[Basics for the Use of Andexanet]

BACKGROUND

 For life-threatening or uncontrollable bleeding in association with the thrombin inhibitor dabigatran, the monoclonal antibody fragment idarucizumab is available, and for bleeding in association with the direct factor Xa inhibitors rivaroxaban or apixaban, the modified recombinant FXa protein andexanet is available for reversal. These antidotes represent emergency drugs that are typically used only after performing guideline-compliant multimodal measures.

METHODS

 An interdisciplinary group of experienced experts in the fields of angiology, hematology, internal medicine, clinical pharmacology, laboratory medicine, transfusion medicine, anesthesiology, intensive care, and hemostaseology developed recommendations relevant to daily clinical practice based on the current scientific evidence.

RESULTS

 Reversal of oral anticoagulants should be considered for severe bleeding in the following situations: (1) life-threatening bleeding or refractory hemorrhagic shock, (2) intracerebral bleeding, or (3) endoscopically unstoppable gastrointestinal bleeding. After successful hemostasis, anticoagulation (e.g., direct oral anticoagulant, vitamin K antagonist, and heparin) should be resumed promptly, taking into account individual bleeding and thromboembolic risk.

DISCUSSION

 This article aims to facilitate the management of patients with andexanet by all medical disciplines involved, thereby ensuring optimal care of patients during bleeding episodes.

Association of coagulation markers and antiphospholipid antibodies with ischemic and bleeding risk in patients with atrial fibrillation undergoing percutaneous coronary intervention

Background

Antiphospholipid antibodies and other coagulation markers are associated with ischemic risk in patients with coronary artery disease without oral anticoagulation (OAC).

Aim

To assess the association of antiphospholipid antibodies (aPL) and conventional markers of coagulation with ischemic and bleeding risk in patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI).

Patients and methods

In this prospective single center observational cohort study, patients with AF and an indication for OAC were enrolled after PCI. Dilute Russell's viper venom time (DRVVT) was used to determine lupus anticoagulants (LA) in direct OAC-free plasma. Anti-cardiolipin IgG (aCL), IgM and anti-beta2GP-1-IgG (aβ2GP1) were analyzed by enzyme linked immunosorbent assay (ELISA). Fibrinogen C (FIBC), d-dimers and prothrombin fragments 1 and 2 (PF1+2) were measured in citrated plasma. Immature platelet fraction (IPF [%]) and absolute (IPF abs. [103/μl]) were measured in EDTA-blood. The primary ischemic outcome was defined as time to major adverse cardiovascular events (MACE: all-cause death, myocardial infarction, or stroke) assessed at 6 months. Bleeding was defined according to the International Society of Thrombosis and Haemostasis (ISTH) and the Bleeding Academic Research Consortium (BARC).

Results

158 patients were enrolled between May 2020 and May 2021. The median age was 78 years (interquartile range, IQR 72–82), 111 (70%) were male, and 39 (25%) presented with acute coronary syndrome. All Patients were treated with clopidogrel and OAC, 145 (92%) in addition with acetylsalicylic acid (ASA). 32 patients (20%) had ≥1 antiphospholipid antibody (aPL; LA: 19 [12%], aCL: 14 [9%], aβ2GP1: 2 [1%]). D-dimers were elevated in 74 patients (47%), FIBC was increased in 40 (25%) and PF1+2 in 68 patients (43%). IPF [%] was elevated in 28 (18%) and IPF abs. [103/μl] in 11 (7%). The presence of aPL was neither significantly associated with MACE, nor with bleeding risk. Elevated d-dimers were significantly associated with higher risk for MACE (HR=5.1, 95% CI [1.1; 23.4], p=0.04), major ISTH bleeding events (HR= 6.9, 95% CI [1.5; 30.8], p=0.01) and BARC bleeding type 3 or 5 (HR=6.4, 95% CI [1.4; 28.7], p=0.02). Increased levels of FIBC were associated with risk of MACE (HR= 3.6, 95% CI [1.1; 12.0], p=0.03 (Table 1).

Conclusion

In patients with AF undergoing PCI, high levels of d-dimers and fibrinogen C indicate an increased ischemic risk. Elevated d-dimers are associated with higher risk for bleeding. aPL positivity was not significantly associated with outcome possibly due to low sample size. A combined panel of biomarkers might be suitable to assess ischemic and bleeding risk in patients with AF following PCI.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Faculty of Medicine, Freiburg

Comparison of various late gadolinium enhancement magnetic resonance imaging methods to high-definition voltage and activation mapping for detection of atrial cardiomyopathy

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Medtronic

Background/Introduction

Atrial cardiomyopathy (ACM) is associated with the progression from paroxysmal through persistent to permanent atrial fibrillation (AF) and increased arrhythmia recurrence rates after pulmonary vein isolation (PVI).

Purpose

We compare the most common left atrial (LA) late gadolinium enhancement magnetic resonance imaging (LGE-MRI)-methods (Utah-method and image-intensity-ratio (IIR)-methods) and endocardial voltage mapping for ACM-detection and outcome prediction after PVI for AF.

Methods

In this prospective study, 37 ablation-naive patients (66±9 years, 84% male) with persistent AF were included and electrically cardioverted into sinus rhythm. Subsequently, they underwent LA-LGE-MRI and high-definition voltage and activation mapping (2129±484 sites) in sinus rhythm prior to PVI. MRI-post-processing-analyses were performed by two independent expert laboratories (Marrek for the Utah segmentation as describers of this methodology and Adas 3D medical as developers of the Adas software for the IIR-methods) which were blinded to any clinical data. Arrhythmia recurrence was recorded within 12 months following PVI.

Results

The global ACM-extent was highly variable: median LA low-voltage substrate (LA-LVS) was 12.9% at <1.0mV and 2.7% at <0.5mV; median LA-LGE-extent using the Utah-method was 18.3% and 0.03%-93.1% using the IIR-methods. LA activation time was significantly correlated with LA-LVS (r=0.76 at <0.5mV and r=0.82 at <1.0mV, both p<0.0001), but not with LA-LGE-extent.

The highest regional matching between LA-LVS <0.5mV and LA-LGE was found for the anterior wall in 57% of patients using the Utah-method and in 59% using IIR 1.20. The corresponding values for the posterior wall were 19% and 38%, respectively.

Arrhythmia recurrence occurred in 15 (41%) patients. Freedom from arrhythmia was significantly lower in those with relevant LA-LVS (≥2cm2 at 0.5mV) but not in those with relevant LGE (Utah-stages III&IV): 43% versus 81%, p=0.009 and 50% versus 67%, p=0.338, respectively. Furthermore, relevant

LA-LVS was the only predictor for arrhythmia recurrence in multivariate regression analysis.

Conclusion

The different LA-LGE-MRI methods have large dicrepancies regarding extent and distribution of ACM and are different to the extent and regional distribution of LA-LVS as assessed in endocardial high-definition voltage mapping in sinus rhythm. Further improvements of the LA-LGE-MRI-methods are required to enable correct diagnosis of ACM and for future evaluation of MRI-guided ablation protocols.

Vericiguat: a QTc interval study in patients with coronary artery disease

Background

Vericiguat is a soluble guanylate cyclase stimulator developed for the treatment of symptomatic chronic heart failure (HF) in adult patients with ejection fraction less than 45% who had a previous decompensation event. Guidelines on QT studies recommend evaluation of investigational drugs at supratherapeutic exposures in healthy volunteers. We anticipated that supratherapeutic doses of vericiguat would decrease blood pressure. We conducted an adjusted QT study using the therapeutic range of vericiguat in patients with coronary artery disease (CAD), who were expected to be more haemodynamically stable with fewer confounders (e.g., on the electrocardiogram) than a HF population.

Purpose

To assess the effect of vericiguat 10 mg once-daily on placebo-adjusted change from baseline of the Fridericia-corrected QT interval (QTcF) in patients with stable CAD.

Methods

This was a randomised, Phase Ib, placebo-controlled, double blind, double-dummy, multicentre study (NCT03504982). Test drug was vericiguat once-daily (up-titrated from 2.5 mg to 5 mg and then to 10 mg [treatments A, B, C] at 14-day intervals). The positive control was moxifloxacin 400 mg (single dose on Day 8 or Day 50 with placebo on other days [treatment D]; Figure). Patients were randomised to one of two sequences.

We evaluated QTcF interval prolongation potential of vericiguat at increasing doses up to 10 mg, steady state. We investigated the pharmacokinetics, safety and tolerability of vericiguat. A clinically meaningful effect was defined as a QTcF change from baseline >10 ms relative to placebo. Assay sensitivity for moxifloxacin was confirmed by the lower limit of the 90% confidence interval (CI) of the time-matched, baseline-adjusted mean difference to placebo exceeding 5 ms at >1 time point.

Results

A total of 74 patients (66 males and 8 females) with CAD, mean (standard deviation) age 63.4 (8.0) years, were included. Mean difference between vericiguat and placebo in QTcF change from baseline (≤7 h post-dose) was <6 ms; no upper limit of the 90% CIs crossed the threshold of 10 ms. Lower limits of the two-sided 90% CI of the differences between moxifloxacin and placebo in QTcF change from baseline were >5 ms at 3 of 4 time points (Table).

Peak plasma concentration (Cmax) of vericiguat following administration of vericiguat 10 mg was 322 μg/l and median time of maximum concentration (Tmax) was 4.5 h post-dose, in line with concentrations observed following administration of vericiguat 10 mg to patients with HF [1]. For moxifloxacin 400 mg, Cmax was 1960 μg/l and median Tmax was 3 h post-dose, in line with previously reported values [2]. Vericiguat up to 10 mg was generally safe and well tolerated.

Conclusion

This study supports the assessment that administration of vericiguat 10 mg is not associated with clinically meaningful QTc prolongation. These data contribute to the overall safety profile of vericiguat for the treatment of patients with HF.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Funding was provided by Bayer AG, Berlin, Germany, and Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA QTc study design

Next Generation Sequencing reveals profound transcriptomic differences between reticulated and non-reticulated platelets from healthy donors, CCS- and STEMI patients

Background

The youngest circulating platelets – so called reticulated platelets (RP) – represent a highly prothrombotic platelet subpopulation. Previous studies showed that patients with chronic coronary syndrome (CCS) as well as patients with ST-elevation myocardial infarction (STEMI) have higher amounts of RP compared to healthy subjects. It has been suggested that intrinsic properties of RP impact on cardiovascular risk. However, it is unknown if transcriptomic alterations contribute to the prothrombotic properties of RP.

Purpose

This study sought to investigate differences in the transcriptomic landscape of sorted RP versus non-RP, i.e. young and old platelets, in healthy subjects, CCS- and STEMI-patients.

Methods

Blood samples were obtained from healthy subjects as well as from patients with CCS/STEMI (n=8 each) the day after PCI. After staining with SYTO 13, platelets from each donor were sorted into a RP and a non-RP fraction based on their RNA-content. Next Generation Sequencing (NGS) was applied to generate sequencing reads for sorted RP and non-RP from the 3 cohorts. Data was analyzed by use of the Freiburg bioinformatics platform “Galaxy”.

Results

Investigation of transcriptomic alterations in non-RP versus RP by differential gene expression analysis revealed a total number of 2,476 transcripts that were differentially expressed in platelets from healthy donors, 2,075 in CCS-patients and 1,852 in STEMI patients, respectively (adj. p<0.05 in all analyses). Comparison of these transcripts revealed a large overlap of 500 mRNAs which were downregulated and 660 mRNAs which were upregulated in RP in all 3 cohorts. However, there are also distinct groups of transcripts that are differentially expressed in only one of the 3 cohorts. Gene ontology (GO)-analysis of the 500 uniformly enriched transcripts in RP yielded 38 overrepresented GO-terms. A large group was related to cytoskeleton and shape change. Furthermore, GO-terms associated to the platelet activation cascade were overrepresented. Upregulated transcripts included well-known examples like GP6 and GP9, P-selectin, integrin β3, integrin a-IIb, and tubulin α4a. GO-analysis of enriched transcripts in non-RP showed a large group associated to mitosis and cell nucleus/DNA which is surprising since platelets neither contain DNA nor a nucleus. Gene set enrichment analysis (GSEA) determined higher normalized enrichment scores for several gene sets associated to platelet degranulation, aggregation and activation in the STEMI-cohort. Gene sets affecting cell adhesion and platelet calcium homeostasis were overexpressed in particular in CCS-patients.

Conclusion

NGS-results indicate a highly prothrombotic transcriptome of RP from each cohort with high amounts of differentially expressed transcripts overlapping. However, GSEA identified gene sets that are particularly overexpressed in CCS- or STEMI-patients which might contribute to platelet hyperreactivity in these cohorts.

Gene set enrichment analysis

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): PharmCompNet Baden-Wuerttemberg: Kompetenznetzwerk Pharmakologie Baden-Wuerttemberg - Wirkstoffnetzwerke als Grundlagen der individualisierten Arzneistofftherapie

Impact of on-clopidogrel platelet reactivity on incidence of peri-interventional bleeding in patients undergoing transcatheter aortic valve implantation

Background

Transcatheter aortic valve implantation (TAVI) has become clinical routine for patients at intermediate to high risk for surgical aortic valve replacement. The optimal antithrombotic strategy following TAVI is still not well defined. Antithrombotic treatment is administered to prevent hypo-attenuated leaflet thickening, valve thrombosis, or ischemic stroke. However, most of these patients are also at high risk for bleeding. Current guidelines recommend dual antiplatelet therapy although the clinical evidence is limited.

Methods

This analysis enrolled patients undergoing TAVI from 11/2013 until 04/2018. Patients were either on long-term dual antiplatelet therapy with clopidogrel and aspirin or received a loading dose 300 to 600mg of clopidogrel and 400mg aspirin before TAVI. Platelet reactivity was determined by multi-electrode impedance aggregometry after stimulation with arachidonic acid and adenosine diphosphate (ADP) before TAVI as well as at day 1 and 5 thereafter. Peri-interventional bleeding was assessed up to 5 days following TAVI and coded according to BARC-classification.

Results

The present analysis included 484 patients (median age 83 [79–86] years; female sex 54.5%). There were 199 (41.1%) patients with a bleeding event. Most frequent were BARC 2 bleedings in 117 (24.2%) cases followed by BARC 1 (6.0%), BARC 3b in 25 (5.2%) and BARC 3a in 22 (4.5%) cases. On-clopidogrel platelet reactivity tested after stimulation with ADP was significantly lower in patients with bleeding events as compared to patients without bleeding (Figure). No differences were observed in arachidonic acid-induced platelet reactivity as marker for aspirin-efficacy between both groups over time. Multivariate logistic regression analysis identified on-clopidogrel platelet reactivity and use of oral anticoagulation as strongest independent predictors for bleeding events.

Conclusion

On-clopidogrel platelet reactivity is an independent predictor for peri-interventional bleeding in patients undergoing TAVI. Taken together with previous data indicating no association of on-clopidogrel platelet reactivity with peri-interventional ischemic events, the present data question the need for a strong peri-interventional dual antiplatelet therapy in patients undergoing TAVI.

Funding Acknowledgement

Type of funding source: None

55Non-invasive ECG-imaging for identification of atrial arrhythmogenic low voltage substrate in patients with persistent atrial fibrillation

Background/Introduction

Left atrial (LA) fibrosis is associated with increased arrhythmia recurrence rates after pulmonary vein isolation (PVI) and increased stroke risk in patients with atrial fibrillation (AF). So far, detection and quantification of LA fibrosis is only feasible by invasive electrophysiological mapping of low-voltage-substrate (LVS) or delayed enhancement areas in MRI.

Purpose

The aim of this study was to assess the distribution and extent of atrial fibrosis by non-invasive ECG-Imaging (ECGI) in patients with persistent AF prior to PVI.

Methods

Thirty-seven consecutive patients (66 ± 9 years, 84% male) presenting for their first PVI were included. Patients with AF were cardioverted into sinus rhythm (SR). One day prior to AF ablation procedure, patients underwent ECGI in SR using the 252-electrode-array (CardioInsight) and a low-X-ray-dose, non-injected cardiac CT-scan to assess the relationship between ECGI-electrodes and cardiac epicardial structures. Prior to PVI, high-density biatrial voltage and activation maps were acquired in SR (CARTO-3). Localization and extent of atrial LVS (relevant fibrosis: LA-LVS: ≥5cm2 at <0.5mV threshold) and biatrial activation times depicted by CARTO were compared with atrial activation/conduction times assessed by non-invasive ECGI.  Presence of LA-LVS was classified according to its extent into 3 stages and compared to the inter- and intraatrial conduction delay in ECGI.

Results

Relevant atrial fibrosis was found in 17/37(46%) patients. Presence of biatrial LVS resulted in a linear increase of the biatrial activation time in CARTO-SR-maps (146 ± 18ms in patients without LVS vs 184 ± 27ms in patients with LVS, p < 0.001) and in non-invasive ECGI (133 ± 11ms vs 170 ± 20ms, p < 0.001).

Both the extent of biatrial LVS and invasively measured total activation time correlated well with non-invasive total atrial conduction time (TACT) in ECGI (r = 0.91 and r = 0.82, respectively, figure). Moreover, the extent of LA-LVS showed an excellent correlation to TACT in ECGI (r = 0.89).

A combination of inter-atrial (RA-LA) conduction delay and TACT in ECGI allowed to quantify the extent of LA-LVS and to distinguish between three stages of LA-LVS: Stage 1 (minimal LA-LVS: 1 ± 2cm2): ECGI revealed rapid RA&LA activation with short TACT 132 ± 9ms; Stage 2 (moderate LA-LVS: 14 ± 8cm2 involving the anteroseptal LA) was associated with delayed LA activation and prolonged TACT measuring 161 ± 7ms; Stage 3 (extensive LA-LVS involving the anteroseptal and posterior LA: 26 ± 17cm2) was characterized by a significantly delayed LA activation with a TACT of 178 ± 24ms in ECGI.

Conclusion

Analysis of interatrial conduction delay and total atrial conduction time (TACT) in non-invasive ECGI allows accurate staging of patients with arrhythmogenic atrial LVS who present an increased risk for arrhythmia recurrences and stroke.

Abstract Figure.

2349Selatogrel, a novel P2Y12 inhibitor for emergency use, achieves rapid, consistent and sustained platelet inhibition following single-dose subcutaneous administration in stable CAD patients

Background

In the setting of AMI, rapid platelet inhibition is desirable but the onset of pharmacodynamic (PD) effect of oral platelet P2Y12 inhibitors is delayed, sometimes for hours. Subcutaneous (s.c) administration of a rapidly-acting P2Y12 inhibitor would overcome many of the limitations of available therapies. Patients with stable CAD were investigated initially.

Purpose

To characterise the inhibition of platelet aggregation and pharmacokinetics (PK) of a single dose of selatogrel, a novel s.c P2Y12 inhibitor, in patients with stable CAD.

Methods

Patients with stable CAD receiving oral antiplatelet therapy (aspirin and/or oral P2Y12 inhibitor) were randomized to 1 of 8 groups based on treatment (selatogrel or matching placebo), dose (8 mg or 16 mg) and s.c injection site (thigh or abdomen). Venous blood samples were collected into PPACK anticoagulant tubes. Platelet reactivity was assessed by VerifyNow PRU (P2Y12 reaction units) test before and 15 min, 30 min and 1, 2, 4, 8 and 24 h after injection. Light-transmittance aggregometry (LTA; ADP 20 uM) was also performed. PK samples were collected up to 24 h post-dose. Adverse events occurring within 30 days were recorded. Responders were defined as having PRU <100 at 30 min after injection and lasting ≥3 h.

Results

345 patients (mean age 65 y; 20% female; 31% diabetes) received selatogrel 8 mg (n=114), selatogrel 16 mg (n=115) or placebo (n=116). 97% were on background therapy with aspirin (or its derivative carbasalate) and 35% with oral P2Y12 inhibitor (clopidogrel 23%, prasugrel 4%, ticagrelor 8%). 89% of subjects were responders to selatogrel 8 mg, 90% to selatogrel 16 mg and 16% to placebo (P<0.0001). At 15 min post-dose, PRU values (mean±SD) were 10±25 with selatogrel 8 mg, 5±10 with selatogrel 16 mg and 163±73 with placebo (Figure). PRU levels were maintained at 2 and 4 h for both doses and gradually returned to pre-dose levels by 24 h post-dose (Figure). LTA results were consistent with the VerifyNow results. PD responses were similar for thigh and abdomen injection sites. Selatogrel was well tolerated: mild dyspnoea (or moderate dyspnoea, n=1, with 16 mg) occurred in 5% and 9% with selatogrel 8 mg and 16 mg, respectively, vs 0% with placebo; dizziness occurred in 4% and 4% vs 1%, respectively, without significant haemodynamic or ECG changes. Bleeding events occurred in 9.6% and 4.3% with selatogrel 8 mg and 16 mg, respectively, vs 6.9% with placebo. Pharmacokinetic data will be presented.

Conclusions

Selatogrel has a rapid PD effect following s.c injection in patients with stable CAD, within 15 min in most patients. The consistent and high levels of P2Y12 inhibition with a single 8 mg or 16 mg dose are sustained for over 4 hours, following which platelet reactivity progressively recovers over 24 h. Selatogrel was well tolerated, with mostly mild, transient dyspnoea observed in <10% patients. These data support further studies of selatogrel for emergency treatment of AMI patients.

Acknowledgement/Funding

Fully funded by Idorsia Pharmaceuticals Ltd

P3502Transmission electron microscopy reveals ultrastructural differences between reticulated and non-reticulated human platelets

Acknowledgement/Funding

PharmCompNet Baden-Württemberg: Kompetenznetzwerk Pharmakologie Baden-Württemberg

252Guided de-escalation of antiplatelet treatment in patients with acute coronary syndrome and multivessel coronary artery disease: a post-hoc analysis of the TROPICAL-ACS trial

Background

The TROPICAL-ACS trial showed that platelet function testing (PFT) guided de-escalation of P2Y12-inhibitor is a safe alternative treatment strategy in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). No specific data are available on the efficacy of this strategy in patients with multivessel coronary artery disease (CAD).

Purpose

To investigate the safety and efficacy of guided de-escalation of P2Y12-inhibitor treatment in patients with multivessel CAD.

Methods

Two-thousand six-hundred-two biomarker-positive ACS patients were 1:1 randomized to either conventional treatment with prasugrel for 12 months (control group) or to a PFT guided de-escalation treatment strategy (guided de-escalation group). The primary endpoint (net clinical benefit) was defined as the composite of cardiovascular mortality (CVM), myocardial infarction (MI), stroke, and clinically overt bleeding (bleeding ≥ grade 2 according to the BARC criteria). The ischemic endpoint was defined as the composite of CVM, MI or stroke. We used log-rank statistics and Cox regression analysis with interaction testing to assess the effect of multivessel CAD on the primary and ischemic endpoints.

Results

Patients with multivessel (n=709) versus single-vessel CAD (n=1,901) exhibited a higher risk for the primary endpoint (10.2% vs. 7.6%; HR 1.36; 95% CI 1.02–1.81; p=0.034). Guided de-escalation was non-inferior to conventional treatment for the primary endpoint in both patients with single-vessel CAD (6.7% vs. 8.5%; pnon-inferiority = 0.001; Figure 1A) and multivessel CAD (9,5% vs. 10.9%; pnon-inferiority=0.041; Figure 1B). Moreover, there was no significant interaction in the prognostic value of guided de-escalation between single-vessel and multivessel CAD for both the primary (HR 0.78 [0.56–1.08]; p=0.137 in patients with single-vessel CAD vs. 0.86 [0.54–1.37; p=0.524 in patients with multivessel CAD; pinteraction=0.732) and combined ischemic endpoints (HR 0.80 [0.44–1.45]; p=0.456 in patients with single-vessel CAD vs. 0.71 [0.35–1. 46]; p=0.356 in patients with multivessel CAD; pinteraction=0.823).

Kaplan-Meier curves

Conclusion

A guided de-escalation of P2Y12-inhibitor appears to be safe and effective in ACS patients with both single-vessel and multivessel CAD.

Acknowledgement/Funding

Klinikum der Universität München, Roche Diagnostics, Eli Lilly, and Daiichi Sankyo.

Clinical implications of drug-drug interactions with P2Y12 receptor inhibitors

Polypharmacy in patients undergoing coronary artery stenting or in those presenting with an acute coronary syndrome is common. Nevertheless, the risk of drug-drug interactions in patients treated simultaneously with P2Y12 receptor inhibitors is less well considered in routine clinical practice. Whereas the irreversible P2Y12 receptor inhibitors clopidogrel and prasugrel are prodrugs requiring cytochrome P450 (CYP) enzymes for metabolic activation, such activation is not necessary for the direct-acting reversible P2Y12 receptor inhibitor ticagrelor. Several drugs frequently used in cardiology have been shown to interact with the metabolism of P2Y12 receptor inhibitors in pharmacodynamic studies. Whereas several drug-drug interactions have been described for clopidogrel and ticagrelor, prasugrel seems to have a low potential for drug-drug interactions. The clinical implications of these interactions have raised concern. In general, concomitant administration of P2Y12 receptor antagonists and strong inhibitors or inducers of CYP3A/CYP2C19 should be performed with caution in patients treated with clopidogrel/ticagrelor. Under most circumstances, clinicians have the option of prescribing alternative drugs with less risk of drug-drug interactions when used concomitantly with P2Y12 receptor inhibitors.

High on-treatment platelet reactivity and P2Y12 antagonists in clinical trials

Dual antiplatelet therapy with aspirin and clopidogrel in patients undergoing percutaneous coronary intervention (PCI) and in patients with acute coronary syndromes (ACS) has substantially decreased the rate of cardiovascular events. Within the past decade, the variability in pharmacodynamic response as well as the moderate antiplatelet efficacy of clopidogrel has raised major concerns, since high on-clopidogrel platelet reactivity has consistently been associated with increased risk for ischaemic events in PCI patients. The variability in response could be linked to genetic polymorphisms impacting on activity of cytochrome P450 enzymes as well as clinical and demographic variables, but, taken together, factors identified so far can explain only up to approximately 12% of this variability in adenosine diphosphate-induced platelet aggregation on clopidogrel. Regulatory agencies as well as major cardiac societies suggest the use of other anti-platelet medications or alternative dosing strategies for clopidogrel in patients with reduced effectiveness of clopidogrel. This review will focus on the current status of alternate strategies for more sufficient suppression of high platelet reactivity.

Personalizing antiplatelet therapy with clopidogrel

Dual antiplatelet therapy with aspirin and clopidogrel is the accepted standard for prevention of ischemic complications after percutaneous coronary intervention and has been shown to reduce cardiovascular events in patients with acute coronary syndromes (ACSs). There is substantial interindividual variability in antiplatelet response to clopidogrel. Various clinical studies have demonstrated that patients with high on-clopidogrel platelet reactivity incur an increased risk for ischemic events. In recent years, several clinical and demographic variables as well as multiple genetic factors contributing to the variability in antiplatelet response to clopidogrel have been identified. We discuss strategies based on platelet function testing or genotyping for improvement of antiplatelet effects of clopidogrel and thereby clinical outcome.

A clinical trial on absorption and N-acetylation of oral and rectal mesalazine

BACKGROUND

Mesalazine (5-ASA) is a standard treatment for ulcerative colitis. Extent of absorption and N-acetylation determine systemic exposure to 5-ASA, and are thereby relevant for the safety of the treatment. The aim of the study was to compare absorption and N-acetylation of 5-ASA following rectal or oral drug administration. Healthy subjects were compared to patients with ulcerative colitis to evaluate the impact of chronic inflammation of colorectal mucosa on disposition of 5-ASA.

MATERIALS AND METHODS

First, 12 healthy adults were randomized to receive 2 g of 5-ASA by each of four different formulations: oral delayed release granules, 30 mL enema, 60 mL rectal foam, and 120 mL rectal foam. Second, 12 patients with active ulcerative colitis received 60 mL rectal foam. Pharmacokinetic analysis was performed by determination of 5-ASA and its acetylated, pharmacologically inactive metabolite (Ac-5-ASA) in plasma and urine.

RESULTS

First, systemic exposure to 5-ASA was markedly lower after rectal drug administration as compared to oral dosing (P < 0.001; e.g. median relative bioavailability of 60 mL rectal foam: 36%). Second, N-acetylation of rectal 5-ASA was lower in patients than in healthy subjects [area under the curve (AUC) ratio Ac-5-ASA/5-ASA: 1.6 +/- 0.5 vs. 2.3 +/- 0.4, mean +/- SD, P < 0.01]. High peak plasma concentrations of 5-ASA were correlated with high microscopic disease activity (r = 0.67, P < 0.05).

CONCLUSIONS

Rectal delivery of 5-ASA results in low systemic drug exposure with potentially reduced toxicity in comparison with oral drug administration. Chronic inflammation of colorectal mucosa might be a relevant source of variability in pharmacokinetics of 5-ASA.

Effect of lysine clonixinate on the pharmacokinetics and anticoagulant activity of phenprocoumon

The effect of the non-steroidal anti-inflammatory drug lysine clonixinate ([2-(3-chloro-o-toluidino)nicotinic acid]-L-lysinate, CAS 55837-30-4) on the pharmacokinetics and anticoagulant activity of phenprocoumon (4-hydroxy-3-(1-phenylpropyl)-coumarin, CAS 435-97-2) was investigated in an open, randomised, two-fold, cross-over study in 12 healthy male volunteers. These subjects received a single dose of 18 mg phenprocoumon without or with concomitant treatment with lysine clonixinate (125 mg five times a day for 3 days before and 13 days after ingestion of a single dose of phenprocoumon). Pharmacokinetic parameters of phenprocoumon following oral administration were: CL/f: 0.779 +/- 0.157 ml/min, half-life of elimination: 147.2 +/- 19.9 h; free fraction in serum: 0.51 +/- 0.20%. These parameters were not significantly altered by concomitant treatment with lysine clonixinate. Prothrombin time increased from 13.3 +/- 1.3 s (at time 0) to 17.7 +/- 2.7 s following phenprocoumon and from 13.3 +/- 1.2 s to 18.0 +/- 2.2 s following combined administration. Prothrombin time returned to the pretreatment values 240 h after administration of phenprocoumon. The integrated effect (AUEC0-288 h) was identical following both treatments (4.303 +/- 461 and 4.303 +/- 312 s x h for phenprocoumon alone and phenprocoumon with lysine clonixinate, respectively). Thus, lysine clonixinate administered in therapeutic doses does not affect the pharmacokinetics and anticoagulant activity of phenproxoumon.

Systemic bioavailability of nasally applied chlorphenamine maleate (0.4% nasal spray) relative to tablets administered perorally

AIM

This study investigated the bioavailability of single doses of 1.12 and 2.24 mg chlorphenamine maleate applied intranasally (0.4% nasal spray) relative to a single peroral dose of 8 mg chlorphenamine maleate (tablets).

METHODS

Twenty-four (24) subjects were treated with single nasal doses of 1.12 mg and 2.24 mg chlorphenamine maleate (0.4% nasal spray) and two 4 mg chlorphenamine maleate tablets (Piriton) on 3 separate study days according to a 3-way cross-over design with a 7-day wash-out between periods. Blood was sampled before and at 0.25, 0.50, 1.0, 2.0, 3.0, 4.0, 6.0, 8.0, 12, 16 and 24 hours after drug administration. Additional blood samples were obtained 36, 48 and 72 hours after peroral administration only. All subjects were included in the pharmacokinetic analysis.

RESULTS

Nasally applied chlorphenamine maleate was readily absorbed, reaching peak plasma levels after 0.25 to 3.0 hours. The dose-normalized estimated mean Cmax values were 1.24, 1.43 and 1.21 ng/ml for the peroral tablet and the 1.12 mg and 2.24 mg nasal dose, respectively. The dose-normalized estimated mean AUC(0-infinity) values were 25.91, 26.44 and 25.56 ng x h/ml for the tablet and the 1.12 and 2.24 mg nasal dose, respectively. The estimated treatment ratios (nasal dose to tablet) of the dose-normalized values for the 1.12 mg nasal dose were 1.15 (900 CI: 1.0-1.32) and 1.02 (90% CI: 0.88-1.18) for Cmax and AUC(0-infinity), respectively, for the 2.24 mg nasal dose they were 0.98 (90% CI: 0.85-1.13) and 0.99 (90% CI: 0.85-1.13) for Cmax and AUC(0-infinity), respectively. The other pharmacokinetic characteristics (tmax, t(1/2), lambda(z), AUC(0-tf), MRTtot, CL/f and Vz/f) were comparable across all treatments. These data indicate that the disposition of chlorphenamine maleate was independent of the route and dose of administration.

CONCLUSIONS

Chlorphenamine maleate is readily absorbed after nasal application using a 0.4% nasal spray. The nasal administration showed that the systemic bioavailability at the two dose levels used was comparable to that for the tablet. Maximum concentrations on the low dose, however, were higher and those on the high dose were comparable to those for the tablet. The nasal application of chlorphenamine maleate does not alter the overall systemic exposure compared to the oral route.

Pharmacokinetics of tilidine in terminal renal failure

The aim of the present study was to investigate the pharmacokinetics of tilidine and its metabolites during the dialysis procedure and in the dialysis-free interval. Tilidine is a prodrug that is metabolized presystemically into the active metabolite nortilidine. Nortilidine is degraded thereafter to bisnortilidine and several polar metabolites. Nine patients with a creatinine clearance < 5 ml/min were treated in a crossover design with single oral doses of 1.5 mg/kg on the day of dialysis (dialysis performed from 3 to 6 hours after drug administration) and on a day in the dialysis-free interval. Blood samples were taken frequently and analyzed for tilidine, nortilidine, and bisnortilidine. Drug and metabolite concentrations were also measured in aliquots of dialysate collected during dialysis. Only negligible amounts of tilidine, nortilidine, and bisnortilidine (about 0.9% of the dose) were recovered from the dialysate. The pharmacokinetics of nortilidine and its inactive metabolite bisnortilidine was not affected by dialysis. The presystemic apparent clearance of the prodrug tilidine was decreased significantly during the dialysis-free interval. A significant decrease of the rate of elimination and an increase of the AUC of bisnortilidine were observed if these parameters were compared with data obtained from healthy volunteers. The plasma concentrations of nortilidine were comparable in patients and normal volunteers. Thus, a reduction of the dose of tilidine in patients with severely impaired kidney function seems not to be required. Tilidine and its metabolites cannot be removed from the body by dialysis.

Comparison of the initial hemodynamic effects of immediate-release versus sustained-release isosorbide-5-mononitrate following single oral doses

In this double-blind, randomized, placebo-controlled cross-over study, the authors investigated the initial time course of effects of isosorbide-5-mononitrate (IS-5-MN) on hemodynamic parameters in 15 healthy male volunteers after administering a single oral dose of either an immediate-release formulation (IS-5-MN 20 mg) or of a sustained-release formulation (IS-5-MN 50 mg). The latter formulation released 15 mg IS-5-MN immediately, while 35 mg of the dose was sustained release. The onset of effect on the a/b-ratio of the finger pulse curve (20 minutes after administration) and on heart rate following orthostatic challenge (30 minutes) was not different following ingestion of either the immediate-release or the sustained-release formulation. Only the systolic blood pressure following orthostatic challenge was affected earlier after ingestion of the immediate-release form of IS-5-MN (10 vs. 30 minutes). There was no statistically significant difference in the maximum effect on the measured hemodynamic parameters between the two formulations. There was no significant difference with respect to the effect per dose between both of the active treatments (i.e., IS-5-MN 20 mg immediate release and IS-5-MN 50 mg sustained release) within 6 hours after administration. The hemodynamic findings were consistent with the observed rates of the increase of plasma concentrations of IS-5-MN following both formulations. Thus, the administration of the sustained-release formulation of IS-5-MN 50 mg caused similar maximum effects when compared with an immediate-release formulation (20 mg). While the onset of effect of IS-5-MN on the a/b-ratio of the finger pulse curve and on heart rate following orthostasis was similar after administration of either the immediate- or the sustained-release formulation, the onset of effect of the sustained-release formulation on systolic blood pressure orthostasis was determined slightly later. However, the latter difference seems to be of minor clinical relevance.

Age-dependent differences in the anticoagulant effect of phenprocoumon in patients after heart valve surgery

OBJECTIVE

An enhanced response to warfarin and an increased risk of major bleeding has been observed in older patients. The reason for this increase in sensitivity remains unknown. It could be due to pharmacodynamic reasons, pharmacokinetic reasons, or both.

METHODS

We therefore followed an anticoagulant regimen with phenprocoumon in 19 older (76 years) and 19 younger patients (50 years) following heart valve replacement. INR values were determined frequently. At the 4th and around the 24th day after starting treatment with phenprocoumon, we also measured the total and unbound plasma concentration of phenprocoumon.

RESULTS

The dose requirement to obtain the desired anticoagulant effect was significantly lower in the older patients than in the younger patients (26.3 vs. 37.3 micrograms.kg-1.day-1). The total plasma concentration (2.19 vs. 2.43 micrograms.ml-1), the percentage unbound drug in the plasma (0.61 vs. 0.64%) and the unbound plasma concentration (13.8 vs. 15.1 ng.ml-1) did not differ significantly between older and younger patients. The dose-adjusted INR (INR/dose) was higher in the older patients (110 vs. 67) but the INR adjusted for the unbound plasma concentration (INR/Cuss) which reflects the intrinsic sensitivity to the drug, was not significantly different (192 vs. 173). However, the older patients had an about 30% significantly lower metabolic clearance based on unbound drug (84 vs. 115 ml.kg-1.h-1).

CONCLUSIONS

Older patients (> 70 years) require a dose approximately 30% lower than younger patients (< 160 years). Pharmacokinetic reasons (reduced metabolic clearance) are mainly responsible for the lower dose requirement of the older patients after heart valve surgery.

Digital pulse plethysmography as a non-invasive method for predicting drug-induced changes in left ventricular preload

OBJECTIVE

Changes in the contour of the plethysmographically recorded digital pulse curve after nitrate ingestion are well known, but it has not been fully established whether these changes reflect nitrate action on left ventricular (LV) preload or afterload. Therefore, we compared the pulse wave contour after administration of equieffective doses of nitroglycerin and nifedipine.

METHODS

In 20 patients with coronary artery disease we measured aortic blood pressure curve in the aorta ascendens, digital volume pulse curve with a photoelectric pulse pickup, Riva Rocci blood pressure and heart rate after administration of either 0.8 mg nitroglycerin or 10 mg nifedipine.

RESULTS

Peak plasma concentrations of nitroglycerin and nifedipine were achieved 5 min and 20 min after ingestion of the drugs. Systolic aortic blood pressure decreased after both nitroglycerin and nifedipine to 19.4 mmHg, but diastolic blood pressure decreased only after nifedipine by 10.5 mmHg (P < 0.05). Riva Rocci blood pressures showed a similar time course. Heart rate increased from 67.4 to 70.9 beats.min-1 after nitroglycerin and from 58.9 to 69.4 beats.min-1 after nifedipine. The calculated a/b ratio of the aortic pressure curve increased after both medications (nitroglycerin, from 1.66 to 1.99; nifedipine, from 1.66 to 1.93) and its time course mimicked that of the systolic blood pressure. The a/b ratio of the digital pulse curve did not change after nifedipine, but showed a pronounced rise after nitroglycerin from 1.29 to 1.84. With regard to pharmacological actions, nitroglycerin causes a reduction in LV preload and afterload, whereas nifedipine has only LV-afterload-reducing activity.

CONCLUSION

We conclude, that the reduction in afterload did not cause the typical changes in wave contour of the peripheral pulse curve which occur with organic nitrates. Most likely changes in the a/b ratio reflect changes in LV preload.

A pharmacodynamic and pharmacokinetic comparison of intravenous quinaprilat and oral quinapril

Quinaprilat is the active metabolite of quinapril, an orally active angiotensin-converting enzyme (ACE) inhibitor. The dose-response and duration-of-effect after single intravenous doses of quinaprilat and placebo (part A) and after administration of oral quinapril solution and intravenous quinaprilat (part B) were assessed in a randomized, crossover study of two groups of 12 healthy volunteers. Pharmacodynamic effects of quinaprilat and oral quinapril were assessed by measurement of blood pressure changes after an infusion of angiotensin I (A-I) at a dose previously determined to produce an increase in diastolic blood pressure of 25 mmHg under standardized conditions (A-I pressor response). A clear dose-response relationship was demonstrated for quinaprilat in this pharmacodynamic model, with 0.5 mg as the lowest effective dose. Doses of 1.0 mg and higher partially suppressed A-I pressor response for at least 6 hours. Onset of action was observed within 15 minutes of intravenous administration of quinaprilat and was independent of dose, whereas peak effect and duration of action appeared to be dose related. Quinaprilat doses of 2.5 mg and 10 mg achieved approximately 50% and > 80% inhibition of the A-I pressor response, respectively. In part B, these doses of intravenous quinaprilat were compared with oral doses of quinapril previously found to produce 50% (2.5 mg) and 90% (10 mg) inhibition of the A-I pressor response. The magnitude of effect was similar after administration of 20 mg quinapril orally and 10 mg quinaprilat intravenously. Duration of action was longer, however, after administration of intravenous quinaprilat (10 mg) than after oral quinapril (20 mg), due to the higher maximum plasma concentration (Cmax) of quinaprilat. Mean area under the plasma concentration-time curve extrapolated to infinity (AUC0-infinity) of quinaprilat was similar after the 10-mg dose of intravenous quinaprilat and the 20-mg dose of oral quinapril. Based on the concentrations of quinaprilat observed in this study, the absolute bioavailability of quinapril was approximately 50%; intravenous quinaprilat should therefore produce a pharmacodynamic response similar to that obtained with oral quinapril at approximately half the dose.

Short-term hemodynamic, anti-ischemic, and antianginal effects of pirsidomine, a new sydnonimine

Pirsidomine is a new sydnonimine compound in clinical development. As a prodrug, it is transformed into a nitric oxide-releasing metabolite in vivo. In animal tests there were no signs of tolerance with repeated administration. The short-term effects of 10, 20, and 40 mg of the drug on pulmonary hemodynamics and ischemic parameters were examined at rest and during exercise in a double-blind, randomized, placebo-controlled study. The study included 48 patients with documented coronary artery disease and exercise-induced ST-segment depression. Compared with the baseline test, there was a reduction of diastolic pulmonary artery pressure with pirsidomine at rest (placebo: -0.4 +/- 0.5 mm Hg; 10 mg: - 1.5 +/- 2.4 mm Hg; 20 mg: - 1.4 +/- 1.1 mm Hg; 40 mg: - 2.3 +/- 1.3 mm Hg [p < 0.05 ]) and at the highest comparable workload (placebo: -2.8 +/- 1.9 mm Hg; 10 mg: -7.3 +/- 6.8 mm Hg; 20 mg: -8.4 +/- 7.9 mm Hg [p <0.05]; 40 mg: -13.8 +/- 7.1 mm Hg [p <0.05]). ST-segment depression decreased at the highest comparable workload (placebo: -0.33 +/- 0.49 mm; 10 mg: -1.33 +/- 1.37 mm [p <0.05]; 20 mg: -1.33 +/- 0.83 mm [p <0.05]; 40 mg: -1.96 +/- 0.86 mm [p <0.05]) and total exercise time increased (placebo: 15 +/- 48 s; 10 mg: 98 +/- 126 s; 20 mg: 165 +/- 251 s [p <0.05]; 40 mg: 155 +/- 174 s [p <0.05]). Of 40 patients who complained of angina pectoris symptoms in the baseline test, 15 became free of angina pectoris with pirsidomine. Compared with placebo, blood pressure, heart rate during exercise, and cardiac output during exercise showed no significant change. Plasma concentration response relations of the metabolite revealed concentrations that caused a half-maximum effect of 6 ng/ml, 13 ng/ml, 20 ng/ml, and 28 ng/ml in reduction of ST-segment depression, reduction of diastolic pulmonary artery pressure, relief of angina pectoris symptoms, and an increase in exercise duration, respectively. Thus, pirsidomine is an effective anti-ischemic and antianginal agent. A significant preload reduction was obtained with plasma metabolite concentrations lower than those necessary to achieve a satisfactory antianginal effect.

Prolongation of the PQ interval as a measure of therapeutic inequivalence between two formulations of diltiazem

We studied the use of atrioventricular (AV) conduction time to assess the therapeutic equivalence of two diltiazem formulations in 20 volunteers in a double-blind, cross-over trial. ECG recording was carried out before and at several intervals after drug administration, and prolongation of the PQ interval (delta PQ) was taken as a pharmacodynamic response. In addition, diltiazem plasma concentrations were determined in 8 subjects. The effect of diltiazem increased proportionally with the plasma concentration and could be detected up to 10 h after administration. The area under the effect-time curve (AUEC(0-10)), the peak effect (Emax), and the effect mean residence time (MRTE) showed significant differences. In contrast to the pharmacodynamics, the pharmacokinetic profiles of diltiazem do not vary to the same extent. We conclude that the formulations are therapeutically different. Furthermore, at the administered dose, delta PQ appears to be a sensitive measure for assessing the electrophysiological properties of diltiazem.

Pharmacokinetics and pharmacodynamics of ramipril and piretanide administered alone and in combination

The pharmacokinetics and pharmacodynamics of single oral doses of 5 mg ramipril and 6 mg piretanide administered separately and in combination were determined in a single blind, randomised, 3-period cross-over study in 24 healthy male volunteers. The peak plasma concentrations of ramipril and ramiprilat increased slightly (from 11.9 to 14.8 ng/ml, and from 6.39 to 8.96 ng/ml, respectively) as did the area under the plasma concentration-time curve of ramipril (0-4 h) and ramiprilat (0-24 h) (from 15.8 to 19.8 ng.ml-1.h, and from 63.4 to 74.6 ng.ml-1.h, respectively). The urinary excretion of ramiprilat also rose (from 6.82 to 7.73% of dose) following simultaneous treatment with piretanide. These effects were probably due to reduced first-pass metabolism of ramipril/ramiprilat to inactive metabolites. The blood pressure lowering effect, the time course of inhibition of ACE activity in plasma and the concentration-response relationship for the inhibition of plasma ACE activity were not affected by piretanide. The peak plasma concentration of piretanide was somewhat reduced (from 285 to 244 ng/ml) following simultaneous treatment with ramipril. No other pharmacokinetic parameter was affected. Piretanide increased urine flow, and sodium, chloride and potassium excretion, especially during the first 2 hours following administration. These pharmacodynamic parameters were not affected by ramipril. Thus, simultaneous administration of single oral doses of ramipril and piretanide caused modest changes in the peak and average plasma concentrations of both drugs, which did not lead to detectable alterations in the pharmacodynamic parameters measured in healthy volunteers.