Raute Sunder-Plassmann

Pharmacoresistance in epilepsy: A pilot PET study with the p-glycoprotein substrate R-[(11)C]verapamil

Summary:  Purpose and Methods: Regional overexpression of the multidrug transporter P‐glycoprotein (P‐gp) in epileptic brain tissue may lower target site concentrations of antiepileptic drugs and thus contribute to pharmacoresistance in epilepsy. We used the P‐gp substrate R‐[11C]verapamil and positron emission tomography (PET) to test for differences in P‐gp activity between epileptogenic and nonepileptogenic brain regions of patients with drug‐resistant unilateral temporal lobe epilepsy (n = 7). We compared R‐[11C]verapamil kinetics in homologous brain volumes of interest (VOIs) located ipsilateral and contralateral to the seizure focus. Results: Among different VOIs, radioactivity was highest in the choroid plexus. The hippocampal VOI could not be used for data analysis because it was contaminated by spill‐in of radioactivity from the adjacent choroid plexus. In several other temporal lobe regions that are known to be involved in seizure generation and propagation ipsilateral influx rate constants K1 and efflux rate constants k2 of R‐[11C]verapamil were descriptively increased as compared to the contralateral side. Parameter asymmetries were most prominent in parahippocampal and ambient gyrus (K1, range: −3.8% to +22.3%; k2, range: −2.3% to +43.9%), amygdala (K1, range: −20.6% to +31.3%; k2, range: −18.0% to +38.9%), medial anterior temporal lobe (K1, range: −8.3% to +14.5%; k2, range: −14.5% to +31.0%) and lateral anterior temporal lobe (K1, range: −20.7% to +16.8%; k2, range: −24.4% to +22.6%). In contrast to temporal lobe VOIs, asymmetries were minimal in a region presumably not involved in epileptogenesis located outside the temporal lobe (superior parietal gyrus, K1, range: −3.7% to +4.5%; k2, range: −4.2% to +5.8%). In 5 of 7 patients, ipsilateral efflux (k2) increases were more pronounced than ipsilateral influx (K1) increases, which resulted in ipsilateral reductions (10%–26%) of R‐[11C]verapamil distribution volumes (DV). However, for none of the examined brain regions, any of the differences in K1, k2 and DV between the epileptogenic and the nonepileptogenic hemisphere reached statistical significance (p > 0.05, Wilcoxon matched pairs test). Conclusions: Even though we failed to detect statistically significant differences in R‐[11C]verapamil model parameters between epileptogenic and nonepileptogenic brain regions, it cannot be excluded from our pilot data in a small sample size of patients that regionally enhanced P‐gp activity might contribute to drug resistance in some patients with temporal lobe epilepsy.

Morphine Decreases Clopidogrel Concentrations and Effects A Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVES This study sought to examine the possible drug-drug interactions between clopidogrel and morphine. BACKGROUND Because morphine-the recommended treatment for pain of myocardial infarction-is associated with poor clinical outcome, we hypothesized that morphine lowers the plasma levels of clopidogrel active metabolite as well as its effects on platelets. METHODS Twenty-four healthy subjects received a loading dose of 600 mg clopidogrel together with placebo or 5 mg morphine intravenously in a randomized, double-blind, placebo-controlled, cross-over trial. Pharmacokinetics was determined by liquid chromatography tandem mass spectrometry, and clopidogrel effects were measured by platelet function tests. RESULTS Morphine injection delayed clopidogrel absorption (p = 0.025) and reduced the area under the curve levels of its active metabolite by 34% (p = 0.001). Morphine delayed the maximal inhibition of platelet aggregation on average by 2 h (n = 24; p < 0.001). Residual platelet aggregation was higher 1 to 4 h after morphine injection (n = 24; p < 0.005). Furthermore, morphine delayed the inhibition of platelet plug formation under high shear rates (P2Y-Innovance; n = 21; p < 0.004) and abolished the 3-fold prolongation in collagen adenosine diphosphate-induced closure times seen in extensive and rapid metabolizers (n = 16; p = 0.001). CONCLUSIONS Morphine delays clopidogrel absorption, decreases plasma levels of clopidogrel active metabolite, and retards and diminishes its effects, which can lead to treatment failure in susceptible individuals. (Drug/Drug Interactions of Aspirin and P2Y12-inhibitors; NCT01369186).

Clinical ResearchAntithrombotic TherapyMorphine Decreases Clopidogrel Concentrations and Effects: A Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVES This study sought to examine the possible drug-drug interactions between clopidogrel and morphine. BACKGROUND Because morphine-the recommended treatment for pain of myocardial infarction-is associated with poor clinical outcome, we hypothesized that morphine lowers the plasma levels of clopidogrel active metabolite as well as its effects on platelets. METHODS Twenty-four healthy subjects received a loading dose of 600 mg clopidogrel together with placebo or 5 mg morphine intravenously in a randomized, double-blind, placebo-controlled, cross-over trial. Pharmacokinetics was determined by liquid chromatography tandem mass spectrometry, and clopidogrel effects were measured by platelet function tests. RESULTS Morphine injection delayed clopidogrel absorption (p = 0.025) and reduced the area under the curve levels of its active metabolite by 34% (p = 0.001). Morphine delayed the maximal inhibition of platelet aggregation on average by 2 h (n = 24; p < 0.001). Residual platelet aggregation was higher 1 to 4 h after morphine injection (n = 24; p < 0.005). Furthermore, morphine delayed the inhibition of platelet plug formation under high shear rates (P2Y-Innovance; n = 21; p < 0.004) and abolished the 3-fold prolongation in collagen adenosine diphosphate-induced closure times seen in extensive and rapid metabolizers (n = 16; p = 0.001). CONCLUSIONS Morphine delays clopidogrel absorption, decreases plasma levels of clopidogrel active metabolite, and retards and diminishes its effects, which can lead to treatment failure in susceptible individuals. (Drug/Drug Interactions of Aspirin and P2Y12-inhibitors; NCT01369186).

A microsatellite polymorphism in the heme oxygenase-1 gene promoter is associated with increased bilirubin and HDL levels but not with coronary artery disease

Heme oxygenase 1 (HO-1) is involved in the generation of the endogenous anti-oxidant bilirubin which exerts beneficial effects against arteriosclerosis. A (GT) repeat polymorphism in the HO-1 promoter region modulates HO-1 expression in response to oxidative stress. Recently, this polymorphism has been reported to protect from coronary artery disease in Orientals. We intended to confirm this observation in Caucasians. We studied 649 individuals with myocardial infarction (n=258), stable coronary artery disease (n=180) and controls without coronary artery disease (n=211). Carriers of short alleles (<25 repeats) had higher bilirubin levels (median 0.66 mg/dL, IQR 0.49 to 0.91) compared to non-carriers (median 0.61 mg/dL, IQR 0.45 to 0.82; p=0.03) and a more favourable lipid profile (HDL median 47 mg/dL, IQR 40 to 50 vs. median 45, IQR 37 to 55, p=0.01; triglycerides median 118 mg/dL, IQR 87 to 174 vs. median 132, IQR 97 to 191, p=0.03). However, no significant differences of the genotype distribution were observed between the three groups in this Caucasian study population (p=0.94). Although potentially beneficial effects of the short HO-1 allele on lipid profile and serum bilirubin were observed, in contrast to Orientals, the HO-1 genotype was not associated with coronary artery disease in Caucasians.

Influence of functional haplotypes in the drug transporter gene ABCB1 on central nervous system drug distribution in humans

Single nucleotide polymorphisms in the human multidrug‐resistance gene ABCB1 have been reported to be associated with altered expression and function of P‐glycoprotein, an efflux transporter, expressed at the blood‐brain barrier. To test whether certain ABCB1 haplotypes contribute to interindividual differences in central nervous system drug distribution, brain distribution of a model P‐glycoprotein substrate, the calcium channel inhibitor verapamil, was measured by positron emission tomography (PET) in 2 groups of healthy volunteers.

Identification of a Homozygous PSTPIP1 Mutation in a Patient With a PAPA-Like Syndrome Responding to Canakinumab Treatment

BACKGROUND Pyogenic sterile arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome (OMIM 604416) is a rare autosomal dominant inherited autoinflammatory syndrome characterized by pyogenic sterile arthritis and less frequently accompanied by pyoderma gangrenosum and acne. It is associated with dominant missense mutations in the proline-serine-threonine phosphatase-interacting protein 1 gene (PSTPIP1) located on chromosome 15. The patient was diagnosed as having features of a PAPA-like syndrome in which cutaneous manifestations, such as pyoderma gangrenosum and acne fulminans, predominated. OBSERVATIONS Sequencing of the PSTPIP1 gene was performed in the patient and his extended family. The patients DNA analysis revealed a homozygous nucleotide exchange c.773G>C in the PSTPIP1 gene, leading to the substitution of glycine 258 by alanine (p.Gly258Ala), a previously reported heterozygous polymorphism. Heterozygous changes were identified in both of the patients parents and in 7 other family members, all of whom were asymptomatic. The patient was treated with canakinumab, a human anti-interleukin 1β monoclonal antibody, which led to rapid remission of the symptoms. CONCLUSIONS To our knowledge, this is the first reported case of the resolution of dermatological symptoms associated with a PAPA-like syndrome using canakinumab treatment. Further study of the p.Gly258Ala variant is warranted to determine whether this mutation has a role in causing an apparently recessive cutaneous syndrome resembling PAPA syndrome.

Is Low Serum Bilirubin an Independent Risk Factor for Coronary Artery Disease in Men but Not in Women

For many years, the bile pigment bilirubin was considered to be only a toxic waste product formed during heme catabolism. Recent evidence, however, suggests that bilirubin acts as a potent physiologic antioxidant that may provide important protection against arteriosclerosis, coronary artery disease (CAD), and inflammation (1)(2)(3). The antioxidant capacity of bilirubin and its potent ability to scavenge peroxyl radicals have led to the concept that mildly increased circulatory bilirubin may have a physiologic function to protect against disease processes that involve oxygen and peroxyl radicals (4). Indeed, inverse correlations between the presence of CAD and total bilirubin concentrations in the circulation were reported recently in several independent studies (5)(6). Additionally, plasma bilirubin correlates inversely with several established risk factors for CAD, including smoking, increased LDL-cholesterol, diabetes, and obesity, but is directly proportional to the protective factor HDL-cholesterol (5)(7). The effect of bilirubin on the risk of cardiovascular disease is apparent in men (8) but is less clear in women (6)(9)(10). In the present study, we therefore examined the influence of gender on total bilirubin concentrations. All patients referred to the Department of Cardiology, University of Vienna, between August 1999 and September 2001 for whom clinical data were available were included in our study. Patients were divided in a CAD and a non-CAD group. The CAD group consisted of 544 patients (157 females and 387 males) with clinically relevant CAD. Clinically relevant CAD was defined as an exercise-induced ischemic ST-segment depression >0.1 mV (12%) (11) and/or a history of myocardial infarction (53%) or coronary intervention [coronary artery bypass (8%) or percutaneous transluminal coronary angioplasty (27%)]. In the non-CAD group (359 patients; 186 females and 173 males), the presence of CAD …

Differential impact of cytochrome 2C9 allelic variants on clopidogrel-mediated platelet inhibition determined by five different platelet function tests

BACKGROUND The antiplatelet effect of clopidogrel is subject to considerable inter-individual variations. In vitro high on-treatment residual platelet reactivity (HRPR) has been linked to cytochrome P450 (CYP) 2C19*2 carriage, and both were significantly associated with the occurrence of adverse events after coronary stenting. It has been shown that besides CYP2C19, CYP2C9 is involved in the hepatic biotransformation of clopidogrel to its active metabolite. Consequently, CYP2C9 polymorphisms may also affect the extent of clopidogrel-mediated platelet inhibition. We therefore studied the influence of CYP2C9 allelic variants on clopidogrel-mediated platelet inhibition as assessed by 5 platelet function tests. METHODS On-clopidogrel residual platelet reactivity was assessed by light transmission aggregometry (LTA), the VerifyNow P2Y12 assay, the VASP assay, multiple electrode aggregometry (MEA), and the Impact-R in 288 patients after angioplasty and stenting for cardiovascular disease. Allelic variants CYP2C9*2 and *3 were determined using a RealTime PCR assay. RESULTS A significantly higher on-treatment platelet reactivity was found for patients with loss-of-function (LOF) status (wt/*3, *2/*2, *3/*3) compared to normal-function genotype (wt/wt, wt/*2) using the VerifyNow assay (P=0.01). An in trend increase was seen with LTA (P=0.06) while results did not differ for the VASP assay, MEA or the Impact-R. Further, in univariate and multivariable logistic regression analysis the LOF genotype was associated with HRPR determined by the VerifyNow P2Y12 assay (P=0.02) but not by any other assay. CONCLUSION Results from the VerifyNow P2Y12 assay are significantly influenced by CYP2C9 LOF variants leading to decreased clopidogrel-mediated platelet inhibition and an increased rate of HRPR.

Simultaneous analysis of MDR1 C3435T, G2677T/A, and C1236T genotypes by multiplexed mutagenically separated PCR.

Abstract P-Glycoprotein (PGP) encoded by the multi-drug-resistance 1 ( MDR1) gene is a member of theATP-binding cassette (ABC) transporter family, drug-transporting proteins involved in the bioavailability and pharmacokinetics of various drugs. Several single nucleotide polymorphisms (SNPs) in the MDR1 gene have been identified so far that may influence PGP expression levels and function. Thus, genotyping for MDR1 polymorphisms and determining specific haplotypes may become an important tool in predicting individual susceptibility to developing drug resistance. We developed a new multiplexed allele-specific PCR method based on the principle of mutagenically separated PCR (MS-PCR) for rapid and reliable simultaneous genoptyping of the C3435T polymorphism in exon 26 of the MDR1 gene and two additional SNPs (G2677T/A in exon 21 and C1236T in exon 12), which are in linkage disequilibrium with MDR1 C3435T. The accuracy and reliability of this method was confirmed by sequencing the respective regions in the MDR1 gene. This newly developed MDR1 MS-PCR will facilitate fast, accurate and economic analysis of MDR1 genotypes and will provide important information in optimizing individual therapeutic approaches.

The endocardial binary appearance (‘binary sign’) is an unreliable marker for echocardiographic detection of Fabry disease in patients with left ventricular hypertrophy

AIMS The binary sign, a binary appearance of the left ventricular endocardial border, was suggested to be an echocardiographic hallmark in diagnosing Fabry disease, a hereditary, lysosomal storage disorder. The aim of the present study was to examine the reliability of the binary sign as a screening tool to identify patients with Fabry disease. METHODS AND RESULTS In total 309 subjects with an interventricular septum (IVS) thickness of ≥12 mm were investigated, of which 14 had a confirmed diagnosis of Fabry disease. Urinary globotriaosylceramide testing was used to rule out Fabry disease in the control group. From all patients echocardiographic images of the apical four-chamber view were analysed offline by a blinded observer. A binary sign was seen in 63 patients (20%), 4 had Fabry disease and 59 belonged to the control group. Although the proportion of binary signs in patients with Fabry disease was higher (29%) compared with the control group (20%) this difference was not statistically significant. The sensitivity and specificity were 28% (95% confidence interval (CI): 12-65%) and 80% (95% CI: 76-85%), respectively. In a logistic regression model adjusted for age, sex and presence of Fabry disease, the occurrence of a binary sign was highly dependent on the IVS thickness (odds ratio: 1.21; 95% CI: 1.1-1.35; P<0.001). CONCLUSION The endocardial binary appearance is associated with the degree of septal hypertrophy but cannot adequately distinguish between patients with Fabry disease and patients with other causes of left ventricular hypertrophy.