Less abnormal uterine bleeding with dabigatran than warfarin in women treated for acute venous thromboembolism

Essentials Factor Xa inhibitors cause more abnormal menstrual bleeding (AUB) than vitamin-K antagonists (VKA). We analyzed data of AUB in women, evaluating dabigatran versus VKA. We observed a 41% lower risk of AUB in women on dabigatran compared to those on VKA. Our findings of lower AUB risk on dabigatran should be corroborated in future studies.

SUMMARY

Introduction Although direct oral anticoagulants (DOACs) are associated with a better safety profile than warfarin in patients with acute venous thromboembolism (VTE), direct factor Xa inhibitors involve a higher risk of abnormal uterine bleeding (AUB). We aimed to determine the risk of AUB during anticoagulation with dabigatran compared with warfarin. Methods Post-hoc analysis of the pooled RE-COVER studies and the RE-MEDY trial. Incidences of AUB, based on a defined preferred terms search for adverse events, in female patients aged 18-50 years treated with dabigatran, were compared with those in women treated with warfarin. Results Of the 2964 women included in the above-mentioned trials, 1280 women were in the relevant age category (18-50 years) and included in the current analysis. A total of 643 patients were randomized to treatment with dabigatran and 637 to treatment with warfarin. The overall rate of AUB was 8.1%, 5.9% for the women treated with dabigatran and 9.6% in those treated with warfarin, for an odds ratio for dabigatran-treated patients of 0.59 (95% confidence interval [CI], 0.39-0.90; P = 0.015). In the dabigatran-treated patients, three (0.5%) suffered major bleeding (MB) vs. five (0.8%) in the warfarin-treated patients (HR, 0.65; 95% CI, 0.15-2.72). MB or non-major relevant bleeding occurred in 30 (4.7%) patients randomized to receive dabigatran and 57 (8.9%) randomized to receive warfarin (HR, 0.53; 95% CI, 0.34-0.83). None of the bleeding events was fatal. Conclusion Dabigatran treatment was associated with a significantly (41%) lower risk of AUB than warfarin. Future studies in daily practice are needed to corroborate these findings.

Integrating new approaches to atrial fibrillation management: the 6th AFNET/EHRA Consensus Conference

There are major challenges ahead for clinicians treating patients with atrial fibrillation (AF). The population with AF is expected to expand considerably and yet, apart from anticoagulation, therapies used in AF have not been shown to consistently impact on mortality or reduce adverse cardiovascular events. New approaches to AF management, including the use of novel technologies and structured, integrated care, have the potential to enhance clinical phenotyping or result in better treatment selection and stratified therapy. Here, we report the outcomes of the 6th Consensus Conference of the Atrial Fibrillation Network (AFNET) and the European Heart Rhythm Association (EHRA), held at the European Society of Cardiology Heart House in Sophia Antipolis, France, 17-19 January 2017. Sixty-two global specialists in AF and 13 industry partners met to develop innovative solutions based on new approaches to screening and diagnosis, enhancing integration of AF care, developing clinical pathways for treating complex patients, improving stroke prevention strategies, and better patient selection for heart rate and rhythm control. Ultimately, these approaches can lead to better outcomes for patients with AF.

Treatment of acute pulmonary embolism with dabigatran versus warfarin

Dabigatran was non-inferior to warfarin for prevention of recurrent venous thromboembolism (VTE), and dabigatran had a lower rate of bleeding compared with warfarin in two large-scale randomised trials, RE-COVER and RE-COVER II. In this study, we investigate the efficacy and safety of dabigatran versus warfarin according to the index event that qualified the patient for enrollment, either symptomatic pulmonary embolism (PE) with or without deep-vein thrombosis (DVT), or DVT alone. We then analyse the anticoagulant effect of dabigatran vs warfarin on patients enrolled with PE. The pooled dataset for the efficacy analysis consisted of 2553 and 2554 patients who were randomised to dabigatran and warfarin, respectively. Recurrent VTE/VTE-related death during the study period and additional 30-day follow-up occurred in 2.7 % of all patients on dabigatran and in 2.4 % on warfarin (hazard ratio [HR] 1.09 [95 % confidence interval 0.77, 1.54]). In patients with PE as their index event, recurrent VTE/VTE-related death occurred in 2.9 % vs 3.1 % of patients (HR 0.93 [0.53, 1.64]). There were significantly fewer major bleeding events in patients treated with dabigatran than with warfarin (HR 0.60 [0.36, 0.99]). The pattern was similar both in patients with PE and in those with DVT alone as the index event. These analyses of the pooled dataset from the RECOVER and RE-COVER II trials indicate that dabigatran is as effective as warfarin in preventing recurrent VTE, regardless of whether patients present with symptomatic PE (with or without DVT) or with symptomatic DVT alone. Dabigatran was also associated with a lower risk of bleeding than warfarin, regardless of the index event.

Bleeding events with dabigatran or warfarin in patients with venous thromboembolism

Dabigatran was as effective as warfarin for the acute treatment of venous thromboembolism in the RE-COVER and RE-COVER II trials. We compared the incidence of bleeding with dabigatran versus warfarin in pooled data from these studies. The localisation, bleeding severity, and the impact of key factors on the incidence of bleeding, were compared between the dabigatran and warfarin treatment group. Altogether, 2553 patients received dabigatran and 2554 warfarin, each for a mean of 164 days. The incidence of any bleeding event was significantly lower with dabigatran (hazard ratio [HR] 0.70; 95 % confidence interval [CI], 0.61–0.79), as was the incidence of the composite of MBEs and clinically relevant non-major bleeding events (HR 0.62; 95 % CI, 0.50–0.76). The incidence of major bleeding events (MBEs) was also significantly lower with dabigatran in the double-dummy phase (HR, 0.60; 95 % CI, 0.36–0.99) but not statistically different between the two treatment arms when the entire treatment period is considered (HR 0.73 95 % CI, 0.48–1.11). Increasing age, reduced renal function, Asian ethnicity, and concomitant antiplatelet therapy were associated with higher bleeding rates in both treatment groups. The reduction in bleeding with dabigatran compared to warfarin was consistent among the subgroups and with a similar pattern for intracranial, and urogenital major bleeding. In conclusion, treatment of venous thromboembolism with dabigatran is associated with a lower risk of bleeding compared to warfarin. This reduction did not differ with respect to the location of bleeding or among predefined subgroups.

Dabigatran versus Warfarin for Acute Venous Thromboembolism in Elderly or Impaired Renal Function Patients: Pooled Analysis of RE-COVER and RE-COVER II

Management of acute venous thromboembolism (VTE) with anticoagulants in elderly patients and those with chronic kidney disease poses special challenges. The RE-COVER and RE-COVER II trials showed that dabigatran 150 mg twice daily was as effective as warfarin over 6 months in preventing recurrent VTE, with a lower bleeding risk. We now assess the effects of old age and renal impairment (RI) on pooled trial outcomes in 5,107 patients: 4,504 aged <75 years and 603 aged ≥75 years. The primary efficacy outcome was symptomatic VTE/VTE-related death. Safety outcomes were centrally adjudicated major bleeding events (MBEs), MBEs or clinically relevant non-major bleeding events (MBEs/CRBEs) and any bleeds. Baseline renal function was categorized as normal, mild RI or moderate RI. A total of 3,698 had normal renal function and 1,100 and 237 had mild and moderate RI, respectively (23 patients with severe RI and 49 with missing creatinine clearance data were not included). For dabigatran, VTE/VTE-related death decreased from 3.1% (normal renal function) to 1.9% for mild RI and to 0.0% for moderate RI. For warfarin, the event rates were 2.6, 1.6 and 4.1%, respectively. Overall, major bleeding increased with increasing RI (p = 0.0037) and with age (p = 0.4350), with no apparent difference between the dabigatran and warfarin patients. Dabigatran shows better efficacy than warfarin in RI and in the elderly patients, probably because of an increase in the concentration of dabigatran. However, bleeding risk increases with both dabigatran and warfarin in the presence of RI.

Efficacy of dabigatran versus warfarin in patients with acute venous thromboembolism in the presence of thrombophilia: Findings from RE-COVER®, RE-COVER™ II, and RE-MEDY™

It is unclear whether thrombophilia causes resistance to anticoagulant therapy. Post hoc analyses of data from RE-COVER®, RE-COVER™ II, and RE-MEDY™ were performed to compare dabigatran etexilate with warfarin for the treatment and prevention of venous thromboembolism (VTE) in patients with thrombophilia or antiphospholipid antibody syndrome (APS). There were no significant differences in symptomatic VTE/VTE-related deaths between dabigatran etexilate and warfarin in patients with or without thrombophilia. All bleeding event categories were less frequent with dabigatran etexilate than with warfarin, regardless of whether patients had thrombophilia, no thrombophilia, or were not tested. However, these differences did not reach significance in every group. In patients with APS, there was no significant difference in VTE/VTE-related deaths between the two treatment arms. Rates of bleeding events tended to be lower with dabigatran etexilate than with warfarin, reaching statistical significance for any bleeding event. In conclusion, the efficacy and safety of dabigatran etexilate were not significantly affected by the presence of thrombophilia or APS. ClinicalTrials.gov RECOVER Identifier: NCT00291330; RECOVER II Identifier: NCT00680186; RE-MEDY Identifier: NCT00329238

An open-label study of the pharmacokinetics and pharmacodynamics of dabigatran etexilate 150mg once daily in Caucasian patients with moderate renal impairment undergoing primary unilateral elective total knee or hip replacement surgery

BACKGROUND

In adults with moderate renal impairment (creatinine clearance [CrCl] 30-50mL/min) undergoing total hip or knee replacement (THR/TKR), the recommended dose of dabigatran etexilate is 150mg once daily (qd). We investigated the steady state pharmacokinetics, pharmacodynamics and safety in these patients.

METHODS

Single-arm, open-label phase 4 study (NCT01184989) in Caucasian patients receiving dabigatran etexilate 75mg 1-4h after surgery and 150mg qd on days 2-10 (TKR) or days 2-35 (THR). Plasma total dabigatran concentrations (day 6±1) were determined by high-performance liquid chromatography tandem mass spectrometry and indirectly using the commercially available diluted thrombin time (dTT) assay (Hemoclot® Thrombin Inhibitors).

RESULTS

Of 112 patients (mean CrCl 42.5mL/min, age 79.1years, 69.6% female), 100 completed the study. Geometric mean trough and peak dabigatran concentrations were 47.5ng/mL (10th-90th percentile 19.7-120) and 166ng/mL (49.1-364), respectively. There were four major bleeding events and no venous thromboembolic events. Dabigatran concentrations determined from dTT (and falling within the assay range of 50-500ng/mL) underestimated actual values by 7.6% (90% confidence interval 5.3, 9.9), which is within the acceptance limits of ±15%.

CONCLUSIONS

These findings in Caucasians with moderate renal impairment undergoing THR or TKR support the use of the 150mg qd dose of dabigatran etexilate. With adequate set-up, calibration and quality control the dTT assay might be appropriate for situations, such as serious bleeding or a need for urgent surgery, where determination of dabigatran levels would be helpful.

Observational study of dabigatran etexilate 150mg in patients with moderate renal impairment undergoing elective total hip or knee replacement

INTRODUCTION

The standard dabigatran etexilate dosage for prevention of venous thromboembolism (VTE) after elective total hip or knee replacement (THR/TKR) is 220mg once daily (qd), with 150mg qd for patients with moderate renal impairment. As clinical trial experience in patients with moderate renal impairment was limited at the time of approval, we conducted an observational study to evaluate the 150mg qd dose.

MATERIALS AND METHODS

This open-label, prospective, uncontrolled, observational study in patients with creatinine clearance (CrCl) 30-50mL/min was conducted in seven European countries. Patients received 75mg dabigatran etexilate 1-4h after surgery and 150mg qd on days 2-10 (TKR) or 2-35 (THR), per the European Summary of Product Characteristics. Coprimary outcomes were major bleeding events (MBEs) and a composite of symptomatic VTE and all-cause mortality.

RESULTS

428 renally impaired patients with median CrCl 43.4mL/min (range 30.0-49.9), and median age 80years (range 32-96) received dabigatran etexilate: median treatment duration THR 31days, TKR 28days. Ten MBEs occurred in nine patients (2.1%; 95% confidence interval [CI]: 1.0-4.0; THR 1.8%; TKR 2.4%); none were fatal or involved a critical organ. Symptomatic VTE and all-cause mortality occurred in three patients (0.7%; 95% CI: 0.1-2.0; THR 0.9%; TKR 0.5%). Overall, 54 patients discontinued treatment prematurely, including 35 due to an adverse event (nine bleeding-related) and 16 switching to another anticoagulant.

CONCLUSIONS

Dabigatran etexilate 150mg qd had a good safety profile and was efficacious in fragile, elderly, renally impaired patients undergoing THR or TKR. These findings from the clinical practice setting add to the existing clinical trial data.

Dabigatran etexilate for thromboprophylaxis in over 5000 hip or knee replacement patients in a real-world clinical setting

BACKGROUND

Thromboprophylaxis is recommended for patients undergoing total hip or total knee replacement (THR, TKR). An international, open-label, prospective, observational, single-arm study in a routine clinical setting was performed to assess the safety and efficacy of dabigatran etexilate 220 mg once daily in patients undergoing THR or TKR, and in subgroups of patients with potentially increased risk of bleeding or venous thromboembolism (VTE).

MATERIALS AND METHODS

Patients were ≥18 years and required to be eligible to receive dabigatran 220 mg once daily (first dose 110 mg 1-4 h after THR/TKR surgery) according to the European Summary of Product Characteristics. The primary safety and efficacy outcomes were incidence of major bleeding events (MBEs), and the composite incidence of symptomatic VTE events and all-cause mortality, respectively.

RESULTS

In total, 5292 patients (median age 64 years) were enrolled and received dabigatran (2734 THR and 2558 TKR). Median drug exposure was 31 days (THR 34 days; TKR 27 days). Overall incidence of MBEs was 0.72 % (95 % confidence interval [CI] 0.51, 0.98), and this rate was comparable between types of surgery and was not significantly affected by protocol-defined risk factors. The overall incidence of symptomatic VTE and all-cause mortality was 1.04 % (95 % CI 0.78, 1.35); the only significant risk factor was history of VTE events (odds ratio 5.59; 95 % CI 2.53, 11.08). A post-hoc analysis showed that the incidence of MBEs in this observational study was similar to or lower than those reported in previous phase 3 trials.

CONCLUSIONS

Results from this observational study of dabigatran etexilate administered to patients undergoing THR or TKR surgery are reassuring and supportive of those obtained in dabigatran phase 3 trials.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00846807.

Safety and efficacy of switching from low molecular weight heparin to dabigatran in patients undergoing elective total hip or knee replacement surgery

Background

The aim of this study was to assess the safety and efficacy of switching therapy from low molecular weight heparin (LMWH; enoxaparin) to dabigatran for prevention of venous thromboembolic events (VTE) in patients undergoing elective total hip or knee replacement surgery (THR/TKR).

Methods

This was a prospective, multicenter, open-label, single-arm, observational, study in patients undergoing THR or TKR who were to receive enoxaparin 40 mg for thromboprophylaxis. Enoxaparin was initiated before or after surgery according to local practice, and was switched to dabigatran 220 mg once daily at a time point chosen by the investigator. The coprimary endpoints were major bleeding events, and the composite of symptomatic VTE and all-cause mortality, from last use of enoxaparin to 24 h after last intake of dabigatran.

Results

Altogether, 168 (81 THR, 87 TKR) patients were enrolled, of whom 161 received both enoxaparin and dabigatran, 2 received dabigatran only and 5 received enoxaparin only. The median time of the first dabigatran tablet was 24.0 h after the last LMWH dosage and the median number of days on dabigatran treatment was 36 days. No symptomatic VTE or death occurred during the study. One major bleeding event was seen at the surgical site and required treatment cessation. Three minor bleeding events were observed.

Conclusions

In the normal clinical setting, switching from LMWH to dabigatran in patients who had undergone THR and TKR was safe and effective in preventing VTE. The reported adverse events and serious adverse events were consistent with the known safety profile for dabigatran. Switching from a subcutaneous to an oral anticoagulant may offer greater convenience in the outpatient setting after discharge.

Trial registration

ClinicalTrials.gov identifier NCT01153698.

Oral dabigatran etexilate versus enoxaparin for venous thromboembolism prevention after total hip arthroplasty: pooled analysis of two phase 3 randomized trials

Background

Two phase 3 trials compared 28–35 days of treatment with oral dabigatran 220 mg or 150 mg (RE-NOVATE) or 220 mg (RE-NOVATE II) once daily with subcutaneous enoxaparin 40 mg once daily for prevention of venous thromboembolism (VTE) after elective total hip arthroplasty.

Methods

This prespecified pooled analysis compared the outcomes for the dabigatran 220 mg dose with enoxaparin, which included 4,374 patients. Total VTE (venographic and symptomatic) plus all-cause mortality (primary efficacy), major VTE (proximal deep vein thrombosis [DVT] or non-fatal pulmonary embolism) plus VTE-related death, and bleeding events were evaluated. Efficacy analysis was based on the modified intention-to-treat (ITT) population and safety analysis was based on all treated patients. The common risk difference (RD) for dabigatran versus enoxaparin was estimated using a fixed effects model.

Results

Total VTE and all-cause mortality occurred in 6.8 % (114/1,672) and 7.7 % (129/1,682) (RD:–0.8 %, 95 % confidence interval [CI] –2.6 to 0.9) for dabigatran and enoxaparin, respectively. Major VTE plus VTE-related mortality occurred in 2.7 % (46/1,714) and 4.0 % (69/1,711) (RD: –1.4 %, 95 % CI –2.6 to –0.2) of patients receiving dabigatran 220 mg and enoxaparin, respectively. Major bleeding occurred in 1.7 % (37/2,156) and 1.3 % (27/2,157) (RD: 0.5 %, 95 % CI –0.2 to 1.2), for dabigatran and enoxaparin respectively.

Conclusions

Extended prophylaxis with oral dabigatran 220 mg once daily was as effective as enoxaparin 40 mg once daily in reducing the risk of total VTE and all-cause mortality after total hip arthroplasty, with a similar bleeding profile. The clinically relevant outcome of major VTE and VTE-related death was significantly reduced with dabigatran versus enoxaparin.

Trial registration

NCT00657150 and NCT00168818

Treatment with dabigatran or warfarin in patients with venous thromboembolism and cancer

The efficacy and safety of dabigatran for treatment of venous thromboembolism (VTE) were demonstrated in two trials. It is unclear if the results pertain to patients with cancer and VTE. Data from two randomised trials comparing dabigatran and warfarin for acute VTE were pooled. Primary efficacy outcome was symptomatic recurrent VTE and related death from randomisation to the end of the treatment period. Safety outcomes were major, major and clinically relevant non-major, and any bleeding during the oral-only treatment period. Patients with active cancer (=within 5 years) at baseline or diagnosed during the study were analysed. Compared with 4,772 patients without cancer, recurrent VTE occurred more frequently in 335 patients with cancer at any time (hazard ratio [HR] 3.3; 95 % confidence interval [CI], 2.1-5.3) and more often in 114 with cancer diagnosed during the study compared to 221 with cancer at baseline (HR 2.6; 95 % CI, 1.1-6.2). There was no significant difference in efficacy between dabigatran and warfarin for cancer at baseline (HR 0.75; 95 % CI, 0.20-2.8) or diagnosed during the study (HR 0.63; 95 % CI, 0.20-2.0). Major bleeding (HR 4.1; 95 % CI, 2.2-7.5) and any bleeding (HR 1.5; 95 % CI, 1.2-2.0) were more frequent in patients with cancer than without, but with similar incidence in cancer with dabigatran or warfarin. In conclusion, in cancer patients, dabigatran provided similar clinical benefit as warfarin. VTE recurrence or bleeding were similar in patients on dabigatran or warfarin. The efficacy of dabigatran has not been assessed in comparison with low-molecular-weight heparin.

Treatment of venous thromboembolism - effects of different therapeutic strategies on bleeding and recurrence rates and considerations for future anticoagulant management

Effective treatment of venous thromboembolism (VTE) strikes a balance between prevention of recurrence and bleeding complications. The current standard of care is heparin followed by a vitamin K antagonist such as warfarin. However, this option is not without its limitations, as the anticoagulant effect of warfarin is associated with high inter- and intra-patient variability and patients must be regularly monitored to ensure that anticoagulation is within the narrow target therapeutic range. Several novel oral anticoagulant agents are in the advanced stages of development for VTE treatment, some of which are given after an initial period of heparin treatment, in line with current practice, while others switch from high to low doses after the initial phase of treatment. In this review we assess the critical considerations for treating VTE in light of emerging clinical data for new oral agents and discuss the merits of novel treatment regimens for patients who have experienced an episode of deep vein thrombosis or pulmonary embolism.

Type of anaesthesia and the safety and efficacy of thromboprophylaxis with enoxaparin or dabigatran etexilate in major orthopaedic surgery: pooled analysis of three randomized controlled trials

Background

There has been a shift towards greater use of neuraxial over general anaesthesia for patients undergoing total hip or knee arthroplasty. Furthermore, suggestions that peripheral nerve block may reduce adverse effects have recently been put forward. Although older studies showed a reduction in venous thromboembolism (VTE) with neuraxial compared with general anaesthesia, this difference has not been confirmed in studies using effective current thromboprophylaxis. We used a large data set to investigate the pattern of anaesthesia usage, and whether anaesthesia type affects efficacy and bleeding outcomes of thromboprophylaxis overall, within each treatment group, or for the novel oral anticoagulant dabigatran etexilate versus enoxaparin.

Methods

Three previously reported trials compared 220 mg and 150 mg dabigatran etexilate once daily with enoxaparin after knee or hip arthroplasty. A pooled analysis was performed in patients receiving general or neuraxial anaesthesia, or the combination of either with peripheral nerve block (n = 8062). Outcome measures were major VTE plus VTE-related mortality, major bleeding and major plus clinically relevant bleeding events.

Results

General, neuraxial and combination anaesthesia were used in 29%, 52% and 19% of patients, respectively. Differences in efficacy and safety between anaesthesia subgroups were small and not significant, except for a slightly higher rate of major VTE and VTE-related mortality with general versus neuraxial anaesthesia (odds ratio: 1.40; 95% confidence interval: 1.03–1.90; p = 0.035) in the overall population. There were no significant effects of anaesthesia type on efficacy or safety of dabigatran etexilate versus enoxaparin.

Conclusions

Anaesthesia type did not greatly affect efficacy and safety outcomes in the pooled population of all three treatment groups. The efficacy and safety of dabigatran etexilate was comparable with enoxaparin, regardless of type of anaesthesia.

Trial registration

ClinicalTrials.gov identifiers: NCT00168805, NCT00168818, NCT00152971.

Evaluation of the acute coronary syndrome safety profile of dabigatran etexilate in patients undergoing major orthopedic surgery: findings from four Phase 3 trials

INTRODUCTION

Several anticoagulants have been associated with a 'rebound effect' that potentially increases the risk of thrombosis and cardiovascular events following discontinuation. Four Phase 3 trials of dabigatran etexilate in major orthopedic surgery incorporated measures to assess the risk of acute coronary syndrome (ACS) events during and after treatment.

MATERIALS AND METHODS

Patients in RE-MOBILIZE®, RE-MODEL™, RE-NOVATE®, and RENOVATE® II were randomized to dabigatran etexilate (150 mg or 220mg once daily) or enoxaparin for 6-35 days, and followed for up to 90 days. ACS data were tabulated from investigator-reported serious adverse events using ACS-specific Medical Dictionary for Regulatory Authorities (MedDRA) lower-level terms. To ensure that all ACS events were identified in the initial three studies, RE-MOBILIZE®, RE-MODEL™, and RE-NOVATE®, a broader list of MedDRA terms was prespecified that would trigger treatment-blinded adjudication.

RESULTS

When pooling the four trials, patients receiving dabigatran etexilate 220 mg had the fewest treatment-emergent, investigator-reported ACS events (6 [0.16%] vs 14 [0.51%] for dabigatran 150 mg and 13 [0.35%] for enoxaparin). Corresponding post-treatment rates were 2 (0.06%), 1 (0.04%), and 4 (0.11%). Similarly, treatment-emergent centrally adjudicated definite or likely ACS events in the first three trials were fewer in patients on dabigatran 220 mg (16 [0.60%]) than dabigatran 150 mg (26 [0.95%]) and enoxaparin (20 [0.74%]). The corresponding numbers post treatment were 2, 2, and 7. None of these between-group differences were statistically significant.

CONCLUSION

No increased ACS signal was detected with dabigatran etexilate compared with enoxaparin during or after treatment.

Long-term, high intake of vitamin C decreases size and increases quantity of liver mitochondria in Guinea-pigs

Microsomal cytochrome P450 is an important enzyme involved in drug metabolism and bioactivation in the liver. In guinea-pigs, the specific amount of cytochrome P450 depends on dietary vitamin C intake. Short-term vitamin C treatment can induce non-genomic effects on hepatocytes, such as activating mitochondrial respiration without changing cytochrome concentration. The aim of this investigation was to elucidate the long-term effects of a low or high vitamin C diet on the quantity and size of mitochondria in the hepatocytes of guinea-pigs. After 6 - 8 weeks of vitamin C feeding, the group receiving a low vitamin C content in their food (10 mg/100 g food) had significantly less mitochondria, but of a larger size, than the group receiving a high vitamin C content (680 mg/100 g food). This animal model investigation demonstrated that treatment with long-term vitamin C can induce morphological changes in the mitochondria of hepatocytes.

Health technology assessment and its role in the future development of the Indian healthcare sector

Public expenditure on healthcare in India is low by international comparison, and access to essential treatment pushes many uninsured citizens below the poverty line. In many countries, policymakers utilize health technology assessment (HTA) methodologies to direct investments in healthcare, to obtain the maximum benefit for the population as a whole. With rising incomes and a commitment from the Government of India to increase the proportion of gross domestic product spent on health, this is an opportune moment to consider how HTA might help to allocate healthcare spending in India, in an equitable and efficient manner. Despite the predominance of out-of-pocket payments in the Indian healthcare sector, payers of all types are increasingly demanding value for money from expenditure on healthcare. In this review we demonstrate how HTA can be used to inform several aspects of healthcare provision. Areas in which HTA could be applied in the Indian context include, drug pricing, development of clinical practice guidelines, and prioritizing interventions that represent the greatest value within a limited budget. To illustrate the potential benefits of using the HTA approach, we present an example from a mature HTA market (Canada) that demonstrates how a new treatment for patients with atrial fibrillation - although more expensive than the current standard of care - improves clinical outcomes and represents a cost-effective use of public health resources. If aligned with the prevailing cultural and ethical considerations, and with the necessary investment in expert staff and resources, HTA promises to be a valuable tool for development of the Indian healthcare sector.

Switching from enoxaparin to dabigatran etexilate: pharmacokinetics, pharmacodynamics, and safety profile

Purpose

Dabigatran etexilate is an oral, reversible, direct thrombin inhibitor licensed for the prevention of venous thromboembolism and stroke prevention in patients with atrial fibrillation. The aim of this study was to investigate whether, and to what extent, a switch from enoxparin to dabigatran etexilate affects the pharmacokinetic (PK) and pharmacodynamic (PD) parameters and safety profile of dabigatran.

Methods

Enoxaparin 40 mg was administered subcutaneously once daily for 3 days followed by a single dose of dabigatran etexilate 220 mg (test treatment) on day 4 in an open-label, two-way cross-over trial in healthy volunteers. Dabigatran plasma levels were measured using a validated high-performance liquid chromatography tandem mass spectrometry method. Anticoagulant activity was measured using a number of clotting tests, including prothrombinase-induced clotting time (PiCT), activated partial thromboplastin time (aPTT), ecarin clotting time (ECT), and diluted thrombin time (dTT).

Results

PK, PD, and safety data were available for 23 subjects for each treatment. The adjusted geometric mean test/reference ratio of area under the concentration–time curve for total dabigatran was 84% (90% confidence interval 67.2–105.0%) and 86% (67.0–110.0%) for maximum plasma concentration. The PiCT test/reference ratio, which represents the activity of enoxaparin and dabigatran, was elevated by approximately 15% for peak maximum effect ratio to baseline and total area under the effect curve (AUEC_0-48) activity, suggesting that some anticoagulant activity of enoxaparin was still present. Enoxaparin pre-treatment increased the AUEC_0–48 of activated partial thromboplastin time by approximately 14%. All other dabigatran-related PD markers were unaffected. Tolerability was good, with only mild and reversible adverse events during the treatment.

Conclusion

Prior administration of enoxaparin did not meaningfully affect the PK or PD properties of dabigatran, and the switch from enoxaparin to dabigatran etexilate was well tolerated among the study subjects. These data support the safety of switching patients from enoxaparin to dabigatran etexilate.

The PFA-100R cannot detect blood group-dependent inhibition of platelet function by eptifibatide or abciximab at therapeutic plasma concentrations

Previous investigations revealed that AB0 blood groups are associated with divergent concentrations of several coagulation factors. Concentrations of von Willebrand factor (vWF) and factor VIII are lower in individuals with blood group 0 compared to subjects with blood group A, B or AB, which might in turn result in a reduced inhibition of platelet aggregation in individuals with blood group 0. The aim of the present in vitro investigation was to elucidate the impact of AB0 blood group-dependent vWF concentrations on eptifibatide and abciximab mediated inhibition of GPIIb/IIIa function. Platelet function was measured with the platelet function analyzer PFA-100(R) at baseline and at increasing concentrations of eptifibatide and abciximab. It was stratified for blood group 0 vs A. If measured with the collagen/ADP cartridge, blood group 0 was associated with a prolonged mean baseline closure time in comparison with blood group A (94.3 +/- 14.6 s vs. 74.6 +/- 9.9 s, p = 0.007) which was paralleled by reduced concentrations of vWF and factor VIII. In contrast, no statistically significant differences in closure times (167.4 +/- 83.9 s vs. 140.1 +/- 99.0 s, p = 0.562) could be found in the presence of eptifibatide (0.1 microg/ml). Higher concentrations of abciximab (1 microg/ml) than those of eptifibatide were needed to increase the closure times in both cartridges of the PFA-100, but at this concentration of abciximab differences in closure times could not be detected most probably due to higher variability at these drug concentrations. The PFA-100(R) is not suitable for monitoring abciximab or eptifibatide within the therapeutic concentration range because the highest concentrations where the PFA-100(R) had measurable closure times of below 300 s is much too low to lead to the necessary platelet inhibition and, consequently, does not resemble the in vivo situation.

Coagulation status in coronary artery disease patients with type II diabetes mellitus compared with non-diabetic coronary artery disease patients using the PFA-100® and ROTEM®

Previous investigations in patients with coronary artery disease (CAD) revealed differences in thromboelastographic parameters indicating different states of coagulability. The aim of the present study was to investigate the coagulation status of patients with documented CAD and type II diabetes mellitus (DM) and non-diabetic patients with coronary artery disease with the PFA-100® and the ROTEM®. No differences were found in platelet function as measured with collagen/epinephrine (263.6 ± 70.6 s vs. 254.6 ± 65.3 s) and collagen/ADP cartridges (105.3 ± 63.2 s vs. 90.6 ± 47.3 s) in CAD patients with DM and CAD patients without DM. Measured with the EXTEM reagent of the ROTEM®, mean maximum clot elasticity (MCE) in patients with CAD and DM (233.6 ± 86.9) was significantly longer than in CAD patients without DM (186.7 ± 54.5), (p = 0.03). A similar result was seen using the INTEM reagent; patients with CAD and DM (234.4 ± 83.9) showed a higher value for MCE than CAD patients without DM (190.8 ± 57.8) which was of borderline significance (p = 0.053). Moreover, a weak trend for higher maximum clot firmness (MCF) was seen in CAD patients with DM compared with CAD patients without DM with the EXTEM reagent (68.1 ± 7.5 vs. 63.6 ± 8.6, p = 0.08) and the INTEM reagent (68.4 ± 7.2 vs. 64.1 ± 8.2, p = 0.09). The ROTEM® analysis indicates increased coagulability in patients with coronary artery disease and diabetes mellitus compared to non-diabetic CAD patients. Moreover, the ROTEM® device seems to be an appropriate and easy-to-use tool to describe the coagulation status in these patients groups.

Dabigatran etexilate--a novel, reversible, oral direct thrombin inhibitor: interpretation of coagulation assays and reversal of anticoagulant activity

Dabigatran etexilate is an oral, reversible direct thrombin inhibitor that is approved in the EU and several other countries for the prevention of venous thromboembolism after elective hip and knee replacement, and is in advanced clinical development for other thromboembolic disorders. Dabigatran has a predictable pharmacokinetic profile, allowing for a fixed-dose regimen without the need for routine coagulation monitoring. In certain clinical situations such as serious bleeding into critical organs (e.g. intracerebral bleeding), potential overdose and emergency surgery, clinicians will need to make an assessment of the anticoagulant status of a patient receiving dabigatran before deciding on future management strategies. If available, thrombin clotting time (TT), ecarin clotting time (ECT) and TT determined by Hemoclot thrombin inhibitor assay are sensitive tests to evaluate the anticoagulant effects of dabigatran. Prothrombin time (INR) is less sensitive than other assays and cannot be recommended. The activated partial thromboplastin time (aPTT) can provide a useful qualitative assessment of anticoagulant activity but is less sensitive at supratherapeutic dabigatran levels. There are limited data for activated clotting time (ACT). Overall, the aPTT and TT are the most accessible qualitative methods for determining the presence or absence of anticoagulant effect. Although there is no specific antidote to antagonise the anticoagulant effect of dabigatran, due to its short duration of effect drug discontinuation is usually sufficient to reverse any excessive anticoagulant activity. In case of potential overdose, the feasibility of early administration of activated charcoal and subsequent charcoal filtration are undergoing preclinical evaluation. Dabigatran can also be dialysed in patients with renal impairment. In instances of life-threatening bleeding, where conventional measures have failed or are unavailable, other non-specific prohaemostatic agents such as recombinant activated factor VII and prothrombin complex concentrates can be considered.

Effect of oral contraceptives and ovarian cycle on platelet function

In past decades, numerous epidemiological and clinical studies in women taking oral contraceptives revealed the impact of sex steroids on coagulation factors and the incidence of venous thrombosis. To date, only scarce data regarding the impact of oral contraceptives on platelet function are available. The aim of this study was to further elucidate the impact of sex steroids on platelet function. We conducted an observational study in young women using different types and dosages of monophasic oral contraceptives (OCs) compared to women not taking OCs. During the follicular phase, the mean closure time (CT) in Col/Epi was 168.0 +/- 64.9 s compared to 131.5 +/- 28.9 s during the luteal phase (p=0.012). In Col/Epi cartridges, no difference was detected between women taking second/third generation OCs and low-dose OCs (145.2 +/- 44.3 vs. 169.4 +/- 63.5, p=0.34). In contrast, mean Col/Epi values of women using anti-androgen-containing OCs were less (110.3 +/- 15.6 s) than in both other OC groups (p=0.03 for both comparisons). The same holds for Col/Epi values from women during the follicular- and luteal phases compared to women using anti-androgen-containing OCs (p=0.0002, p=0.013). Significant correlations between progesterone and platelet function in women not using OCs (p=0.02) could be found. In conclusion, the results of the study show that platelet function might be modulated by OCs and the female cycle. As for OCs, the main factor seems to be the progestagen. During the female cycle, the main impact on platelet function might be mediated by progesterone.

Effects of synthetic progestagens on autonomic tone, neurohormones and C-reactive protein levels in young healthy females in reproductive age

BACKGROUND

Heart rate variability and baroreceptor sensitivity are measures of autonomic control. While progestagen-containing replacement therapy in postmenopausal women adversely affects autonomic balance, the impact of hormonal contraceptives with synthetic progestagens on autonomic activity, neurohormones and C-reactive protein levels is not well characterized.

METHODS AND RESULTS

We analyzed parameters of heart rate variability and baroreceptor sensitivity in young healthy females without (n = 27) or on oral contraceptives with synthetic progestagens (n = 31). Demographic characteristics were not different among the examined groups. Total power (controls: 5682+/-3618 vs. hormones: 4800+/-2957 ms2; NS), standard deviation of beat-to-beat intervals (SDNN; 66+/-24 vs. 63+/-20 ms; p = 0.74), other time- and frequency-dependent parameters of heart rate variability and baroreceptor sensitivity (6.0+/-3.2 vs. 6.5+/-2.7 ms/mm Hg; NS) were not significantly different among the groups. Total cholesterol and triglyceride as well as C-reactive protein (CRP) levels were significantly higher in users of hormonal contraceptives than in non-users (cholesterol: 187+/-37 vs. 166+/-28 mg/dL; p = 0.05; triglycerides: 110+/-35 vs. 68+/-30 mg/dL; p = 0.01; CRP: 2.7+/-2.1 vs. 1.0+/-1.4 mg/L; p < 0.001). Heart rate variability, baroreceptor sensitivity, lipid parameters and CRP levels were not affected during the ovarian cycle in non-users of hormonal contraception.

CONCLUSIONS

The use of oral contraceptives containing synthetic progestagens was not associated with a modulation of autonomic tone, while lipid parameters and CRP levels were adversely affected. These data suggest that synthetic progestagens in modern oral contraceptives do not modulate the autonomic balance, but probably affect the atherogenic risk profile of young females in reproductive age.

Impact of ABO blood groups on tirofiban mediated inhibition of platelet function

Previous investigations revealed that ABO blood groups are associated with divergent concentrations of several coagulation factors. Concentrations of von Willebrand factor (vWF) and factor VIII are lower in individuals with blood group O as compared to subjects with blood group A, B or AB which might result in a reduced inhibition of platelet aggregation. The aim of the present in-vitro-investigation was to elucidate the impact of ABO blood group dependent vWF concentrations on tirofiban mediated inhibition of GPIIb/IIIa function. Platelet function was measured with the platelet function analyzer PFA-100 at baseline and at increasing concentrations of tirofiban and stratified for blood group O vs. A. If measured with the collagen/epinephrine cartridge, blood group O was associated with a prolonged mean baseline closure time in comparison with blood group A (175.8 +/- 64.9 s vs. 121.4 +/- 33.4 s, p = 0.037) which was paralleled by reduced concentrations of vWF and factor VIII. In contrast, no differences in closure time (227.6 +/- 76.1 s vs. 223.9 +/- 81.9 s, p = 0.96) could be found in the presence of tirofiban (0.1 microg/ml). Thus, tirofiban mediated GP IIb/IIIa receptor antagonism as determined with the PFA-100 seems to be independent on plasma concentration of vWF.

Monitoring Acetylsalicylic Acid Effects with the Platelet Function Analyzer PFA-100

The efficacy of acetylsalicylic acid (ASA) to prevent thrombotic or embolic events in patients with atherosclerosis was demonstrated in many large trials. Despite this fact, a subpopulation of patients experiences acute myocardial infarction or cerebrovascular ischemia indicating a nonresponsiveness to ASA. These patients would be candidates for an alternative or additional antiplatelet therapy, if they could be reliably identified. The aim of the monitoring of ASA therapy should be the identification of nonresponders to prevent a long-term intake of the drug without adequate benefit, to justify a dose escalation, or to initiate an alternative antiplatelet drug therapy. Considerable progress has been made in the measurement of platelet function. One of the novel devices employed is the platelet function analyzer PFA-100, which was already tested in several studies involving patients with atherothrombosis to detect nonresponsiveness to ASA. Many of these investigations indicate that the PFA-100 could be used for routine identification of nonresponders to ASA and--probably also--for tailoring antiplatelet therapy. The aim of this article is to summarize the data obtained from the studies focusing on the monitoring of ASA therapy by the PFA-100.

Aldosterone Blunts Human Baroreflex Sensitivity by a Nongenomic Mechanism

BACKGROUND

Impaired baroreflex sensitivity (BRS) is a negative predictive factor of mortality in cardiovascular disease. Aldosterone has been shown to decrease BRS in humans and animal models. However, the mode of aldosterone action, whether genomic or nongenomic has not been determined. Therefore, we conducted a clinical study to examine whether BRS, as measured by the phenylephrine method, is impaired in humans by aldosterone by a nongenomic mechanism.

METHODS

In a randomised, double-blinded, fourfold cross-over trial in 16 healthy male volunteers, BRS was tested 15 minutes after initiation of a continuous infusion of aldosterone (3 microg/minute) or placebo. 6 hours earlier, this period was preceded by an injection of either canrenoate (400 mg) or placebo.

RESULTS

BRS was 34.6 +/- 4.7 ms/mm Hg in the placebo/placebo period. It was significantly blunted in the placebo/aldosterone (25.5 +/- 1.8 ms/mm Hg) as well as in the canrenoate/placebo (24.0 +/- 1.5 ms/mm Hg) and the canrenoate/aldosterone (25.4 +/- 2.5 ms/mm Hg) periods.

CONCLUSION

These data suggest that the decreased BRS caused by aldosterone is due to a rapid, thus presumably nongenomic mechanism, as these effects occur in a time frame that excludes genomic aldosterone effects at large. The mineralocorticoid receptor (MR) antagonist canrenoate does not block these effects, but blunts BRS by itself.

Porcine spermatozoa contain more than one membrane progesterone receptor

Progesterone has been shown to be a physiologically relevant inducer of the sperm acrosome reaction. A novel protein intrinsic to microsomal membranes, membrane progesterone receptor (mPR, now termed progesterone membrane receptor component 1, PGMRC1) that binds progesterone with high affinity has been cloned from porcine liver previously, and corresponding antibodies mitigate the progesterone induced acrosome reaction. In this study we aimed at the localization of mPR in porcine spermatozoa. Immunostaining suggested the exclusive occurrence of mPR in a hardly accessible place, possibly the inner acrosomal membrane, with digitonin dramatically increasing the number of positively stained cells. Consistent with the structure prediction for mPR, its short N-terminus (NT) but not the large C-terminal part becomes accessible from outside after digitonin treatment as evidenced by the staining pattern of antibodies directed against different regions of the protein. However, digitonin treatment solubilizes a progesterone binding activity of approximately 140 kDa molecular weight, that is different from mPR, which remains in the cell membrane as demonstrated by Western blotting. Ligand binding studies confirm the dissimilarity of mPR and the digitonin-soluble progesterone binding protein. Chemical modification studies also indicate that the digitonin-soluble progesterone binding protein has a binding site that differs from that of mPR. It is concluded that more than one progesterone receptor is present in porcine spermatozoa.

Delayed genomic and acute nongenomic action of glucocorticosteroids in seasonal allergic rhinitis

BACKGROUND

Glucocorticosteroids are effective in the treatment of allergic rhinitis, a disease characterized by a variety of symptoms, e.g. rhinorrhea and itching. The time course of symptomatic relief for allergic rhinitis by steroids has not been examined in detail to date, although the onset of steroid action is one of the main discriminations between genomic and nongenomic actions of steroids. We therefore investigated the time course of subjective and objective measures of nasal affection after steroid administration in patients with allergic rhinitis following specific allergen challenge.

METHODS

Six female and 18 male volunteers (median age 26 years) with a history of allergic rhinitis but currently free of symptoms were included in this randomized, placebo-controlled, double-blind, three-period crossover study. A single dose of either betamethasone (60 mg), methylprednisolone (400 mg) or placebo was given intravenously, 5 min after intranasal allergen provocation. After 10, 20, 60, 150 and 240 min, nasal itching and nasal obstruction were assessed using a standardized visual analogue scale. In addition, nasal airflow was measured by anterior rhinomanometry.

RESULTS

Nasal itching was markedly reduced following either of the two steroids within 10 min after administration of study drug. Itching was depressed by 38% following betamethasone (P<0.05) and by 18% following methylprednisolone (P=0.07) compared with placebo. Nasal airflow and nasal obstruction were not significantly altered by steroids during the first 2 h of the study. However, after 150 min, nasal airflow was 21% rsp. 19% higher after methylprednisolone and betamethasone (P<0.05) compared with placebo. After 240 min, nasal airflow was increased by 20% following betamethasone (P<0.05) and by 19% following methylprednisolone. Nasal obstruction was also beneficially affected by both steroids 150 and 240 min after administration compared with placebo (P<0.05 for both time points following betamethasone).

CONCLUSION

This study for the first time shows rapid in vivo effects of external glucocorticosteroids in humans. Itching, a pathophysiologically complex sensation, is favourably influenced by steroids within 10 min, therefore presumably via nongenomic mechanisms. Though no detailed mechanisms can be derived from this study, steroid interaction with receptors in the central nervous system may play an important role in mediating this effect.

Early aldosterone up-regulated genes: new pathways for renal disease?

BACKGROUND

The use of aldosterone antagonists has important beneficial effects on the progression of renal and cardiac disease reflected in a decrease of cardiovascular mortality and renal failure. Nevertheless, the incidence of heart and end-stage renal failure continues to increase. This leads to the conclusion that mechanisms independent of the classical aldosterone/mineralocorticoid receptor system may contribute to the pathogenesis of cardiac and renal disease.

METHODS

The mRNA expression profile of human renal epithelial cells in response to aldosterone was characterized using cDNA arrays covering approximately 1430 genes. Differentially expressed genes were further evaluated by quantitative reverse transcription-polymerase chain reaction (RT-PCR), Northern blotting, and estimating the gene products by Western blotting.

RESULTS

Aldosterone treatment of cells resulted in significant up-regulation of several genes within 1 hour, with sgk, p21/waf1, gadd45, and gadd153 being the most significant ones. Long-term treatment (>4 hours) with aldosterone induced the mRNA expression of pparalpha and puralpha. The mineralocorticoid receptor inhibitor spironolactone decreased the mRNA levels of sgk, p21/waf1, and gadd45, whereas the glucocorticoid receptor inhibitor RU 486 reduced the mRNA level of sgk and p21/waf1. Gadd153 was not affected by any of the inhibitors, probably indicating regulation by nonclassic mechanisms.

CONCLUSION

Among the early genes investigated in this study, one transcript has been identified that is not suppressed by antagonists of either glucocorticoid or mineralocorticoid receptor. Further studies should be able to identify other genes regulated in a similar manner that could explain the inefficacy of spironolactone in some cases of aldosterone-mediated kidney disease.

Lack of effect of aprepitant on digoxin pharmacokinetics in healthy subjects

Aprepitant is a highly selective neurokinin-1 receptor antagonist that, in combination with a corticosteroid and a 5-hydroxytryptamine3 (5HT3) receptor antagonist, has been shown to be efficacious in the prevention of highly emetogenic chemotherapy-induced nausea and vomiting. In vitro data suggest that aprepitant is a substrate and a weak inhibitor of P-glycoprotein. Thus, the effect of aprepitant on the pharmacokinetics of digoxin, a P-glycoprotein substrate, was examined in a double-blind, placebo-controlled, randomized, two-period crossover study in 12 healthy subjects. Each subject received daily oral doses of digoxin 0.25 mg on Days 1 through 13 during both treatment periods. Aprepitant 125 mg (or matching placebo) was coadministered orally with digoxin on Day 7, and aprepitant 80 mg (or matching placebo) was coadministered orally with digoxin on Days 8 to 11. Aprepitant did not affect the pharmacokinetics of digoxin. The geometric mean ratios (90% confidence interval [CI]) for plasma AUC0-24 h of digoxin (with/without aprepitant) were 0.99 (0.91, 1.09) and 0.93 (0.83, 1.05) on Days 7 and 11, respectively, and the geometric mean ratios (90% CI) for the 24-hour urinary excretion of immunoreactive digoxin (with/without aprepitant) were 0.91 (0.80, 1.04) and 1.00 (0.91, 1.09) on Days 7 and 11, respectively. Thus, aprepitant, when dosed as a 5-day regimen, did not interact with a known substrate of the P-glycoprotein transporter.

Nongenomic steroid action: controversies, questions, and answers

Steroids may exert their action in living cells by several ways: 1). the well-known genomic pathway, involving hormone binding to cytosolic (classic) receptors and subsequent modulation of gene expression followed by protein synthesis. 2). Alternatively, pathways are operating that do not act on the genome, therefore indicating nongenomic action. Although it is comparatively easy to confirm the nongenomic nature of a particular phenomenon observed, e.g., by using inhibitors of transcription or translation, considerable controversy exists about the identity of receptors that mediate these responses. Many different approaches have been employed to answer this question, including pharmacology, knock-out animals, and numerous biochemical studies. Evidence is presented for and against both the participation of classic receptors, or proteins closely related to them, as well as for the involvement of yet poorly understood, novel membrane steroid receptors. In addition, clinical implications for a wide array of nongenomic steroid actions are outlined.

Novel approaches in the treatment of allergic rhinitis

PURPOSE OF REVIEW

The increasing prevalence of allergic rhinitis, its impact on individual quality of life and social costs, as well as its role as a risk factor for asthma, underline the need for improved treatment options for this disorder. We reviewed the recent literature published in English, dealing with relevant and appropriately controlled clinical trials on the treatment of allergic rhinitis.

RECENT FINDINGS

In addition to well established pharmacological therapies with antihistamines, corticosteroids, decongestants and mast cell stabilizers, new therapeutic options become increasingly important, including leukotriene modifiers, anti-immunoglobulin E antibodies, phosphodiesterase inhibitors and intranasal heparin; there also exist new developments in appropriate allergen specific immunotherapy.

SUMMARY

Promising results, both with established and novel treatment options, are communicated, but further studies are still necessary to confirm these data.

Non-genomic aldosterone action: from the cell membrane to human physiology

According to the traditional model, steroid hormones bind to intracellular receptors and subsequently modulate transcription and protein synthesis, thus triggering genomic events finally responsible for delayed effects. In addition, very rapid effects of steroids mainly affecting intracellular signaling have been widely recognized which are clearly incompatible with the genomic model. These rapid, non-genomic steroid actions are likely to be transmitted via specific membrane receptors. Evidences for non-genomic steroid effects and distinct receptors involved are now presented for all steroid groups including vitamin D(3) and thyroid hormones. Mechanisms of action are being studied with regard to signal perception and transduction involved, and for various steroids including aldosterone a patchy sketch of a membrane receptor/second messenger cascade shows up being not essentially dissimilar to cascades involved in catecholamine or peptide hormone action. Aside non-classical membrane receptors with a high affinity for aldosterone, these effects involve phospholipase C, phosphoinositide turnover, intracellular pH and calcium, protein kinase C and tyrosine kinases. Increasing evidence is being accumulated for rapid physiological responses in humans, e.g. at the level of circulatory or metabolic effects, rendering clinical significance to these rapid actions.

Alterations in platelet function during the ovarian cycle

Steroid hormones may profoundly influence hemostasis; for example, as discussed for hormone replacement therapy, pregnancy and, being less obvious, for the ovarian cycle. We investigated primary hemostasis parameters using a platelet function analyzer (PFA-100) during the follicular and luteal phases in 18 healthy young women without oral contraceptives. During the follicular phase, the mean closure time (CT) was 164.7 +/- 56.7 s, and it decreased to 130.2 +/- 30.6 s in collagen/epinephrine cartridges in the luteal phase (P = 0.0095). No significant difference could be found for CT values in collagen/adenosine diphosphate cartridges during the follicular phase as compared with the luteal phase (97.2 +/- 24.2 s versus 89.6 +/- 18.4 s, P = 0.174). Negative correlations between the CT values in collagen/epinephrine cartridges and von Willebrand factor from both phases of the cycle were found (follicular phase: r = -0.53; luteal phase: r = -0.54). Fibrinogen and fibrinogen degradation products were significantly increased in the luteal phase (2.49 +/- 0.62 g/l versus 2.05 +/- 0.59 g/l and 0.12 +/- 014 versus 0.04 +/- 0.04, P = 0.02 for both parameters) as compared with the follicular phase. No significant differences could be detected for plasminogen, plasmin-antiplasmin complex, prothrombin fragment 1 + 2 and D-dimer between the groups. This study indicates that platelet function is periodically altered during the ovarian cycle due to the influence of progesterone and estrogen on von Willebrand factor concentrations.

Acute effects of aldosterone on intracardiac monophasic action potentials

BACKGROUND

Elevated plasma aldosterone levels represent an independent risk factor for increased mortality in congestive heart failure. Sudden cardiac deaths contribute substantially to the excessive mortality in congestive heart failure and so does atrial fibrillation as one of the major causes of stroke in elderly persons. So far, the electrophysiological properties of aldosterone have not been thoroughly characterized. In the present study, the effects of aldosterone on intracardiac monophasic action potentials were investigated in humans.

METHODS AND RESULTS

Monophasic action potentials were recorded in six patients with supraventricular arrhythmias. Eleven ml of 0.9% NaCl (placebo) were injected intravenously, and monophasic action potentials recorded for 10 min. Thereafter, aldosterone (0.5 mg in 0.9% NaCl) was injected and recording of monophasic action potentials continued as previously. The mean action potential duration at 90% repolarization was calculated for the entire 10-min period of each treatment. All patients were in sinus rhythm and had normal electrolyte status. In the placebo period, mean MAPd90 was 287+/-22 ms (mean+/-S.D.), and 299+/-25 ms following aldosterone (P<0.02). After adjustment for heart rate, the difference remained statistically significant (P<0.01). The maximal effect of aldosterone was seen 4-6 min after injection.

CONCLUSION

Aldosterone increases monophasic action potential duration within minutes after intravenous application. Therefore, this effect is likely to be mediated nongenomically. It may be hypothesized that aldosterone exerts its unfavorable effects partly via altering myocardial repolarization.

Bioequivalence of subcutaneous and intravenous body-weight-independent high-dose low-molecular-weight heparin Certoparin on anti-Xa, Heptest, and tissue factor pathway inhibitor activity in volunteers

The objective of the study was to demonstrate the bioequivalence of subcutaneously (s.c.) and intravenously (i.v.) administered fixed, high-dose low-molecular-weight heparin (LMWH) on anti-activated factor X activity (anti-FXa). Secondary objectives were the analysis of the pharmacodynamic effects on Heptest, thrombin inhibition, tissue factor pathway inhibitor (TFPI), and the urinary excretion of LMWH in the randomized cross-over study following i.v. and s.c. application of 8000 anti-FXa units LMWH Certoparin in 18 healthy subjects. The bioequivalence following s.c. administration was demonstrated from the antilog of the point estimator for the application differences (s.c. minus i.v.) by an area under the activity-time curve (0-24 h) of 101% (range, 93-110%). LMWH was bioequivalent also on Heptest and TFPI, and was 50% on thrombin inhibition. The urinary excretion of biologically active material was 4.1 and 3.6% following i.v. and s.c. administration, respectively. Differences in the pharmacodynamic parameters of the assays indicate specific biological actions of high and low molecular sacharide chains of the LMWH.

Nongenomic effects of aldosterone: cellular aspects and clinical implications

Nongenomic action of aldosterone has been observed in many cell types which often are different from the classic target tissues for mineralocorticoid action, such as vascular cells. As judged from their time scale and insensitivity toward inhibitors of protein synthesis, effects are not mediated by the classic mineralocorticoid receptor pathway. Here we summarize studies on rapid in vitro aldosterone effects, e.g. ion fluxes, and second messengers involved therein. Furthermore, several clinical studies on in vivo aldosterone action have shown rapid effects on cardiovascular parameters, among them baroreflex and vascular resistance. Taken together with the beneficial effect of aldosterone antagonism in heart failure patients that was demonstrated in the Randomized Aldactone Evaluation Study (RALES), aldosterone may be an equally important factor of the renin-angiotensin-aldosterone system in cardiovascular pathogenesis.

Nongenomic cardiovascular effects of triiodothyronine in euthyroid male volunteers

T(3) has been shown to exert cardiovascular effects. These effects have not yet been defined with regard to the mode of action (nongenomic vs. genomic) and with regard to an interaction with the adrenergic system in humans. To address these issues we conducted a randomized, double blind, 6-fold cross-over trial in 18 healthy male volunteers. After pretreatment with the beta-agonist dobutamine, the beta-blocking agent esmolol, or placebo (0.9% NaCl), 100 microg T(3) or placebo were injected. Primary target variables were systemic vascular resistance (SVR) and cardiac output (CO) within 45 min after injection of T(3) vs. placebo after placebo pretreatment. Sympatho-vagal balance was assessed by measurement of heart rate variability. T(3) caused a lower SVR and a higher CO than placebo (P < 0.001) after pretreatment with placebo. An increased low frequency (LF)/high frequency (HF) ratio (power in LF/power in HF band) after T(3) compared with placebo (P = 0.004) suggests an increase in sympathetic tone. After pretreatment with dobutamine, the effects of T(3) on SVR and CO were abolished, and the effect on LF/HF ratio was reversed. After pretreatment with esmolol, the effects on SVR and LF/HF ratio were reversed. Our data show, for the first time, nongenomic cardiovascular effects of T(3) in humans.

Seminal plasma hormone concentration after oral application of progesterone

Previous studies have revealed beneficial in vitro effects of progesterone on sperm function. The aim of this pilot study was to prove if orally given micronized progesterone leads to elevations in progesterone and/or 17alpha-hydroxyprogesterone levels in seminal plasma, since higher seminal plasma levels of these hormones could possibly have a beneficial effect on sperm function as seen in in vitro investigations. Multiple application of micronized progesterone given over 4 days (daily dose 400 mg) to 6 healthy subjects resulted in elevated seminal plasma levels of progesterone (10.90 +/- 9.02 nmol/l vs. 1.43 +/- 0.56 nmol/l, p = 0.04) and 17alpha-hydroxyprogesterone (3.09 +/- 1.72 nmol/l vs. 1.62 +/- 1.26 nmol/l, p = 0.04) whereas no significant difference could be found in testosterone levels (34.82 +/- 13.00 vs. 30.91 +/- 8.56 nmol/l, p = 0.43). In contrast, androstendione levels in seminal plasma were reduced (2.68 1.28 nmol/l vs. 3.65 +/- 1.36 nmol/l, p = 0.01). Although micronized progesterone is rapidly metabolized, oral application resulted in pronounced elevations of progesterone and 17alpha-hydroxyprogesterone in seminal plasma. Further studies will show if oral application of micronized progesterone can induce beneficial effects on sperm function such as those seen in in vitro investigations.

[Drug therapy in the old age. Drug effects in the elderly]

The frequency of multimorbidity in elderly patients may mislead the physician into practicing polypragmasy (polypharmacy), resulting in unpredictable drug interactions. Such interactions are a quite common cause of hospitalization in geriatric patients. Pharmacokinetics are often altered in the aged, and individualized medication should take into consideration not only the patient's age, liver and kidney function, but also the individual variability of hepatic metabolism and drug absorption from the gastrointestinal tract dictated by genetic polymorphism. Drug treatment in the elderly should always be carefully assessed as to its risks and benefits, and, where indicated, certain medications should be replaced by or omitted.

The phosphodiesterase 4 inhibitor roflumilast is effective in the treatment of allergic rhinitis

BACKGROUND

The beneficial effects of phosphodiesterase 4 (PDE4) inhibitors in allergic asthma have been shown in previous preclinical and clinical studies. Because allergic rhinitis and asthma share several epidemiologic and pathophysiologic factors, PDE4 inhibitors might also be effective in allergic rhinitis.

OBJECTIVE

The main objective of this study was to investigate the efficacy of oral roflumilast (500 microg/day) in allergic rhinitis.

METHODS

In a randomized, placebo-controlled, double-blinded, crossover study, 25 subjects (16 male, 9 female; median age, 28 years) with histories of allergic rhinitis but asymptomatic at screening received roflumilast (500 microg once daily) and placebo for 9 days each with a washout period of at least 14 days in between treatment periods. In each of the treatment periods, controlled intranasal allergen provocation with pollen extracts was performed daily beginning the third day of treatment, each time approximately 2 hours after study drug administration. Five and 30 minutes after each allergen provocation, rhinal airflow was measured by means of anterior rhinomanometry and the subjective symptoms obstruction, itching, and rhinorrhea were assessed by means of a standardized visual analog scale.

RESULTS

Rhinal airflow improved almost consistently during the 9 days of roflumilast treatment, and it was significantly higher at study day 9 on roflumilast in comparison with placebo, a result also found for itching and rhinorrhea. With respect to the subjective obstruction score, a significant difference in comparison with placebo could be demonstrated within 4 days.

CONCLUSION

This study shows that a PDE4 inhibitor, roflumilast, effectively controls symptoms of allergic rhinitis. Thus PDE4 inhibitors might be a future treatment option not only in allergic asthma but also in allergic rhinitis or the combination of the 2 diseases.

Impact of pharmacotherapy on lymphocyte volumes and activity of the Na+/H+ exchanger in patients with congestive heart failure

Previous studies in patients with congestive heart failure (CHF) have revealed abnormalities of cellular volume that might have an impact on the dysregulation of peripheral vascular resistance. Human mononuclear leukocytes (HML) represent a model for the study of cellular volume regulation. We investigated the impact of enalapril and carvedilol on HML volume and on the activity of the Na+/H+ exchanger in 26 patients with CHF and 20 volunteers. Over a period of 4 weeks, 18 patients received enalapril in addition to the previous therapy while 8 patients additionally received carvedilol. HML diameters and the activity of the Na+/H+ exchanger were measured by a Coulter Counter. Both patient groups showed abnormally increased initial volumes of HML compared to the volunteer group at baseline. Four weeks of therapy with enalapril in addition to therapy with diuretics and digoxin did not result in a statistically significant reduction of lymphocyte volume, whereas add-on therapy with carvedilol to therapy with ACE inhibitors, diuretics and digoxin reduced the volume significantly. Alterations could not be found in the activity of the Na+/H+ exchanger in either patient group compared to volunteers. Supplementary drug therapy with carvedilol in patients with CHF leads to a reduction of the increased lymphocytic volume, possibly reflecting the beneficial effect of beta-blockade.

Acute effects of a single oral dose of carvedilol on cardiac sympathovagal balance in man

Modulation of autonomic activity is considered to be a prognostic marker in patients with cardiovascular disease. The aim of the present study was to evaluate the modulation of sympathovagal balance after single-dose administration of carvedilol using various autonomic tests as challenges of sympathovagal balance. We conducted a randomized double-blind, placebo-controlled study in 18 male volunteers and applied a crossover design. While heart rate variability (HRV) remained unchanged in 24-hour measurements, modulatory effects on sympathovagal balance were demonstrated in controlled autonomic maneuvers at expected maximal drug levels of carvedilol: time-dependent HRV parameters indicative of vagal tone were increased during controlled breathing (15 cycles/min) in the supine body position by carvedilol. The percentage of successive normal RR intervals > 50 ms (pNN50) was increased to 39.8+/-5.1 vs. 32.7+/-4.7% in the placebo group (p < 0.05), root mean square successive differences (rMSSD) to 81.5+/-10.8 vs. 69.3+/-9.1 ms (p < 0.05 vs. placebo). In contrast, carvedilol versus placebo significantly reduced time- and frequency-domain parameters after an active standing-up procedure. This included rMSSD (26.5+/-2.8 ms vs. 34.9+/-3.8 ms), pNN50 (6.9+/-2.2% vs. 12.4+/-2.5%). total power (4329+/-592 ms2 vs. 6428+/-1158 ms2), low frequency (1472+/-179 ms2 vs. 2093+/-284 ms2) and high frequency power (251+/-42 ms2 vs. 353+/-92 ms2) of heart rate variability. Apparently, the effects of even small doses of carvedilol, too low to induce effects detectable in the 24-hour analysis of HRV testing, can be detected on controlled maneuvers of autonomic because of their ability to modulate autonomic balance. Under conditions of vagal stimulation, a potentially beneficial augmentation of HRV parameters indicative for this component is induced by carvedilol, while under conditions of sympathetic activation, carvedilol effects seem opposite. Interpretation of the latter results, in particular, requires further investigation.

Laboratory diagnosis of heparin-induced thrombocytopenia type II after clearance of platelet factor 4/heparin complex

Laboratory confirmation of heparin-induced thrombocytopenia (HIT) is limited by assay sensitivity. We investigated whether laboratory confirmation can be improved after antigen clearance by determining free antibody and combining the results of antigenic and biologic assays. Blood samples were collected over 5 to 6 weeks in 14 HIT patients. As an antigenic assay, the fluorescence-linked immunofiltration assay (FLIFA) was performed, and as a biologic assay, the carbon 14-labeled serotonin release assay was performed. At day 1 when heparin was stopped, 11 of 14 patients showed positive results in both assays; thus each assay had a sensitivity of 80%. The 3 patients with negative results seroconverted in one or both assays during the subsequent 7 days. Combining the positive results of the assays increased the sensitivity to 100% at day 7, regardless of whether the antigenic or the biologic assay was performed first. Both assays became negative in all patients within 5 to 6 weeks. The sensitivity of antigen and biologic assays in HIT patients increased to 100% after the time course of the heparin-induced antibody. We assume that in some HIT patients the free antibody can be detected after withdrawal of heparin and after clearance of the platelet-factor 4/heparin complex.

Impact of plasmapheresis on platelet hemostatic capacity in healthy voluntary blood donors detected by the platelet function analyzer PFA-100

Previous flow cytometry studies showed that platelet activation may occur during cytapheresis, cardiopulmonary bypass and hemodialysis. The aim of this pilot study was to determine if the impact of plasmapheresis leads to alterations in platelet hemostatic capacity. Plasmapheresis was carried out in 30 volunteers using an Autopherese C (Baxter) and an MCS3p (Haemonetics). Blood samples were collected and analyzed immediately before and after plasmapheresis. As a result of the plasmapheresis on the Autopherese C, the mean closure time (CT) for collagen/epinephrine (Col/Epi) increased from 118.2 +/- 25.1 to 149.9 +/- 35.0 s and from 88.7 +/- 16.9 to 98.5 +/- 26.3 s for collagen/ADP (Col/ADP), respectively. Seven subjects showed impaired CTs after plasmapheresis for Col/Epi. For Col/ADP, five subjects showed impaired CTs after apheresis. Statistical analysis (McNemar test) showed a significant difference before and after apheresis for Col/Epi (P = 0.024) but not for Col/ADP (P = 0.088). Similar results were shown for plasmapheresis carried out with the MCS3p. These findings show that plasmapheresis can cause an impairment of platelet function in healthy volunteers as measured by the PFA-100, an effect of so far unknown clinical significance.