Showing papers in "Clinical Pharmacology & Therapeutics in 2011"
TL;DR: Recommendations were developed for 53 drugs associated with genes coding for CYP2D6, CYP3A5, and HLA‐B*5701, and factor V Leiden (FVL).
Abstract: Currently, there are very few guidelines linking the results of pharmacogenetic tests to specific therapeutic recommendations. Therefore, the Royal Dutch Association for the Advancement of Pharmacy established the Pharmacogenetics Working Group with the objective of developing pharmacogenetics-based therapeutic (dose) recommendations. After systematic review of the literature, recommendations were developed for 53 drugs associated with genes coding for CYP2D6, CYP2C19, CYP2C9, thiopurine-S-methyltransferase (TPMT), dihydropyrimidine dehydrogenase (DPD), vitamin K epoxide reductase (VKORC1), uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1), HLA-B44, HLA-B*5701, CYP3A5, and factor V Leiden (FVL).
877 citations
TL;DR: The slow rate at which pharmacogenetic tests are being adopted in clinical practice is partly due to the lack of specific guidelines on how to adjust medications on the basis of the genetic test results.
Abstract: The slow rate at which pharmacogenetic tests are being adopted in clinical practice is partly due to the lack of specific guidelines on how to adjust medications on the basis of the genetic test results. One of the goals of the Clinical Pharmacogenetics Implementation Consortium (CPIC) of the National Institutes of Health’s Pharmacogenomics Research Network (http://www.pgrn.org) and the Pharmacogenomics Knowledge Base (PharmGKB, http://www.pharmgkb.org) is to provide peer-reviewed, updated, evidence-based, freely accessible guidelines for gene/drug pairs. These guidelines will facilitate the translation of pharmacogenomic knowledge from bench to bedside.
848 citations
TL;DR: An international DILI Expert Working Group of clinicians and scientists reviewed current DILi terminology and diagnostic criteria so as to develop more uniform criteria that would define and characterize the spectrum of clinical syndromes that constitute D ILI.
Abstract: Drug-induced liver injury (DILI) is the most frequent reason cited for the withdrawal of approved drugs from the market and accounts for up to 15% of the cases of acute liver failure. Investigators around the globe have begun to identify and study patients with DILI; several large registries and tissue banks are being established. In order to gain the maximum scientific benefit from these efforts, the definitions and terminology related to the clinical phenotypes of DILI must be harmonized. For this purpose, an international DILI Expert Working Group of clinicians and scientists reviewed current DILI terminology and diagnostic criteria so as to develop more uniform criteria that would define and characterize the spectrum of clinical syndromes that constitute DILI. Consensus was established with respect to the threshold criteria for definition of a case as being DILI, the pattern of liver injury, causality assessment, severity, and chronicity. Consensus was also reached on approaches to characterizing DILI in the setting of chronic liver diseases, including autoimmune hepatitis (AIH).
735 citations
TL;DR: The purpose of this article is to assist in the interpretation and use of CYP2C9 and VKORC1 genotype data for estimating therapeutic warfarin dose to achieve an INR of 2–3, should genotype results be available to the clinician.
Abstract: Warfarin is a widely used anticoagulant with a narrow therapeutic index and large interpatient variability in the dose required to achieve target anticoagulation. Common genetic variants in the cytochrome P450-2C9 (CYP2C9) and vitamin K–epoxide reductase complex (VKORC1) enzymes, in addition to known nongenetic factors, account for ~50% of warfarin dose variability. The purpose of this article is to assist in the interpretation and use of CYP2C9 and VKORC1 genotype data for estimating therapeutic warfarin dose to achieve an INR of 2–3, should genotype results be available to the clinician. The Clinical Pharmacogenetics Implementation Consortium (CPIC) of the National Institutes of Health Pharmacogenomics Research Network develops peer-reviewed gene–drug guidelines that are published and updated periodically on http://www.pharmgkb.org based on new developments in the field. 1 Focused Literature review The Supplementary Notes online include a systematic literature review of CYP2C9 and VKORC1 genotype and warfarin dosing, which forms the basis for this guideline. drug: w arF arin Warfarin (Coumadin and others) is the most commonly used oral anticoagulant worldwide, with annual prescriptions typically equaling 0.5–1.5% of the population. It is prescribed for treatment and prevention of thrombotic disorders. 2 Although highly efficacious, warfarin’s narrow therapeutic index and wide interindividual variability make its dosing notoriously challenging. 3–5 Complications from inappropriate warfarin dosing are among the adverse events most frequently reported to the US Food and Drug Administration (FDA) and one of the most common reasons for emergency room visits. 6 Warfarin is often dosed empirically: an initial dose is prescribed, typically followed by at least weekly measurement of the INR and subsequent dose adjustment. The initial dose is often based on population averages (e.g., 3–5 mg/day), but stable doses to achieve an INR of 2–3 can range from 1–20 mg/ day. The iterative process to define the appropriate dose can take weeks to months, and during this period patients are at increased risk of over- or under-anticoagulation and thus at risk of thromboembolism or bleeding.
596 citations
TL;DR: Dosing recommendations for azathioprine, mercaptopurine (MP), and thioguanine based on TPMT genotype are provided and homozygous wild‐type individuals show lower activeThiopurine nucleolides and less myelosuppression.
Abstract: Thiopurine methyltransferase (TPMT) activity exhibits monogenic co-dominant inheritance, with ethnic differences in the frequency of occurrence of variant alleles. With conventional thiopurine doses, homozygous TPMT-deficient patients (~1 in 178 to 1 in 3,736 individuals with two nonfunctional TPMT alleles) experience severe myelosuppression, 30-60% of individuals who are heterozygotes (~3-14% of the population) show moderate toxicity, and homozygous wild-type individuals (~86-97% of the population) show lower active thioguanine nucleolides and less myelosuppression. We provide dosing recommendations (updates at http://www.pharmgkb.org) for azathioprine, mercaptopurine (MP), and thioguanine based on TPMT genotype.
567 citations
TL;DR: Inappropriate prescribing is particularly common in older patients and is associated with adverse drug events (ADEs), hospitalization, and wasteful utilization of resources.
Abstract: Inappropriate prescribing is particularly common in older patients and is associated with adverse drug events (ADEs), hospitalization, and wasteful utilization of resources. We randomized 400 hospitalized patients aged ≥ 65 years to receive either the usual pharmaceutical care (control) or screening with STOPP/START criteria followed up with recommendations to their attending physicians (intervention). The Medication Appropriateness Index (MAI) and Assessment of Underutilization (AOU) index were used to assess prescribing appropriateness, both at the time of discharge and for 6 months after discharge. Unnecessary polypharmacy, the use of drugs at incorrect doses, and potential drug-drug and drug-disease interactions were significantly lower in the intervention group at discharge (absolute risk reduction 35.7%, number needed to screen to yield improvement in MAI = 2.8 (95% confidence interval 2.2-3.8)). Underutilization of clinically indicated medications was also reduced (absolute risk reduction 21.2%, number needed to screen to yield reduction in AOU = 4.7 (95% confidence interval 3.4-7.5)). Significant improvements in prescribing appropriateness were sustained for 6 months after discharge.
451 citations
TL;DR: Recent instances of the use of PBPK in decision‐making during regulatory review are reviewed, based on Center for Drug Evaluation and Research reviews of several submissions for investigational new drugs and new drug applications received between July 2008 and June 2010.
Abstract: Physiologically based pharmacokinetic (PBPK) modeling and simulation is a tool that can help predict the pharmacokinetics of drugs in humans and evaluate the effects of intrinsic (e.g., organ dysfunction, age, genetics) and extrinsic (e.g., drug-drug interactions) factors, alone or in combinations, on drug exposure. The use of this tool is increasing at all stages of the drug development process. This report reviews recent instances of the use of PBPK in decision-making during regulatory review. The examples are based on Center for Drug Evaluation and Research reviews of several submissions for investigational new drugs (INDs) and new drug applications (NDAs) received between July 2008 and June 2010. The use of PBPK modeling and simulation facilitated the following types of decisions: the need to conduct specific clinical pharmacology studies, specific study designs, and appropriate labeling language. The report also discusses the challenges encountered when PBPK modeling and simulation were used in these cases and recommends approaches to facilitating full utilization of this tool.
437 citations
TL;DR: Evidence is provided for the use of CYPC19 genotype–directed antiplatelet therapy in patients with acute coronary syndromes who are receiving clopidogrel, particularly among those undergoing percutaneous coronary intervention (PCI).
Abstract: CYP2C19 is one of the principal enzymes involved in the bioactivation of the antiplatelet prodrug clopidogrel. A common loss-of-function allele, CYP2C19*2 (c.681G>A; rs4244285), is associated with increased risk for serious adverse cardiovascular events in both heterozygous and homozygous patients (~25–50% of the population) with acute coronary syndromes (ACSs) who are receiving clopidogrel, particularly among those undergoing percutaneous coronary intervention (PCI). We provide evidence from published literature and guidelines for CYPC19 genotype–directed antiplatelet therapy (periodically updated at http://www.pharmgkb.org).
434 citations
TL;DR: The effectiveness of behavioral and pharmacological approaches to mitigating weight gain in the context of quitting smoking are reviewed and mechanisms that could potentially account for the effects of smoking and nicotine on body weight are considered.
Abstract: Smokers generally gain weight when they quit smoking; this weight gain can lessen some of the health benefits of quitting smoking. We review the effectiveness of behavioral and pharmacological approaches to mitigating weight gain in the context of quitting smoking and consider mechanisms that could potentially account for the effects of smoking and nicotine on body weight. Understanding how nicotine affects body weight may lead to novel pharmacological and behavioral interventions for obesity as well as concurrent obesity and nicotine dependence.
424 citations
TL;DR: The results indicate that, whereas total approvals are currently at a 25‐year low, the percentage of priority products is nearly 50% of the total—a 30‐year high and provides the underpinnings of a fundamental shift in the structure of the research‐based industry.
Abstract: The first decade of the 21st century was a challenging period for the pharma sector and could prove to be a turning point in the evolution of the industry. We examine drug development performance metrics for new product approvals during 2000-2009 and compare them with those of the prior two decades. The results indicate that, whereas total approvals are currently at a 25-year low, the percentage of priority products is nearly 50% of the total--a 30-year high. Following enactment of the Prescription Drug Use Fee Act of 1992 (PDUFA), the mean duration of the approval phases of drug development declined by more than 1 year over the 30-year period--to a low of 1.2 years in 2005-2009--whereas the duration of the clinical phases increased. The longer clinical phases were due, in part, to a greater number of approved central nervous system (CNS) and antineoplastic agents, two therapeutic classes with relatively long average development times (8.1 and 6.9 years, respectively). The results provide the underpinnings of a fundamental shift in the structure of the research-based industry.
314 citations
TL;DR: The specific roles of ERα and ERβ and the therapeutic potential of ER subtype–selective agonists in bone and metabolic homeostasis, depression, vasomotor symptoms, neurodegenerative diseases, and cancer are reviewed and it must be stated that appropriate clinical studies are necessary to validate these compounds as agents for the prevention and treatment of diseases.
Abstract: Over the past two decades, we have learned that estrogens play important physiological roles not only in women but also in men and that the biological effects of estrogen are mediated by not one but two distinct estrogen receptors (ERs), ERα and ERβ. Our appreciation of the physiological importance of estrogen and the mechanisms by which it acts has significantly increased over the years; however, we are only now beginning to decipher the roles of ERα and ERβ in different organs and to elucidate how selective ligands, acting through either of the two ERs, can prevent or treat various age- or sex-specific diseases. The specific roles of ERα and ERβ and the therapeutic potential of ER subtype-selective agonists in bone and metabolic homeostasis, depression, vasomotor symptoms, neurodegenerative diseases, and cancer are reviewed herein. It must be stated, however, that appropriate clinical studies are necessary to validate these compounds as agents for the prevention and treatment of diseases.
TL;DR: There is a minimal concentration threshold above which endoxifen is effective against the recurrence of breast cancer and that ~80% of tamoxifens takers attain this threshold, according to the Women's Healthy Eating and Living Study.
Abstract: We explored whether breast cancer outcomes are associated with endoxifen and other metabolites of tamoxifen and examined potential correlates of endoxifen concentration levels in serum including cytochrome P450 2D6 (CYP2D6) metabolizer phenotype and body mass index (BMI) Concentration levels of tamoxifen, endoxifen, 4-hydroxytamoxifen (4OH-tamoxifen), and N-desmethyltamoxifen (ND-tamoxifen) were measured from samples taken from 1,370 patients with estrogen receptor (ER)-positive breast cancer who were participating in the Women's Healthy Eating and Living (WHEL) Study We tested these concentration levels for possible associations with breast cancer outcomes and found that breast cancer outcomes were not associated with the concentration levels of tamoxifen, 4-hydroxytamoxifen, and ND-tamoxifen For endoxifen, a threshold was identified, with women in the upper four quintiles of endoxifen concentration appearing to have a 26% lower recurrence rate than women in the bottom quintile (hazard ratio (HR) = 074; 95% confidence interval (CI), (055-100)) The predictors of this higher-risk bottom quintile were poor/intermediate metabolizer genotype, higher BMI, and lower tamoxifen concentrations as compared with the mean for the cohort as a whole This study suggests that there is a minimal concentration threshold above which endoxifen is effective against the recurrence of breast cancer and that ~80% of tamoxifen takers attain this threshold
TL;DR: It is concluded that vaporized cannabis augments the analgesic effects of opioids without significantly altering plasma opioid levels, and may allow for opioid treatment at lower doses with fewer side effects.
Abstract: Cannabinoids and opioids share several pharmacologic properties and may act synergistically. The potential pharmacokinetics and the safety of the combination in humans are unknown. We therefore undertook a study to answer these questions. Twenty-one individuals with chronic pain, on a regimen of twice-daily doses of sustained-release morphine or oxycodone were enrolled in the study and admitted for a 5-day inpatient stay. Participants were asked to inhale vaporized cannabis in the evening of day 1, three times a day on days 2-4, and in the morning of day 5. Blood sampling was performed at 12-h intervals on days 1 and 5. The extent of chronic pain was also assessed daily. Pharmacokinetic investigations revealed no significant change in the area under the plasma concentration-time curves for either morphine or oxycodone after exposure to cannabis. Pain was significantly decreased (average 27%, 95% confidence interval (CI) 9, 46) after the addition of vaporized cannabis. We therefore concluded that vaporized cannabis augments the analgesic effects of opioids without significantly altering plasma opioid levels. The combination may allow for opioid treatment at lower doses with fewer side effects.
TL;DR: The results suggest that a metabolic drug–drug interaction exists betweenclopidogrel and omeprazole but not between clopidOGrel and pantoprazole.
Abstract: Four randomized, placebo-controlled, crossover studies were conducted among 282 healthy subjects to investigate whether an interaction exists between clopidogrel (300-mg loading dose/75-mg/day maintenance dose) and the proton-pump inhibitor (PPI) omeprazole (80 mg) when they are administered simultaneously (study 1); whether the interaction, if any, can be mitigated by administering clopidogrel and omeprazole 12 h apart (study 2) or by increasing clopidogrel to 600-mg loading/150-mg/day maintenance dosing (study 3); and whether the interaction applies equally to the PPI pantoprazole (80 mg) (study 4). Relative to levels after administration of clopidogrel alone in studies 1,2,3, and 4, coadministration of PPI decreased the AUC(0-24) of the clopidogrel active metabolite H4 by 40, 47, 41, and 14% (P ≤ 0.002), respectively; increased maximal platelet aggregation (MPA) induced by 5 micromol/l adenosine diphosphate (ADP) by 8.0, 5.6, 8.1, and 4.3% (P ≤ 0.014), respectively; and increased the vasodilator-stimulated phosphoprotein phosphorylation-platelet reactivity index (VASP-PRI) by 20.7, 27.1, 19.0 (P < 0.0001), and 3.9% (P = 0.3319), respectively. The results suggest that a metabolic drug-drug interaction exists between clopidogrel and omeprazole but not between clopidogrel and pantoprazole.
TL;DR: A better understanding of the mechanisms involved in the resistance of stem cells to chemotherapy could lead to the discovery of new therapeutic targets and improvement of current anticancer strategies.
Abstract: Stem cells possess the dual properties of self-renewal and pluripotency. Self-renewal affords these populations the luxury of self-propagation, whereas pluripotency allows them to produce the multitude of cell types found in the body. Protection of the stem cell population from damage or death is critical because these cells need to remain intact throughout the life of an organism. The principal mechanism of protection is through expression of multifunctional efflux transporters—the adenosine triphosphate–binding cassette (ABC) transporters that are the “guardians” of the stem cell population. Ironically, it has been shown that these ABC efflux pumps also afford protection to cancer stem cells (CSCs), shielding them from the adverse effects of chemotherapeutic insult. It is therefore imperative to gain a better understanding of the mechanisms involved in the resistance of stem cells to chemotherapy, which could lead to the discovery of new therapeutic targets and improvement of current anticancer strategies.
Clinical Pharmacology & Therapeutics (2011) 89 4, 491–502. doi:10.1038/clpt.2011.14
TL;DR: Among the poor metabolizers, 93% had (Z)‐endoxifen levels below IC90 values, underscoring the role of CYP2D6 deficiency in compromised tamoxIFen bioactivation, and carriers of reduced‐function CYp2C9 (*2, *3) alleles had lower plasma concentrations of active metabolites (P < 0.004), pointing to the roleof additional pathways.
Abstract: The therapeutic effect of tamoxifen depends on active metabolites, e.g., cytochrome P450 2D6 (CYP2D6) mediated formation of endoxifen. To test for additional relationships, 236 breast cancer patients were genotyped for CYP2D6, CYP2C9, CYP2B6, CYP2C19, CYP3A5, UGT1A4, UGT2B7, and UGT2B15; also, plasma concentrations of tamoxifen and 22 of its metabolites, including the (E)-, (Z)-, 3-, and 4′-hydroxymetabolites as well as their glucuronides, were quantified using liquid chromatography–tandem mass spectrometry (MS). The activity levels of the metabolites were measured using an estrogen response element reporter assay; the strongest estrogen receptor inhibition was found for (Z)-endoxifen and (Z)-4-hydroxytamoxifen (inhibitory concentration 50 (IC50) 3 and 7 nmol/l, respectively). CYP2D6 genotypes explained 39 and 9% of the variability of steady-state concentrations of (Z)-endoxifen and (Z)-4-hydroxytamoxifen, respectively. Among the poor metabolizers, 93% had (Z)-endoxifen levels below IC90 values, underscoring the role of CYP2D6 deficiency in compromised tamoxifen bioactivation. For other enzymes tested, carriers of reduced-function CYP2C9 (*2, *3) alleles had lower plasma concentrations of active metabolites (P < 0.004), pointing to the role of additional pathways.
Clinical Pharmacology & Therapeutics (2011) 89 5, 708–717. doi:10.1038/clpt.2011.27
TL;DR: Agents with the strongest supporting evidence for efficacy in the treatment of CIPN include topical pain relievers, and serotonin and norepinephrine reuptake inhibitors, such as venlafaxine and duloxetine.
Abstract: Chemotherapy-induced peripheral neuropathy (CIPN) is a common, dose-limiting side effect of many chemotherapeutic agents. Although many therapies have been investigated for the prevention and/or treatment of CIPN, there is no well-accepted proven therapy. In addition, there is no universally accepted, well-validated measure for the assessment of CIPN. The agents for which there are the strongest preliminary data regarding their potential efficacy in preventing CIPN are intravenous calcium and magnesium (Ca/Mg) infusions and glutathione. Agents with the strongest supporting evidence for efficacy in the treatment of CIPN include topical pain relievers, such as baclofen/amitriptyline/ketamine gel, and serotonin and norepinephrine reuptake inhibitors, such as venlafaxine and duloxetine. Other promising therapies are also reviewed in this paper. Cutaneous electrostimulation is a nonpharmacological therapy that appears, from an early pilot trial, to be potentially effective in the treatment of CIPN. Finally, there is a lack of evidence of effective treatments for the paclitaxel acute pain syndrome (P-APS), which appears to be caused by neurologic injury.
TL;DR: This review focuses on the recent advancements in iPSC technology including disease modeling and control setting in its analytical paradigm and discusses the potential of i PSC technology in personalized medicine.
Abstract: Induced pluripotent stem cell (iPSC) technology is revolutionizing medical science, allowing the exploration of disease mechanisms and novel therapeutic molecular targets, and offering opportunities for drug discovery and proof-of-concept studies in drug development. This review focuses on the recent advancements in iPSC technology including disease modeling and control setting in its analytical paradigm. We describe how iPSC technology is integrated into existing paradigms of drug development and discuss the potential of iPSC technology in personalized medicine.
TL;DR: Exposure to simvastatin was significantly reduced at 1 and 5 weeks after tocilizumab infusion in 12 patients with RA, and the time course of tocilIZumab's CRP‐reducing effect paralleled that of simVastatin pharmacokinetics.
Abstract: In rheumatoid arthritis (RA), interleukin-6 (IL-6) concentration is elevated, which may cause reduced cytochrome P450 (CYP) activity and increased exposure (peak plasma concentration and area under the plasma concentration-vs.-time curve (AUC)) to certain drugs. Tocilizumab may reverse IL-6-induced suppression of CYP3A4 activity. In this study, exposure to simvastatin was significantly reduced at 1 and 5 weeks after tocilizumab infusion in 12 patients with RA. The mean effect ratio for simvastatin AUC(last) was 43% (90% confidence interval (CI), 34-55%) at 1 week after tocilizumab infusion (day 15) and 61% (90% CI, 47-78%) at 5 weeks after tocilizumab infusion, as compared with baseline (day 1); both ratios were significantly lower than the bioequivalence boundary (80-125%). Mean plasma C-reactive protein (CRP) levels normalized within 1 week after tocilizumab was initiated; the time course of tocilizumab's CRP-reducing effect paralleled that of simvastatin pharmacokinetics. The study findings suggest that caution should be exercised when starting tocilizumab in RA patients who are taking simvastatin.
TL;DR: This microdose study quantitatively predicted a drug–drug interaction involving the renal clearance of metformin at ThD by pyrimethamine, which is a useful in vivo inhibitor of MATE proteins.
Abstract: A microdose study of metformin was conducted to investigate the predictability of drug-drug interactions at the therapeutic dose (ThD). Healthy subjects received a microdose (100 µg) or ThD (250 mg) of metformin orally, with or without a potent and competitive multidrug and toxin extrusion (MATE) inhibitor, pyrimethamine (50 mg, p.o.), in a crossover fashion. Pyrimethamine significantly reduced the renal clearance of metformin by 23 and 35% at the microdose and ThD, respectively. At ThD, but not at microdose, it caused significant increases in the maximum concentration (C(max)) and area under the plasma concentration-time curve (AUC) of metformin (142 and 139% of control values, respectively). Human canalicular membrane vesicles showed pyrimethamine-inhibitable metformin uptake. Pyrimethamine did not affect plasma lactate/pyruvate after ThD of metformin but significantly reduced the renal clearance of creatinine, thereby causing elevation of plasma creatinine level. This microdose study quantitatively predicted a drug-drug interaction involving the renal clearance of metformin at ThD by pyrimethamine. Pyrimethamine is a useful in vivo inhibitor of MATE proteins.
TL;DR: It is found that pravastatin and paroxetine, when administered together, had a synergistic effect on blood glucose, which is not a general effect of combined therapy with selective serotonin reuptake inhibitors (SSRIs) and statins.
Abstract: The lipid-lowering agent pravastatin and the antidepressant paroxetine are among the most widely prescribed drugs in the world. Unexpected interactions between them could have important public health implications. We mined the US Food and Drug Administration's (FDA's) Adverse Event Reporting System (AERS) for side-effect profiles involving glucose homeostasis and found a surprisingly strong signal for comedication with pravastatin and paroxetine. We retrospectively evaluated changes in blood glucose in 104 patients with diabetes and 135 without diabetes who had received comedication with these two drugs, using data in electronic medical record (EMR) systems of three geographically distinct sites. We assessed the mean random blood glucose levels before and after treatment with the drugs. We found that pravastatin and paroxetine, when administered together, had a synergistic effect on blood glucose. The average increase was 19 mg/dl (1.0 mmol/l) overall, and in those with diabetes it was 48 mg/dl (2.7 mmol/l). In contrast, neither drug administered singly was associated with such changes in glucose levels. An increase in glucose levels is not a general effect of combined therapy with selective serotonin reuptake inhibitors (SSRIs) and statins.
TL;DR: It is suggested that common genetic variants selected for an extreme phenotype of statin‐induced myopathy also predispose to more common milder statin intolerance and may, for this reason, impact lipid‐lowering efficacy.
Abstract: SLCO1B1 gene variants are associated with severe statin-induced myopathy. We examined whether these variants are also associated with general statin intolerance in a large population of patients with type 2 diabetes receiving statins as part of routine clinical care. A total of 4,196 individuals were genotyped for rs4149056 (Val174Ala) and rs2306283 (Asp130Asn). Intolerance was defined by serum biochemistry and also by discontinuation, switching, or reduction in dose of the prescribed statin drug. Ala174 was associated with higher intolerance (odds ratio = 2.05, P = 0.043), whereas Asp130 was associated with lower intolerance (odds ratio = 0.71, P = 0.026). Ala174 was associated with a lower low-density lipoprotein cholesterol (LDLc) response to statins (P = 0.01) whereas 130D was associated with a greater LDLc response to statins (P = 0.048), as previously reported; however, this association was no longer present when data for statin-intolerant individuals were removed from the analysis. This study suggests that common genetic variants selected for an extreme phenotype of statin-induced myopathy also predispose to more common milder statin intolerance and may, for this reason, impact lipid-lowering efficacy.
TL;DR: It is indicated that hepatic uptake via OATPs makes the dominant contribution to the hepatic elimination of atorvastatin at a subtherapeutic microdose.
Abstract: Clearance of atorvastatin occurs through hepatic uptake by organic anion transporting polypeptides (OATPs) and subsequent metabolism by cytochrome P450 (CYP) 3A4. To demonstrate the relative importance of OATPs and CYP3A4 in the hepatic elimination of atorvastatin in vivo, a clinical cassette microdose study was performed. A cocktail consisting of a microdose of atorvastatin along with probe substrates for OATPs (pravastatin) and CYP3A4 (midazolam) was orally administered to eight healthy volunteers. The pharmacokinetics of this cocktail was observed at baseline, after an oral dose of 600 mg rifampicin (an inhibitor of OATPs), and after an intravenous dose of 200 mg itraconazole (a CYP3A4 inhibitor). Rifampicin increased the pravastatin dose-normalized area under the plasma concentration-time curve (AUC) (4.6-fold), and itraconazole significantly increased the midazolam dose-normalized AUC (1.7-fold). The atorvastatin dose-normalized AUC increased 12-fold when coadministered with rifampicin but did not change when coadministered with itraconazole. These results indicate that hepatic uptake via OATPs makes the dominant contribution to the hepatic elimination of atorvastatin at a subtherapeutic microdose.
TL;DR: This review explores each of these translational mechanisms within a historical framework for the field of pharmacogenomics through three distinct mechanisms: retrospective assessment of previously known findings in a clinical practice‐based setting, discovery of new associations in huge observational cohorts, and prospective application in a setting capable of providing real‐time decision support.
Abstract: Health-care information technology and genotyping technology are both advancing rapidly, creating new opportunities for medical and scientific discovery. The convergence of these two technologies is now facilitating genetic association studies of unprecedented size within the context of routine clinical care. As a result, the medical community will soon be presented with a number of novel opportunities to bring functional genomics to the bedside in the area of pharmacotherapy. By linking biological material to comprehensive medical records, large multi-institutional biobanks are now poised to advance the field of pharmacogenomics through three distinct mechanisms: (i) retrospective assessment of previously known findings in a clinical practice-based setting, (ii) discovery of new associations in huge observational cohorts, and (iii) prospective application in a setting capable of providing real-time decision support. This review explores each of these translational mechanisms within a historical framework.
TL;DR: A mix of approaches are proposed to generate comparative‐effectiveness data in the early marketing period, including sequential cohort monitoring with secondary health‐care data and propensity score (PS) balancing, as well as extended follow‐up of phase III and phase IV trials, indirect comparisons of placebo‐controlled trials, and modeling and simulation of virtual trials.
Abstract: Comparative-effectiveness research (CER) aims to produce actionable evidence regarding the effectiveness and safety of medical products and interventions as they are used outside of controlled research settings. Although CER evidence regarding medications is particularly needed shortly after market approval, key methodological challenges include (i) potential bias due to channeling of patients to the newly marketed medication because of various patient-, physician-, and system-related factors; (ii) rapid changes in the characteristics of the user population during the early phase of marketing; and (iii) lack of timely data and the often small number of users in the first few months of marketing. We propose a mix of approaches to generate comparative-effectiveness data in the early marketing period, including sequential cohort monitoring with secondary health-care data and propensity score (PS) balancing, as well as extended follow-up of phase III and phase IV trials, indirect comparisons of placebo-controlled trials, and modeling and simulation of virtual trials.
University of Minnesota1, University of Wisconsin-Madison2, Oregon Health & Science University3, Harvard University4, University of Maryland, College Park5, University of Connecticut Health Center6, University of California, Los Angeles7, University of California, San Francisco8, Nabi Biopharmaceuticals9, University of Nebraska Medical Center10
TL;DR: It is demonstrated, as proof of concept, that 3′AmNic‐rEPA elicits Abs to nicotine and is associated with higher continuous abstinence rates (CAR) and its further development as a treatment for nicotine dependence is justified.
Abstract: NicVAX, a nicotine vaccine (3'AmNic-rEPA), has been clinically evaluated to determine whether higher antibody (Ab) concentrations are associated with higher smoking abstinence rates and whether dosages and frequency of administration are associated with increased Ab response. This randomized, double-blinded, placebo-controlled multicenter clinical trial (N = 301 smokers) tested the results of 200- and 400-µg doses administered four or five times over a period of 6 months, as compared with placebo. 3'AmNic-rEPA recipients with the highest serum antinicotine Ab response (top 30% by area under the curve (AUC)) were significantly more likely than the placebo recipients (24.6% vs. 12.0%, P = 0.024, odds ratio (OR) = 2.69, 95% confidence interval (CI), 1.14-6.37) to attain 8 weeks of continuous abstinence from weeks 19 through 26. The five-injection, 400-µg dose regimen elicited the greatest Ab response and resulted in significantly higher abstinence rates than placebo. This study demonstrates, as proof of concept, that 3'AmNic-rEPA elicits Abs to nicotine and is associated with higher continuous abstinence rates (CAR). Its further development as a treatment for nicotine dependence is therefore justified.
TL;DR: The regulatory guidances, the newly approved molecular entity drug products, and drug product labels in the Physician's Desk Reference are surveyed to gain a better understanding of the impact of obesity on drug therapy.
Abstract: Obesity has become a worldwide challenge with significant health and socioeconomic implications. One of the major implications is its impact on drug therapy. In order to gain a better understanding of this impact, we surveyed the regulatory guidances, the newly approved molecular entity drug products, and drug product labels in the Physician's Desk Reference. This review summarizes the findings of the survey along with the existing knowledge on pharmacokinetic and pharmacodynamic changes associated with obesity.
TL;DR: Placental perfusion experiments can be used to predict placental drug transfer when adjusting for extra parameters and can be useful for assessing drug therapy risks and benefits in pregnancy and to develop a pharmacokinetic model to account for nonplacental Pharmacokinetic parameters in the perfusion results.
Abstract: Dual perfusion of a single placental lobule is the only experimental model to study human placental transfer of substances in organized placental tissue. To date, there has not been any attempt at a systematic evaluation of this model. The aim of this study was to systematically evaluate the perfusion model in predicting placental drug transfer and to develop a pharmacokinetic model to account for nonplacental pharmacokinetic parameters in the perfusion results. In general, the fetal-to-maternal drug concentration ratios matched well between placental perfusion experiments and in vivo samples taken at the time of delivery of the infant. After modeling for differences in maternal and fetal/neonatal protein binding and blood pH, the perfusion results were able to accurately predict in vivo transfer at steady state (R² = 0.85, P < 0.0001). Placental perfusion experiments can be used to predict placental drug transfer when adjusting for extra parameters and can be useful for assessing drug therapy risks and benefits in pregnancy.
TL;DR: This review provides an overview of studies assessing the clinical utility of various biomarkers on the basis of hypothesis‐driven selection as well as hypothesis‐free approaches from novel “‐omics” technologies.
Abstract: Risk prediction for type 2 diabetes (T2D) and cardiovascular disease (CVD) remains suboptimal even after the introduction of global risk assessment by various scores. This has prompted the search for additional biomarkers. A variety of blood biomarkers representing various pathophysiological pathways of insulin resistance and atherosclerosis, as well as markers of subclinical disease and genetic markers, have been investigated. This review provides an overview of studies assessing the clinical utility of various biomarkers on the basis of hypothesis-driven selection as well as hypothesis-free approaches from novel "-omics" technologies. So far, the assessment of genotypes and of several candidate biomarkers from blood has resulted in only small improvements in the accuracy of prediction of CVD and T2D over and above that predicted on the basis of established risk factors. Integrated approaches, combining biomarkers from genomics, transcriptomics, proteomics, and metabolomics, as well as serial measurements of biomarkers, are required to make a complete assessment of the potential clinical usefulness of biomarkers for risk prediction of cardiometabolic disease.
TL;DR: Isoniazid (INH)‐induced hepatotoxicity remains a significant clinical problem, and the current mechanistic hypothesis is incomplete; it is believed to involve cytotoxicity caused by bioactivation of acetylhydrazine, a metabolite of INH.
Abstract: Chara C teristi C s of i nh- i ndu C ed h epatotoxi C ity INH remains a mainstay for the treatment of tuberculosis; however, its use is associated with serious hepatotoxicity and potentially fatal liver injury. 3 Hepatotoxicity is often associ ated with nausea and right upper-quadrant abdominal pain; however, it can also be asymptomatic, and diagnosis depends on measuring serum levels of bilirubin and the liver enzyme alanine aminotransferase (ALT). 3,4 The use of INH is asso ciated with elevated serum levels of ALT in up to 20% of patients, whereas overt hepatotoxicity can occur in up to 1% of patients. 3–5 There is virtually always a delay between starting