Pharmacogenetics of Neonatal Opioid Toxicity Following Maternal Use of Codeine During Breastfeeding: A Case–Control Study

Does Preoperative Pharmacogenomic Testing of Patients Undergoing TKA Improve Postoperative Pain? A Randomized Trial

BACKGROUND

Pharmacogenomics is an emerging and affordable tool that may improve postoperative pain control. One challenge to successful pain control is the large interindividual variability among analgesics in their efficacy and adverse drug events. Whether preoperative pharmacogenomic testing is worthwhile for patients undergoing TKA is unclear.

QUESTIONS/PURPOSES

(1) Are the results of preoperative pharmacogenetic testing associated with lower postoperative pain scores as measured by the Overall Benefit of Analgesic Score (OBAS)? (2) Do the results of preoperative pharmacogenomic testing lead to less total opioids given? (3) Do the results of preoperative pharmacogenomic testing lead to changes in opioid prescribing patterns?

METHODS

Participants of this randomized trial were enrolled from September 2018 through December 2021 if they were aged 18 to 80 years and were undergoing primary TKA under general anesthesia. Patients were excluded if they had chronic kidney disease, a history of chronic pain or narcotic use before surgery, or if they were undergoing robotic surgery. Preoperatively, patients completed pharmacogenomic testing (RightMed, OneOME) and a questionnaire and were randomly assigned to the experimental group or control group. Of 99 patients screened, 23 were excluded, one before randomization; 11 allocated patients in each group did not receive their allocated interventions for reasons such as surgery canceled, patients ultimately undergoing spinal anesthesia, and change in surgery plan. Another four patients in each group were excluded from the analysis because they were missing an OBAS report. This left 30 patients for analysis in the control group and 38 patients in the experimental group. The control and experimental groups were similar in age, gender, and race. Pharmacogenomic test results for patients in the experimental group were reviewed before surgery by a pharmacist, who recommended perioperative medications to the clinical team. A pharmacist also assessed for clinically relevant drug-gene interactions and recommended drug and dose selection according to guidelines from the Clinical Pharmacogenomics Implementation Consortium for each patient enrolled in the study. Patients were unaware of their pharmacogenomic results. Pharmacogenomic test results for patients in the control group were not reviewed before surgery; instead, standard perioperative medications were administered in adherence to our institutional care pathways. The OBAS (maximum 28 points) was the primary outcome measure, recorded 24 hours postoperatively. A two-sample t-test was used to compare the mean OBAS between groups. Secondary measures were the mean 24-hour pain score, total morphine milligram equivalent, and frequency of opioid use. Postoperatively, patients were assessed for pain with a VAS (range 0 to 10). Opioid use was recorded preoperatively, intraoperatively, in the postanesthesia care unit, and 24 hours after discharge from the postanesthesia care unit. Changes in perioperative opioid use based on pharmacogenomic testing were recorded, as were changes in prescription patterns for postoperative pain control. Preoperative characteristics were also compared between patients with and without various phenotypes ascertained from pharmacogenomic test results.

RESULTS

The mean OBAS did not differ between groups (mean ± SD 4.7 ± 3.7 in the control group versus 4.2 ± 2.8 in the experimental group, mean difference 0.5 [95% CI -1.1 to 2.1]; p = 0.55). Total opioids given did not differ between groups or at any single perioperative timepoint (preoperative, intraoperative, or postoperative). We found no difference in opioid prescribing pattern. After adjusting for multiple comparisons, no difference was observed between the treatment and control groups in tramadol use (41% versus 71%, proportion difference 0.29 [95% CI 0.05 to 0.53]; nominal p = 0.02; adjusted p > 0.99).

CONCLUSION

Routine use of pharmacogenomic testing for patients undergoing TKA did not lead to better pain control or decreased opioid consumption. Future studies might focus on at-risk populations, such as patients with chronic pain or those undergoing complex, painful surgical procedures, to test whether pharmacogenomic results might be beneficial in certain circumstances.

LEVEL OF EVIDENCE

Level I, therapeutic study.

The Potential Impact of Preemptive Pharmacogenetic Genotyping in the Neonatal Intensive Care Unit

OBJECTIVE

To evaluate the use of drugs with pharmacogenomic (PGx) guidelines from the Clinical Pharmacogenetics Implementation Consortium in early childhood.

STUDY DESIGN

A retrospective observational study of patients admitted to the neonatal intensive care (NICU) between 2005 and 2018 with at least 1 subsequent hospitalization at or after 5 years of age was performed to determine PGx drug exposure. Data regarding hospitalizations, drug exposures, gestational age, birth weight, and congenital anomalies and/or a primary genetic diagnosis were collected. Incidence of PGx drug and drug class exposures was determined and patient specific factors predictive of exposure were investigated.

RESULTS

During the study, 19 195 patients received NICU care and 4196 (22%) met study inclusion; 67% received 1-2, 28% 3-4, and 5% 5 or more PGx-drugs in early childhood. Preterm gestation, low birth weight (<2500 g), and the presence of any congenital anomalies and/or a primary genetic diagnosis were statistically significant predictors of Clinical Pharmacogenetics Implementation Consortium drug exposures (P < .01, P < .01, P < .01, respectively).

CONCLUSIONS

Preemptive PGx testing in patients in the NICU could have a significant impact on medical management during the NICU stay and throughout early childhood.

Significance of UGT1A6, UGT1A9, and UGT2B7 genetic variants and their mRNA expression in the clinical outcome of renal cell carcinoma

UDP-glucuronosyltransferase (UGT) metabolizes a number of endogenous and exogenous substrates. Renal cells express high amounts of UGT; however, the significance of UGT in patients with renal cell carcinoma (RCC) remains unknown. In this study, we profile the mRNA expression of UGT subtypes (UGT1A6, UGT1A9, and UGT2B7) and their genetic variants in the kidney tissue of 125 Japanese patients with RCC (Okayama University Hospital, Japan). In addition, we elucidate the association between the UGT variants and UGT mRNA expression levels and clinical outcomes in these patients. The three representative genetic variants, namely, UGT1A6 541A > G, UGT1A9 i399C > T, and UGT2B7-161C > T, were genotyped, and their mRNA expression levels in each tissue were determined. We found that the mRNA expression of the three UGTs (UGT1A6, UGT1A9, and UGT2B7) are significantly downregulated in RCC tissues. Moreover, in patients with RCC, the UGT2B7-161C > T variant and high UGT2B7 mRNA expression are significantly correlated with preferable cancer-specific survival (CSS) and overall survival (OS), respectively. As such, the UGT2B7-161C > T variant and UGT2B7 mRNA expression level were identified as significant independent prognostic factors of CSS and CSS/OS, respectively. Taken together, these findings indicate that UGT2B7 has a role in RCC progression and may, therefore, represent a potential prognostic biomarker for patients with RCC.

Dutch Pharmacogenetics Working Group (DPWG) guideline for the gene-drug interaction between CYP2D6 and opioids (codeine, tramadol and oxycodone)

The current Dutch Pharmacogenetics Working Group (DPWG) guideline, describes the gene-drug interaction between CYP2D6 and the opioids codeine, tramadol and oxycodone. CYP2D6 genotype is translated into normal metaboliser (NM), intermediate metaboliser (IM), poor metaboliser (PM) or ultra-rapid metaboliser (UM). Codeine is contraindicated in UM adults if doses >20 mg every 6 h (q6h), in children ≥12 years if doses >10 mg q6h, or with additional risk factors. In PMs, an alternative analgesic should be given which is not or to a lesser extent metabolised by CYP2D6 (not tramadol). In IMs with insufficient analgesia, a higher dose or alternative analgesic should be given. For tramadol, the recommendations for IMs and PMs are the same as the recommendation for codeine and IMs. UMs should receive an alternative drug not or to a lesser extent metabolised by CYP2D6 or the dose should be decreased to 40% of the commonly prescribed dose. Due to the absence of effect on clinical outcomes of oxycodone in PMs, IMs and UMs no action is required. DPWG classifies CYP2D6 genotyping for codeine "beneficial" and recommends testing prior to, or shortly after initiation of treatment in case of higher doses or additional risk factors. CYP2D6 genotyping is classified as "potentially beneficial" for tramadol and can be considered on an individual patient basis.

Effect of Ultrasound-Guided Fascia Iliac Compartment Block with Nalbuphine and Ropivacaine on Preoperative Pain in Older Patients with Hip Fractures: A Multicenter, Triple-Blinded, Randomized, Controlled Trial

INTRODUCTION

Pain management for older patients with hip fractures is challenging. This study aimed to investigate the effect of ultrasound-guided fascia iliac compartment block (UGFICB) using different doses of nalbuphine in combination with ropivacaine on preoperative analgesia in older patients with hip fractures.

METHODS

In this multicenter randomized controlled trial, 280 elderly patients with hip fracture were randomly allocated into four UGFICB groups (n = 70 in each group): a ropivacaine group (30 mL 0.1% ropivacaine + 0.9% normal saline) and three ropivacaine plus nalbuphine groups (5, 10, and 20 mg nalbuphine, respectively). The primary outcomes were the duration of analgesia at rest and on passive movement. Secondary outcomes included sensory block area, side effects, and vital signs. The doses of rescue analgesia with parecoxib sodium were also analyzed.

RESULTS

The addition of nalbuphine dose-dependently increased the duration of analgesia at rest and on passive movement (P < 0.05) and expanded the area of sensory block (P < 0.05). Compared with the ropivacaine group, the pain scores at rest and on movement at 6 and 8 h after the block were lower in three ropivacaine plus nalbuphine groups (P < 0.05), without between-group differences at 2, 4, and 12 h. The four groups had comparable side effects (nausea and vomiting) and vital signs (P > 0.05).

CONCLUSIONS

UGFICB with 5, 10, and 20 mg nalbuphine added to ropivacaine prolonged the analgesia duration, increased sensory block area, reduced pain, and decreased the doses of rescue parecoxib sodium for older patients after hip fracture, without obvious side effects. Among these three doses, nalbuphine 20 mg in combination with ropivacaine provided the longest duration of analgesia and the largest sensory block area.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2000029934).

Headaches in Pregnancy and Postpartum: ACOG Clinical Practice Guideline No. 3

PURPOSE

To provide updated evidence-based recommendations for the evaluation and treatment of primary and secondary headaches in pregnancy and postpartum.

TARGET POPULATION

Pregnant and postpartum patients with a history of or experiencing primary or new secondary headaches.

METHODS

This guideline was developed using an a priori protocol in conjunction with a writing team consisting of two specialists in obstetrics and gynecology appointed by the ACOG Committee on Clinical Practice Guidelines-Obstetrics and one external subject matter expert. ACOG medical librarians completed a comprehensive literature search for primary literature within Cochrane Library, Cochrane Collaboration Registry of Controlled Trials, EMBASE, PubMed, and MEDLINE. Studies that moved forward to the full-text screening stage were assessed by two authors from the writing team based on standardized inclusion and exclusion criteria. Included studies underwent quality assessment, and a modified GRADE (Grading of Recommendations Assessment, Development, and Evaluation) evidence-to-decision framework was applied to interpret and translate the evidence into recommendation statements.

RECOMMENDATIONS

This Clinical Practice Guideline includes recommendations on interventions to prevent primary headache in individuals who are pregnant or attempting to become pregnant, postpartum, or breastfeeding; evaluation for symptomatic patients presenting with primary and secondary headaches during pregnancy; and treatment options for primary and secondary headaches during pregnancy and lactation. Recommendations are classified by strength and evidence quality. Ungraded Good Practice Points are included to provide guidance when a formal recommendation could not be made because of inadequate or nonexistent evidence.

Papaver Plants: Current Insights on Phytochemical and Nutritional Composition Along with Biotechnological Applications

The genus Papaver is highly esteemed in the pharmacy industry, in the culinary field, and as ornamental plants. These plants are also valued in traditional medicine. Among all Papaver species, Papaver somniferum L. (opium poppy) is the most important species in supplying phytochemicals for the formulation of drugs, mainly alkaloids like morphine, codeine, rhoeadine, thebaine, and papaverine. In addition, Papaver plants present other types of phytochemicals, which altogether are responsible for its biological activities. Therefore, this review covers the phytochemical composition of Papaver plants, including alkaloids, phenolic compounds, and essential oils. The traditional uses are reviewed along with their pharmacological activities. Moreover, safety aspects are reported to provide a deep overview of the pharmacology potential of this genus. An updated search was carried out in databases such as Google Scholar, ScienceDirect, and PubMed to retrieve the information. Overall, this genus is a rich source of alkaloids of different types and also contains interesting phenolic compounds, such as anthocyanins, flavonols, and the characteristic indole derivatives nudicaulins. Among other pharmacological properties, numerous preclinical studies have been published about the analgesic, anticancer, antimicrobial, antioxidant, and antidiabetic activities of Papaver plants. Although it highlights the significant impact of this genus for the treatment of a variety of diseases and conditions, as a future prospect, characterization works accompanying preclinical studies are required along with clinical and toxicology studies to establish a correlation between the scientific and traditional knowledge.

Perspectives from the Society for Pediatric Research: pharmacogenetics for pediatricians

This review evaluates the pediatric evidence for pharmacogenetic associations for drugs that are commonly prescribed by or encountered by pediatric clinicians across multiple subspecialties, organized from most to least pediatric evidence. We begin with the pharmacogenetic research that led to the warning of increased risk of death in certain pediatric populations ("ultrarapid metabolizers") who are prescribed codeine after tonsillectomy or adenoidectomy. We review the evidence for genetic testing for thiopurine metabolism, which has become routine in multiple pediatric subspecialties. We discuss the pharmacogenetic research in proton pump inhibitors, for which clinical guidelines have recently been made available. With an increase in the prevalence of behavioral health disorders including attention deficit hyperactivity disorder (ADHD), we review the pharmacogenetic literature on selective serotonin reuptake inhibitors, selective norepinephrine reuptake inhibitors, and ADHD medications. We will conclude this section on the current pharmacogenetic data on ondansetron. We also provide our perspective on how to integrate the current research on pharmacogenetics into clinical care and what further research is needed. We discuss how institutions are managing pharmacogenetic test results and implementing them clinically, and how the electronic health record can be leveraged to ensure testing results are available and taken into consideration when prescribing medications. IMPACT: While many reviews of pharmacogenetics literature are available, there are few focused on pediatrics. Pediatricians across subspecialties will become more comfortable with pharmacogenetics terminology, know resources they can use to help inform their prescribing habits for drugs with known pharmacogenetic associations, and understand the limitations of testing and where further research is needed.

Reviewing pharmacogenetics to advance precision medicine for opioids

BACKGROUND

Adequate opioid prescribing is critical for therapeutic success of pain management. Despite the widespread use of opioids, optimized opioid therapy remains unresolved with risk of accidental lethal overdosing. With the emergence of accumulating evidence linking genetic variation to opioid response, pharmacogenetic based treatment recommendations have been proposed.

OBJECTIVE

The aim of this review is to evaluate pharmacogenetic evidence and provide an overview on genes involved in the pharmacokinetics and pharmacodynamics of opioids.

METHODS

For this review, a systematic literature search of published articles was used in PubMed®, with no language restriction and between the time period of January 2000 to December 2020. We reviewed randomized clinical studies, study cohorts and case reports that investigated the influence of genetic variants on selected opioid pharmacokinetics and pharmacodynamics. In addition, we reviewed current CPIC clinical recommendations for pharmacogenetic testing.

RESULTS

Results of this review indicate consistent evidence supporting the association between selected genetic variants of CYP2D6 for opioid metabolism. CPIC guidelines include recommendations that indicate the avoidance of tramadol use, in addition to codeine, in CYP2D6 poor metabolizers and ultrarapid metabolizers, and to monitor intermediate metabolizers for less-than-optimal response. While there is consistent evidence for OPRM1 suggesting increased postoperative morphine dosing requirements in A118G G-allele carriers, the clinical relevance remains limited.

CONCLUSION

There is emerging evidence of clinical relevance of CYP2D6 and, to a lesser extent, OPRM1 polymorphism in personalized opioid drug dosing. As a result, first clinics have started to implement pharmacogenetic guidelines for CYP2D6 and codeine.

Quadratus lumborum or transversus abdominis plane block for postoperative analgesia after cesarean: a double-blinded randomized trial

Background

Multimodal analgesia (MMA) is the current standard practice to provide post-cesarean analgesia. The aim of this study was to compare the analgesic efficacy of quadratus lumborum (QL) block and transversus abdominis plane (TAP) block as an adjunct to MMA.

Methods

Eighty mothers undergoing cesarean delivery under spinal anesthesia were randomized to receive either TAP or transmuscular QL block (QLB) with 20 mL 0.375% ropivacaine on each side. Postoperatively, all the subjects were assessed at 2, 4, 6, 8, 12, 18, and 24 hours. The primary outcome was the time to first analgesic request. The secondary outcomes were the pain scores during rest and movement, number of doses of tramadol, postoperative nausea-vomiting, sedation, and mother’s satisfaction with the pain management.

Results

The median (IQR) time to first analgesic request was 12 (9.25, 13) hours in the QL group and 9 (8.25, 11.37) hours in the TAP group (p = 0.0008). Patients in QL group consumed less doses of tramadol than those in TAP group (p < 0.0001). Pain scores were significantly lower in the QL group at all time points (p < 0.0001) except at 8^th hour when at rest, p = 0.0024, and on movement, p = 0.0028. The maternal satisfaction was significantly higher in the QL group (p = 0.0017).

Conclusion

Our study showed the significant delay in time to first analgesic request in QL group patients. Patients in the QL group had lower pain scores, required fewer analgesic supplements, and had more satisfaction. Nausea-vomiting and sedation were comparable.

Trends in Postpartum Opioid Prescribing: A Time Series Analysis

Opioids are commonly prescribed following childbirth, but data are lacking on trends in postpartum opioid prescribing over time. We examined whether a highly publicized 2006 case report questioning the safety of codeine during lactation was associated with changes in postpartum opioid prescribing. We conducted a cross-sectional time series analysis of all publicly funded prescriptions for opioids to postpartum women in Ontario, Canada, from April 1, 2000, to March 31, 2017. The intervention was the publication of a case report in 2006 attributing the death of a breastfeeding neonate to maternal codeine use. The primary outcome was the rate of opioid prescribing to postpartum women. Among postpartum women eligible for prescription drug coverage, 17.5% filled an opioid prescription in the third quarter of 2006 (immediately prior to the intervention), with codeine representing 89.8% of all prescriptions. By the fourth quarter of 2010, only 12.2% of postpartum women filled an opioid prescription, representing a decline of 30% (P < 0.01), with codeine representing 71.9% of all prescriptions. During this period, we observed sizeable relative increases in the proportion of opioid prescriptions filled for morphine, hydromorphone, and oxycodone. By 2017, among women prescribed opioids post partum, 39.0% filled a prescription for codeine, while the remainder filled prescriptions for oxycodone (18.6%), morphine (25.5%), and hydromorphone (16.9%). A highly publicized case report questioning the safety of maternal codeine use during breastfeeding was associated with significant changes in opioid prescribing to postpartum women, including a decline in overall opioid prescribing and a shift from codeine to stronger opioids.

Preterm Physiologically Based Pharmacokinetic Model. Part II: Applications of the Model to Predict Drug Pharmacokinetics in the Preterm Population

BACKGROUND

Preterm neonates are usually not part of a traditional drug development programme, however they are frequently administered medicines. Developing modelling and simulation tools, such as physiologically based pharmacokinetic (PBPK) models that incorporate developmental physiology and maturation of drug metabolism, can be used to predict drug exposure in this group of patients, and may help to optimize drug dose adjustment.

OBJECTIVE

The aim of this study was to assess and verify the predictability of a preterm PBPK model using compounds that undergo diverse renal and/or hepatic clearance based on the knowledge of their disposition in adults.

METHODS

A PBPK model was developed in the Simcyp Simulator V17 to predict the pharmacokinetics (PK) of drugs in preterm neonates. Drug parameters for alfentanil, midazolam, caffeine, ibuprofen, gentamicin and vancomycin were collated from the literature. Predicted PK parameters and profiles were compared against the observed data.

RESULTS

The preterm PBPK model predicted the PK changes of the six compounds using ontogeny functions for cytochrome P450 (CYP) 1A2, CYP2C9 and CYP3A4 after oral and intravenous administrations. For gentamicin and vancomycin, the maturation of renal function was able to predict the exposure of these two compounds after intravenous administration. All PK parameter predictions were within a twofold error criteria.

CONCLUSION

While the developed preterm model for the prediction of PK behaviour in preterm patients is not intended to replace clinical studies, it can potentially help with deciding on first-time dosing in this population and study design in the absence of clinical data.

Pharmacogenomics of oxycodone: a narrative literature review

Oxycodone is a semisynthetic μ- and κ-opioid receptor with agonist with a broad scope of use including postoperative analgesia as well as control of neuropathic and cancer pain. Advantages over other opioids include prolonged duration of action, greater potency than morphine and lack of histamine release or ceiling effect. Individual responses to oxycodone can vary due to genetic differences. This review article aims to summarize the oxycodone literature and provide context on its pharmacogenomics and pharmacokinetics. The evidence for clinical effect of genetic polymorphisms on oxycodone is conflicting. There is stronger evidence linking polymorphic genetic enzymes CYP2D6 and CYP3A with therapeutic outcomes. Further, research is needed to discern all of oxycodone's metabolites and their contribution to the overall analgesic effect.

Clinical Pharmacogenetics Implementation Consortium Guideline for CYP2D6, OPRM1, and COMT Genotypes and Select Opioid Therapy

Opioids are mainly used to treat both acute and chronic pain. Several opioids are metabolized to some extent by CYP2D6 (codeine, tramadol, hydrocodone, oxycodone, and methadone). Polymorphisms in CYP2D6 have been studied for an association with the clinical effect and safety of these drugs. Other genes that have been studied for their association with opioid clinical effect or adverse events include OPRM1 (mu receptor) and COMT (catechol-O-methyltransferase). This guideline updates and expands the 2014 Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for CYP2D6 genotype and codeine therapy and includes a summation of the evidence describing the impact of CYP2D6, OPRM1, and COMT on opioid analgesia and adverse events. We provide therapeutic recommendations for the use of CYP2D6 genotype results for prescribing codeine and tramadol and describe the limited and/or weak data for CYP2D6 and hydrocodone, oxycodone, and methadone, and for OPRM1 and COMT for clinical use.

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.

Characterization of the intergenerational impact of in utero and postnatal oxycodone exposure

Prescription opioid abuse during and after pregnancy is a rising public health concern. While earlier studies have documented that offspring exposed to opioids in utero have impaired neurodevelopment, a significant knowledge gap remains in comparing the overall development between offspring exposed in utero and postnatally. Adding a layer of complexity is the role of heredity in the overall development of these exposed offspring. To fill in these important knowledge gaps, the current study uses a preclinical rat model mimicking oxycodone (oxy) exposure in utero (IUO) and postnatally (PNO) to investigate comparative and intergenerational effects in the two different treatment groups. While significant phenotypic attributes were observed with the two treatments and across the two generations, RNA sequencing revealed alterations in the expression of key synaptic genes in the two exposed groups in both generations. RNA sequencing and post validation of genes using RT-PCR highlighted the differential expression of several neuropeptides associated with the hypocretin system, a system recently implicated in addiction. Further, behavior studies revealed anxiety-like behaviors and social deficits that persisted even in the subsequent generations in the two treatment groups. To summarize, our study for the first time reveals a new line of investigation on the potential risks associated with oxy use during and after pregnancy, specifically the disruption of neurodevelopment and intergenerational impact on behavior.

Personalized pediatric anesthesia and pain management: problem-based review

Pharmacogenetics, the genetic influence on the interpersonal variability in drug response, has enabled tailored pharmacotherapy and emerging 'personalized medicine.' Although oncology spearheaded the clinical implementation of personalized medicine, other specialties are rapidly catching up. In anesthesia, classical examples of genetically mediated idiosyncratic reactions have been long known (e.g., malignant hyperthermia and prolonged apnea after succinylcholine). The last two decades have witnessed an expanding body of pharmacogenetic evidence in anesthesia. This review highlights some of the prominent pharmacogenetic associations studied in anesthesia and pain management, with special focus on pediatric anesthesia.

Ultrasound-guided transversus abdominis plane block using ropivacaine and dexmedetomidine in patients undergoing caesarian sections to relieve post-operative analgesia: A randomized controlled clinical trial

Dexmedetomidine, which is a highly selective α2 adrenoreceptor agonist, enhances the analgesic efficacy and prolongs the analgesic duration when administered in combination with local anesthetics. The current study aimed to evaluate the effects of dexmedetomidine combined with ropivacaine in ultrasound-guided transversus abdominis plane (TAP) block on post-operative analgesia following cesarean section (CS). A total of 70 patients scheduled for CS were divided randomly into 2 groups: The ropivacaine (R) group, in which patients were administered bilateral 20 ml 0.3% ropivacaine and 2 ml 0.9% normal saline, and the dexmedetomidine (RD) group, in which patients were administered bilateral 20 ml 0.3% ropivacaine and 2 ml dexmedetomidine (0.5 µg/kg). The primary outcome was pain-free duration, and secondary outcomes included heart rate (HR) and mean blood pressure (MBP) measurements, visual analogue scale (VAS) pain scores, number of patients who required rescue analgesic, time to first request for analgesia and patient satisfaction. There was no significant difference in HR and MBP between the two groups at 1 h post-surgery (P>0.05). However, VAS pain scores decreased at 6 and 8 h post-surgery [2 (1-2) vs. 0 (0-0.25) and 2 (2-3) vs. 0 (0-1), respectively; P<0.05], pain-free duration was prolonged (5.91±1.08 vs. 9.62±1.46 h; P<0.05), the number of patients who required rescue analgesic was reduced (19 vs. 9; P<0.05), the time to first request for analgesia was prolonged (7.10±1.21 vs. 11.60±2.11 h; P<0.05) and patient satisfaction was improved [3.5 (3-4) vs. 4 (4-5); P<0.05] in the RD group compared with the R group. Furthermore, no bradycardia or hypotension was observed. In conclusion, the results of the present study demonstrated that adding 0.5 µg/kg dexmedetomidine to 0.3% ropivacaine used in TAP block in patients undergoing CS prolonged pain-free duration, decreased VAS pain scores, reduced the number of patients who required rescue analgesic, prolonged the time to first request for analgesia and improved the patient satisfaction without serious side effects.

The Advantages and Challenges of Diversity in Pharmacogenomics: Can Minority Populations Bring Us Closer to Implementation?

Health disparities exist among minorities in the United States, with differences seen in disease prevalence, mortality, and responses to medications. These differences are multifactorial with genetic variation explaining a portion of this variability. Pharmacogenomics aims to find the effect of genetic variations on drug response, with the goal of optimizing drug therapy and development. Although genome-wide association studies have been useful in unbiasedly surveying the genome for genetic drivers of clinically relevant phenotypes, most of these studies have been conducted in mainly participants of European and Asian descent, contributing to a growing health disparity in precision medicine. Diversity is important to pharmacogenomic studies, and there may be real advantages to the use of these complex genomes in pharmacogenomics. In this review we will outline some of the advantages and confounders of pharmacogenomics in minorities, describe the role of genetic variation in pharmacologic pathways, and highlight a number of population-specific findings.

Quantifying breast milk intake by term and preterm infants for input into paediatric physiologically based pharmacokinetic models

Despite the many benefits of breast milk, mothers taking medication are often uncertain about the risks of drug exposure to their infants and decide not to breastfeed. Physiologically based pharmacokinetic models can contribute to drug‐in‐milk safety assessments by predicting the infant exposure and subsequently, risk for toxic effects that would result from continuous breastfeeding. This review aimed to quantify breast milk intake feeding parameters in term and preterm infants using literature data for input into paediatric physiologically based pharmacokinetic models designed for drug‐in‐milk risk assessment. Ovid MEDLINE and Embase were searched up to July 2, 2019. Key study reference lists and grey literature were reviewed. Title, abstract and full text were screened in nonduplicate. Daily weight‐normalized human milk intake (WHMI) and feeding frequency by age were extracted. The review process retrieved 52 studies. A nonlinear regression equation was constructed to describe the WHMI of exclusively breastfed term infants from birth to 1 year of age. In all cases, preterm infants fed with similar feeding parameters to term infants on a weight‐normalized basis. Maximum WHMI was 152.6 ml/kg/day at 19.7 days, and weighted mean feeding frequency was 7.7 feeds/day. Existing methods for approximating breast milk intake were refined by using a comprehensive set of literature data to describe WHMI and feeding frequency. Milk feeding parameters were quantified for preterm infants, a vulnerable population at risk for high drug exposure and toxic effects. A high‐risk period of exposure at 2–4 weeks of age was identified and can inform future drug‐in‐milk risk assessments.

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.

Pharmacogenomic network analysis of the gene-drug interaction landscape underlying drug disposition

In recent decades the identification of pharmacogenomic gene-drug associations has evolved tremendously. Despite this progress, a major fraction of the heritable inter-individual variability remains elusive. Higher-dimensional phenomena, such as gene-gene-drug interactions, in which variability in multiple genes synergizes to precipitate an observable phenotype have been suggested to account at least for part of this missing heritability. However, the identification of such intricate relationships remains difficult partly because of analytical challenges associated with the complexity explosion of the problem. To facilitate the identification of such combinatorial pharmacogenetic associations, we here propose a network analysis strategy. Specifically, we analyzed the landscape of drug metabolizing enzymes and transporters for 100 top selling drugs as well as all compounds with pharmacogenetic germline labels or dosing guidelines. Based on this data, we calculated the posterior probabilities that gene i is involved in metabolism, transport or toxicity of a given drug under the condition that another gene j is involved for all pharmacogene pairs (i, j). Interestingly, these analyses revealed significant patterns between individual genes and across pharmacogene families that provide insights into metabolic interactions. To visualize the gene-drug interaction landscape, we use multidimensional scaling to collapse this similarity matrix into a two-dimensional network. We suggest that Euclidian distance between nodes can inform about the likelihood of epistatic interactions and thus might provide a useful tool to reduce the search space and facilitate the identification of combinatorial pharmacogenomic associations.

Opioids as Substrates and Inhibitors of the Genetically Highly Variable Organic Cation Transporter OCT1

Genetic variants in the hepatic uptake transporter OCT1, observed in 9% of Europeans and white Americans, are known to affect pharmacokinetics and efficacy of tramadol, morphine, and codeine. Here, we report further opioids to be substrates and inhibitors of OCT1. Methylnaltrexone, hydromorphone, oxymorphone, and meptazinol were identified as OCT1 substrates. Methylnaltrexone is the strongest OCT1 substrate currently reported. It showed 86-fold higher accumulation in OCT1-overexpressing cells compared to control cells. We observed substantial differences in the inhibitory potency among structurally highly similar morphinan opioids (IC₅₀ ranged from 6.4 μM for dextrorphan to 2 mM for oxycodone). The ether linkage of C4-C5 in the morphinan ring leads to a strong reduction of inhibitory potency. In conclusion, although polyspecific, OCT1 possesses a strong selectivity for its ligands. In contrast to methylnaltrexone and hydromorphone, oxycodone and hydrocodone do not interact with OCT1 and may be safer for use in individuals with genetic OCT1 deficiency.

Pharmacogenomic Testing In Pediatrics: Navigating The Ethical, Social, And Legal Challenges

For the past several years, the implementation of pharmacogenetic (PGx) testing has become widespread in several centers and clinical practice settings. PGx testing may be ordered at the point-of-care when treatment is needed or in advance of treatment for future use. The potential benefits of PGx testing are not limited to adult patients, as children are increasingly using medications more often and at earlier ages. This review provides some background on the use of PGx testing in children as well as mothers (prenatally and post-natally) and discusses the challenges, benefits, and the ethical, legal, and social implications of providing PGx testing to children.

Exposures Through Breast Milk: An Analysis of Exposure and Information Calls to U.S. Poison Centers, 2001-2017

Introduction: We described calls to U.S. poison centers (PCs) related to potential exposure to substances through breast milk. Materials and Methods: We analyzed National Poison Data System calls between 2001 and 2017 with "Exposure through breast milk" or "Drug use during breastfeeding" as the coded scenario. Data handling and descriptive statistics were carried out using SAS JMP 12.01. Results: U.S. PCs received 76,416 information calls and 2,319 exposure calls related to breast milk. Exposure calls were from a residence in 76% (n = 1,758), from health care facilities (HCFs) in 15.5% (n = 360), and from a workplace in 0.6% (n = 15). A total of 466 exposures (20.1%) were subsequently managed at a HCF: 269 were evaluated and released (58%), 38 were admitted to intensive care unit (8.2%), and 53 were admitted to hospital floor (11%). Medical outcomes included 1 death (0.04%), 8 major effect (0.3%), 43 moderate effect (1.9%), 170 minor effect (7.3%), and 390 no effect (16.8%). Exposure calls that reported major effects involved opioids, benzodiazepines, ethanol, cyclobenzaprine, insulin, and amphetamines. Exposure calls most commonly involved antibiotics, antifungals, benzodiazepines, opioids, and selective serotonin reuptake inhibitors (SSRIs). A total of 1,192 exposures (51.4%) had reported signs/symptoms including drowsiness, agitation, rash, and vomiting/diarrhea. Information calls most commonly involved systemic antibiotics, SSRIs, antihistamines, corticosteroids, and benzodiazepines. Conclusions: Substances common to both exposure and information calls included antibiotics, benzodiazepines, and SSRIs. Most cases of severe toxicity included potential exposures through breast milk to benzodiazepines and opioids. These data may help inform educational outreach, risk assessment, and bedside care for breastfeeding mothers.

Pharmacogenomic considerations for medications in the perioperative setting

Several high-profile examples of adverse outcomes from medications used in the perioperative setting are well known (e.g., malignant hyperthermia, prolonged apnea, respiratory depression, inadequate analgesia), leading to an increased understanding of genetic susceptibilities underlying these risks. Pharmacogenomic information is increasingly being utilized in certain areas of medicine. Despite this, routine preoperative genetic screening to inform medication risk is not yet standard practice. In this review, we assess the current readiness of pharmacogenomic information for clinical consideration for several common perioperative medications, including description of key pharmacogenes, pharmacokinetic implications and potential clinical outcomes. The goal is to highlight medications for which emerging or considerable pharmacogenomic information exists and identify areas for future potential research.

Drug-gene and drug-drug interactions associated with tramadol and codeine therapy in the INGENIOUS trial

Background: Tramadol and codeine are metabolized by CYP2D6 and are subject to drug-gene and drug-drug interactions. Methods: This interim analysis examined prescribing behavior and efficacy in 102 individuals prescribed tramadol or codeine while receiving pharmaco-genotyping as part of the INGENIOUS trial (NCT02297126). Results: Within 60 days of receiving tramadol or codeine, clinicians more frequently prescribed an alternative opioid in ultrarapid and poor metabolizers (odds ratio: 19.0; 95% CI: 2.8-160.4) as compared with normal or indeterminate metabolizers (p = 0.01). After adjusting the CYP2D6 activity score for drug-drug interactions, uncontrolled pain was reported more frequently in individuals with reduced CYP2D6 activity (odds ratio: 0.50; 95% CI: 0.25-0.94). Conclusion: Phenoconversion for drug-drug and drug-gene interactions is an important consideration in pharmacogenomic implementation; drug-drug interactions may obscure the potential benefits of genotyping.

Genetics of perioperative pain management

PURPOSE OF REVIEW

The current review will discuss the current literature on genetics of pain and analgesia, with special emphasis on perioperative setting. We will also discuss pharmacogenetics-based management guidelines, current clinical status and future perspectives.

RECENT FINDINGS

Recent literature suggests that the interindividual variability in pain and postoperative analgesic response is at least in part because of one's genetic make-up. Some of the well characterized polymorphisms that are associated with surgical pain and opioid-related postoperative adverse outcomes are described in catechol-O-methyl transferase, CYP2D6 and μ-opioid receptor (OPRM1), ATP-binding cassette subfamily B member 1, ABCC3, organic cation transporter 1 genes. Clinical Pharmacogenetics Implementation Consortium has put forth recommendations on CYP2D6 genotype-based opioid selection and dosing. The list of drug-gene pairs studied continue to expand.

SUMMARY

Pharmacogenetic approach marks the dawn of personalized pain medicine both in perioperative and chronic pain settings.

A Case of Toxic Breast-feeding?

Opiates are frequently prescribed postpartum for pain relief after cesarean delivery, episiotomies, and headaches. It is estimated that greater than 30% of breast-feeding mothers in the United States are prescribed opiates for pain relief associated with childbirth. Many opiates are readily transferred to human milk, although life-threatening events are rare. We report a 6-day-old breast-feeding infant whose mother was taking hydromorphone for pain relief from a cesarean delivery and whose clinical course was suggestive of opiate toxicity. This case emphasizes the importance of thorough medication history taking in postpartum breast-feeding mothers whose infants may present with symptoms of opiate toxicity. Semisynthetic opiates are frequently not detected on emergency department urine toxicology screens. The pertinent literature is reviewed.

Analyses of Adverse Drug Reactions-Nationwide Active Surveillance Network: Canadian Pharmacogenomics Network for Drug Safety Database

Adverse drug reactions (ADRs) are a major problem in modern medicine, representing up to the fourth-highest cause of mortality. Pharmacogenomic tests are 1 of the most promising methods to tackle the challenge of ADRs. The objective of this study was to analyze the clinical and demographic information of the pan-Canadian active surveillance network, Canadian Pharmacogenomics Network for Drug Safety (CPNDS). Information entered into the database by trained active surveillors between May 15, 2005 and May 9, 2017 was collected and analyzed. Specific data included for analysis were number of ADR reports, reports of drug use without ADRs, date of onset of ADR, suspected drugs, concomitant drugs, and fatal ADR cases. The CPNDS database consisted of 93,974 reports of medication use, including 10,475 reports of ADRs, of which 72.6% occurred in pediatric patients (≤21 years old). Self-reported ancestries were predominantly Europe (38.2%), Canada (9.6%), and East Asia (4.9%). The 5 most frequent ADRs were cutaneous ADRs, peripheral neuropathy, cardiotoxicity, central nervous system toxicity, and ototoxicity. The 5 drugs most commonly suspected to cause ADRs were methotrexate, vincristine, doxorubicin, cisplatin, and L-asparaginase. The CPNDS database is a valuable resource to identify clinical and genomic predictors of ADRs. The database also highlights our candidate ADRs for pharmacogenomic discovery research to identify additional ADR biomarkers. Additionally, the database provides information that can be used for developing strategies to prevent ADRs and raises awareness of ADRs among Canadian healthcare professionals.

Gender, genetics, and analgesia: understanding the differences in response to pain relief

Genetic variations and gender contribute significantly to the large interpatient variations in opioid-related serious adverse effects and differences in pain relief with other analgesics. Opioids are the most commonly used analgesics to relieve moderate-to-severe postoperative pain. Narrow therapeutic index and unexplained large interpatient variations in opioid-related serious adverse effects and analgesia negatively affect optimal perioperative outcomes. In surgical, experimental, chronic, and neuropathic pain models, females have been reported to have more pain than males. This review focuses on literature evidence of differences in pain relief due to multiple genetic variations and gender of the patient.

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.

Role of ultrasound guided transversus abdominis plane block as a component of multimodal analgesic regimen for lower segment caesarean section: a randomized double blind clinical study

Background

While opioids are the mainstay for post-operative analgesia after lower segment caesarean section, they are associated with various untoward effects. Ultrasound guided transversus abdominis plane (TAP) block has been postulated to provide effective analgesia for caesarean section. We evaluated the analgesic efficacy of this block for post caesarean analgesia in a randomised controlled trial.

Methods

One hundred thirty-nine mothers undergoing caesarean delivery were randomised to receive TAP block with either 20 ml 0.375% ropivacaine or 20 ml saline after obtaining informed consent. All the subjects received a standard spinal anaesthetic and diclofenac was administered for post-operative pain. Breakthrough pain was treated with tramadol. Post-operatively, all the subjects were assessed at 0, 2, 4, 6, 8, 10, 12, 18 & 24 h. The primary outcome was the time to first analgesic request. The secondary measures of outcome were pain, nausea, sedation, number of doses of tramadol administered and satisfaction with the pain management.

Results

The median (interquartile range) time to first analgesic request was prolonged in the TAP group compared to the control group (p < 0.0001); 11 h (8,12) and 4 h (2.5,6) respectively. The median (interquartile range) number of doses of tramadol consumed in the TAP group was 0 (0,1) compared to 2 (1,2) in the control group (p < 0.0001). At all points in the study, pain scores both at rest and on movement were lower in the study group (p < 0.0001). Maternal satisfaction with pain relief was also higher in the study group (p 0.0002). One subject in the TAP group had convulsions following injection of local anaesthetic solution. She was managed conservatively with supportive treatment following which she recovered.

Conclusion

TAP block reduces pain, prolongs the duration of analgesia and decreases supplemental opioid consumption when used for multimodal analgesia for pain relief after caesarean section. However, the risk of local anaesthetic systemic toxicity remains unknown with this block. Hence larger safety trials and measures to limit this complication need to be ascertained.

Trial registration

The trial was registered with the Clinical Trial Registry of India (CTRI/2017/03/008194) on 23/03/2017 (trial registered retrospectively).

Update of the Scientific Opinion on opium alkaloids in poppy seeds

Poppy seeds are obtained from the opium poppy (Papaver somniferum L.). They are used as food and to produce edible oil. The opium poppy plant contains narcotic alkaloids such as morphine and codeine. Poppy seeds do not contain the opium alkaloids, but can become contaminated with alkaloids as a result of pest damage and during harvesting. The European Commission asked EFSA to provide an update of the Scientific Opinion on opium alkaloids in poppy seeds. The assessment is based on data on morphine, codeine, thebaine, oripavine, noscapine and papaverine in poppy seed samples. The CONTAM Panel confirms the acute reference dose (ARfD) of 10 μg morphine/kg body weight (bw) and concluded that the concentration of codeine in the poppy seed samples should be taken into account by converting codeine to morphine equivalents, using a factor of 0.2. The ARfD is therefore a group ARfD for morphine and codeine, expressed in morphine equivalents. Mean and high levels of dietary exposure to morphine equivalents from poppy seeds considered to have high levels of opium alkaloids (i.e. poppy seeds from varieties primarily grown for pharmaceutical use) exceed the ARfD in most age groups. For poppy seeds considered to have relatively low concentrations of opium alkaloids (i.e. primarily varieties for food use), some exceedance of the ARfD is also seen at high levels of dietary exposure in most surveys. For noscapine and papaverine, the available data do not allow making a hazard characterisation. However, comparison of the dietary exposure to the recommended therapeutical doses does not suggest a health concern for these alkaloids. For thebaine and oripavine, no risk characterisation was done due to insufficient data. However, for thebaine, limited evidence indicates a higher acute lethality than for morphine and the estimated exposure could present a health risk.

Clinical pharmacogenomics testing in the era of next generation sequencing: challenges and opportunities for precision medicine

INTRODUCTION

The rapid development and dramatic decrease in cost of sequencing techniques have ushered the implementation of genomic testing in patient care. Next generation DNA sequencing (NGS) techniques have been used increasingly in clinical laboratories to scan the whole or part of the human genome in order to facilitate diagnosis and/or prognostics of genetic disease. Despite many hurdles and debates, pharmacogenomics (PGx) is believed to be an area of genomic medicine where precision medicine could have immediate impact in the near future. Areas covered: This review focuses on lessons learned through early attempts of clinically implementing PGx testing; the challenges and opportunities that PGx testing brings to precision medicine in the era of NGS. Expert commentary: Replacing targeted analysis approach with NGS for PGx testing is neither technically feasible nor necessary currently due to several technical limitations and uncertainty involved in interpreting variants of uncertain significance for PGx variants. However, reporting PGx variants out of clinical whole exome or whole genome sequencing (WES/WGS) might represent additional benefits for patients who are tested by WES/WGS.

No. 349-Substance Use in Pregnancy

OBJECTIVES

To improve awareness and knowledge of problematic substance use in pregnancy and to provide evidence-based recommendations for the management of this challenging clinical issue for all health care providers.

OPTIONS

This guideline reviews the use of screening tools, general approach to care, and recommendations for the clinical management of problematic substance use in pregnancy.

OUTCOMES

Evidence-based recommendations for screening and management of problematic substance use during pregnancy and lactation.

EVIDENCE

Updates in the literature were retrieved through searches of Medline, PubMed, and The Cochrane Library published from 1996 to 2016 using the following key words: pregnancy, electronic cigarettes, tobacco use cessation products, buprenorphine, and methadone. Results were initially restricted to systematic reviews and RCTs/controlled clinical trials. A subsequent search for observational studies was also conducted because there are few RCTs in this field of study. Articles were restricted to human studies published in English. Additional articles were located by hand searching through article reference lists.

VALUES

The quality of evidence was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care. Recommendations for practice were ranked according to the method described in that report.

BENEFITS, HARMS, AND COSTS

This guideline is intended to increase the knowledge and comfort level of health care providers caring for pregnant women who have substance use disorders. Improved access to health care and assistance with appropriate addiction care lead to reduced health care costs and decreased maternal and neonatal morbidity and mortality.

RECOMMENDATIONS

Drugs in Lactation

One impediment to breastfeeding is the lack of information on the use of many drugs during lactation, especially newer ones. The principles of drug passage into breastmilk are well established, but have often not been optimally applied prospectively. Commonly used preclinical rodent models for determining drug excretion into milk are very unreliable because of marked differences in milk composition and transporters compared to those of humans. Measurement of drug concentrations in humans remains the gold standard, but computer modeling is promising. New FDA labeling requirements present an opportunity to apply modeling to preclinical drug development in place of conventional animal testing for drug excretion into breastmilk, which should improve the use of medications in nursing mothers.

Pharmacogenetics: a general review on progress to date

BACKGROUND

Pharmacogenetics is not a new subject area but its relevance to drug prescribing has become clearer in recent years due to developments in gene cloning and DNA genotyping and sequencing.

SOURCES OF DATA

There is a very extensive published literature concerned with a variety of different genes and drugs.

AREAS OF AGREEMENT

There is general agreement that pharmacogenetic testing is essential for the safe use of drugs such as the thiopurines and abacavir.

AREAS OF CONTROVERSY

Whether pharmacogenetic testing should be applied more widely including to the prescription of certain drugs such as warfarin and clopidogrel where the overall benefit is less clear remains controversial.

GROWING POINTS

Personal genotype information is increasingly being made available directly to the consumer. This is likely to increase demand for personalized prescription and mean that prescribers need to take pharmacogenetic information into account. Projects such as 100 000 genomes are providing complete genome sequences that can form part of a patient medical record. This information will be of great value in personalized prescribing.

AREAS TIMELY FOR DEVELOPING RESEARCH

Development of new drugs targeting particular genetic risk factors for disease. These could be prescribed to those with an at risk genotype.

Clinical Pharmacogenetics of Cytochrome P450-Associated Drugs in Children

Cytochrome P450 (CYP) enzymes are commonly involved in drug metabolism, and genetic variation in the genes encoding CYPs are associated with variable drug response. While genotype-guided therapy has been clinically implemented in adults, these associations are less well established for pediatric patients. In order to understand the frequency of pediatric exposures to drugs with known CYP interactions, we compiled all actionable drug-CYP interactions with a high level of evidence using Clinical Pharmacogenomic Implementation Consortium (CPIC) data and surveyed 10 years of electronic health records (EHR) data for the number of children exposed to CYP-associated drugs. Subsequently, we performed a focused literature review for drugs commonly used in pediatrics, defined as more than 5000 pediatric patients exposed in the decade-long EHR cohort. There were 48 drug-CYP interactions with a high level of evidence in the CPIC database. Of those, only 10 drugs were commonly used in children (ondansetron, oxycodone, codeine, omeprazole, lansoprazole, sertraline, amitriptyline, citalopram, escitalopram, and risperidone). For these drugs, reports of the drug-CYP interaction in cohorts including children were sparse. There are adequate data for implementation of genotype-guided therapy for children for three of the 10 commonly used drugs (codeine, omeprazole and lansoprazole). For the majority of commonly used drugs with known CYP interactions, more data are required to support pharmacogenomic implementation in children.

No 349 - Consommation de substances psychoactives pendant la grossesse

OBJECTIFS

Accroître la sensibilisation à la consommation problématique de substances psychoactives pendant la grossesse et les connaissances à ce sujet, et formuler des recommandations factuelles relatives à la prise en charge de cet épineux problème clinique à l'intention de l'ensemble des fournisseurs de soins.

OPTIONS

La présente directive clinique analyse l'utilisation d'outils de dépistage, l'approche générale de soins et les recommandations pour la prise en charge clinique de la consommation problématique de substances psychoactives pendant la grossesse.

ISSUES

Recommandations factuelles pour le dépistage et la prise en charge de la consommation problématique de substances psychoactives pendant la grossesse et l'allaitement.

RECHERCHE DOCUMENTAIRE

La littérature à jour a été obtenue au moyen de recherches dans Medline, PubMed et la Bibliothèque Cochrane visant les articles publiés entre 1996 et 2016, avec les mots clés suivants : « pregnancy », « electronic cigarettes », « tobacco use cessation products », « buprenorphine » et « methadone ». Les résultats ont d'abord été restreints aux analyses systématiques, aux ECR et aux essais cliniques contrôlés. Ensuite, en raison de la rareté des ECR sur le sujet, des recherches d'études observationnelles ont également été menées. Les articles sélectionnés ont été limités aux études chez l'humain publiées en anglais, puis d'autres articles ont été trouvés manuellement, par l'analyse des listes de références.

VALEURS

La qualité des données a été évaluée au moyen des critères énoncés dans le rapport du Groupe d'étude canadien sur les soins de santé préventifs. Les recommandations visant la pratique ont été classées conformément à la méthode décrite dans ce rapport. AVANTAGES, DéSAVANTAGES ET COûTS: La présente directive clinique a pour but d'améliorer les connaissances et le degré d'aisance des fournisseurs qui dispensent des soins aux femmes enceintes ayant un trouble de l'usage d'une substance. L'amélioration de l'accès aux soins de santé et de l'aide pour obtenir un traitement adéquat de la dépendance fait diminuer les coûts de santé et les taux de morbidité et de mortalité chez la mère et l'enfant. RECOMMANDATIONS.

A cost-effectiveness analysis of maternal CYP2D6 genetic testing to guide treatment for postpartum pain and avert infant adverse events

Mothers with a CYP2D6 ultrarapid metabolizer phenotype may expose their infants to risk of adverse events when taking codeine while breastfeeding, by producing more of the active metabolite, morphine. Pharmacogenetic testing may be a valuable tool to identify such mothers, but testing can be costly. The objective of the study was to determine the incremental costs of genotyping to avert neonatal adverse events during maternal pharmacotherapy. A cost-effectiveness analysis, using a decision model, was performed with a hypothetical cohort of prenatal subjects. Parameter estimates, costs and ranges for sensitivity analyses were ascertained from the literature and expert opinion. Sensitivity analyses were conducted to assess the robustness of the results. Probabilistic sensitivity analysis revealed an incremental cost-effectiveness (ICER) of $10 433 (Canadian dollars) for genotyping compared to no genotyping per adverse event averted. Results were sensitive to hospital admission costs. The ICER was lower when evaluating only subjects having caesarean deliveries or those from ethnic populations known to have a high prevalence of ultra-rapid metabolizers. Although genotyping to guide pharmacotherapy was not cost saving, the cost to avert an infant adverse event may represent good value for money in specific populations. With a growing demand for personalized medicine, these findings are relevant for decision makers, clinicians and patients.

Design and evaluation of a pharmacogenomics information resource for pharmacists

OBJECTIVE

To develop and evaluate a pharmacogenomics information resource for pharmacists.

MATERIALS AND METHODS

We built a pharmacogenomics information resource presenting Food and Drug Administration (FDA) drug product labelling information, refined it based on feedback from pharmacists, and conducted a comparative usability evaluation, measuring task completion time, task correctness and perceived usability. Tasks involved hypothetical clinical situations requiring interpretation of pharmacogenomics information to determine optimal prescribing for specific patients.

RESULTS

Pharmacists were better able to perform certain tasks using the redesigned resource relative to the Pharmacogenomic Knowledgebase (PharmGKB) and the FDA Table of Pharmacogenomic Biomarkers in Drug Labeling. On average, participants completed tasks in 107.5 s using our resource, compared to 188.9 s using PharmGKB and 240.2 s using the FDA table. Using the System Usability Scale, participants rated our resource 79.62 on average, compared to 53.27 for PharmGKB and 50.77 for the FDA table. Participants found the correct answers for 100% of tasks using our resource, compared to 76.9% using PharmGKB and 69.2% using the FDA table.

DISCUSSION

We present structured, clinically relevant pharmacogenomic FDA drug product label information with visualizations to help explain the relationships between gene variants, drugs, and phenotypes. The results from our evaluation suggest that user-centered interfaces for pharmacogenomics information can increase ease of access and comprehension.

CONCLUSION

A clinician-focused pharmacogenomics information resource can answer pharmacogenomics-related medication questions faster, more correctly, and more easily than widely used alternatives, as perceived by pharmacists.