Orosomucoid (alpha1-acid glycoprotein) plasma concentration and genetic variants: effects on human immunodeficiency virus protease inhibitor clearance and cellular accumulation

BACKGROUND AND OBJECTIVE: Protease inhibitors are highly bound to orosomucoid (ORM) (alpha1-acid glycoprotein), an acute-phase plasma protein encoded by 2 polymorphic genes, which may modulate their disposition. Our objective was to determine the influence of ORM concentration and phenotype on indinavir, lopinavir, and nelfinavir apparent clearance (CL(app)) and cellular accumulation. Efavirenz, mainly bound to albumin, was included as a control drug. METHODS: Plasma and cells samples were collected from 434 human immunodeficiency virus-infected patients. Total plasma and cellular drug concentrations and ORM concentrations and phenotypes were determined. RESULTS: Indinavir CL(app) was strongly influenced by ORM concentration (n = 36) (r2 = 0.47 [P = .00004]), particularly in the presence of ritonavir (r2 = 0.54 [P = .004]). Lopinavir CL(app) was weakly influenced by ORM concentration (n = 81) (r2 = 0.18 [P = .0001]). For both drugs, the ORM1 S variant concentration mainly explained this influence (r2 = 0.55 [P = .00004] and r2 = 0.23 [P = .0002], respectively). Indinavir CL(app) was significantly higher in F1F1 individuals than in F1S and SS patients (41.3, 23.4, and 10.3 L/h [P = .0004] without ritonavir and 21.1, 13.2, and 10.1 L/h [P = .05] with ritonavir, respectively). Lopinavir cellular exposure was not influenced by ORM abundance and phenotype. Finally, ORM concentration or phenotype did not influence nelfinavir (n = 153) or efavirenz (n = 198) pharmacokinetics. CONCLUSION: ORM concentration and phenotype modulate indinavir pharmacokinetics and, to a lesser extent, lopinavir pharmacokinetics but without influencing their cellular exposure. This confounding influence of ORM should be taken into account for appropriate interpretation of therapeutic drug monitoring results. Further studies are needed to investigate whether the measure of unbound drug plasma concentration gives more meaningful information than total drug concentration for indinavir and lopinavir.

Are plasma levels valid surrogates for cellular concentrations of antiretroviral drugs in HIV-infected patients?

Total plasma concentrations are currently measured for therapeutic drug monitoring of HIV protease inhibitors (PIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs). However, the pharmacological target of antiretroviral drugs reside inside cells. To study the variability of their cellular accumulation, and to determine to which extent total plasma concentrations (TPC) correlate with cellular concentrations (CC), plasma and peripheral blood mononuclear cells (PBMCs) were simultaneously collected at single random times after drug intake from 133 HIV infected patients. TPC levels were analysed by high-performance liquid chromatography with ultraviolet detection and CC by LC-MS/MS from peripheral blood mononuclear cells. The best correlations between TPC and CC were observed for nelfinavir (NFV, slope=0.93, r=0.85), saquinavir (SQV, slope=0.76, r=0.80) and lopinavir (LPV, slope=0.87, r=0.63). By contrast, TPC of efavirenz (EFV) exhibited a moderate correlation with CC (slope=0.69, r=0.58), while no correlation was found for nevirapine (NVP, slope=-0.3, r=0.1). Interindividual variability in the CC/TPC ratio was lower for protease inhibitors (coefficients of variation 76%, 61%, and 80% for SQV, NFV and LPV, respectively) than for nonnucleoside reverse transcriptase inhibitors (coefficients of variation 101% and 318%, for EFV and NVP). As routine CC measurement raises practical difficulties, well-correlated plasma concentrations (ie, NFV, SQV and LPV) can probably be considered as appropriate surrogates for cellular drug exposure. For drugs such as EFV or NVP, there may be room for therapeutic drug monitoring improvement using either direct CC determination or other predictive factors such as genotyping of transporters or metabolizing enzyme genes.

A validated assay by liquid chromatography-tandem mass spectrometry for the simultaneous quantification of elvitegravir and rilpivirine in HIV positive patients

Because of the large variability in the pharmacokinetics of anti-HIV drugs, therapeutic drug monitoring in patients may contribute to optimize the overall efficacy and safety of antiretroviral therapy. An LC–MS/MS method for the simultaneous assay in plasma of the novel antiretroviral agents rilpivirine (RPV) and elvitegravir (EVG) has been developed to that endeavor. Plasma samples (100 μL) extraction is performed by protein precipitation with acetonitrile, and the supernatant is subsequently diluted 1:1 with 20-mM ammonium acetate/MeOH 50:50. After reverse-phase chromatography, quantification of RPV and EVG, using matrix-matched calibration samples, is performed by electrospray ionization–triple quadrupole mass spectrometry by selected reaction monitoring detection using the positive mode. The stable isotopic-labeled compounds RPV-13C6 and EVG-D6 were used as internal standards. The method was validated according to FDA recommendations, including assessment of extraction yield, matrix effects variability (<6.4%), as well as EVG and RPV short and long-term stability in plasma. Calibration curves were validated over the clinically relevant concentrations ranging from 5 to 2500 ng/ml for RPV and from 50 to 5000 ng/ml for EVG. The method is precise (inter-day CV%: 3–6.3%) and accurate (3.8–7.2%). Plasma samples were found to be stable (<15%) in all considered conditions (RT/48 h, +4°C/48 h, −20°C/3 months and 60°C/1 h). Selected metabolite profiles analysis in patients' samples revealed the presence of EVG glucuronide, that was well separated from parent EVG, allowing to exclude potential interferences through the in-source dissociation of glucuronide to parent drug. This new, rapid and robust LCMS/MS assay for the simultaneous quantification of plasma concentrations of these two major new anti-HIV drugs EVG and RPV offers an efficient analytical tool for clinical pharmacokinetics studies and routine therapeutic drug monitoring service.

CYP3A5*3 and POR*28 genetic variants influence the required dose of tacrolimus in heart transplant recipients

BACKGROUND After heart transplantation (HTx), the interindividual pharmacokinetic variability of immunosuppressive drugs represents a major therapeutic challenge due to the narrow therapeutic window between over-immunosuppression causing toxicity and under-immunosuppression leading to graft rejection. Although genetic polymorphisms have been shown to influence pharmacokinetics of immunosuppressants, data in the context of HTx are scarce. We thus assessed the role of genetic variation in CYP3A4, CYP3A5, POR, NR1I2, and ABCB1 acting jointly in immunosuppressive drug pathways in tacrolimus (TAC) and ciclosporin (CSA) dose requirement in HTx recipients. METHODS Associations between 7 functional genetic variants and blood dose-adjusted trough (C0) concentrations of TAC and CSA at 1, 3, 6, and 12 months after HTx were evaluated in cohorts of 52 and 45 patients, respectively. RESULTS Compared with CYP3A5 nonexpressors (*3/*3 genotype), CYP3A5 expressors (*1/*3 or *1/*1 genotype) required around 2.2- to 2.6-fold higher daily TAC doses to reach the targeted C0 concentration at all studied time points (P ≤ 0.003). Additionally, the POR*28 variant carriers showed higher dose-adjusted TAC-C0 concentrations at all time points resulting in significant differences at 3 (P = 0.025) and 6 months (P = 0.047) after HTx. No significant associations were observed between the genetic variants and the CSA dose requirement. CONCLUSIONS The CYP3A5*3 variant has a major influence on the required TAC dose in HTx recipients, whereas the POR*28 may additionally contribute to the observed variability. These results support the importance of genetic markers in TAC dose optimization after HTx.

Ribavirin Concentrations Do Not Predict Sustained Virological Response in HIV/HCV-Coinfected Patients Treated with Ribavirin and Pegylated Interferon in the Swiss HIV Cohort Study.

BACKGROUND Ribavirin (RBV) is an essential component of most current hepatitis C (HCV) treatment regimens and still standard of care in the combination with pegylated interferon (pegIFN) to treat chronic HCV in resource limited settings. Study results in HIV/HCV-coinfected patients are contradicting as to whether RBV concentration correlates with sustained virological response (SVR). METHODS We included 262 HCV treatment naïve HIV/HCV-coinfected Swiss HIV Cohort Study (SHCS) participants treated with RBV and pegIFN between 01.01.2001-01.01.2010, 134 with HCV genotype (GT) 1/4, and 128 with GT 2/3 infections. RBV levels were measured retrospectively in stored plasma samples obtained between HCV treatment week 4 and end of therapy. Uni- and multivariable logistic regression analyses were used to evaluate the association between RBV concentration and SVR in GT 1/4 and GT 2/3 infections. The analyses were repeated stratified by treatment phase (week 4-12, 13-24, >24) and IL28B genotype (CC versus CT/TT). RESULTS SVR rates were 35.1% in GT 1/4 and 70.3% in GT 2/3 infections. Overall, median RBV concentration was 2.0 mg/L in GT 1/4, and 1.9 mg/L in GT 2/3, and did not change significantly across treatment phases. Patients with SVR had similar RBV concentrations compared to patients without SVR in both HCV genotype groups. SVR was not associated with RBV levels ≥2.0 mg/L (GT 1/4, OR 1.19 [0.5-2.86]; GT 2/3, 1.94 [0.78-4.80]) and ≥2.5 mg/L (GT 1/4, 1.56 [0.64-3.84]; GT 2/3 2.72 [0.85-8.73]), regardless of treatment phase, and IL28B genotype. CONCLUSION In HIV/HCV-coinfected patients treated with pegIFN/RBV, therapeutic drug monitoring of RBV concentrations does not enhance the chance of HCV cure, regardless of HCV genotype, treatment phase and IL28B genotype.

Clinical Practice Recommendations on Genetic Testing of CYP2C9 and VKORC1 Variants in Warfarin Therapy

OBJECTIVE To systematically review evidence on genetic variants influencing outcomes during warfarin therapy and provide practice recommendations addressing the key questions: (1) Should genetic testing be performed in patients with an indication for warfarin therapy to improve achievement of stable anticoagulation and reduce adverse effects? (2) Are there subgroups of patients who may benefit more from genetic testing compared with others? (3) How should patients with an indication for warfarin therapy be managed based on their genetic test results? METHODS A systematic literature search was performed for VKORC1 and CYP2C9 and their association with warfarin therapy. Evidence was critically appraised, and clinical practice recommendations were developed based on expert group consensus. RESULTS Testing of VKORC1 (-1639G>A), CYP2C9*2, and CYP2C9*3 should be considered for all patients, including pediatric patients, within the first 2 weeks of therapy or after a bleeding event. Testing for CYP2C9*5, *6, *8, or *11 and CYP4F2 (V433M) is currently not recommended. Testing should also be considered for all patients who are at increased risk of bleeding complications, who consistently show out-of-range international normalized ratios, or suffer adverse events while receiving warfarin. Genotyping results should be interpreted using a pharmacogenetic dosing algorithm to estimate the required dose. SIGNIFICANCE This review provides the latest update on genetic markers for warfarin therapy, clinical practice recommendations as a basis for informed decision making regarding the use of genotype-guided dosing in patients with an indication for warfarin therapy, and identifies knowledge gaps to guide future research.

Clinical Practice Recommendations For The Management And Prevention Of Cisplatin-Induced Hearing Loss Using Pharmacogenetic Markers

Currently no pharmacogenomics-based criteria exist to guide clinicians in identifying individuals who are at risk of hearing loss from cisplatin-based chemotherapy. This review summarizes findings from pharmacogenomic studies that report genetic polymorphisms associated with cisplatin-induced hearing loss and aims to (1) provide up-to-date information on new developments in the field; (2) provide recommendations for the use of pharmacogenetic testing in the prevention, assessment and management of cisplatin-induced hearing loss in children and adults; and (3) identify knowledge gaps to direct and prioritize future research. These practice recommendations for pharmacogenetic testing in the context of cisplatin-induced hearing loss reflect a review and evaluation of recent literature and are designed to assist clinicians in providing optimal clinical care for patients receiving cisplatin based chemotherapy.

Risk of incident stroke in patients with Alzheimer disease or vascular dementia

OBJECTIVE To explore the risk of ischemic stroke, hemorrhagic stroke, or TIA in patients with Alzheimer disease (AD) or vascular dementia (VD). METHODS We conducted a follow-up study with a nested case-control analysis using the UK-based General Practice Research Database. We included patients aged 65 years and older with an incident diagnosis of AD or VD between 1998 and 2008 and a comparison group of dementia-free patients. We estimated incidence rates of ischemic stroke, hemorrhagic stroke, or TIA in patients with AD, VD, or without dementia, and we calculated odds ratios with 95% confidence intervals (CIs) of developing such an outcome in patients with AD or VD, stratified by use of antipsychotic drugs. RESULTS We followed 6,443 cases with AD, 2,302 with VD, and 9,984 dementia-free patients over time and identified 281 cases with incident ischemic stroke, 139 with hemorrhagic stroke, and 379 with TIA. The incidence rates of ischemic stroke for patients with AD, VD, or no dementia were 4.7/1,000 person-years (PYs) (95% CI 3.8-5.9), 12.8/1,000 PYs (95% CI 9.8-16.8), and 5.1/1,000 PYs (95% CI 4.3-5.9), respectively. Compared with dementia-free patients, the odds ratio of developing a TIA for patients with AD treated with atypical antipsychotic drugs was 4.5 (95% CI 2.1-9.2). CONCLUSIONS Patients with VD, but not AD, have a markedly higher risk of developing an ischemic stroke than those without dementia. In patients with AD, but not VD, use of atypical antipsychotic drugs was associated with an increased risk of TIA.

EMAS position statement: Testosterone replacement therapy in the aging male‏.

INTRODUCTION Late-onset hypogonadism (LOH) represents a common clinical entity in aging males, characterized by the presence of symptoms (most usually of a sexual nature, such as decreased libido, decreased spontaneous erections and erectile dysfunction) and signs, in combination with low serum testosterone concentrations. Whether testosterone replacement therapy (TRT) should be offered to those individuals is still under extensive debate. AIMS The aim of this position statement is to provide and critically appraise evidence on TRT in the aging male, focusing on pathophysiology and characteristics of LOH, indications for TRT, available therapeutic agents, monitoring and treatment-associated risks. MATERIALS AND METHODS Literature review and consensus of expert opinion. RESULTS AND CONCLUSIONS Diagnosis and treatment of LOH is justified, if a combination of symptoms of testosterone deficiency and low testosterone is present. Patients receiving TRT could profit with regard to obesity, metabolic syndrome, type 2 diabetes mellitus, sexual function and osteoporosis and should undergo scheduled testing for adverse events regularly. Potential adverse effects of TRT on cardiovascular disease, prostate cancer and sleep apnea are as yet unclear and remain to be investigated in large-scale prospective studies. Management of aging men with LOH should include individual evaluation of co-morbidities and careful risk versus benefit assessment.

Differences in the EEG profiles of early and late responders to antipsychotic treatment in first-episode, drug-naive psychotic patients

The aim of this study was to search for differences in the EEG of first-episode, drug-naive patients having a schizophrenic syndrome which presented different time courses in response to antipsychotic treatment. Thirteen patients who fulfilled DSM-IV diagnosis for schizophrenia or schizophreniform disorder participated in this study. Before beginning antipsychotic treatment, the EEG was recorded. On the same day psychopathological ratings were assessed using the ADMDP system, and again after 7 and 28 days of treatment. The resting EEG (19 leads) was subject to spectral analysis involving power values for six frequency bands. The score for the schizophrenic syndrome was used to divide the patients into two groups: those who displayed a clinically meaningful improvement of this syndrome (reduction of more than 30%) after 7 days of treatment (early responders, ER) and those who showed this improvement after 28 days (late responders. LR). Analysis of variance for repeated measures between ER, LR and their matched controls with the 19 EEG leads yielded highly significant differences for the factor group in the alpha2 and beta2 frequency band. No difference was found between the slow-wave frequency bands. Compared to controls the LR group showed significantly higher alpha2 and beta2 power and, in comparison to the ER group, significantly higher alpha2 power. There were no significant differences between the ER and the control group. These findings point to differences in brain physiology between ER and LR. The implications for diagnosis and treatment are discussed.

Safety of drug-eluting stents

Drug-eluting stents (DESs) effectively reduce angiographic restenosis and the clinical need for repeat revascularization procedures as compared with bare-metal stents. Widely publicized concerns arose recently about the incidence of late and very late stent thrombosis with the use of first-generation DESs. Recent systematic reviews and large-scale registry studies demonstrated similar rates of overall mortality and myocardial infarction for patients treated with either DESs or bare-metal stents during long-term follow-up. Careful selection of stent type according to patient and lesion characteristics as well as monitoring of adherence to dual antiplatelet therapy could maximize the therapeutic potential of these devices. The purpose of the present Review is to provide the reader with an overview of the benefits and risks of first-generation DESs that could help physicians select the most appropriate stent type for each patient.

An Atypical Mitochondrial Carrier That Mediates Drug Action in Trypanosoma brucei

Elucidating the mechanism of action of trypanocidal compounds is an important step in the development of more efficient drugs against Trypanosoma brucei. In a screening approach using an RNAi library in T. brucei bloodstream forms, we identified a member of the mitochondrial carrier family, TbMCP14, as a prime candidate mediating the action of a group of anti-parasitic choline analogs. Depletion of TbMCP14 by inducible RNAi in both bloodstream and procyclic forms increased resistance of parasites towards the compounds by 7-fold and 3-fold, respectively, compared to uninduced cells. In addition, down-regulation of TbMCP14 protected bloodstream form mitochondria from a drug-induced decrease in mitochondrial membrane potential. Conversely, over-expression of the carrier in procyclic forms increased parasite susceptibility more than 13-fold. Metabolomic analyses of parasites over-expressing TbMCP14 showed increased levels of the proline metabolite, pyrroline-5-carboxylate, suggesting a possible involvement of TbMCP14 in energy production. The generation of TbMCP14 knock-out parasites showed that the carrier is not essential for survival of T. brucei bloodstream forms, but reduced parasite proliferation under standard culture conditions. In contrast, depletion of TbMCP14 in procyclic forms resulted in growth arrest, followed by parasite death. The time point at which parasite proliferation stopped was dependent on the major energy source, i.e. glucose versus proline, in the culture medium. Together with our findings that proline-dependent ATP production in crude mitochondria from TbMCP14-depleted trypanosomes was reduced compared to control mitochondria, the study demonstrates that TbMCP14 is involved in energy production in T. brucei. Since TbMCP14 belongs to a trypanosomatid-specific clade of mitochondrial carrier family proteins showing very poor similarity to mitochondrial carriers of mammals, it may represent an interesting target for drug action or targeting.

Drug-induced torsades de pointes in an underserved urban population. Methadone: is there therapeutic equipoise?

BACKGROUND Although it has been well established that methadone use can result in prolonged QTc/torsades de pointes (TdP) and has been labeled as one of the main drugs that cause TdP, it is still prescribed indiscriminately, and several cases of methadone-associated TdP have been seen in our community. METHODS Our objective was to determine the associated factors for prolonged QTc and the development of torsades de pointes (TdP) in our underserved patient population. We found 12,550 ECGs with prolonged QTc between 2002 and 2013. Medical records were reviewed in order to identify precipitating factors for prolonged QTc and to detect incidence of TdP. RESULTS We identified 2735 patients with prolonged QTc who met the inclusion criteria. Of these, 89 (3%) experienced TdP. There was a greater prevalence of HIV infection in the TdP group (11.2 vs. 3.7%, p < 0.001). Furosemide, hydrochlorothiazide, selective serotonin reuptake inhibitors (SSRIs), amiodarone, ciprofloxacin, methadone, haloperidol, and azithromycin were the drugs most often associated with prolonged QTc (31, 8.2, 7.6, 7.1, 3.9, 3.4 and 3.3%, respectively). However, the agents most commonly associated with TdP were furosemide (39.3%), methadone (27%), SSRIs (19.1%), amiodarone (18%), and dofetilide (9%). The medications with statistical significance in the multivariate analysis for TdP development in descending order were as follows: ranolazine (odds ratios [OR] = 53.61, 95% confidence interval [CI] 5.4-524, p < 0.001), dofetilide (OR = 25, CI 6.47-103.16, p < 0.001), voriconazole (OR = 21.40, CI 3.24-124.25, p < 0.001), verapamil (OR = 10.98, CI 2.62-44.96, p < 0.001), sotalol (OR = 12.72, 1.95-82.81, p = 0.008), methadone (OR = 9.89, CI 4.05-24.15, p < 0.001), and SSRI (OR = 2.26, CI 1.10-5.96, p < 0.001). This multivariate analysis revealed that amiodarone and HIV infection were not implicated in TdP. CONCLUSION Methadone was by far the leading medication implicated in the development of TdP and an independent predictor in both univariate and multivariate analyses despite the fact that it was not the most common QT-prolonging medication in our population.