Enhanced uptake of blood coagulation factor VIII containing immune complexes by antigen presenting cells.

Essentials Anti-factor (F) VIII antibody formation is a major complication in the treatment of hemophilia A. We investigated uptake of FVIII and FVIII immune complex by bone marrow derived dendritic cells. Immune complex formation increased uptake of FVIII 3-4 fold in a Fcγ receptor dependent manner. FVIII immune complex binding to Fcγ receptors may modulate immune tolerance induction. SUMMARY: Background A major complication in the treatment of hemophilia A is the development of inhibitory antibodies targeting coagulation factor VIII (FVIII). Eradication of these inhibitors can be established by immune tolerance induction (ITI), which consists of daily administration of high dosages of FVIII. FVIII immune complexes (FVIII-IC) could be formed following FVIII infusion in patients with pre-existing anti-FVIII antibodies. Objectives Here we studied endocytosis of FVIII-IC by bone marrow-derived dendritic cells (BMDCs). Methods BMDCs were pulsed with FVIII/FVIII-IC and uptake was assessed by flow cytometry and confocal imaging. Results BMDCs were able to efficiently internalize FVIII-IC in a dose-dependent manner, 3-4-fold more efficiently when compared with equimolar concentrations of non-complexed FVIII. Uptake of FVIII-IC, but not FVIII alone, could be inhibited with anti-Fcγ receptor (FcγR) antibody 2.4G2, indicating functional involvement of FcγR. No internalization of FVIII-IC was observed in BMDCs lacking FcγRI, FcγRIIb, FcγRIII and FcγRIV. Genetic ablation of FcγRIIb, FcγRIII or FcγRIV individually did not affect the ability of anti-FVIII IgG to promote the uptake of FVIII. BMDCs lacking FcγRI showed lower FVIII-IC uptake levels when compared with other single FcγR null BMDCs. Expression of the inhibitory FcγRIIb alone was sufficient to internalize FVIII-IC more efficiently than FVIII. Conclusions FcγR are critical in the internalization of FVIII-IC by BMDCs and multiple FcγR can contribute independently to this process. Our findings provide a basis for future studies to address whether the outcome of ITI is dependent on the interplay between FVIII-IC and inhibitory and activating FcγR.

[Relationship between maintenance dosages of fluindione (Préviscan) and warfarin (Coumadin) for patients 70 years and older]. / Nomogramme d'équivalence entre les posologies de fluindione (Préviscan) et de warfarine (Coumadine) pour des patients de 70 ans et plus.

INTRODUCTION: Switching from fluindione, an indanedione vitamin K antagonist derivative, to warfarin, a coumarin one, or vice versa, requires to know the relationships between dosages of these two molecules. METHODS: We conducted a prospective study in 288 consecutive patients aged 70 years and over, converted from fluindione to warfarin. Patients who were retained for the analysis were those for whom maintenance dosages were obtained for both vitamin K antagonists. RESULTS: Eighty-two patients, mean aged 83 ± 6 years, were analysed. The average daily maintenance dosages were 13.8 ± 6.7 mg (range 5-35) and 3.7 ± 1.7 mg (range 1-8) for fluindione and warfarin, respectively. Using a linear regression model, we built a transition algorithm for the maintenance dosages of warfarin and fluindione. CONCLUSION: This is the first study to propose a conversion algorithm to help prescribers to estimate the maintenance dosage when it is necessary for a patient to switch from fluindione to warfarin or conversely.

[Therapeutic education of elderly patients under antivitamin - K treatment: evaluation of the program after 5 years]. / Education thérapeutique de patients âges traités par AVK. Biltan d'un programme après 5 années d'existence.

INTRODUCTION: Elderly people with vitamin K antagonists (VKA) have a higher risk of potentially serious hemorrhagic complications. An education program for patients (EPP) aged > or = 75 years with VKA was set up in 2008 in a French geriatric hospital. It includes individual and group sessions conducted by a nurse and a geriatrician. OBJECTIVES: The aim of this study was to assess this EPP after 5 years. Strengths, weaknesses and difficulties of implementation were highlighted, and some improvements were proposed. METHODS: This study is an external audit conducted by a pharmacist trained in EPP. Files of consecutive patients included in the program between may 2008 and March 2013 were reviewed allowing the data collection of patients characteristics and results of the different sessions. The educational objectives were assessed by the rate of correct responses to the questionnaires during the program. The results are presented taking into account the changes made during the 5 years of the program. RESULTS: One hundred forty-three patients, mean age 83.3 +/- 6.5 years, were included in the EPP. 51 sessions were conducted (2.8 patients/session on average). 58% of selected patients were hospitalized. The mean time between the start of anticoagulant treatment and the incLusion in the program was 48.9 +/- 71 months. For 95 patients (66.4%) the medication management at home required a caregiver who was present for sessions in 82 cases (57.3%). The questionnaires form and the organisation of the sessions were gradually improved between 2008 and the end of 2010. Thus, the impact of the EPP has been estimated from November 2010 to March 2013. The correct responses rates before and after the sessions were respectively: 47.8% vs 91.3% for knowledge of INR target values, 25.4% vs 91.3% for knowledge of hemorrhagic signs, 14.9% vs 87.0% for knowledge of the situations or the medications that may disturb the INR equilibrium. Furthermore, the mean number of correct responses, for the 23 patients participating in the entire program, is statistically different between the educational diagnostic and immediate evaluation (3.7/7 vs 5.4/7 p = 0.023) and no significant difference is observed between immediate and distant evaluation (5.4/7 vs 5.8/7 p = 0.720). CONCLUSION: An improvement of patient knowledge was observed with regard to the main educational objectives. Some improvements are proposed: to disseminate information to general practitioners, to add the follow up of INR values to assess an impact on anticoagulant treatment stability. Furthermore, this program is now adapted to the new oral anticoagulants. It is the role of hospital or community pharmacists to initiate and/or assess this type of EPP.

Heme binds to factor VIII and inhibits its interaction with activated factor IX.

BACKGROUND: Heme is a redox active macrocyclic compound that is released upon tissue damage or hemorrhages. The extracellular release of large amounts of heme saturates scavenging heme-binding proteins. Free heme has been proposed to affect coagulation and has been co-purified with the factor VIII (FVIII)-von Willebrand factor (VWF) complex. The sites from which heme is released upon injury overlap with the sites to which FVIII is targeted for performing its hemostatic functions. OBJECTIVES: To investigate the interaction of heme with FVIII and the consequence for the procoagulant activity of FVIII in vitro. METHODS AND RESULTS: Heme bound to several sites on FVIII with high apparent affinity. Heme-binding inhibited FVIII procoagulant activity in a dose-dependent manner. FVIII inactivation in the presence of saturating amounts of heme implicated a reduced interaction of FVIII with activated FIX, as shown by ELISA, surface plasmon resonance and fluorescence quenching. Heme-mediated inactivation of FVIII was prevented by VWF, but not by human serum albumin, a heme-binding protein known for its protective activity in hemolytic conditions. CONCLUSIONS: Our data identify FVIII as a novel heme-binding protein. Occupation of high affinity heme-binding sites on FVIII at low concentrations of free heme did not inactivate FVIII. Conversely, large molar excesses of heme over FVIII, which correspond to conditions of extensive heme release, inhibited FVIII activity in vitro. It remains to be demonstrated whether, under such conditions, heme-mediated modulation of the activity of FVIII plays some role in the regulation of coagulation.

Development and performance of a new hydrofluoroalkane (HFA 134a)-based metered dose inhaler (MDI) of salmeterol.

In response to the Montreal Protocol, a salmeterol (Serevent) metered dose inhaler (MDI) has been developed containing the non-chlorofluorocarbon propellant, hydrofluoroalkane 134a (HFA), to replace the marketed Serevent chlorofluorocarbon (CFC) propellant MDI. This paper details the pharmaceutical assessment of salmeterol HFA MDI and confirms that this product meets the current Committee for Proprietary Medicinal Products regulatory requirements, and is comparable to the CFC MDI in product performance. Criteria investigated included fine particle mass (FPM), dose delivery and uniformity, priming requirements and simulated-use-testing. Dose delivery was unaffected by changing product orientation during storage. The mean dose delivered per actuation ranged from 21.3 to 22.4 microg, and all individual doses were within the +/-25% defined limits of the target ex-actuator dose of 21 microg. The FPM results, defined as the mass of particles between 1.1 and 4.7 microm in diameter (the sum of the mass deposited on stages 3-5 of the Andersen Cascade Impactor), were similar for the HFA and CFC products. The mean FPM values of the two HFA clinical batches were 8.7 and 10.1 microg, covering the values obtained during the development, and the one of the CFC clinical batch was 10.0 microg. Comparability in aerosol characteristics was also demonstrated when the salmeterol HFA inhaler was tested using a large volume spacer (Volumatic).

Pharmacodynamics and pharmacokinetics of single nasal (5 mg and 10 mg) and oral (50 mg) doses of ephedrine in healthy subjects.

OBJECTIVE: To determine the cardiovascular, subjective effects and potential of abuse liability of single dose (-) ephedrine (E) administered orally (50 mg) or intranasally (10 mg and 5 mg). METHODS: Sixteen healthy Caucasian men with no history of drug/alcohol/nicotine abuse or dependence received intranasal single doses of E 5 mg, 10 mg and oral doses of 50 mg and placebo in a double-blind, double-dummy, crossover study. Dependent measures included assessment of subjective feelings by Addiction Research Centre Inventory (ARCI). Profile of Mood States (POMS). visual analogue scales (VAS); "drug liking", "any drug effect", subjective quality of sleep and blood pressure and heart rate. Plasma E concentrations were also determined. RESULTS: (-) E increased supine systolic, diastolic blood pressure (P < 0.01). Changes in supine systolic blood pressure (areas under the 8 h of the experimental sessions) were -59 +/- 47 mmHgh with placebo, -59 +/- 57 mmHg-h with E5 mg by the nasal route, -18 +/- 48 mmHg x h with E 10 mg by the nasal route and 13 +/- 58 mmHgh with E 50 mg by the oral route (P<0.001). (-) E-induced orthostatic hypotension (P < 0.01) (maximal systolic blood pressure drop: E 50 mg 14 +/- 10 mmHg, P < 0.03; E 10 mg 11 +/- 6 mmHg, P = 0.08 compared with placebo) and resulted in decreased tiredness (placebo -2 +/- 39 mm x h, E 5 mg -17 +/- 39 mm x h, E 10 mg -30 +/- 42 mm x h, E 50 mg -24 +/- 35 mm x h; P < 0.03). E did not modify ARCI subscales--in particular the "amphetamine" subscale--but showed a tendency for drug liking (P= 0.09). On the "any drug effect" questionnaire, subjects could identify drug effect (P=0.007). Maximal plasma E concentration (Cmax) and areas under the curves for up to 8 h were proportional to the doses. Elimination half-life was approximately 6 h. A clockwise hysteresis was observed for systolic blood pressure in all but one subject with E 50 mg by the oral route. CONCLUSION: E even at low doses and by the nasal route can decrease tiredness in healthy persons; this is accompanied by a substantial increase in blood pressure and orthostatic hypotension exposing individuals in case of intensive physical exercise to cardiovascular risks. No clear evidence of abuse liability in healthy drug naive subjects was observed.