: Inhaled bronchodilators are the key-stone of chronic obstructive pulmonary disease (COPD) management. Olodaterol 5 µg, a long-acting β2-adrenoceptor agonist (LABA) is one such bronchodilator indicated as a once-daily maintenance therapy.

Areas covered: This article reviews the several trials that have assessed olodaterol as a COPD therapy. It covers safety and tolerability data and provides the reader with an expert opinion on its use as a treatment for COPD.

Expert opinion: Olodaterol improves lung function for 24 h and reduces rescue medication use. It may also improve dyspnea, exercise tolerance, and health-related quality of life. It is well tolerated with an acceptable cardiovascular and respiratory adverse event profile. There is some evidence that olodaterol, as well as other LABAs, can reduce exacerbation frequency, but not FEV1 decline and death.

LABAs alone are indicated in group A/B COPD subjects. Olodaterol and indacaterol are administered once-daily and may offer an adherence advantage over other LABAs with more frequent dosing schedules. Co-administration of an olodaterol/tiotropium fixed dose combination in a single inhaler device is recommended as step-up in group A/B COPD subjects not sufficiently treated by olodaterol alone or as initial therapy in those with severe exertional dyspnea.     

Recent advances in the development of coagulation factors and procoagulants for the treatment of hemophilia

Hemophilia is a family of rare bleeding disorders. The two primary types, hemophilia A and hemophilia B, are caused by recessive X-chromosome linked mutations that result in deficiency of coagulation factor VIII (FVIII) or factor IX (FIX), respectively. Clinically, hemophilia is manifested by spontaneous bleeding, particularly into the joints (haemarthrosis) and soft tissue, and excessive bleeding following trauma or surgery. The total overall number of hemophilia patients worldwide is approximately 400,000, however only about 100,000 of these individuals are treated. The first treatment of hemophilia was initiated when it was determined that the clotting deficiency could be corrected by a plasma fraction taken from normal blood. The discovery of factor VIII enrichment by cryoprecipitation of plasma opened a new era of therapy which eventually led to the production of factor concentrates and the subsequent development of highly purified forms of plasma factors. The most significant improvements have been the availability of recombinant forms of factors VIII and IX. Unfortunately, recombinant factors still retain some of the limitations of plasma concentrates. These limitations include development of antibody responses in patients and the relatively short half-life of the molecules requiring frequent injection to maintain effective concentration. Treatment beyond replacement of native factors has been tried. They include the development of modified factor VIII and IX molecules with improved potency, stability and circulating half-life and enhancement of a prothrombotic responses and/or stabilization of coagulation factors via inhibition of key negative regulatory pathways. These approaches will be reviewed in this commentary.     

Levonorgestrel-releasing intra-uterine systems as female contraceptives

Introduction: The availability and use of long-acting reversible contraceptives (LARCs), such as levonorgestrel intrauterine systems (LNG-IUSs), have increased in recent times.

Areas covered: The authors provide a narrative review of the LNG-IUSs currently available worldwide as female contraceptives (LNG-IUS 13.5, 19.5 and 52 mg). Specific features of the devices and their parameters of efficacy and tolerability were considered as outcomes.

Expert opinion: The one-handed 3.8-mm-diameter inserter of LNG-IUS 13.5 mg and 19.5 mg may be particularly suitable in nulliparous women. While LNG-IUSs 13.5, 19.5 mg and LNG 52 mg should be used by women simply looking for an effective contraceptive method for up to 3, 4 or 5 years, LNG-IUS 52 mg has also been approved for the treatment of heavy menstrual bleeding and endometrial protection during hormone replacement therapy. LNG-IUS 52 mg is ideal for women who are experiencing a certain hyperestrogenic hormonal environment, with heavy menstrual bleeding due to hormonal imbalances, adenomyosis or fibroids, in the case of symptomatic endometriosis or for endometrial protection during hormone estrogenic replacement therapy in non-hysterectomized women.