Potential genetic causes of heterogeneity of treatment effects

Increased risk of hearing loss associated with macrolide use: a systematic review and meta-analysis

The increased risk of hearing loss with macrolides remains controversial. We aimed to systematically review and meta-analyze data on the clinical risk of hearing loss, tinnitus, and ototoxicity following macrolide use. A systematic search was conducted across PubMed, MEDLINE, Cochrane, and Embase databases from database inception to May 2023. Medical Subject Heading (MeSH) terms and text keywords were utilized, without any language restrictions. In addition to the electronic databases, two authors manually and independently searched for relevant studies in the US and European clinical trial registries and Google Scholar. Studies that involved (1) patients who had hearing loss, tinnitus, or ototoxicity after macrolide use, (2) intervention of use of macrolides such as azithromycin, clarithromycin, erythromycin, fidaxomicin, roxithromycin, spiramycin, and/or telithromycin, (3) comparisons with specified placebos or other antibiotics, (4) outcomes measured as odds ratio (OR), relative risk (RR), hazard ratio (HR), and mean difference for ototoxicity symptoms using randomized control trial (RCT)s and observational studies (case-control, cross-section, and cohort studies) were included. Data extraction was performed independently by two extractors, and a crosscheck was performed to identify any errors. ORs along with their corresponding 95% confidence intervals (CIs) were estimated using random-effects models. The Preferred Reporting Items for Systematic Reviews and Meta-analyses reporting guidelines for RCTs and Meta-Analysis of Observational Studies in Epidemiology guidelines for observational studies were followed. We assessed the hearing loss risk after macrolide use versus controls (placebos and other antibiotics). Based on data from 13 studies including 1,142,021 patients (n = 267,546 for macrolide and n = 875,089 for controls), the overall pooled OR was 1.25 (95% CI 1.07-1.47). In subgroup analysis by study design, the ORs were 1.37 (95% CI 1.08-1.73) for RCTs and 1.33 (95% CI 1.24-1.43) for case-control studies, indicating that RCT and case-control study designs showed a statistically significant higher risk of hearing loss. The group with underlying diseases such as multiple infectious etiologies (OR, 1.16 [95% CI 0.96-1.41]) had a statistically significant lower risk than the group without (OR, 1.53 [95% CI 1.38-1.70] P = .013). The findings from this systematic review and meta-analysis suggest that macrolide antibiotics increase the risk of hearing loss and that healthcare professionals should carefully consider this factor while prescribing macrolides.

Assessing heterogeneity of treatment effect in multiple sclerosis trials

Multiple sclerosis (MS) is heterogeneous with respect to outcomes, and evaluating possible heterogeneity of treatment effect (HTE) is of high interest. HTE is non-random variation in the magnitude of a treatment effect on a clinical outcome across levels of a covariate (i.e. a patient attribute or set of attributes). Multiple statistical techniques can evaluate HTE. The simplest but most bias-prone is conventional one variable-at-a-time subgroup analysis. Recently, multivariable predictive approaches have been promoted to provide more patient-centered results, by accounting for multiple relevant attributes simultaneously. We review approaches used to estimate HTE in clinical trials of MS.

VARIANTS OF THE FORMATION AND COURSE OF DRUG-RESISTANT EPILEPSY IN CHILDREN WITH GENETIC POLYMORPHISMS OF CYP2C9, CYP2C19, CYP3A4

OBJECTIVE

The aim: To clarify the frequency with which various variants of the formation and course of drug-resistant epilepsy occur in children with genetic polymor¬phisms of cytochromes CYP2C9, CYP2C19, CYP3A4.

PATIENTS AND METHODS

Materials and methods: The genotyping of CYP2C9*2, CYP2C9*3, CYP2C19*2, CYP3A4*1B by the allele-specific polymerase chain reaction was performed in 116 children with drug-resistant epilepsy aged from 2 to 17 years. Thirty cases (boys-15; girls-15) with a follow-up period of more than 5 years were analyzed in detail.

RESULTS

Results: Of 30 cases analyzed, polymorphisms were not detected in 8 (26.67%) children, and 22 (73.33%) had polymorphisms of the CYP2C9, CYP2C19 and CYP3A4 genes associated with a slow metabolism of AED. In children with polymorphisms of the CYP450 genes, the wave-like course of the disease with the periods of remission and its failures was characteristic, while for children with a presumably normal metabolism there was the initial resistance to the treatment with AED.

CONCLUSION

Conclusions: Individual changes in the AED metabolism affect the course of drug-resistant epilepsies. For patients with a slow metabolism of AED the wave-like course of the disease and the "slipping off" phenomenon were more characteristic.

Computational medicine, present and the future: obstetrics and gynecology perspective

Medicine is, in its essence, decision making under uncertainty; the decisions are made about tests to be performed and treatments to be administered. Traditionally, the uncertainty in decision making was handled using expertise collected by individual providers and, more recently, systematic appraisal of research in the form of evidence-based medicine. The traditional approach has been used successfully in medicine for a very long time. However, it has substantial limitations because of the complexity of the system of the human body and healthcare. The complex systems are a network of highly coupled components intensely interacting with each other. These interactions give those systems redundancy and thus robustness to failure and, at the same time, equifinality, that is, many different causative pathways leading to the same outcome. The equifinality of the complex systems of the human body and healthcare system demand the individualization of medical care, medicine, and medical decision making. Computational models excel in modeling complex systems and, consequently, enabling individualization of medical decision making and medicine. Computational models are theory- or knowledge-based models, data-driven models, or models that combine both approaches. Data are essential, although to a different degree, for computational models to successfully represent complex systems. The individualized decision making, made possible by the computational modeling of complex systems, has the potential to revolutionize the entire spectrum of medicine from individual patient care to policymaking. This approach allows applying tests and treatments to individuals who receive a net benefit from them, for whom benefits outweigh the risk, rather than treating all individuals in a population because, on average, the population benefits. Thus, the computational modeling-enabled individualization of medical decision making has the potential to both improve health outcomes and decrease the costs of healthcare.

Lack of association of SCN2A rs17183814 polymorphism with the efficacy of lamotrigine monotherapy in patients with focal epilepsy from Herzegovina area, Bosnia and Herzegovina

OBJECTIVE

We assessed the influence of the SCN2A gene polymorphism c.56 G > A rs17183814 on the response to lamotrigine monotherapy in patients with focal epilepsy in Herzegovina area, Bosnia and Herzegovina.

MATERIAL AND METHODS

For SCN2A polymorphism c.56 G > A rs17183814, one hundred patients with epilepsy who were receiving lamotrigine in monotherapy and seventy-one age and sex matched healthy controls were genotyped using TaqMan assay. All patients were Caucasians from the region of Herzegovina, Bosnia and Herzegovina. Genotyping was conducted using a polymerase chain reaction in real time. Patients were divided into two groups: responders and non-responders.

RESULTS

Of all patients with epilepsy, 33% were non-responders, and 67% were responders. The mean age of non-responders was 38.8 vs. group of responders in which it was 35.2. Mean age of onset of seizures in epilepsy patients was 26.7 for non-responders and 25.4 for responders. In patients with epilepsy, the mean age of seizure onset was 26.7 for non-responders and 25.4 for responders. For SCN2A c.56 G > A gene polymorphism, we did not observe any significant differences in genotypic or allelic frequency between patients with epilepsy and healthy controls. Genotype or allelic frequencies of SCN2A c.56 G > A gene polymorphism did not significantly differ for AG or GG genotypes in the non-responders vs. responders.

CONCLUSION

There was no significant association in patients with focal epilepsy between studied genotypes and response to lamotrigine monotherapy in Herzegovina patients with focal epilepsy. However, we need studies in a bigger cohort of patients with epilepsy to be assessed in the future.

A Systems Biology Approach for Personalized Medicine in Refractory Epilepsy

Epilepsy refers to a common chronic neurological disorder that affects all age groups. Unfortunately, antiepileptic drugs are ineffective in about one-third of patients. The complex interindividual variability influences the response to drug treatment rendering the therapeutic failure one of the most relevant problems in clinical practice also for increased hospitalizations and healthcare costs. Recent advances in the genetics and neurobiology of epilepsies are laying the groundwork for a new personalized medicine, focused on the reversal or avoidance of the pathophysiological effects of specific gene mutations. This could lead to a significant improvement in the efficacy and safety of treatments for epilepsy, targeting the biological mechanisms responsible for epilepsy in each individual. In this review article, we focus on the mechanism of the epilepsy pharmacoresistance and highlight the use of a systems biology approach for personalized medicine in refractory epilepsy.

Association of SCN1A gene polymorphism with antiepileptic drug responsiveness in the population of Thrace, Greece

INTRODUCTION

The aim was to examine the influence of the SCN1A gene polymorphism IVS5-91 rs3812718 G>A on the response to antiepileptic drugs (AEDs) in monotherapy or polytherapy.

MATERIAL AND METHODS

Two hundred epilepsy patients and 200 healthy subjects were genotyped for SCN1A IVS5-91 rs3812718 G>A polymorphism using TaqMan assay. Patients were divided into drug-responsive and drug-resistant patients. The drug-responsive group was further studied, comparing monotherapy in maximum and minimum doses and monotherapy-responsive and -resistant groups.

RESULTS

There were no statistically significant differences in the allelic frequencies and genotype distributions between patients and controls (p = 0.178). The distribution of SCN1A IVS5-91 rs3812718 G>A genotypes was similar between drug-responsive and drug-resistant patients (p = 0.463). The differences in genotype distributions (A/A or A/G vs. G/G) between monotherapy-responsive and -resistant groups were statistically significant (p = 0.021). Within the monotherapy-responsive group, patients with the A/A or A/G genotype needed higher dose AEDs than patients with the G/G genotype (p = 0.032). The relative risk for generalized epilepsy due to A-containing genotypes was of marginal statistical significance when compared with the G/G genotype (p = 0.05).

CONCLUSIONS

Overall, our findings demonstrate an association of SCN1A IVS5-91 rs3812718 G>A polymorphism with AED responsiveness in monotherapy without evidence of an effect on drug-resistant epilepsy.

Integration of Genomics in Primary Care

Primary care is changing rapidly. The wide-scale expansion of electronic medical records is redefining the way we approach chronic disease management, and automated decision support is increasingly being leveraged to reduce risk and optimize quality. Many of these interventions are now beginning to integrate genomic data. We explore the convergence of these 2 forces (expansion of clinical informatics and integration of translational genomics), and we highlight several applications where these forces are helping our patients avoid potentially preventable events. Because gene-environment interactions are dynamic, the utility of gene-based decision support varies over time. Primary care providers will serve a key role as our patients navigate these changes.

COMT polymorphism modulates the resting-state EEG alpha oscillatory response to acute nicotine in male non-smokers

Performance improvements in cognitive tasks requiring executive functions are evident with nicotinic acetylcholine receptor (nAChR) agonists, and activation of the underlying neural circuitry supporting these cognitive effects is thought to involve dopamine neurotransmission. As individual difference in response to nicotine may be related to a functional polymorphism in the gene encoding catechol-O-methyltransferase (COMT), an enzyme that strongly influences cortical dopamine metabolism, this study examined the modulatory effects of the COMT Val158Met polymorphism on the neural response to acute nicotine as measured with resting-state electroencephalographic (EEG) oscillations. In a sample of 62 healthy non-smoking adult males, a single dose (6 mg) of nicotine gum administered in a randomized, double-blind, placebo-controlled design was shown to affect α oscillatory activity, increasing power of upper α oscillations in frontocentral regions of Met/Met homozygotes and in parietal/occipital regions of Val/Met heterozygotes. Peak α frequency was also found to be faster with nicotine (vs. placebo) treatment in Val/Met heterozygotes, who exhibited a slower α frequency compared to Val/Val homozygotes. The data tentatively suggest that interindividual differences in brain α oscillations and their response to nicotinic agonist treatment are influenced by genetic mechanisms involving COMT.

Pharmacogenetics in schizophrenia: a review of clozapine studies

OBJECTIVES

Clozapine is quite effective to treat schizophrenia, but its use is complicated by several factors. Although many patients respond to antipsychotic therapy, about 50% of them exhibit inadequate response, and ineffective medication trials may entail weeks of unremitted illness, potential adverse drug reactions, and treatment nonadherence. This review of the literature sought to describe the main pharmacogenetic studies of clozapine and the genes that potentially influence response to treatment with this medication in schizophrenics.

METHODS

We searched the PubMed database for studies published in English in the last 20 years using keywords related to the topic.

RESULTS AND CONCLUSIONS

Our search yielded 145 studies that met the search and selection criteria. Of these, 21 review articles were excluded. The 124 studies included for analysis showed controversial results. Therefore, efforts to identify key gene mechanisms that will be useful in predicting clozapine response and side effects have not been fully successful. Further studies with new analysis approaches and larger sample sizes are still required.

Bortezomib and heart failure: case-report and review of the French Pharmacovigilance database

Bortezomib is a proteasome inhibitor commonly indicated for the treatment of multiple myeloma and non Hodgkin lymphoma. Cardiac adverse drug reactions of this drug are not clearly established. We report case where direct involvement of bortezomib in the occurrence of heart failure is strongly suspected and 22 other cases spontaneously reported to the French Pharmacovigilance System. This report should increase cardiologist awareness about the risk of heart failure related to this drug. Moreover, these cases underline the need for a systematic cardiac screening in patients exposed to bortezomib.

The long-term safety of antiepileptic drugs

Antiepileptic drugs (AEDs) are used by millions of people worldwide for the treatment of epilepsy, as well as in many other neurological and psychiatric conditions. They are frequently associated with adverse effects (AEs), which have an impact on the tolerability and success of treatment. Half the people who develop intolerable AEs discontinue treatment early on after initiation, while the majority of people will continue to be exposed to their effects for long periods of time. The long-term safety of AEDs reflects their potential for chronic, cumulative dose effects; rare, but potentially serious late idiosyncratic effects; late, dose-related effects; and delayed, teratogenic or neurodevelopmental effects. These AEs can affect every body system and are usually insidious. With the exception of delayed effects, most other late or chronic AEs are reversible. To date, there is no clear evidence of a carcinogenic effect of AEDs in humans. While physicians are aware of the long-term AEs of old AEDs (the traditional liver enzyme-inducing AEDs and valproate), information about AEs of new AEDs (such as lamotrigine, levetiracetam, oxcarbazepine, topiramate or zonisamide), particularly of their teratogenic effects, has emerged over the years. Sporadic publications have raised issues about AEs of the newer AEDs eslicarbazepine, retigabine, rufinamide, lacosamide and perampanel but their long-term safety profiles may take years to be fully appreciated. Physicians should not only be aware of the late and chronic AEs of AEDs but should systematically enquire and screen for these according to the individual AED AE profile. Care should be taken for individuals with comorbid conditions that may render them more susceptible to specific AEs. Prevention and appropriate management of long-term AED AEs is expected to improve adherence to treatment, quality of life and control of epilepsy.

Identifying early events of gene expression in breast cancer with systems biology phylogenetics

Advanced omics technologies such as deep sequencing and spectral karyotyping are revealing more of cancer heterogeneity at the genetic, genomic, gene expression, epigenetic, proteomic, and metabolomic levels. With this increasing body of emerging data, the task of data analysis becomes critical for mining and modeling to better understand the relevant underlying biological processes. However, the multiple levels of heterogeneity evident within and among populations, healthy and diseased, complicate the mining and interpretation of biological data, especially when dealing with hundreds to tens of thousands of variables. Heterogeneity occurs in many diseases, such as cancers, autism, macular degeneration, and others. In cancer, heterogeneity has hampered the search for validated biomarkers for early detection, and it has complicated the task of finding clonal (driver) and nonclonal (nonexpanded or passenger) aberrations. We show that subtyping of cancer (classification of specimens) should be an a priori step to the identification of early events of cancers. Studying early events in oncogenesis can be done on histologically normal tissues from diseased individuals (HNTDI), since they most likely have been exposed to the same mutagenic insults that caused the cancer in their neighboring tissues. Polarity assessment of HNTDI data variables by using healthy specimens as outgroup(s), followed by the application of parsimony phylogenetic analysis, produces a hierarchical classification of specimens that reveals the early events of the disease ontogeny within its subtypes as shared derived changes (abnormal changes) or synapomorphies in phylogenetic terminology.

Concept-based learning of personalized prescribing

The variability of drug response in different patients can be caused by various factors including age, change in renal function, co-medication and genotype. Traditionally, these personal variables are considered by clinicians prior to issuing a prescription. This paper provides an overview of a process to individualize prescribing for a patient with an emphasis on how to train (learning) clinicians in skillful rational prescribing. For this purpose the 6STEP methodology, a concept-based learning strategy to achieve a structured therapeutic plan, has been introduced. In contrast to older educational approaches which focused primarily on the drugs or the process of prescribing, the 6STEP is a patient-centred method resulting in individualized therapy. The six interlinked steps provide the (training) prescriber with a structured framework that facilitates a rationalized therapeutic decision by focusing on the individual patient parameters that influence drug response. Educational tools for rational prescribing involve understanding of basic and clinical pharmacological principles, practicing to write 6STEP therapeutic plans, learning from feedback sessions on these plans and actively obtaining up to date information on drugs and therapeutic standards from online resources.

Liver expression quantitative trait loci: a foundation for pharmacogenomic research

Expression quantitative trait loci (eQTL) analysis can provide insights into the genetic regulation of gene expression at a genomic level and this information is proving extremely useful in many different areas of research. As a consequence of the role of the liver in drug metabolism and disposition, the study of eQTLs in primary human liver tissue could provide a foundation for pharmacogenomics. Thus far, four genome-wide eQTL studies have been performed using human livers. Many liver eQTLs have been found to be reproducible and a proportion of these may be specific to the liver. Already these data have been used to interpret and inform clinic genome-wide association studies, providing potential mechanistic evidence for clinical associations and identifying genes which may impact clinical phenotypes. However, the utility of liver eQTL data has not yet been fully explored or realized in pharmacogenomics. As further liver eQTL research is undertaken, the genetic regulation of gene expression will become much better characterized and this knowledge will create a rational basis for the prospective pharmacogenomic study of many drugs.

Clinical experience with daptomycin in Europe: the first 2.5 years

Objectives

To describe the patient populations and infections being treated with daptomycin, as well as the efficacy and safety outcomes.

Patients and methods

Data from the European Cubicin Outcomes Registry and Experience (EU-CORE^SM), retrospectively collected at 118 institutions between January 2006 and August 2008, were analysed.

Results

Daptomycin treatment was documented in 1127 patients with diverse infections, including complicated skin and soft tissue infections (33%), bacteraemia (22%), endocarditis (12%) and osteomyelitis (6%). It was used empirically, before microbiological results became available, in 53% of patients. Staphylococcus aureus was the most common pathogen (34%), with 52% of isolates resistant to methicillin; coagulase-negative staphylococci and enterococci were also frequent, with 22% of Enterococcus faecium isolates resistant to vancomycin. Daptomycin was used as first-line therapy in 302 (27%) patients. When used second line, the most common reasons for discontinuation of previous antibiotic were treatment failure and toxicity or intolerance. The use of concomitant antibiotics was reported in 65% of patients. Most frequent doses were 6 mg/kg (47%) and 4 mg/kg (32%). The median duration of daptomycin therapy was 10 days (range 1–246 days) in the inpatient setting and 13 days (range 2–189 days) in the outpatient setting. The overall clinical success rate was 79%, with a clinical failure rate of <10% for all infection types. Low failure rates were observed in first- and second-line therapy (6% and 8%, respectively). Daptomycin demonstrated a favourable safety and tolerability profile regardless of treatment duration.

Conclusions

Daptomycin has a relevant role in the treatment of Gram-positive infections.

Can we predict which patient will fail drug treatment for overactive bladder? A think tank discussion

The treatment of overactive bladder (OAB) has evolved over the past 20 years to include a number of behavioral, pharmacological, and minimally invasive treatments. After behavioral therapy, pharmacological therapy with antimuscarinics remains the mainstay of treatment. Despite this, a large number of patients will "fail" or be unsatisfied with drugs therapy. It would be extremely helpful to patients and clinicians to be able to predict who those patients are. However, there are a number of barriers. First and foremost are defining "success" and "failure" and this can vary dramatically from one patient to another. Endpoints other than the traditional variables used in clinical trials may be more effective in evaluating treatments and helping to predict outcomes. Along similar lines, there are various definitions for OAB that is "refractory" to conventional treatments and this term needs clarification. In many cases, response to therapy may be affected by factors such as comorbidities, metabolism of drugs, concurrent therapies, etc. These factors are sometimes obvious and sometimes not, and for a variety of reasons it can be quite difficult to predict or determine their effect on outcome. Finally, many patients with OAB include have mixed (stress and urgency) symptoms. It is important to sort out the OAB component of mixed symptoms and mixed urinary incontinence (MUI) when determining effects of therapy.

Disposition of chiral and racemic fluoxetine and norfluoxetine across childbearing

OBJECTIVE

To add to the limited data on the clinical pharmacology of antidepressants during pregnancy, we examined the dose-corrected chiral and racemic levels (level/dose) of fluoxetine (FLX) and norfluoxetine (NorFLX) during pregnancy and early postpartum.

METHODS

The authors evaluated 17 pregnant women who received fluoxetine therapy. Doses were recorded weekly across gestation and postpartum. At 20, 30, and 36 weeks of gestation, during delivery, and 12 weeks after delivery, the depression level was assessed with the Hamilton Rating Scale for Depression (HRS-D), and plasma samples were analyzed for levels of S- and R-FLX and S- and R-NorFLX.

RESULTS

The mean ratios of the chiral parent drug (S-FLX + R-FLX) to metabolite levels (S-NorFLX + R-NorFLX) decreased across pregnancy. The differences were significant between 20-36 weeks and 30-36 weeks. After delivery, the mean dose-corrected level of the active moiety S-FLX and the mean ratio of the chiral parent drug (S-FLX + R-FLX) to metabolite level (S-NorFLX + R-NorFLX) significantly increased between delivery and 12 weeks postpartum. Most of the fluoxetine-treated subjects experienced remitted depressive episodes and euthymic mood levels during pregnancy and postpartum.

CONCLUSIONS

The findings extend earlier reports of increased antidepressant metabolism during pregnancy and refractory metabolism after delivery. These data may inform treatment decisions related to dosing in patients who receive fluoxetine during pregnancy.

The oxidative metabolism of dimemorfan by human cytochrome P450 enzymes

To characterize the human cytochrome P450 (P450) forms involved in dimemorfan oxidation (DFO), human liver microsomes, and recombinant P450s were investigated. Liquid chromatography-mass spectral analysis suggested that metabolite (M)1 ([M + H](+) m/z at 272.200) and M2 ([M + H](+) m/z at 242.190) were d-3-hydroxymethyl-N-methylmorphinan and d-3-methylmorphinan, respectively. Kinetic analyses of microsomal DFO showed that the substrate concentration showing a half-maximal velocity (S(50)) of M1 formation was less than that of M2. Microsomal M1 and M2 formation activities correlated significantly with the CYP2D6 marker, dextromethorphan O-demethylation activity. The M2 formation activity was also correlated with the CYP3A4 marker, nifedipine oxidation activity. Microsomal M1 and M2 formation was most sensitive to the inhibition by a CYP2D6 inhibitor, paroxetine and a CYP3A4 inhibitor, ketoconazole, respectively. The immunoinhibition-defined P450 contributions indicated the participation of CYP2C9, CYP2C19, and CYP2D6 in the M1 formation and CYP2B6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 in the M2 formation. Among recombinant P450s, CYP2D6 had the highest intrinsic clearance with a K(m) value of 0.02 mM in forming M1. CYP2B6, CYP2C9, and CYP2C19 had the K(m) or S(50) values smaller than those (1 mM) of CYP2D6 and CYP3A4 in forming M2. These results indicated the participation of multiple P450 forms in DFO.

Opioid switching and rotation in primary care: implementation and clinical utility

BACKGROUND

Opioid therapy is the standard treatment for moderate-to-severe cancer pain and is becoming a more frequent treatment for moderate-to-severe chronic noncancer pain. Response to opioids varies significantly between patients and even within the individual patient at different stages of treatment. Finding an opioid at a dose that provides adequate long-term analgesia with minimal adverse effects can be difficult. Opioid switching and opioid rotation, at different stages of therapy, represent two clinical strategies used to optimize opioid response for patients with moderate-to-severe pain.

OBJECTIVES

Review the theoretical and clinical evidence supporting the concepts of opioid switching and rotation, outline the conditions under which these practices should be considered, and briefly suggest practical steps for their implementation.

SCOPE

Clinical literature, clinical practice and guideline databases, and professional society websites were searched for articles or reports describing opioid switching or opioid rotation in chronic pain therapy; variability in patient response to opioid therapy; physiologic, pharmacologic, and genetic factors that affect clinical response to opioids; and practical approaches to maximizing analgesia and minimizing adverse effects in opioid therapy. It is outside the scope of this review to evaluate the pharmacoeconomic aspects that affect changes in opioid therapy.

FINDINGS

The variability in de novo clinical response to opioids likely represents the interaction of the varying properties of the individual opioids with the variability in individual patient biology. This interaction forms the rationale for opioid switching and explains its clinical utility. As with opioid switching, success with opioid rotation is related to the myriad of factors determining an individual patient's response to a specific opioid. However, the benefits of opioid rotation also derive from a partial reversal of tolerance at the mu-opioid receptor and the response of different micro-opioid receptor subtypes to the different opioids.

Serotonin transporter gene variation and refractory mesial temporal epilepsy with hippocampal sclerosis

We performed a molecular epidemiology study in a population of 105 mesial temporal lobe epilepsy with hippocampal sclerosis (MTE-HS) patients in order to investigate the role of a polymorphism in the serotonin transporter gene (SLC6A4) in the prediction of antiepileptic drug (AED) treatment response. Homozygous carriers of the 12-repeat allele had an almost fourfold increase in risk for a MTE-HS not responding to medical treatment (OR 3.88; CI 95% 1.40-10.7; p=0.006) compared to carriers of the 10-repeat allele. Therefore, a polymorphism of SLC6A4 might be a genetic marker of pharmacoresistance in MTE-HS patients.

A preliminary pharmacogenetic investigation of adverse events from topiramate in heavy drinkers

Topiramate, an anticonvulsant medication, is an efficacious treatment for alcohol dependence. To date, little is known about genetic moderators of side effects from topiramate. The objective of this study was to examine 3 single nucleotide polymorphisms (SNPs) of the glutamate receptor GluR5 gene (GRIK1) as predictors of topiramate-induced side effects in the context of a laboratory study of topiramate. Heavy drinkers (n=51, 19 women and 32 men), 75% of whom met criteria for an alcohol use disorder, completed a 5-week dose escalation schedule to a target dose of either 200 or 300 mg or matched placebo. The combined medication groups were compared with placebo-treated individuals for side effects at target dose. Analyses revealed that an SNP in intron 9 of the GRIK1 gene (rs2832407) was associated with the severity of topiramate-induced side effects and with serum levels of topiramate. Genes underlying glutamatergic neurotransmission, such as the GRIK1 gene, may help predict heterogeneity in topiramate-induced side effects. Future studies in larger samples are needed to more fully establish these preliminary findings.

Daptomycin in endocarditis and bacteraemia: a British perspective

Assessment of the place of daptomycin in the treatment of endocarditis and bacteraemia requires assimilation of data from one open-label randomized comparative clinical trial sized for equivalence, from registry data and from case reports. Selected relevant animal models and in vitro data are also considered in an effort to produce an integrated assessment of the current place of daptomycin in treatment. The evidence for the use of daptomycin is best in Staphylococcus aureus bacteraemia and endocarditis, but also includes some data on infections due to Enterococcus spp., especially if vancomycin-resistant. The emergence of resistance in a minority of patients on current dose regimens may mean that trials have to be repeated with higher doses, or the drug used in a combined therapy where rifampicin may be the best choice. In general, equivalence to comparator antibiotic regimens and a correlation for in vitro and in vivo findings have been demonstrated, but there are important gaps in the clinical data including a comparative equivalence trial in streptococcal and enterococcal endocarditis. Clinical benefit might be anticipated, but has not been proved, over aminoglycoside-containing regimens, and economic assessments are critical in the decision as to when and how daptomycin is deployed.

Clinical experience with daptomycin: bacteraemia and endocarditis

Serious infections due to Staphylococcus aureus, especially those due to methicillin-resistant S. aureus, have become a major challenge. Vancomycin has long been the drug of choice for treatment of such infections, but failures due to its slow bactericidal activity coupled with increasing MICs have necessitated a search for new, more effective agents. Daptomycin has been studied by a number of investigators and has proved to be effective for bacteraemic infections due to staphylococci as well as vancomycin-resistant enterococci and other Gram-positive organisms. In addition, in a randomized controlled trial comparing daptomycin monotherapy with potentially synergistic therapy with either vancomycin or beta-lactam, both used in combination with an aminoglycoside, daptomycin achieved comparable outcomes but with significantly less nephrotoxicity.

Perspectives on pain and intellectual disability

Historically, individuals with intellectual disability (ID) have been excluded from pain research and assumed to be insensitive or indifferent to pain. The weight of the evidence suggests that individuals with ID have been subject to practices and procedures with little regard for their ability to experience or express pain. A number of issues central to improving understanding of pain in ID will be introduced and current research related to the definition of pain and its social context, underlying sensory and metabolic systems and factors influencing judgments about the ability to experience pain will be reviewed. Accumulating evidence from interdisciplinary research designed to improve assessment, understand individual differences, and evaluate bias and beliefs about pain suggests that new perspectives are emerging and beginning to shape an innovative frontier of research that will ultimately pay tremendous dividends for improving the quality of life of individuals with ID.

Be smart, exercise your heart: exercise effects on brain and cognition

An emerging body of multidisciplinary literature has documented the beneficial influence of physical activity engendered through aerobic exercise on selective aspects of brain function. Human and non-human animal studies have shown that aerobic exercise can improve a number of aspects of cognition and performance. Lack of physical activity, particularly among children in the developed world, is one of the major causes of obesity. Exercise might not only help to improve their physical health, but might also improve their academic performance. This article examines the positive effects of aerobic physical activity on cognition and brain function, at the molecular, cellular, systems and behavioural levels. A growing number of studies support the idea that physical exercise is a lifestyle factor that might lead to increased physical and mental health throughout life.

Healthcare policy implications of heterogeneity of treatment effects

Heterogeneity of treatment effects (HTE) is a phenomenon wherein the same treatment produces different responses in different patients. Following scientific presentations at a conference on HTE in drug therapy, a roundtable panel discussed the policymaking implications of this phenomenon in the current healthcare environment. The presentation of evidence on HTE served as a backdrop for this more pragmatic, solutions-based discussion of how HTE should be addressed in light of the trend in healthcare toward use of evidence-based medicine along with professional society clinical practice guidelines for specific disease states. Overall, the panel concluded that a specific agent should be used when the clinician is equipped with sound data. However, in the absence of such data, care has to be individualized, using the clinician's best judgment regarding available treatment options. The sharing of data across all levels of the healthcare infrastructure is crucial for policymakers seeking to ensure quality care while considering the phenomenon of HTE and, at the same time, keeping cost-effectiveness a major concern.