Pharmacodynamic Effects of Vorapaxar in Prior Myocardial Infarction Patients Treated With Potent Oral P2Y12 Receptor Inhibitors With and Without Aspirin: Results of the VORA-PRATIC Study.

Background Vorapaxar as an adjunct to dual antiplatelet therapy (DAPT) reduces thrombotic events in patients with prior myocardial infarction at the expense of increased bleeding. Withdrawal of aspirin has emerged as a bleeding reduction strategy. The pharmacodynamic effects of vorapaxar with potent P2Y12 inhibitors as well as the impact of dropping aspirin is unexplored and represented the aim of the VORA-PRATIC (Vorapaxar Therapy in Patients With Prior Myocardial Infarction Treated With Newer Generation P2Y12 Receptor Inhibitors Prasugrel and Ticagrelor) study. Methods and Results Post-myocardial infarction patients (n=130) on standard DAPT (aspirin+prasugrel or ticagrelor) were randomized to 1 of 3 arms: (1) triple therapy: aspirin+prasugrel/ticagrelor+vorapaxar; (2) dual therapy (drop aspirin): prasugrel/ticagrelor+vorapaxar; (3) DAPT: aspirin+prasugrel/ticagrelor. Pharmacodynamic assessments were performed at 3 time points (baseline and 7 and 30 days). Vorapaxar reduced CAT (collagen-ADP-TRAP)-induced platelet aggregation, a marker of platelet-mediated global thrombogenicity (triple therapy versus DAPT at 30 days: mean difference=-27; 95% CI,-35 to -19; P<0.001; primary end point). This effect was attenuated but still significant in the absence of aspirin (dual therapy versus DAPT at 30 days: mean difference=-15; 95% CI,-23 to -7; P<0.001; between-group comparisons, P<0.05). Vorapaxar abolished TRAP-induced aggregation (P<0.001), without affecting thrombin generation and clot strength. There were no differences in markers of P2Y12 reactivity. Markers sensitive to aspirin-induced effects increased (P<0.001) in the dual-therapy arm. Conclusions In post-myocardial infarction patients treated with potent P2Y12 inhibitors, vorapaxar reduces platelet-driven global thrombogenicity, an effect that persisted, albeit attenuated, in the absence of aspirin and without affecting markers of P2Y12 reactivity or clot kinetics. The clinical implications of these PD observations warrant future investigation. Registration URL: https://www.clini​caltr​ials.gov. Unique identifier: NCT02545933.

Effects of Methylnaltrexone on Ticagrelor-Induced Antiplatelet Effects in Coronary Artery Disease Patients Treated With Morphine.

OBJECTIVES: The aim of this study was to assess if intravenous methylnaltrexone can counteract the effects of morphine on the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of ticagrelor. BACKGROUND: Morphine delays the onset of action of oral P2Y12 receptor inhibitors, including ticagrelor, by inhibiting gastric emptying and leading to delayed drug absorption. Methylnaltrexone is a peripheral opioid receptor antagonist that has the potential to prevent opioid-induced peripherally mediated side effects (e.g., gastric emptying inhibition) without affecting analgesia. METHODS: In this prospective, randomized, double-blind, placebo-controlled, crossover study, aspirin-treated patients with stable coronary artery disease (n = 30) were randomized to receive methylnaltrexone (0.3 mg/kg intravenous) or matching placebo. After methylnaltrexone or placebo administration, all patients received morphine (5 mg intravenous). This was followed 15 min later by a 180-mg loading dose of ticagrelor. Patients crossed over to the alternative study treatment after 7 ± 2 days of washout. PK and PD assessments were performed at 12 time points (6 pre- and 6 post-crossover). PK analysis included measurement of plasma levels of ticagrelor and its major active metabolite (AR-C124910XX). PD assessments included VerifyNow P2Y12, light transmittance aggregometry, and vasodilator-stimulated phosphoprotein. RESULTS: Only marginal changes in plasma levels of ticagrelor (and its major active metabolite) were observed with ticagrelor: maximum plasma concentration and area under the plasma concentration versus time curve from time 0 to the last measurable concentration were 38% and 30% higher, respectively, in patients receiving methylnaltrexone compared with those receiving placebo, but no differences in time to maximum plasma concentration were observed. There were no differences in P2Y12 reaction units by VerifyNow P2Y12 between groups at each time point, including 2 h (the primary endpoint; p = 0.261). Similarly, there were no differences in PD markers assessed by light transmittance aggregometry and vasodilator-stimulated phosphoprotein. CONCLUSIONS: In patients with coronary artery disease receiving morphine, intravenous administration of the peripheral opioid receptor antagonist methylnaltrexone leads to only marginal changes in plasma levels of ticagrelor and its major metabolite, without affecting levels of platelet reactivity. (Effect of Methylnaltrexone on the PK/PD Profiles of Ticagrelor in Patients Treated With Morphine; NCT02403830).

Concurrent Nontuberculous Mycobacteria Infection and High-Grade Anterior Mediastinal Extraskeletal Osteosarcoma (ESOS): Is There a Connection?

BACKGROUND Extraskeletal osteosarcomas (ESOS) of the mediastinum are extremely rare and may present with concurrent nontuberculous mycobacteria infection. CASE REPORT We present the second documented case of high-grade anterior mediastinal extraskeletal osteosarcoma in a 59-year-old man with a history of treated, latent tuberculosis (TB). Sputum samples grew Mycoplasma avium complex and Mycobacterium fortuitum. Imaging showed a right-sided 7.6 cm mass with compression of the main bronchus. Subsequent biopsy with vimentin staining established the diagnosis of ESOS. Due to the patient's rapidly declining performance status, he was not deemed a candidate for surgery or chemotherapy. He subsequently expired within one month of presentation. CONCLUSIONS We present a unique case of high-grade anterior mediastinum ESOS and a review of the literature regarding all documented cases of ESOS to date. We suggest there is a possible link between mediastinal masses and nontuberculous mycobacteria infection.

Pharmacodynamic Effects of Switching From Prasugrel to Ticagrelor: Results of the Prospective, Randomized SWAP-3 Study.

OBJECTIVES: This study sought to assess the pharmacodynamic (PD) effects of switching to ticagrelor patients who were treated with prasugrel after undergoing percutaneous coronary intervention in the setting of an acute coronary syndrome. BACKGROUND: In clinical practice, there is a frequent need to switch between P2Y12 receptor inhibitors. However, concerns on drug interactions have emerged when switching therapies. To date, the PD effects of switching from prasugrel to ticagrelor have yet to be investigated. METHODS: This was a prospective, randomized, open-label, 3-arm, parallel-design study conducted in patients (n = 82) on maintenance dual antiplatelet therapy with aspirin (81 mg QD) and prasugrel (10 mg QD). Patients were randomized to continue prasugrel 10 mg QD or switch to ticagrelor 90 mg bid, with or without a 180 mg loading dose (LD), for 1 week. PD assessments included P2Y12 reaction units (PRU) by VerifyNow, platelet reactivity index by vasodilator-stimulated phosphoprotein (VASP), and platelet aggregation by light transmittance aggregometry (LTA) at a total of 6 time points: baseline, 2 h, 4 h, 24 h, 48 h, and 1 week after randomization. RESULTS: After switching to ticagrelor, PRU levels decreased as early as 2 h after drug administration. Mean PRU levels remained low during the study time course, without evidence of drug interactions. The primary endpoint of noninferiority of ticagrelor (2 arms combined) versus prasugrel measured by PRU at 1 week was met (least squares mean difference: -18; 95% confidence interval: -41 to 5). There was no increase in rates of high on-treatment platelet reactivity (PRU >208), which were overall very low throughout the study time course. Similar levels of platelet reactivity were observed irrespective of the use of a ticagrelor LD. Parallel findings were observed with VASP and LTA. CONCLUSIONS: Switching from prasugrel to ticagrelor leads to transiently higher levels of platelet inhibition, irrespective of the use of a LD, without evidence of drug interactions. (Pharmacodynamic Evaluation of Switching From Prasugrel to Ticagrelor [SWAP3]; NCT02016170).

Rapid thrombelastography delivers real-time results that predict transfusion within 1 hour of admission.

BACKGROUND: Recognition of trauma-induced coagulopathy by conventional coagulation testing (CCT) is limited by their slow results, incomplete characterization, and their poor predictive nature. Rapid thrombelastography (r-TEG) delivers a more comprehensive assessment of the coagulation system but has not been prospectively validated in trauma patients. The purpose of this pilot study was to evaluate the timeliness of r-TEG results, their correlation with CCTs, and the ability of r-TEG to predict early blood transfusion. METHODS: Over a 5-month period, 583 consecutive major trauma activations were prospectively entered into a database, of which 272 met entry criteria. r-TEG and CCTs (prothrombin time, international normalized ratio, partial thromboplastin time, and platelet count) were obtained on all patients. Graphical results for r-TEG were displayed "real time" in the trauma bay. Spearman's correlation and regression models were used to compare r-TEG and CCTs. RESULTS: Early r-TEG values (activated clotting time [ACT], k-time, and r-value) were available within 5 minutes, late r-TEG values (maximal amplitude and α-angle) within 15 minutes, and CCTs within 48 minutes (p < 0.001). ACT, r-value, and k-time showed strong correlation with prothrombin time, international normalized ratio, and partial thromboplastin time (all r >0.70; p < 0.001), whereas maximal amplitude (r = -0.49) and α-angle (r = 0.40) correlated with platelet count (both p < 0.001). Linear regression demonstrated ACT predicted red blood cells (coef. 0.05; 95% confidence interval [CI], 0.04-0.06; p < 0.001), plasma (coef. 0.03; 95% CI, 0.02-0.04; p < 0.001), and platelet (coef. 0.06; 95% CI, 0.04-0.07; p < 0.001) transfusions within the first 2 hours of arrival. Controlling for all demographics and Emergency Department vitals, ACT >128 predicted massive transfusion (≥10 U) in the first 6 hours (odds ratio, 5.15; 95% CI, 1.36-19.49; p = 0.01). In addition, ACT <105 predicted patients who did not receive any transfusions in the first 24 hours (odds ratio, 2.80; CI, 1.02-7.07; p = 0.04). CONCLUSIONS: Graphical r-TEG results are available within minutes, correlate with conventional coagulation test that are not as rapidly available, and are predictive of early transfusions of packed red blood cells, plasma, and platelets.

Incidence of papilledema and obesity in children diagnosed with idiopathic ''benign'' intracranial hypertension: case series and review.

Idiopathic intracranial hypertension is an important cause of headaches in the pediatric population and can lead to permanent blindness if not diagnosed in a timely manner. The aim of this study was to characterize the incidence of papilledema and obesity in children with idiopathic intracranial hypertension. We retrospectively analyzed 27 patients followed at The University of Texas Houston Pediatric Neurology Clinic. Papilledema was absent in 13 (48%) patients. The majority of our patients were nonobese (70%). Our results are contrary to the current medical practice of associating papilledema and obesity with idiopathic intracranial hypertension in childhood and highlight the importance of revised diagnostic criteria in this population needed to detect and manage this condition.