Interethnic differences in genetic polymorphisms of CYP2D6 in the U.S. population: clinical implications

The Effectiveness of Tramadol in Pain Relief in Chronic Diseases: A Review Based on Clinical Trials

Tramadol is a synthetic opioid with a central effect from the aminocyclohexanol group, which has two main mechanisms of action, including as a weak agonist of opioid receptors and as a norepinephrine and serotonin reuptake inhibitor. The present study presents a review based on clinical trials designed in 2023. In July 2023, six international databases, including Medline/PubMed, ProQuest, Scopus, EMBASE, Google Scholar, and ISI (Web of Science), were searched and 58 articles were included in the study. The results of most studies showed that tramadol can be used as an analgesic drug, although in some studies it was shown that tramadol is not therapeutically superior in reducing pain compared to other treatments. Also, complications related to this treatment have been reported in some studies. Physicians should consider these factors to prevent drug toxicity, poor pain relief, use disorder in patients, and unpredictable complications. It should be noted that there is not enough evidence to support the long-term effectiveness of tramadol, but this argument also extends to nonopioid and other types of opioid analgesics, and the lack of long-term trials is due to regulatory and ethical issues. Although opioids can cause addiction when used for a long time, tramadol has a reasonable safety profile. According to the patient's condition and the clinical judgment of the medical professional, tramadol can be prescribed for patients, but the consequences of its use must be considered and a personalized treatment algorithm should be selected if the benefits outweigh the risks of the drug.

Sertraline induced acute hepatocellular liver injury in patient with major depressive disorder: a case report

This case report describes a patient with major depressive disorder (MDD) who developed acute hepatocellular liver injury after being treated with sertraline, a selective serotonin reuptake inhibitor (SSRI). The diagnosis of MDD was made two years prior, and the patient had previously responded partially to escitalopram and cognitive-behavioral therapy (CBT). Upon switching to sertraline 50 mg daily, the patient presented with severe symptoms indicative of acute liver injury, including elevated liver enzymes, jaundice, and gastrointestinal distress. Following the discontinuation of sertraline, the patient's liver function tests gradually normalized over a 90-day period, confirming the diagnosis of sertraline-induced hepatotoxicity. This case underscores the importance of continuous monitoring for potential liver injury in patients treated with sertraline. The findings contribute to the existing body of evidence on the hepatotoxic risks associated with SSRIs and highlight the need for personalized treatment strategies to mitigate adverse effects and enhance patient safety. Further research is needed to explore the long-term safety and efficacy of sertraline, particularly in vulnerable populations.

Effects of pharmacogenetic profiles on pediatric pain relief and adverse events with ibuprofen and oxycodone

Introduction

Individual genetic variation may influence clinical effects for pain medications. Effects of CYP2C9, CYP3A4, and CYP2D6 polymorphisms on clinical effectiveness and safety for ibuprofen and oxycodone were studied.

Objective

Primary objectives were to AU2 evaluate if allelic variations would affect clinical effectiveness and adverse events (AEs) occurrence.

Methods

This pragmatic prospective, observational cohort included children aged 4 to 16 years who were seen in a pediatric emergency department with an acute fracture and prescribed ibuprofen or oxycodone for at-home pain management. Saliva samples were obtained for genotyping of allelic variants, and daily telephone follow-up was conducted for 3 days. Pain was measured using the Faces Pain Scale-Revised.

Results

We included 210 children (n = 140 ibuprofen and n = 70 oxycodone); mean age was 11.1 (±SD 3.5) years, 33.8% were female. Median pain reduction on day 1 was similar between groups [ibuprofen 4 (IQR 2,4) and oxycodone 4 (IQR 2,6), P = 0.69]. Over the 3 days, the oxycodone group experienced more AE than the ibuprofen group (78.3% vs 53.2%, P < 0.001). Those with a CYP2C9*2 reduced function allele experienced less adverse events with ibuprofen compared with those with a normal functioning allele CYP2C9*1 (P = 0.003). Neither CYP3A4 variants nor CYP2D6 phenotype classification affected clinical effect or AE.

Conclusion

Although pain relief was similar, children receiving oxycodone experienced more AE, overall, than those receiving ibuprofen. For children receiving ibuprofen or oxycodone, pain relief was not affected by genetic variations in CYP2C9 or CYP3A4/CYP2D6, respectively. For children receiving ibuprofen, the presence of CYP2C9*2 was associated with less adverse events.

Child and Adolescent Bariatric Surgery in an Urban Tertiary Center: Special Anesthetic Considerations for Obesity

Children and adolescents with obesity who present for weight loss surgery are a unique subset of patients. A thorough understanding of the perioperative needs of these individuals is essential to avoid deleterious complications. This review illustrates the necessity for specialized care, including the continued need of specified drug dosing and a systematic approach in the management of the pediatric bariatric patient.

Pharmacogenetic Gene-Drug Associations in Pediatric Burn and Surgery Patients

Management of critically ill patients requires simultaneous administration of many medications. Treatment for patient comorbidities may lead to drug-drug interactions which decrease drug efficacy or increase adverse reactions. Current practices rely on a one-size-fits-all dosing approach. Pharmacogenetic testing is generally reserved for addressing problems rather than used proactively to optimize care. We hypothesized that burn and surgery patients will have one or more genetic variants in drug metabolizing pathways used by one or more medications administered during the patient's hospitalization. The aim of this study was to determine the frequency of variants with abnormal function in the primary drug pathways and identify which medications may be impacted. Genetic (19 whole exome and 11 whole genome) and medication data from 30 pediatric burn and surgery patients were analyzed to identify pharmacogene-drug associations. Nineteen patients were identified with predicted altered function in one or more of the following genes: CYP2C9, CYP2C19, CYP2D6, and CYP3A4. The majority had decreased function, except for several patients with CYP2C19 rapid or ultrarapid variants. Some drugs administered during hospitalization that rely on these pathways include hydrocodone, oxycodone, methadone, ibuprofen, ketorolac, celecoxib, diazepam, famotidine, diphenhydramine, and glycopyrrolate. Approximately one-third of the patients tested had functionally impactful genotypes in each of the primary drug metabolizing pathways. This study suggests that genetic variants may in part explain the vast variability in drug efficacy and suggests that future pharmacogenetics research may optimize dosing regimens.

Comparative Evaluation of Safety and Efficacy of Alternate Schedule (AS) of Sunitinib in Asian and Non-Asian Patient Population for the Treatment of Metastatic Renal Cell Cancer (mRCC): A Meta-Analysis

Background: Treatment of metastatic renal cell carcinoma (mRCC) using traditional schedule (TS, 4/2) of Sunitinib is associated with higher adverse effects compared to the alternate schedule (AS, 2/1 upfront or when switched from TS). Objective: This meta-analysis aims to compare the safety, efficacy, and percentage of patients requiring dose reduction or dose interruption between Asian (AP) and non-Asian population (NAP) receiving AS of sunitinib. Methods: Electronic databases (PubMed, EMBASE, Cochrane Library) were searched to identify studies published in the English language between May 2009- May 2019, which included patients (>18 years) with mRCC receiving AS of sunitinib. Data were analyzed using the random effect model and t-test. P <  0.05 was considered statistically significant. Results: Of 1922, 16 studies were included (eight AP, eight NAP). Among all grade AEs, mucositis (RR:0.22; 95% CI:0.12–0.40), cardiotoxicity (RR: 0.52; 95% CI: 0.31–0.88), nausea (RR:0.21; 95% CI: 0.10–0.44), hand-foot syndrome (RR:0.33; 95% CI:0.13–0.83), rash (RR: 0.52; 95% CI: 0.34–0.79), and aspartate transaminase (RR:0.57; 95% CI:0.33–0.98) were more common in AP. Leukopenia (RR:2.57; 95% CI:1.47–4.49), proteinemia (RR:4.45; 95% CI:2.12–9.33), and stomatitis (RR:4.33; 95% CI:2.6–7.23) occurred more commonly in NAP. Further, PFS was significantly longer in NAP, while longer OS was observed in AP (p <  0.001). Dose reduction was significantly higher in AP than NAP (52.08% vs. 40.6%, p = 0.0088). Conclusion: Safety profile of AS of sunitinib was similar with variations in the efficacy, dose reduction between AP and NAP. Sunitinib dose or schedule modification may mitigate AEs and enhance efficacy outcomes in mRCC by extending the treatment duration.

Malar reshaping technique using bidirectional barb thread suspension procedure for 3-dimensional aging in Asian faces

Background: Aging is a natural process that causes skin texture changes, facial volume loss, and altered 3-dimensional topography of the underlying tissues.

Objective: The aim of this study is to assess the malar reshaping strategy in Asian patients using bidirectional suspension-barbed threads.

Methods: A prospective interventional study was conducted on Asian patients presenting with mild-to-moderate facial aging who were treated with the Definisse double-needle thread in the Hong Kong Special Administrative Region. The primary endpoint was assessed using the Global Aesthetic Improvement Scale and scoring the benefit of anterior projection using a questionnaire. Patient safety was the secondary endpoint measured.

Results: Twenty Asian patients (4 men [20%] and 16 women [80%]; age <45 to ≥45 years) were included in the study. The patients experienced marked improvement (score 2) in their appearance, except for the follow-up after 1 month. One month after the procedure, patients scored 1 for optimal cosmetic improvement in their looks. The nasolabial fold disappeared in all patients (n = 20 [100%]) and the face looked slimmer. Nine patients (45%) reported that the focus seemed centralized. Four patients (20%) reported prominence of the nose and chin. Redness, swelling, and bruising were the most common adverse events experienced by 75% of patients (n = 15), followed by pain (n = 6; 30%). All adverse events resolved within 4 weeks after their incidence. Because 80% of our patients were women, these positive cosmetic outcomes may be of interest across the aging female population.

Conclusion: Overall, 3-dimensional facial rejuvenation with the Definisse thread seems to be an effective, safe, and minimally invasive office-based procedure to achieve immediate and long-term effects. These absorbable barbed sutures used in the malar reshaping technique can result in satisfactory esthetic enhancement of 3-dimensional aging, including sagginess, jowling, central facial heaviness, and tissue descent in female and male Asian patients.

Pharmacogenomics in Children

Historically genetics has not been considered when prescribing drugs for children. However, it is clear that genetics are not only an important determinant of disease in children but also of drug response for many important drugs that are core agents used in the therapy of common problems in children. Advances in therapy and in the ethical construct of children's research have made pharmacogenomic assessment for children much easier to pursue. It is likely that pharmacogenomics will become part of the therapeutic decision-making process for children, notably in areas such as childhood cancer where weighing benefits and risks of therapy is crucial.

Evaluation of Pharmacogenomics Testing of Cytochrome P450 Enzymes in the Military Health System From 2015 to 2020

Pharmacogenomics (PGx) plays a fundamental role in personalized medicine, providing an evidence-based treatment approach centered on the relationship between genomic variations and their effect on drug metabolism. Cytochrome P450 (CYP450) enzymes are responsible for the metabolism of most clinically prescribed drugs and a major source of variability in drug pharmacokinetics and pharmacodynamics. To assess the prevalence of PGx testing within the Military Health System (MHS), testing of specific CYP450 enzymes was evaluated. Data were retrospectively obtained from the Military Health System Management Analysis and Reporting Tool (M2) database. Patient demographics were identified for each test, along with TRICARE status, military treatment facility, clinic, and National Provider Identifier. A total of 929 patients received 1,833 PGx tests, predominantly composed of active duty/guard service members (N = 460; 49.5%), with highest testing rates in the army (51.5%). An even distribution in testing was observed among gender, with the highest rates in Caucasians (41.7%). Of the CYP enzymes assessed, CYP2C19 and CYP2D6 accounted for 87.8% of all PGx CYP testing. The majority of patients were tested in psychiatry clinics (N = 496; 53.4%) and primary care clinics (N = 233; 25.1%), accounting for 56.4% and 24.8% of all tests, respectively. Testing was found to be provider driven, suggesting a lack of a standardized approach to PGx and its application in patient care within the MHS. We initially recommend targeted education and revising testing labels to be more uniform and informative. Long-term recommendations include establishing pharmacy-driven protocols and point-of-care PGx testing to optimize patient outcomes.

Effects of CYP2D6 Genetic Polymorphism and Drug Interaction on the Metabolism of Dacomitinib

We aim to study the effects of CYP2D6 variants and drug-drug interaction on the metabolism of dacomitinib. CYP2D6 variants were incubated with 25-1000 μM dacomitinib for 40 min at 37 °C, and the reaction was terminated by cooling to -80 °C immediately. For an in vivo experiment, 18 male Sprague-Dawley rats were randomly divided into three groups (n = 6): a single dose of 5 mg/kg dacomitinib (group A), a single dose of 6 mg/kg trazodone (group B), and a combined group (group C). Processed samples were analyzed by ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS.) The relative clearance of dacomitinib was reduced for most of the variants. Moreover, the inhibitory potency of classic CYP inhibitors on dacomitinib metabolism was significantly different among the main subtypes of CYP2D6. Interestingly, compared with gefitinib, even the same CYP2D6 variants showed significant differences in metabolic activity, suggesting that the activity of CYP2D6 has strong variability. In addition, the interaction between trazodone and dacomitinib was determined both in vitro and in vivo. When dacomitinib was given in combination with trazodone, the blood exposure to these two drugs increased remarkably. The mechanistic study revealed that the interaction followed the noncompetitive inhibition. We demonstrated that the activity of CYP2D6 variants to metabolize dacomitinib was significantly reduced. In combination with the CYP2D6 inhibitor, the degree of activity inhibition of different variants obviously differed. When trazodone and dacomitinib were used in combination, the body exposure to the two drugs increased significantly. This study provides data for the precise use of dacomitinib in clinical settings.

The Adverse Cardiovascular Effects and Cardiotoxicity of Kratom (Mitragyna speciosa Korth.): A Comprehensive Review

Background: Kratom or Mitragyna speciosa (Korth.) has received overwhelming attention recently due to its alleged pain-relieving effects. Despite its potential therapeutic value, kratom use has been linked to many occurrences of multiorgan toxicity and cardiotoxicity. Accordingly, the current narrative review aimed to provide a detailed account of kratom's adverse cardiovascular effects and cardiotoxicity risk, based on in vitro studies, poison center reports, coroner and autopsy reports, clinical case reports, and clinical studies. Methods: An electronic search was conducted to identify all research articles published in English from 1950 to 2021 using the major research databases, such as Google Scholar, Web of Science, PubMed, Scopus, Mendeley, EMBASE, Cochrane Library, and Medline. We then analyzed the literature's discussion of adverse cardiovascular effects, toxicity, and mortality related to kratom use. Results: Our findings revealed that, although in vitro studies have found kratom preparations' most abundant alkaloid-mitragynine-to cause a prolonged QTc interval and an increased risk of torsades de pointes, a clinical study examining humans' regular consumption of kratom did not report such a risk. However, this latter study did show that regular kratom use could induce an increased QTc interval in a dose-dependent manner. A few case reports also highlighted that kratom consumption is associated with ventricular arrhythmia and cardiopulmonary arrest, but this association could have ensued when kratom was co-administered with another substance. Similarly, analyses of national poison data showed that kratom's most common adverse acute cardiovascular effects include tachycardia and hypertension. Meanwhile, coroner and autopsy reports indicated that kratom's cardiovascular sequelae encompass coronary atherosclerosis, myocardial infarction, hypertensive cardiovascular disease, left ventricular hypertrophy, cardiac arrhythmia, cardiomegaly, cardiomyopathy, focal band necrosis in the myocardium, and myocarditis. Given the available data, we deduced that all cardiac eventualities reported in the literature could have been compounded by polysubstance use and unresolved underlying medical illnesses. Conclusion: Although kratom use has been associated with death and cardiotoxicity, especially at higher doses and when associated with other psychoactive drugs, the dearth of data and methodological limitations reported in existing studies do not allow a definitive conclusion, and further studies are still necessary to address this issue.

Safety evaluation of oliceridine for the management of postoperative moderate-to-severe acute pain

INTRODUCTION

Opioids for managing postoperative pain are associated with side effects including opioid-induced respiratory depression (OIRD) and gastrointestinal complications. Opioids induce analgesia via G-protein signaling, while adverse effects are mediated by the β-arrestin pathway. Oliceridine is a biased ligand that preferentially activates G-protein signaling over β-arrestin, theoretically reducing adverse effects. Oliceridine has been approved by the Food and Drug Administration to treat acute pain severe enough to require intravenous opioid analgesics.

AREAS COVERED

Preclinical and clinical trials demonstrate the analgesic efficacy of oliceridine. Available evidence suggests that oliceridine may have a lower risk of OIRD and gastrointestinal complications compared to conventional opioids.

EXPERT OPINION

The analgesic efficacy of oliceridine has been evaluated in several clinical trials. However, safety data were obtained from an open-label observational study and studies assessing adverse effects as secondary outcomes, as post-hoc analyses, or from retrospective studies. These may be affected by gaps in detecting adverse events, heterogeneity in the original studies, and the limitations of retrospective studies. Prospective trials examining the safety of oliceridine versus conventional opioids are needed. Studies are also needed to assess the safety and efficacy of oliceridine in obstetric and pediatric populations, and in the context of multimodal analgesia and Enhanced Recovery after Surgery protocols.

Functional assessment of the effects of CYP3A4 variants on acalabrutinib metabolism in vitro

AIM

We aimed (i) to study the effects of genetic polymorphism of cytochrome P450 3A4 (CYP3A4) and drug interactions on acalabrutinib (ACA) metabolism and (ii) to investigate the mechanisms underlying the effects of CYP3A4 variants on the differential kinetic profiles of ACA and ibrutinib.

METHOD

Recombinant human CYP3A4 and variants were expressed using a Bac-to-Bac baculovirus expression system. The cell microsome was prepared and subjected to kinetic study. The analyte concentrations were determined by UPLC-MS/MS. A molecular docking assay was employed to investigate the mechanisms leading to differences in kinetic profiles.

RESULTS

The kinetic parameters of ACA, catalyzed by CYP3A4 and 28 of its variants, were determined, including V_max, K_m, and K_si. CYP3A4.6-8, 12, 13, 17, 18, 20, and 30 lost their catalytic function. No significant differences were found for CYP3A4.4, 5, 10, 15, 31, and 34 compared with CYP3A4.1 with respect to intrinsic clearance (V_max/K_m, Clint). However, the Clint values of CYP3A4.9, 14, 16, 19, 23, 24, 28, 32 were obviously decreased, ranging from 0.02 to 0.05 μL/min/pmol. On the contrary, the catalytic activities of CYP3A4.2, 3, 11, 29, and 33 were increased dramatically. The Clint value of CYP3A4.11 was 5.95 times as high as that of CYP3A4.1. Subsequently, CYP3A4.1, 3, 11, 23, and 28 were chosen to study the kinetic changes in combination with ketoconazole. Interestingly, we found the inhibitory potency of ketoconazole varied in different variants. In addition, the kinetic parameters of ibrutinib and ACA were accordingly compared in different CYP3A4 variants. Significant differences in relative clearance were observed among variants, which would probably influence the distance between the redox site and the heme iron atom.

CONCLUSION

Genetic polymorphism of CYP3A4 extensively changes its ACA-metabolizing enzymatic activity. In combination with a CYP inhibitor, its inhibitory potency also varied among different variants. Even the same variants exhibited different capabilities catalyzing ACA. Its enzymatic capabilities are probably determined by the distance between the substrate and the heme iron atom, which could be impacted by mutation.

Oliceridine: A Novel Drug for the Management of Moderate to Severe Acute Pain - A Review of Current Evidence

Optimal pain relief requires a balance between adequate analgesia and risk of adverse effects. Opioids remain the cornerstone for managing moderate to severe pain, but are associated with opioid-induced respiratory depression (OIRD) and gastrointestinal complications. Opioids exert their analgesic effects predominantly via G-protein signaling, however, adverse effects including OIRD are mediated by the β-arrestin pathway. Oliceridine is the first of a new class of biased opioid agonists that preferentially activate G-protein signaling over β-arrestin, which would theoretically improve analgesia and reduce the risk of adverse effects. Oliceridine is approved by the Food and Drug Administration (FDA) for the treatment of moderate to severe acute pain. The efficacy of Oliceridine was mainly established in two randomized controlled Phase III clinical trials of patients experiencing moderate to severe pain after bunionectomy (APOLLO-1) and abdominoplasty (APOLLO-2). The results of the APOLLO studies demonstrate that Oliceridine, when administered via patient-controlled analgesia (PCA) demand boluses of 0.35mg and 0.5mg, provides superior analgesia compared to placebo, and is equianalgesic to PCA morphine 1mg demand boluses, without significant difference in the incidence of respiratory complications. In a more pragmatic trial of surgical and non-surgical patients, the ATHENA observational cohort study reported rapid onset of analgesia with Oliceridine given with or without multimodal analgesia. However, these studies were designed to evaluate analgesic efficacy, and it is still uncertain if Oliceridine has a better safety profile than conventional opioids. Although several post hoc analyses of pooled data from the APOLLO and ATHENA trials reported that Oliceridine was associated with lower OIRD and gastrointestinal complications compared to morphine, prospective studies are needed to elucidate if biased agonists such as Oliceridine reduce the risk of adverse effects compared to conventional opioids.

Could Cytochrome P450 2D6, 3A4 and 3A5 Polymorphisms Explain the Variability in Clinical Response to Clomiphene Citrate of Anovulatory PCOS Women?

INTRODUCTION

Cytochrome P450 2D6, 3A4 and 3A5 are involved in the metabolism of many drugs. These enzymes have a genetic polymorphism responsible for different metabolic phenotypes. They play a role in the metabolism of clomiphene citrate (CC), which is used to induce ovulation. Response to CC treatment is variable, and no predictive factors have thus far been identified.

OBJECTIVE

To study a possible link between the cytochrome P450 2D6, 3A4 and 3A5 polymorphisms and clinical response to CC.

STUDY DESIGN

Seventy-seven women with anovulatory Polycystic Ovarian Syndrome (PCOS) treated with CC were included which determined their cytochrome P450 2D6, 3A4 and 3A5 genotypes and used the results to predict ovarian response to this drug. Predicted responses based on the cytochrome genotypes were compared with the observed clinical responses using the calculation of a weighted Kappa coefficient.

MAIN OUTCOME MEASURES

Number of dominant follicles assessed by ultrasound at the end of the follicular phase and confirmation of ovulation by blood progesterone assay in the luteal phase.

RESULTS

Concordance between the predicted and observed responses for the combination of the three cytochromes was 36.71%, with a negative Kappa coefficient (K = -0.0240), which corresponds to a major disagreement. Similarly, for predictions based on the cytochrome P450 2D6 genotype alone, only 39.24% of predictions were verified (coefficient K = -0.0609).

CONCLUSION

The genetic polymorphism of cytochromes P450 2D6, 3A4 and 3A5 does not appear to influence clinical response to CC used to induce ovulation in anovulatory PCOS women.

Pharmacogenetics of Obsessive-Compulsive Disorder: An Evidence-Update

Pharmacogenetics has become increasingly important in the treatment of psychiatric disorders because approximately 50% of individuals who take psychotropic medications do not typically respond to them. Obsessive-compulsive disorder (OCD) is one such chronic and often debilitating mental illness with significant non-response to even the first-line medication, serotonin reuptake inhibitors. Precision medicine utilizing genetic testing panels has received significant attention based on the evidence that the variability of antidepressant response and adverse effects is partly due to the variability in an individual's genome. Thus, extensive research has investigated the role of genetic factors on antidepressant response in major depressive disorder (MDD) and their utility for guiding antidepressant treatment to significantly improving outcomes in individuals with MDD. However, limited progress remains in the pharmacogenetics of OCD. This chapter will provide an overview of the recent findings in the pharmacogenetics of OCD. Promising results with limited replications have been reported for the cytochrome P450 liver metabolism genes in addition to several serotonergic and glutamatergic system genes, which may play an important role in antidepressant response in the treatment of OCD.

Relative addictive potential of opioid analgesic agents

Opioid overdoses and deaths continue to be a problem in the USA with a significant portion related to prescribed opioid analgesic agents. The role of pharmacogentic factors in opioid addiction is an active area of research. While all opioid analgesic agents have some addictive potential, it is clear that there are some with greater addictive potential. Oxycodone is the most widely abused opioid analgesic and it appears to predispose to chronic use with high likability by users. Fentanyl and hydromorphone are both very lipophilic allowing rapid penetration into the CNS, but are not rated as highly as other agents. Providers should consider the risk of addiction with the opioids they prescribe and give those with a lower addictive potential.

A comparative analysis of kratom exposure cases in Thailand and the United States from 2010-2017

Background: Interest in the Southeast Asian natural remedy kratom has increased in Western countries recently, along with increasing concern over its potential toxic effects.Objective: To describe and compare demographics, common co-exposure substances, clinical effects, treatments, and medical outcomes of kratom "abuse" exposures in the United States (US) and Thailand.Methods: This is a retrospective analysis of kratom "abuse" exposures, defined as use when attempting to gain a psychotropic effect, reported to the National Poison Data System (NPDS) in the US and the Ramathibodi Poison Center (RPC) in Thailand from 2010 to 2017. Multivariate analysis identified risk factors for severe medical outcomes, defined as both ICU admissions and death.Results: Nine-hundred-twenty-eight cases were included (760 from NPDS and 168 from RPC). A greater proportion of cases involved co-exposures in Thailand (64.8% versus 37.4%; odds ratio [OR] = 3.10, 95% confidence interval [CI] = 2.15-4.47, p < .01). Both countries had a similar prevalence of opioid and benzodiazepine co-ingestions, but the US had more co-ingestions with other sedatives (4.6% versus 0%, OR = 0, 95% CI = 0-0.47, p < .01). Common clinical effects included tachycardia (30.4%), agitation/irritability (26.2%), and drowsiness/lethargy (21.1%). Six deaths occurred, including one single-substance exposure in the US, three multiple-substance exposures in the US, and two multiple-substance exposures in Thailand. Severe medical outcomes were reported more frequently in the US (OR = 18.82, 95% CI = 5.85-60.56, p < .01).Conclusions: Despite lower frequencies of co-ingestants overall, US kratom abuse exposures yielded greater clinical severity. This disparity may be attributable to differences in the products labeled "kratom," greater sedative co-exposures in the US, and/or differences in population genetics or use patterns.

Clinical Tolerability and Safety of Tramadol in Hospitalized Patients

Tramadol is a schedule IV, monoaminergic and μ-opioid-receptor analgesic with unique pharmacology properties. Though it is well established and widely utilized, there is little guidance on tramadol's place in therapy, including tolerability, safety and monitoring guidelines. Retrospective chart review of 250 patients who received oral tramadol during their hospitalization from January 1, 2018 to December 31, 2018. Of the 250 patients, 10.8% had cancer as their primary diagnosis while 8.8% were admitted for hematologic reasons. 79.1% of patients had acute pain. Palliative care consult or ICU admission resulted in significant discontinuation of tramadol (p < 0.05 odds ratio 6.88, 2.39). There was no significant relationship of hypoglycemia when evaluating days on tramadol, total number of doses on tramadol, and MEDD start and end (p = 0.36, 0.88, 0.15, 0.23 consecutively). The longer that patients were on tramadol and the more doses they received during their inpatient stay, the greater risk of a severe drug-drug interaction (p < 0.05; R 0.29). In hospitalized patients, the risk of major and severe drug-drug interactions with tramadol increased with dose and duration. Hospital medicine, bone marrow transplant, and emergency medicine teams predominantly used tramadol.

Cytochrome P450 2D6 polymorphism in eastern Indian population

OBJECTIVES:

Cytochrome P₄₅₀ 2D6 (CYP2D6) enzyme metabolizes a quarter of prescription drugs. Polymorphisms of CYP2D6 gene and resultant phenotypic variations in metabolic activity have been described in various populations. We assessed the prevalence of CYP2D6 activity phenotypes, employing dextromethorphan (DXM) as probe drug in subjects with at least two parental generations residing in eastern India.

MATERIALS AND METHODS:

Unrelated healthy subjects took 60 mg DXM after fasting overnight. Blood samples were collected 3 h after dosing and plasma separated. DXM and its primary metabolite dextrorphan (DXT) were measured by liquid chromatography with tandem mass spectrometry. The DXM-to-DXT metabolic ratio (MR) was obtained for each subject. Histogram of MR values suggested bimodal distribution. A polynomial regression equation derived through probit analysis was solved to identify the antimode of the MR values. Subjects with log(MR) < antimode were extensive metabolizers (EMs). Log(MR) ≥ antimode indicated poor metabolizers (PMs).

RESULTS:

We evaluated the results from 97 participants. The median MR was 0.209 (interquartile range: 0.090–0.609), while the antimode for MR was 3.055. From these, it was inferred that three subjects were PMs, while the rest were EMs. CYP2D6 polymorphism prevalence is low (3.09%; 95% confidence interval: 0.35%–6.54%) in the population of eastern India and matches the prevalence in other zones of the country.

CONCLUSIONS:

Differences in CYP2D6 activity has treatment implications and may lead to adverse events or therapeutic failure. Phenotyping of subjects receiving CYP2D6 metabolized drugs may help clinicians personalize treatment and avert adverse drug-drug interactions. However, the frequency of the PM phenotype is low in India, and routinely phenotyping for CYP2D6 activity will not be cost-effective. We cannot recommend it at this stage.

Transcriptional Profiling and Biological Pathway(s) Analysis of Type 2 Diabetes Mellitus in a Pakistani Population

The epidemic of type 2 diabetes mellitus (T2DM) is an important global health concern. Our earlier epidemiological investigation in Pakistan prompted us to conduct a molecular investigation to decipher the differential genetic pathways of this health condition in relation to non-diabetic controls. Our microarray studies of global gene expression were conducted on the Affymetrix platform using Human Genome U133 Plus 2.0 Array along with Ingenuity Pathway Analysis (IPA) to associate the affected genes with their canonical pathways. High-throughput qRT-PCR TaqMan Low Density Array (TLDA) was performed to validate the selected differentially expressed genes of our interest, viz., ARNT, LEPR, MYC, RRAD, CYP2D6, TP53, APOC1, APOC2, CYP1B1, SLC2A13, and SLC33A1 using a small population validation sample (n = 15 cases and their corresponding matched controls). Overall, our small pilot study revealed a discrete gene expression profile in cases compared to controls. The disease pathways included: Insulin Receptor Signaling, Type II Diabetes Mellitus Signaling, Apoptosis Signaling, Aryl Hydrocarbon Receptor Signaling, p53 Signaling, Mitochondrial Dysfunction, Chronic Myeloid Leukemia Signaling, Parkinson's Signaling, Molecular Mechanism of Cancer, and Cell Cycle G1/S Checkpoint Regulation, GABA Receptor Signaling, Neuroinflammation Signaling Pathway, Dopamine Receptor Signaling, Sirtuin Signaling Pathway, Oxidative Phosphorylation, LXR/RXR Activation, and Mitochondrial Dysfunction, strongly consistent with the evidence from epidemiological studies. These gene fingerprints could lead to the development of biomarkers for the identification of subgroups at high risk for future disease well ahead of time, before the actual disease becomes visible.

Implications of Perioperative Polypharmacy in Adolescents Undergoing Bariatric Surgery: a Single-Center Experience

Adolescents seeking bariatric surgery may present with pre-existing psychiatric diagnoses for which they use chronic medications. To heighten awareness concerning perioperative polypharmacy in adolescents with extreme obesity, we conducted a retrospective review of patients undergoing laparoscopic sleeve gastrectomy between February 2010 and May 2017 at Children's National Health System (CNHS). A total of 167 adolescent patients had pre-existing psychiatric diagnoses which included depression (50%), anxiety (23%), ADHD (23%), and binge eating disorder (11%). Medications prescribed to treat these diagnoses included selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs). Additionally, all patients were given fentanyl, ondansetron, morphine, and acetaminophen perioperatively. Although no life threatening symptoms of drug-drug interactions (DDIs) were appreciated, the combined use of many different potent drugs in these patients warrants attention.

Ventricular Arrhythmia Risk Based on Ethnicity in COVID-19 Patients on Hydroxychloroquine and Azithromycin Combination: Viewpoint

There are many reports available now, which are mostly observational or registry trial outcomes having varied results on coronavirus 2019 (COVID-19) patients put on hydroxychloroquine and azithromycin combination. Some are showing increased in-hospital mortality and ventricular arrhythmia increase, while some are showing overall benefit with significant viral RNA load reduction. Everyday things are getting more complicated with the publication of these different outcomes. This needs to be addressed.

Drugs in pregnancy: Pharmacologic and physiologic changes that affect clinical care

Pharmacologic interventions play a major role in obstetrical care throughout pregnancy, labor and delivery and the postpartum. Traditionally, obstetrical providers have utilized standard dosing regimens developed for non-obstetrical indications based on pharmacokinetic knowledge from studies in men or non-pregnant women. With the recognition of pregnancy as a special pharmacokinetic population in the late 1990s, investigators have begun to study drug disposition in this unique patient dyad. Many of the basic physiologic changes that occur during pregnancy have significant impact on drug absorption, distribution and clearance. Activity of Phase I and Phase II drug metabolizing enzymes are differentially altered by pregnancy, resulting in drug concentrations sufficiently different for some medications that efficacy or toxicity is affected. Placental transporters play a major dynamic role in determining fetal drug exposure. In the past two decades, we have begun to expand our understanding of obstetrical pharmacology; however, to truly optimize pharmacologic care of our pregnant patients and their developing fetus, additional research is critically needed.

Pharmacogenomics in pregnancy

Pregnant women frequently take prescription and over the counter medications. The efficacy of medications is affected by the many physiological changes during pregnancy, and these events may be further impacted by genetic factors. Research on pharmacogenomic and pharmacokinetic influences on drug disposition during pregnancy has lagged behind other fields. Clinical investigators have demonstrated altered activity of several drug metabolizing enzymes during pregnancy. Emerging evidence also supports the influence of pharmacogenomic variability in drug response for many important classes of drugs commonly used in pregnancy. Prescribing medications during pregnancy requires an understanding of the substantial dynamic physiologic and metabolic changes that occur during gestation. Pharmacogenomics also contributes to the inter-individual variability in response to many medications, and more research is needed to understand how best to manage drug therapy in pregnant women.

The Role of CYP450 Drug Metabolism in Precision Cardio-Oncology

As many novel cancer therapies continue to emerge, the field of Cardio-Oncology (or onco-cardiology) has become crucial to prevent, monitor and treat cancer therapy-related cardiovascular toxicity. Furthermore, given the narrow therapeutic window of most cancer therapies, drug-drug interactions are prevalent in the cancer population. Consequently, there is an increased risk of affecting drug efficacy or predisposing individual patients to adverse side effects. Here we review the role of cytochrome P450 (CYP450) enzymes in the field of Cardio-Oncology. We highlight the importance of cardiac medications in preventive Cardio-Oncology for high-risk patients or in the management of cardiotoxicities during or following cancer treatment. Common interactions between Oncology and Cardiology drugs are catalogued, emphasizing the impact of differential metabolism of each substrate drug on unpredictable drug bioavailability and consequent inter-individual variability in treatment response or development of cardiovascular toxicity. This inter-individual variability in bioavailability and subsequent response can be further enhanced by genomic variants in CYP450, or by modifications of CYP450 gene, RNA or protein expression or function in various 'omics' related to precision medicine. Thus, we advocate for an individualized approach to each patient by a multidisciplinary team with clinical pharmacists evaluating a treatment plan tailored to a practice of precision Cardio-Oncology. This review may increase awareness of these key concepts in the rapidly evolving field of Cardio-Oncology.

Effect heterogeneity and variable selection for standardizing causal effects to a target population

The participants in randomized trials and other studies used for causal inference are often not representative of the populations seen by clinical decision-makers. To account for differences between populations, researchers may consider standardizing results to a target population. We discuss several different types of homogeneity conditions that are relevant for standardization: Homogeneity of effect measures, homogeneity of counterfactual outcome state transition parameters, and homogeneity of counterfactual distributions. Each of these conditions can be used to show that a particular standardization procedure will result in an unbiased estimate of the effect in the target population, given assumptions about the relevant scientific context. We compare and contrast the homogeneity conditions, in particular their implications for selection of covariates for standardization and their implications for how to compute the standardized causal effect in the target population. While some of the recently developed counterfactual approaches to generalizability rely upon homogeneity conditions that avoid many of the problems associated with traditional approaches, they often require adjustment for a large (and possibly unfeasible) set of covariates.

Single Dose Pharmacokinetics of Metoclopramide Oral Tablets Utilizing HPLC-UV Method

Background:

Metoclopramide is a potent dopaminergic antagonist utilized for treating gastrointestinal disorders. The aim of this study was to examine the pharmacokinetics of oral formulation of metoclopramide in the Pakistani volunteers.

Methods:

This open label, single dose, pharmacokinetic study was executed in non-smoking, 12 Pakistani healthy males, treated with a single 20 mg oral tablet dose of metoclopramide on test day. Maximum plasma concentration (Cmax), time to achieve Cmax (Tmax), and area under curve (AUC0-t) of metoclopramide were determined analyzing the serial blood samples using a validated HPLC-UV method.

Results:

The determined values of Cmax, Tmax, and AUC0-t of metoclopramide were 34.51 ± 4.91 ng/ml, 1.56 ± 0.18 and 273.88 ± 114.49 ng.h/ml, respectively.

Conclusion:

The results reveal that the findings of Pakistani individuals are slightly different when compared with the published data of other ethnic origins.

Results and challenges of Cytochrome P450 2D6 (CYP2D6) testing in an ethnically diverse South Florida population

Background

This study focuses on the implementation of CYP2D6 genetic test profiling and the challenges associated with using standard pharmacogenetics panels in a diverse South Florida population.

Methods

A total of 413 participants were recruited to participate in this study through Nicklaus Children's Hospital. Buccal swabs were collected and tested using an extended CYP2D6 panel including 22 alleles. Phenotype, genotype, and allelic frequencies were compared among different racial and ethnic groups.

Results

The majority of participants (75.0%) self‐identified as Hispanics. Four alleles, CYP2D6*4, *17, *41, and *2A, showed a statistically significant difference between White Hispanics and Black Non‐Hispanics. Aggregate frequency of all alleles with decreased function varied between 2.8% and 50.0% in different racial and ethnic groups. Additionally, rare allele combinations were observed in this South Florida cohort.

Conclusions

The heterogeneity among Hispanic groups demonstrated in previous literature and by this study reflects the complexity of ethnicity and suggests that a more granular categorization is needed, one based on ancestry and migration history rather than primary language. Overall, we have determined that there are statistically significant differences in CYP2D6 allele frequencies in the distinct racial and ethnic populations of South Florida, demonstrating a unique genetic makeup within South Florida. However, overall, the frequencies of Poor Metabolizer, Normal Metabolizer, Intermediate Metabolizer, and Ultrarapid Metabolizer did not differ between racial and ethnic groups at a statistically significant level.

Update on the pharmacogenomics of pain management

Pharmacogenomics is the study of genetic variants that impact drug effects through changes in a drug’s pharmacokinetics and pharmacodynamics. Pharmacogenomics is being integrated into clinical pain management practice because variants in individual genes can be predictive of how a patient may respond to a drug treatment. Pain is subjective and is considered challenging to treat. Furthermore, pain patients do not respond to treatments in the same way, which makes it hard to issue a consistent treatment regimen for all pain conditions. Pharmacogenomics would bring consistency to the subjective nature of pain and could revolutionize the field of pain management by providing personalized medical care tailored to each patient based on their gene variants. Additionally, pharmacogenomics offers a solution to the opioid crisis by identifying potentially opioid-vulnerable patients who could be recommended a nonopioid treatment for their pain condition. The integration of pharmacogenomics into clinical practice creates better and safer healthcare practices for patients. In this article, we provide a comprehensive history of pharmacogenomics and pain management, and focus on up to date information on the pharmacogenomics of pain management, describing genes involved in pain, genes that may reduce or guard against pain and discuss specific pain management drugs and their genetic correlations.

Inconsistency in race and ethnic classification in pharmacogenetics studies and its potential clinical implications

Introduction

Racial and ethnic categories are frequently used in pharmacogenetics literature to stratify patients; however, these categories can be inconsistent across different studies. To address the ongoing debate on the applicability of traditional concepts of race and ethnicity in the context of precision medicine, we aimed to review the application of current racial and ethnic categories in pharmacogenetics and its potential impact on clinical care.

Methods

One hundred and three total pharmacogenetics papers involving the CYP2C9, CYP2C19, and CYP2D6 genes were analyzed for their country of origin, racial, and ethnic categories used, and allele frequency data. Correspondence between the major continental racial categories promulgated by National Institutes of Health (NIH) and those reported by the pharmacogenetics papers was evaluated.

Results

The racial and ethnic categories used in the papers we analyzed were highly heterogeneous. In total, we found 66 different racial and ethnic categories used which fall under the NIH race category “White”, 47 different racial and ethnic categories for “Asian”, and 62 different categories for “Black”. The number of categories used varied widely based on country of origin: Japan used the highest number of different categories for “White” with 17, Malaysia used the highest number for “Asian” with 24, and the US used the highest number for “Black” with 28. Significant variation in allele frequency between different ethnic subgroups was identified within 3 major continental racial categories.

Conclusion

Our analysis showed that racial and ethnic classification is highly inconsistent across different papers as well as between different countries. Evidence-based consensus is necessary for optimal use of self-identified race as well as geographical ancestry in pharmacogenetics. Common taxonomy of geographical ancestry which reflects specifics of particular countries and is accepted by the entire scientific community can facilitate reproducible pharmacogenetic research and clinical implementation of its results.

Population pharmacokinetic analysis of tramadol and O-desmethyltramadol with genetic polymorphism of CYP2D6

Aim: Tramadol is widely used to treat acute, chronic, and neuropathic pain. Its primary active metabolite, O-desmethyltramadol (M1), is mainly responsible for its µ-opioid receptor-related analgesic effect. Tramadol is metabolized to M1 mainly by the cytochrome P450 (CYP) 2D6 enzyme, and to other metabolites by CYP3A4 and CYP2B6. The aim of this study was to develop a population pharmacokinetic (PK) model of tramadol and its metabolite using healthy Korean subjects.

Methods: Data on plasma concentrations of tramadol and M1 were obtained from 23 healthy Korean male subjects after a twice-daily oral dose of 100 mg of tramadol, every 12 hrs, for a total of 5 times. Blood samples were collected at 0 (pre-dose), 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 24, 48 and 72 hrs after last administration. Plasma tramadol concentrations were then analyzed using LC/MS. Population PK analysis of tramadol and its metabolite was performed using a nonlinear mixed-effects modeling (NONMEM).

Results: A one-compartment model with combined first-order and zero-order absorption was well fitted to the concentration–time curve of tramadol. M1 was well described by the one-compartment model as an extension of the parent drug (tramadol) model. Genetic polymorphisms of CYP2D6 correlated with the clearance of tramadol, and clearance from the central compartment to the metabolite compartment.

Conclusion: The parent-metabolite model successfully characterized the PK of tramadol and its metabolite M1 in healthy Korean male subjects. These results could be applied to evaluate plasma tramadol concentrations after various dosing regimens.

A genome-wide association study of tramadol metabolism from post-mortem samples

Phase I tramadol metabolism requires cytochrome p450 family 2, subfamily D, polypeptide 6 (CYP2D6) to form O-desmethyltramadol (M1). CYP2D6 genetic variants may infer metabolizer phenotype; however, drug ADME (absorption, distribution, metabolism, and excretion) and response depend on protein pathway(s), not CYP2D6 alone. There is a paucity of data regarding the contribution of trans-acting proteins to idiosyncratic phenotypes following drug exposure. A genome-wide association study identified five markers (rs79983226/kgp11274252, rs9384825, rs62435418/kgp10370907, rs72732317/kgp3743668, and rs184199168/exm1592932) associated with the conversion of tramadol to M1 (M1:T). These SNPs reside within five genes previously implicated with adverse reactions. Analysis of accompanying toxicological meta-data revealed a significant positive linear relationship between M1:T and degree of sample polypharmacy. Taken together, these data identify candidate loci for potential clinical inferences of phenotype following exposure to tramadol and highlight sample polypharmacy as a possible diagnostic covariate in post-mortem genetic studies.

Assessment of CYP2C9, CYP2C19, and CYP2D6 Polymorphisms in Allergic Patients with Chemical Sensitivity

BACKGROUND

Self-reported chemical sensitivity (SCS) is characterized by adverse effects due to exposure to low levels of chemical substances. The clinical manifestations of SCS are similar to the allergy, and a high percentage of individuals with both diseases have been found. Various genes, especially genes of importance to the metabolism of xenobiotic compounds, have been associated with SCS.

OBJECTIVES

The purpose of this study was to investigate whether allergic individuals with chemical sensitivity differed from allergic patients without chemical sensitivity with regard to the distribution of genotype and phenotype of CYP2C9, CYP2C19, and CYP2D6 polymorphisms.

METHODS

A total of 180 patients were enrolled for this study. A questionnaire was employed to collect information on individual chemical sensitivity, while the Skin prick test and the PATCH test were used to verify the presence of an allergic condition against inhalants or contact allergens, respectively. For the evaluation of the CYP2C9, CYP2C19, and CYP2D6 polymorphisms, we used a strategy based on the amplification of the entire gene coupled to direct genomic DNA sequencing analysis.

RESULTS

Overall, a total of 15 different CYP2C9, CYP2C19, and CYP2D6 haplotypes were identified in our population. If the 5 CYP2C9 and the 2 CYP2C19 identified alleles correspond to the previously described ones, 4 of the 8 CYP2D6 haplotypes, detected in the study group, present new SNPs combinations. These new suballeles were categorized as CYP2D6*2M Sa-lento Variant 1, CYP2D6*35B Salento Variant 2, CYP2D6*41 Salento Variant 3, and CYP2D6*4P Salento Variant 4 due to the presence of the key SNPs 2,850 C>T, 31G>A, 2,988 G>A, and 1,846 G>A, respectively. When the allergic individuals are divided into 2 groups according to their SCS score, we observed that the distribution of the CYP2D6 phenotypes was significantly different between the 2 groups.

CONCLUSIONS

Our idea is that the application of the questionnaire that we have adopted has enabled us to diagnose a degree of chemical sensitivity, which results as comorbid of the allergic disease and in which a condition of poor or intermediate metabolizes for the detrimental CYP2D6 alleles, could represent a discriminant between the chemical sensitivity and the health state.

Clinical utility of tafenoquine in the prevention of relapse of Plasmodium vivax malaria: a review on the mode of action and emerging trial data

Tafenoquine is an 8-aminoquinoline with activity against all human life cycle stages of Plasmodium vivax, including dormant liver stages – so called hypnozoites. Its long half-life of ~15 days is allowing for a single exposure regimen. It has been under development since 1980 and received approval by the US Food and Drug Administration in summer 2018 as an anti-relapse drug for P. vivax malaria in patients aged 16 years and older and for prophylaxis of malaria caused by any Plasmodium species in adults. Prior to tafenoquine administration, glucose-6-phosphate dehydrogenase (G6PD) deficiency needs to be excluded by testing. Individuals with a deficient G6PD activity are at risk of tafenoquine-induced hemolysis – as is the case for primaquine, the mainstay drug for P. vivax radical cure. A wealth of clinical studies have been conducted and are still ongoing to assess the safety, tolerability, and efficacy of tafenoquine. This review focuses on data emerging from the latest clinical trials on P. vivax radical cure with tafenoquine, the key studies for regulatory approval of tafenoquine, and elucidates the latest hypothesis on the mode of action.

Analysis of smoking behavior on the pharmacokinetics of antidepressants and antipsychotics: evidence for the role of alternative pathways apart from CYP1A2

Smoking is common among psychiatric patients and has been shown to accelerate the metabolism of different drugs. We aimed to determine the effect of smoking on the serum concentrations of psychopharmacological drugs in a naturalistic clinical setting. Dose-corrected, steady-state serum concentrations of individual patients were analyzed retrospectively by linear regression including age, sex, and smoking for amitriptyline (n=503), doxepin (n=198), mirtazapine (n=572), venlafaxine (n=534), clozapine (n=106), quetiapine (n=182), and risperidone (n=136). Serum levels of amitriptyline (P=0.038), clozapine (P=0.02), and mirtazapine (P=0.002) were significantly lower in smokers compared with nonsmokers after correction for age and sex. In addition, the ratios of nortriptyline/amitriptyline (P=0.001) and nordoxepin/doxepin (P=0.014) were significantly higher in smokers compared with nonsmokers. Smoking may not only induce CYP1A2, but may possibly also affect CYP2C19. Furthermore, CYP3A4, UGT1A3, and UGT1A4 might be induced by tobacco smoke. Hence, a different dosing strategy is required among smoking and nonsmoking patients. Nevertheless, the clinical relevance of the results remained unclear.

Identification of Cytochrome P450 Polymorphisms in Burn Patients and Impact on Fentanyl Pharmacokinetics: A Pilot Study

Pain management is critical for burn care. Unfortunately, interindividual variation in pharmacokinetics (PK) due to burn hypermetabolism and genetic polymorphisms can lead to treatment failures in this at-risk population. Analgesics may be affected by genetic polymorphisms affecting cytochrome P450 (CYP) drug metabolizing enzymes. Fentanyl is a common opiate primarily metabolized by CYP3A4 subtypes. Recent studies demonstrate CYP2D6 variants, affecting fentanyl PK. Functional CYP polymorphisms can significantly alter opiate levels resulting in inadequate analgesia or life-threatening toxicity. The goal of our study was to evaluate fentanyl PK and assess associations with CYP polymorphisms. We obtained samples from the previously banked blood of 13 patients (eight males and five females) with >20% TBSA burns. Mean (SD) patient age was 41.7 (14.5) years, and mean burn size was 25.8 (15.3) %TBSA. Plasma fentanyl was quantified, and CYP genotyping was performed. Pharmacokinetic analysis was performed using Monolix software (Lixsoft, France) with a two-compartment population model best-representing fentanyl profiles. Three CYP slow-metabolizing genotypes were identified, which included CYP2D6*9, CYP2D6*29, and CYP3A4*1B. All three patients with variant polymorphisms had increased serum fentanyl concentrations due to impaired clearance. This pilot study supports the need for further research in this topic, and CYP genotyping of individual patients prior to receiving opiate analgesics to inform precision-guided decisions, improve therapeutic efficacy, and, most importantly, increase patient well-being and safety.

CYP2D6 genotype can help to predict effectiveness and safety during opioid treatment for chronic low back pain: results from a retrospective study in an Italian cohort

Background

Opioids are widely used for chronic low back pain (CLBP); however, it is still unclear how to predict their effectiveness and safety. Codeine, tramadol and oxycodone are metabolized by CYP/CYP450 2D6 (CYP2D6), a highly polymorphic enzyme linked to allele-specific related differences in metabolic activity.

Purpose

CYP2D6 genetic polymorphisms could potentially help to predict the effectiveness and safety of opioid-based drugs in clinical practice, especially in the treatment of CLBP.

Patients and methods

A cohort of 224 Italian patients with CLBP treated with codeine or oxycodone was retrospectively evaluated to determine whether adverse reactions and effectiveness were related to CYP2D6 single-nucleotide polymorphisms. CYP2D6 genotyping was performed using the xTAG^® CYP2D6 Kit v3 (Luminex) to determine CYP2D6 metabolizer phenotype (poor, intermediate, rapid and ultrarapid). Subjects from the cohort were categorized into two groups according to the occurrence of side effects (Case) or benefit (Control) after chronic analgesic treatment. The impact of CYP2D6 polymorphism on treatment outcome was tested at the metabolizer phenotype, diplotype and haplotype levels.

Results

CYP2D6 polymorphism was significantly associated with opioid treatment outcome (Omnibus P=0.018, for both global haplotype and diplotype distribution test). CYP2D6*6 and *9 carriers, alleles characterized by a reduced (*9) or absent (*6) enzymatic activity, were significantly (P<0.05) associated with therapeutic failure. CYP2D6 ultrarapid metabolizers (CYP2D6*2N patients) showed an increased risk of side effects, as would be predicted. Despite their low frequency, CYP2D6 *1/*11, *4/*6 and *41/* 2N diplotypes showed significant (P<0.05) associations of efficacy and side effects with chronic opioid treatment.

Conclusion

Our results showed that reduced CYP2D6 activity is correlated with lack of therapeutic effect. We found that the pharmacogenetic analysis of CYP2D6 could be helpful in foreseeing the safety and effectiveness of codeine or oxycodone treatment in CLBP.

Genetic Polymorphisms and In Silico Mutagenesis Analyses of CYP2C9, CYP2D6, and CYPOR Genes in the Pakistani Population

Diverse distributions of pharmacogenetically relevant variants of highly polymorphic CYP2C9, CYP2D6 and CYPOR genes are responsible for some varied drug responses observed across human populations. There is limited data available regarding the pharmacogenetic polymorphisms and frequency distributions of major allele variants in the Pakistani population. The present in silico mutagenesis study conducted on genotype pharmacogenetic variants and comparative analysis with a global population aims to extend the currently limited pharmacogenetic available evidence for the indigenous Pakistani population. Extracted genomic DNA from 244 healthy individuals' venous blood samples were amplified for distinct variant loci in the CYP2C9, CYP2D6 and CYPOR genes. Two-way sequencing results were compared with standard PubMed data and sequence variant loci confirmed by Chromas. This study revealed significant variations in CYP2C9 (rs1799853, rs1057910 and rs72558189), CYP2D6 (rs16947 and rs1135840), and CYPOR (rs1057868, rs781919285 and rs562750402) variants in intraethnic and interethnic frequency distributions. In silico mutagenesis and three-dimensional protein structural alignment analysis approaches clearly exposed the possible varied impact of rare CYPOR (rs781919285 and rs562750402) single nucleotide polymorphisms (SNPs) and confirmed that the influences of CYP2C9 and CYP2D6 variants are consistent with what was found in earlier studies. This investigation highlighted the need to study pharmacogenetic relevance loci and documentation since evidence could be utilized to elucidate genetic backgrounds of drug metabolism, and provide a basis for future pharmacogenomic studies and adequate dose adjustments in Pakistani and global populations.

Cytochrome P450: Polymorphisms and Roles in Cancer, Diabetes and Atherosclerosis

Cytochromes P450s (CYPs) constitute a superfamily of enzymes that catalyze the metabolism of drugs and other substances. Endogenous substrates of CYPs include eicosanoids, estradiol, arachidonic acids, cholesterol, vitamin D and neurotransmitters. Exogenous substrates of CYPs include the polycyclic aromatic hydrocarbons and about 80% of currently used drugs. Some isoforms can activate procarcinogens to ultimate carcinogens. Genetic polymorphisms of CYPs may affect the enzyme catalytic activity and have been reported among different populations to be associated with various diseases and adverse drug reactions. With regard of drug metabolism, phenotypes for CYP polymorphism range from ultrarapid to poor metabolizers. In this review, we discuss some of the most clinically important CYPs isoforms (CYP2D6, CYP2A6, CYP2C19, CYP2C9, CYP1B1 and CYP1A2) with respect to gene polymorphisms and drug metabolism. Moreover, we review the role of CYPs in renal, lung, breast and prostate cancers and also discuss their significance for atherosclerosis and type 2 diabetes mellitus.

Value of Supportive Care Pharmacogenomics in Oncology Practice

Genomic medicine provides opportunities to personalize cancer therapy for an individual patient. Although novel targeted therapies prolong survival, most patients with cancer continue to suffer from burdensome symptoms including pain, depression, neuropathy, nausea and vomiting, and infections, which significantly impair quality of life. Suboptimal management of these symptoms can negatively affect response to cancer treatment and overall prognosis. The effect of genetic variation on drug response-otherwise known as pharmacogenomics-is well documented and directly influences an individual patient's response to antiemetics, opioids, neuromodulators, antidepressants, antifungals, and more. The growing body of pharmacogenomic data can now guide clinicians to select the safest and most effective supportive medications for an individual patient with cancer from the very first prescription. This review outlines a theoretical patient case and the implications of using pharmacogenetic test results to personalize supportive care throughout the cancer care continuum.

IMPLICATIONS FOR PRACTICE

Integration of palliative medicine into the cancer care continuum has resulted in increased quality of life and survival for patients with many cancer types. However, suboptimal management of symptoms such as pain, neuropathy, depression, and nausea and vomiting continues to place a heavy burden on patients with cancer. As demonstrated in this theoretical case, pharmacogenomics can have a major effect on clinical response to medications used to treat these conditions. Recognizing the value of supportive care pharmacogenomics in oncology and application into routine practice offers an objective choice for the safest and most effective treatment compared with the traditional trial and error method.

Pharmacogenomics and Patient Treatment Parameters to Opioid Treatment in Chronic Pain: A Focus on Morphine, Oxycodone, Tramadol, and Fentanyl

Objective

Opioids are one of the most commonly prescribed medicines for chronic pain. However, their use for chronic pain has been controversial. The objective of this literature review was to identify the role of genetic polymorphisms on patient treatment parameters (opioid dose requirements, response, and adverse effects) for opioids used in malignant and nonmalignant chronic pain. The opioids that this review focuses on are codeine, morphine, oxycodone, tramadol, and fentanyl.

Method

A literature search of databases Medline and Embase was carried out, and studies up to April 2016 were included in this review. Studies were included based on a combination of key words: chronic pain and related terms, pharmacogenetics and related terms, and opioids and related terms.

Results

Among the 1,408 individual papers retrieved from the search in Medline and Embase, 32 original articles were included in this review, with none related to codeine. The 32 papers reported various study designs, opioids, and polymorphisms being studied for associations with treatment outcomes. This literature review reveals that variants in ABCB1, OPRM1, and COMT have been replicated for opioid dosing and variants in ABCB1 have been replicated for both treatment response and adverse effects.

Conclusions

Currently, there are few validated studies to form a strong evidence base to support pharmacogenomics testing when initiating opioid therapy. However, the field of pharmacogenomics in chronic pain is likely to expand over the coming years, with the increasing number of treatment options available and larger cohorts being assembled in order to identify true associations.

Characterization of in vitro and in vivo metabolism of leelamine using liquid chromatography-tandem mass spectrometry

Leelamine is a diterpene compound found in the bark of pine trees and has garnered considerable interest owing to its potent anticancer properties. The aim of the present study was to investigate the metabolic profile of leelamine in human liver microsomes (HLMs) and mice using liquid chromatography-tandem mass spectrometry (LC-MS/MS). We found that leelamine undergoes only Phase I metabolism, which generates one metabolite that is mono-hydroxylated at the C9 carbon of the octahydrophenanthrene ring (M1) both in vitro and in vivo. The structure and metabolic pathway of M1 were determined from the MSⁿ fragmentation obtained by collision-induced dissociation using LC-MS/MS in HLMs. Cytochrome p450 (CYP) 2D6 was found to be the dominant CYP enzyme involved in the biotransformation of leelamine to its hydroxylated metabolite, whereas CYP2C19, CYP1A1, and CYP3A4 contributed to some extent. Moreover, we identified only one metabolite M1, in the urine, but none in the feces. In conclusion, leelamine was metabolized to a mono-hydroxyl metabolite by CYP2D6 and mainly excreted in the urine.