Gene-Based Dose Optimization in Children.

Pharmacogenetics is a key component of precision medicine. Genetic variation in drug metabolism enzymes can lead to variable exposure to drugs and metabolites, potentially leading to inefficacy and drug toxicity. Although the evidence for pharmacogenetic associations in children is not as extensive as for adults, there are several drugs across diverse therapeutic areas with robust pediatric data indicating important, and relatively common, drug-gene interactions. Guidelines to assist gene-based dose optimization are available for codeine, thiopurine drugs, selective serotonin reuptake inhibitors, atomoxetine, tacrolimus, and voriconazole. For each of these drugs, there is an opportunity to clinically implement precision medicine approaches with children for whom genetic test results are known or are obtained at the time of prescribing. For many more drugs that are commonly used in pediatric patients, additional investigation is needed to determine the genetic factors influencing appropriate dose.

Pharmacogenetic evaluation to assess breakthrough psychosis with aripiprazole long-acting injection: a case report.

BACKGROUND: Given the complex nature of symptom presentation and medication regimens, psychiatric clinics may benefit from additional tools to personalize treatments. Utilizing pharmacogenetic information may be helpful in assessing unique responses to therapy. We report herein a case of wearing-off phenomena during treatment with aripiprazole long-acting injectable (LAI) and a proof of concept strategy of how pharmacogenetic information may be used to assess possible genetic factors and also hypothesize potential mechanisms for further study. CASE PRESENTATION: A 51-year-old African American male with schizoaffective disorder was referred to a psychiatric clinic for medication management. After unsuccessful trials of multiple antipsychotics, oral aripiprazole was initiated (up to 30 mg/day) and transitioned to aripiprazole LAI with symptom improvement. At a high dose of aripiprazole LAI (400 mg Q3wks), the patient experienced breakthrough symptoms approximately 3 days prior to his next injection. Various considerations were examined to explain his atypical dose requirements, including but not limited to pharmacogenetic influences. Pharmacogenetic testing ruled out genetic influences on drug metabolism but noted a -141C Del variant in the dopamine-D2 receptor (DRD2) gene associated in prior studies of poor-response to antipsychotics. At this time, a new formulation, aripiprazole lauroxil, was explored due to its availability in higher dose options. Transition to the new formulation (882 mg Q4wks) greatly improved and stabilized the patient's symptoms with no breakthrough psychosis. Comparable daily dose equivalents were achieved with two different formulations due to the Q3wks vs Q4wks dosing strategies, although the two agents have some differences in pharmacokinetic profiles. CONCLUSIONS: We report a case of a patient experiencing wearing-off symptoms with aripiprazole LAI who benefited from switching to aripiprazole lauroxil. Pharmacogenetic testing revealed normal activity for relevant metabolism pathways but a DRD2 -141C variant that may influence brain D2 expression and antipsychotic responsiveness. The clinical utility of DRD2 information and what to do with genotyping results has not been previously addressed, despite availability on clinical test panels. Our case report suggests further investigations of altered dosing strategies and receptor genotype sensitivities to pharmacokinetic factors may be helpful in understanding symptom re-emergence observed in some patients taking LAI antipsychotics.

Population Pharmacokinetic Analysis of Atomoxetine and its Metabolites in Children and Adolescents with Attention-Deficit/Hyperactivity Disorder.

Atomoxetine (ATX) is a non-stimulant used to treat attention-deficit/hyperactivity disorder (ADHD) and systemic exposure is highly variable due to polymorphic cytochrome P450 2D6 (CYP2D6) activity. The objective of this study was to characterize the time course of ATX and metabolites (4-hydroxyatomoxetine (4-OH); N-desmethylatomoxetine (NDA); and 2-carboxymethylatomoxetine (2-COOH)) exposure following oral ATX dosing in children with ADHD to support individualized dosing. A nonlinear mixed-effect modeling approach was used to analyze ATX, 4-OH, and NDA plasma and urine, and 2-COOH urine profiles obtained over 24-72 hours from children with ADHD (n = 23) following a single oral ATX dose. Demographics and CYP2D6 activity score (AS) were evaluated as covariates. Simulations were performed to explore the ATX dosing in subjects with various CYP2D6 AS. A simultaneous pharmacokinetic modeling approach was used in which a model for ATX, 4-OH, and NDA in plasma and urine, and 2-COOH in urine was developed. Plasma ATX, 4-OH, and NDA were modeled using two-compartment models with first-order elimination. CYP2D6 AS was a significant determinant of ATX apparent oral clearance (CL/F), fraction metabolized to 4-OH, and systemic exposure of NDA. CL/F of ATX varied almost 7-fold across the CYP2D6 AS groups: AS 2: 20.02 L/hour; AS 1: 19.00 L/hour; AS 0.5: 7.47 L/hour; and AS 0: 3.10 L/hour. The developed model closely captures observed ATX, 4-OH, and NDA plasma and urine, and 2-COOH urine profiles. Application of the model shows the potential for AS-based dosing recommendations for improved individualized dosing.

How Pharmacogenomics Informs and Influences the Medication Experience.

Both pharmacogenomics (PGx) and the medication experience (MedXp) share a common purpose for their use, which is to optimally tailor medications to each unique individual. The former pursues this aim by using an individual's genetic makeup, while the latter considers the subjective experience of medication-taking in one's life. The different ways by which these fields of study pursue their shared aim have resulted in relatively little understanding of their relationship when utilized in care processes to produce health outcomes. This commentary explores this gap and identifies implications for future research that can help close it to improve person-centered care.

Meeting the New AACP Competencies in Genetics and Clinical Pharmacogenomics at the University of Minnesota.

Objective: Pharmacogenomics (PGx) is increasingly being used for creating individualized treatments for patient care. Healthcare professionals, especially pharmacists, need to understand how genetic variation impacts the efficacy and toxicity of medications. Due to the breadth and complexity of PGx-related information, it has been challenging to determine what information should be included in pharmacy curricula and how best to educate students. Methods: The University of Minnesota College of Pharmacy recently began the process of incorporating into the curriculum expanded competencies for PGx from the American Association of Colleges of Pharmacy (AACP) Pharmacogenomics Special Interest Group (PGx-SIG). We evaluated our curriculum for PGx content, determined what was currently being taught and identified educational gaps. Results: A review of our Doctor of Pharmacy curriculum showed substantial PGx content, although it was inconsistently taught throughout the required courses and in some courses absent. We revised the content of existing courses incorporating content that meet most of the PGx-SIG recommended competencies. Conclusion: There are and will be major changes in our understanding of the influences of PGx on individualized medical treatment. As our understanding grows, information on PGx in pharmacy curriculums will need to keep pace with these changes. We have begun this process at the University of Minnesota by doing a full review of PGx related information and making appropriate revisions in the pharmacy curriculum.

Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline for CYP2D6, CYP2C19, CYP2B6, SLC6A4, and HTR2A Genotypes and Serotonin Reuptake Inhibitor Antidepressants.

Serotonin reuptake inhibitor antidepressants, including selective serotonin reuptake inhibitors (SSRIs; i.e., citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline), serotonin and norepinephrine reuptake inhibitors (i.e., desvenlafaxine, duloxetine, levomilnacipran, milnacipran, and venlafaxine), and serotonin modulators with SSRI-like properties (i.e., vilazodone and vortioxetine) are primary pharmacologic treatments for major depressive and anxiety disorders. Genetic variation in CYP2D6, CYP2C19, and CYP2B6 influences the metabolism of many of these antidepressants, which may potentially affect dosing, efficacy, and tolerability. In addition, the pharmacodynamic genes SLC6A4 (serotonin transporter) and HTR2A (serotonin-2A receptor) have been examined in relation to efficacy and side effect profiles of these drugs. This guideline updates and expands the 2015 Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for CYP2D6 and CYP2C19 genotypes and SSRI dosing and summarizes the impact of CYP2D6, CYP2C19, CYP2B6, SLC6A4, and HTR2A genotypes on antidepressant dosing, efficacy, and tolerability. We provide recommendations for using CYP2D6, CYP2C19, and CYP2B6 genotype results to help inform prescribing these antidepressants and describe the existing data for SLC6A4 and HTR2A, which do not support their clinical use in antidepressant prescribing.

The Pharmacogenetic Impact on the Pharmacokinetics of ADHD Medications.

ADHD is a common condition in both children and adults. The most prescribed medications for the treatment of ADHD include methylphenidate, mixed amphetamine salts, atomoxetine, guanfacine, and clonidine. While each of these medications have their own distinct pharmacokinetic profile, the extent to which pharmacogenetics effects their pharmacokinetic parameters is best described in atomoxetine, followed by methylphenidate. Atomoxetine is predominantly metabolized by cytochrome p450 2D6 (CYP2D6), while methylphenidate is metabolized by carboxylesterase 1 (CES1). Both CYP2D6 and CES1 have multiple variants resulting in varying levels of enzyme activity; however, to date, the functional consequence of variants and alleles for CYP2D6 is better characterized as compared to CES1. Regarding CYP2D6, individuals who are poor metabolizers prescribed atomoxetine experience up to ten-fold higher exposure as compared to normal metabolizers at comparable dosing. Additionally, individuals prescribed methylphenidate with the rs71647871 variant may experience up to 2.5-fold higher exposure as compared to those without. Having this pharmacogenetic information available may aid clinicians and patients when choosing medications and doses to treat ADHD.

Assessing pharmacy students' baseline tolerance for ambiguity, burnout, empathy, quality of life, and stress.

INTRODUCTION: Several factors may affect student wellbeing, including tolerance for ambiguity, burnout, empathy, quality of life, and stress. A better understanding of how pharmacy students score on these scales relative to other health professional students could help educators and schools address and improve student wellbeing. The study objective was to determine a baseline measure of pharmacy student tolerance for ambiguity, burnout, empathy, quality of life, and stress. METHODS: A voluntary survey including several assessment scales (Tolerance for Ambiguity, Oldenburg Burnout Inventory, Interpersonal Reactivity Index [empathy], Quality of Life Scale, and Perceived Stress Scale) was sent by email to all pharmacy students within a standalone college of pharmacy. RESULTS: Two hundred thirty-one pharmacy students completed all aspects of the survey. Comparing each scale with sex, female students trended higher in Interpersonal Reactivity Index and scored significantly higher on the Oldenburg Burnout Inventory (disengagement), while male students scored significantly higher for Quality of Life. Fourth-year students scored significantly higher on the Tolerance for Ambiguity scale as compared to first- and second-year students and on the Quality of Life scale as compared with third-year students. Third-year students experienced the greatest levels of burnout. Differences were also noted based on students' anticipated area of practice (empathy) and desire to work with an underserved population (empathy and stress). CONCLUSIONS: Pharmacy students' responses to the included scales varied greatly when considering various demographic parameters. The significant differences identified are illuminating and represent potential areas for curricular improvement, student support, and further study within pharmacy school curricula.

Sertraline dosing trends in children and adolescents stratified by CYP2C19 genotype.

Aim: Sertraline is a CYP2C19 substrate commonly prescribed to children with anxiety. Materials & methods: This medical record review examined dosing trends and treatment discontinuation in children prescribed sertraline with documented CYP2C19 genotypes. Variables collected included age, weight, diagnosis, concomitant medications, initial sertraline dose, dose changes and CYP2C19 genotypes. Results: A total of 90 individuals (average age: 10.5 years; 40% female) were included. Nearly 80% were prescribed sertraline for anxiety. Initial weight-adjusted doses were similar, but mean weight-adjusted doses of sertraline were 65% higher in increased metabolizers (1.5 mg/kg/day) compared with normal metabolizers (0.91 mg/kg/day; p = 0.067) at the second dose change. Conclusion: While all children started at a similar sertraline dose, different trends in prescribed doses were observed across CYP2C19 genotypes at subsequent dose changes.

Addressing disparities in pharmacogenomics through rural and underserved workforce education.

Introduction: While pharmacogenomic (PGx) testing is routine in urban healthcare institutions or academic health centers with access to existing expertise, uptake in medically-underserved areas is lagging. The primary objective of this workforce education program is to extend access to didactic, case-based and clinical PGx training for pharmacists serving rural Minnesota and populations experiencing health disparities in Minnesota. Methods: A PGx workforce training program funded through the Minnesota Department of Health was offered through the University of Minnesota College of Pharmacy (COP) to pharmacists working in rural and/or underserved areas in the state of Minnesota. Learning activities included a 16-week, asynchronous PGx didactic course covering PGx topics, a 15-min recorded presentation, an in-person PGx case-based workshop, and a live international PGx Conference hosted by the University of Minnesota COP and attendance at our PGx Extension of Community Health Outcomes (ECHO). Results: Twenty-nine pharmacists applied for the initial year of the program, with 12 (41%) being accepted. Four (33%) practiced in a hospital setting, four (33%) in retail pharmacy, two (17%) in managed care, and two (17%) in other areas. The majority had not implemented a PGx program as part of their practice, although nearly all responded definitely or probably yes when asked if they expected their organization to increase its use of PGx testing services over the next three years. All participants either strongly or somewhat agreed that this program helped them identify how and where to access clinical PGx guidelines and literature and improved their ability to read and interpret PGx test results. Eight participants (67%) strongly or somewhat agreed that they expected to increase the number of PGx consultations in their practice, while ten (83%) strongly or somewhat agreed they would be able to apply what they learned in this program to their practice in the next six months to a year. Discussion: This novel PGx training program focused exclusively on pharmacists in rural and/or underserved areas with a delivery method that could be accomplished conveniently and remotely. Although most participants' organizations had yet to implement PGx testing routinely, most anticipated this to change in the next few years.

Knowledge and attitudes of incoming pharmacy students toward pharmacogenomics and survey reliability.

Aims: To assess knowledge and attitudes toward pharmacogenomics (PGx) of incoming doctoral pharmacy students, to evaluate the internal structure and reliability of the PGx survey and to identify variables associated with the different responses. Methods: A PGx survey based on the core pharmacist competencies in PGx was created. Results: Of 83.2% analyzable responses, 91% believed PGx is a useful tool and relevant to future practice but over 70% stated they lack confidence in clinical PGx knowledge. This 38-item PGx survey included three factors showing high reliability. Prior genetic/PGx testing and unsatisfactory medication experiences were associated with a more positive attitude toward PGx. Conclusion: The majority of students have positive attitudes toward PGx, but lack knowledge in genetic concepts and clinical PGx.

A pharmacogenomics (PGx) survey with high reliability showed that incoming doctoral pharmacy students have positive attitudes toward PGx, but lack knowledge of genetic concepts and clinical PGx.

Associations between CES1 variants and dosing and adverse effects in children taking methylphenidate.

Background: Methylphenidate is the most prescribed stimulant to treat attention deficit-hyperactivity disorder (ADHD). Despite its widespread usage, a fair proportion of children are classified as non-responders to the medication. Variability in response and occurrence of adverse events with methylphenidate use may be due to several factors, including drug-drug interactions as well as pharmacogenetic differences resulting in pharmacokinetic and/or pharmacodynamic variances within the general population. The objective of this study was to analyze the effect of carboxylesterase 1 (CES1) variants on the frequency of adverse effects and dosing requirements of methylphenidate in children with ADHD. Methods: This was a retrospective cohort study of children and adolescents who met the inclusion criteria and had a routine visit during the enrollment period were invited to participate. Inclusion criteria included: ADHD diagnosis by a healthcare provider, between 6 and 16 years of age at the time of permission/assent, had not previously been prescribed methylphenidate, and treatment with any methylphenidate formulation for at least three consecutive months. Three months of records were reviewed in order to assess changes in dose and frequency of discontinuing methylphenidate. Participants' ADHD symptoms, medication response, adverse effects, select vitals, and dose were extracted from the electronic health record. Saliva samples were collected by trained study coordinators. Haplotypes were assigned based on copy number in different portions of the CES1 gene. Due to limited numbers, diplotypes (combinations of two haplotypes) were grouped for analysis as CES1A1/CES1A1, CES1A1/CES1A1c and CES1A1c/CES1A1c. Results: A total of 99 participants (n = 30 female; n = 69 male) had both clinical data and CES1 sequencing data, with an average age of 7.7 years old (range 3-15 years). The final weight-based dose in all individuals was 0.79 mg/kg/day. The most common adverse effects reported were decreased appetite (n = 47), weight loss (n = 24), and sleep problems (n = 19). The mean final weight-based dose by haplotype was 0.92 mg/kg for CES1A2/CES1A2, 0.81 mg/kg for CES1A2/CES1P1, and 0.78 mg/kg for CES1P1/CES1P1. After correction for multiple hypothesis testing, only one SNV, rs114119971, was significantly associated with weight-based dosing in two individuals. The individuals with the rs114119971 SNV had a significantly lower weight-based dose (0.42 mg/kg) as compared to those without (0.88 mg/kg; p < 0.001). Discussion: Variation in CES1 activity may impact dose requirements in children who are prescribed methylphenidate, as well as other CES1 substrates. Although intriguing, this study is limited by the retrospective nature and relatively small sample size.

Current strategies for predicting side effects from second generation antipsychotics in youth.

Introduction: Antipsychotic medications are used to treat a number of conditions in children and adolescents. While side effect profiles from second generation antipsychotics (SGAs) may differ from older antipsychotics, they do not come without risk. Knowing which children may be at higher risk for specific outcomes is important clinical information for prescribers. Common side effects and toxicities of SGAs in children include movement disorders, weight gain, and hormonal changes. There are also rare, but potentially dangerous adverse events including neuroleptic malignant syndrome, hypersensitivity and suicidal ideation.Areas covered: This review will summarize and comment on clinical, pharmacological, and genetic factors having evidence as predictors of SGA-associated side effects and toxicities in children.Expert opinion: Observations across studies note that older children and those that do not respond early in treatment may be more at risk for movement disorders, while younger, antipsychotic naive children are at increased risk for weight gain. Relatively fewer studies have looked at pharmacogenetic relationships, although variations in pharmacokinetic and pharmacodynamic genes hold promise to advance drug dosing or selection strategies. Future efforts to assimilate multiple clinical, pharmacological, and genetic factors to facilitate predictive analytics and clinical decision support for prescribers will advance precision care to patients.

Integrating pharmacogenetic testing via medication therapy management in an outpatient family medicine clinic.

Introduction: Pharmacogenetic (PGx) implementation has lagged behind the development of drug/gene pair guidelines. Materials & methods: This was a prospective study assessing the integration of PGx through medication therapy management in an outpatient clinic. Variables collected included patient diagnosis, current medications, failed or discontinued medications, PGx results/recommendations, turnaround time and pre/post clinical ratings. Results: A total of 91 participants completed study procedures with an average enrollment of approximately one consult per week. Participants were referred for testing primarily for guidance for current and future medications. The average number of recommendations per participant was 0.93. Conclusion: Integrating PGx testing into medication therapy management is feasible with PGx results available in under a week resulting in clinical recommendations in over half of patients tested.

Characterizing Pharmacogenetic Testing Among Children's Hospitals.

Although pharmacogenetic testing is becoming increasingly common across medical subspecialties, a broad range of utilization and implementation exists across pediatric centers. Large pediatric institutions that routinely use pharmacogenetics in their patient care have published their practices and experiences; however, minimal data exist regarding the full spectrum of pharmacogenetic implementation among children's hospitals. The primary objective of this nationwide survey was to characterize the availability, concerns, and barriers to pharmacogenetic testing in children's hospitals in the Children's Hospital Association. Initial responses identifying a contact person were received from 18 institutions. Of those 18 institutions, 14 responses (11 complete and 3 partial) to a more detailed survey regarding pharmacogenetic practices were received. The majority of respondents were from urban institutions (72%) and held a Doctor of Pharmacy degree (67%). Among all respondents, the three primary barriers to implementing pharmacogenetic testing identified were test reimbursement, test cost, and money. Conversely, the three least concerning barriers were potential for genetic discrimination, sharing results with family members, and availability of tests in certified laboratories. Low-use sites rated several barriers significantly higher than the high-use sites, including knowledge of pharmacogenetics (P = 0.03), pharmacogenetic interpretations (P = 0.04), and pharmacogenetic-based changes to therapy (P = 0.03). In spite of decreasing costs of pharmacogenetic testing, financial barriers are one of the main barriers perceived by pediatric institutions attempting clinical implementation. Low-use sites may also benefit from education/outreach in order to reduce perceived barriers to implementation.

Pharmacogenomics education, research and clinical implementation in the state of Minnesota.

Several healthcare organizations across Minnesota have developed formal pharmacogenomic (PGx) clinical programs to increase drug safety and effectiveness. Healthcare professional and student education is strong and there are multiple opportunities in the state for learners to gain workforce skills and develop advanced competency in PGx. Implementation planning is occurring at several organizations and others have incorporated structured utilization of PGx into routine workflows. Laboratory-based and translational PGx research in Minnesota has driven important discoveries in several therapeutic areas. This article reviews the state of PGx activities in Minnesota including educational programs, research, national consortia involvement, technology, clinical implementation and utilization and reimbursement, and outlines the challenges and opportunities in equitable implementation of these advances.

Using pharmacogenomics and therapeutic drug monitoring to guide drug selection and dosing in outpatient mental health comprehensive medication management.

Pharmacogenomic (PGx) testing aided by therapeutic drug monitoring (TDM) has the potential to improve medication-related outcomes in some individuals prescribed psychiatric medications. Many commonly prescribed psychiatric medications are metabolized through polymorphic drug metabolizing enzymes such as cytochrome p450 (CYP) 2D6 (CYP2D6) and CYP2C19. Through PGx testing, clinicians can make biologically informed choices when selecting a new medication, and TDM may help inform dose adjustments or assess exposures to current treatments. Herein, we describe 2 complex case reports of individuals with multiple psychiatric diagnoses and extensive histories of medication failures who underwent PGx testing in addition to TDM as part of a pharmacist-led comprehensive medication therapy management evaluation in a community mental health clinic setting.

Pharmacist's attitudes and knowledge of pharmacogenomics and the factors that may predict future engagement.

BACKGROUND: While pharmacists are well positioned to implement pharmacogenomic testing in healthcare systems, uptake has been limited. OBJECTIVE: The primary objective of this survey was to determine how post-graduate education and training influences pharmacist's knowledge and attitudes of pharmacogenomic testing. METHODS: Survey questions were developed by the study team, and responses were collected electronically using REDCap™. The electronic survey was sent to all pharmacists (n=161) within a large, multi-state healthcare system by email. RESULTS: A total of 75 (47%) respondents completed all aspects of the survey. The majority of respondents were female (60%), worked in acute care settings (57%), were full-time employees (80%), and worked in an urban area (85%), with many graduating in or after 2010 (43%). For post-graduate education, 36% of respondents completed a Post-Graduate Year One Residency (PGY-1), and 27% had a board certification. Those that completed a PGY-1 residency were significantly more likely to have received formal training or education on pharmacogenomics than those who had not. They also assessed their own knowledge of pharmacogenomic resources and guidelines higher than those without PGY-1 training. More recent graduates were also significantly more likely to have received formal training or education on pharmacogenomics. Additionally, pharmacists who completed a PGY-1 residency were more likely to respond favorably to pharmacogenomics being offered through pharmacy services. Pharmacists with board certification were more comfortable interpreting results of a pharmacogenomic test than those without board certification. CONCLUSIONS: Pharmacists who have completed a PGY-1 residency or received board certification appear more comfortable with interpretation and implementation of pharmacogenomic testing.

Clinical Pharmacogenetics Implementation Consortium Guideline for Cytochrome P450 (CYP)2D6 Genotype and Atomoxetine Therapy.

Atomoxetine is a nonstimulant medication used to treat attention-deficit/hyperactivity disorder (ADHD). Cytochrome P450 (CYP)2D6 polymorphisms influence the metabolism of atomoxetine thereby affecting drug efficacy and safety. We summarize evidence from the published literature supporting these associations and provide therapeutic recommendations for atomoxetine based on CYP2D6 genotype (updates at www.cpicpgx.org).