Matey, Eric T.

Abstract Clozapine is primarily metabolized via cytochrome P450(CYP)1A2 and to a lesser extent CYP3A4, CYP2C19, and CYP2D6. Metabolic inhibitors of clozapine, such as fluvoxamine and ciprofloxacin, are important to recognize to avoid adverse drug events. Estrogen-containing oral contraceptives (eOCPs) are weaker CYP1A2 and CYP2C19 inhibitors but are associated with a 2-fold increase of clozapine concentrations. The potential for phenoconversion due to a CYP genetic polymorphism can add additional complexities when considering drug interactions. A case report is presented of a suspected interaction between newly initiated clozapine and a prescribed eOCP for which the patient’s pharmacogenomic status was known. A 17-year-old, nonsmoking, White female with a history of schizophrenia was initiated on clozapine 12.5 mg at bedtime with a plan to increase by 25 mg every 4 days in the outpatient setting. The patient was a known rapid CYP1A2 metabolizer without identified sources of CYP1A2 induction and a CYP2C19 rapid metabolizer. Based on pharmacogenomic testing, there was no suspicion for significant gene-drug interactions. Yet, as the patient was prescribed an eOCP, a clozapine concentration was obtained after reaching 150 mg at bedtime. This steady-state clozapine concentration was found to be 560 ng/mL, correlating with worsening sedation and constipation. Given ongoing side effects, clozapine was lowered to 100 mg at bedtime; however, ongoing intolerance ultimately led to clozapine discontinuation. This case highlights the potential interaction between clozapine and eOCP in a CYP1A2 and CYP2C19 rapid metabolizer, leading to clozapine intolerance and discontinuation. The concomitant use of clozapine and eOCPs should be undertaken judiciously.

AbstractBackgroundHow variations predicted by pharmacogenomic testing to alter drug metabolism and therapeutic response affect outcomes for patients with disorders of gut‐ brain interaction is unclear.AimsTo assess the prevalence of pharmacogenomics‐predicted drug‐gene interactions and symptom outcomes for patients with disorders of gut‐brain interaction.MethodsPatients who were treated in our clinical practice for functional dyspepsia/bowel disorder underwent pharmacogenomic testing. The change in symptoms from baseline to 6 months was compared for patients with variations in CYP2D6 and CYP2C19, which metabolize neuromodulators, and SLC6A4, which encodes the sodium‐ dependent serotonin transporter.ResultsAt baseline, 79 of 94 participants (84%) had at least one predicted major drug‐ gene interaction, and all 94 (100%) had at least one predicted moderate interaction. For the 44 participants who completed a survey of their symptoms at 6 months, the mean (SD) irritable bowel syndrome‐symptom severity score decreased from 284 (71) at baseline to 231 (95) at 6 months (p < 0.001). Among patients taking selective serotonin reuptake inhibitors, the decrease in symptom severity (p = 0.03) and pain (p = 0.002) scores from baseline to 6 months was greater for patients with a homozygous SLC6A4 long/long genotype (n = 30) (ie, increased serotonin transporter activity) than for patients with homozygous short/short or heterozygous long/short genotypes (n = 64). Symptom outcomes were not affected by CYP2D6 or CYP2C19 variations.ConclusionsThe homozygous SLC6A4 long/long genotype confers better symptom resolution for patients with disorders of gut‐brain interaction who take selective serotonin reuptake inhibitors than do the homozygous short/short or heterozygous long/short genotypes.

Abstract Purpose To develop a pharmacist-driven, exploratory pharmacogenomics implementation model with the goal of creating a process for pharmacists to interpret pharmacogenomics results from RIGHT 10K Study samples and provide electronic consults to providers. Summary A train-the-trainer model program was initiated whereby pharmacogenomics pharmacists developed a documentation template and a quick reference guide as a standard guide to train other pharmacists. Pharmacists completed electronic consults (e-consults) reviewing pharmacogenomics results, with reference to drug-gene interactions, for patients with “semi-urgent” and “clinically actionable” results, defined as those indicating a potential for gene-drug interactions to cause major harm and those indicating a potential for an adverse drug reaction or reduced efficacy, respectively. Outcomes measured included the number of consults over time, number and role of pharmacists involved, average time to complete e-consults over time, and gene-drug pairs for semi-urgent consults per month. A total of 395 pharmacists were trained. The total number of e-consults completed was 2,843: 61 semi-urgent and 2,782 clinically actionable consults. The average time spent per consult was 24 minutes, and the average number of e-consults per pharmacist was 7. CYP2C19-clopidogrel was the most common gene-drug pair targeted in semi-urgent consults. Conclusion Pharmacy leaders planning to implement similar pharmacogenomics programs can utilize this data to estimate hiring needs for future pharmacogenomics implementation, while also considering the potential additional cost of developing resources.

AbstractClinically relevant adverse drug reactions differ between men and women. The underlying physiological and pharmacological processes contributing to these differences are infrequently studied or reported. As gene expression, cellular regulatory pathways, and integrated physiological functions differ between females and males, aggregating data from combined groups of men and women obscures the ability to detect these differences. This paper summarizes how genetic sex, that is, the presence of sex chromosomes XY for male or XX for female, and the influence of sex hormones affect transporters, receptors, and enzymes involved in drug metabolism. Changing levels of sex steroids throughout life, including increases at puberty, changes with pregnancy, and decreases with age, may directly and indirectly affect drug absorption, distribution, metabolism, and elimination. The direct and indirect effects of sex steroids in the form of exogenous hormones such as those used in hormonal contraceptives, menopausal hormone treatments, transgender therapy, and over‐the‐counter performance enhancing drugs may interfere with metabolism of other pharmaceuticals, and these interactions may vary by dose, formulation, and mode of delivery (oral, injection, or transdermal) of the steroid hormones. Few drugs have sex‐specific labeling or dosing recommendations. Furthermore, there is limited literature evaluating how the circulating levels of sex steroids impact drug efficacy or adverse reactions. Such research is needed in order to improve the understanding of the impact of sex hormones on pharmacological therapies, particularly as medicine moves toward individualizing treatments.

AbstractBackgroundWe characterized the pharmacogenomics (PGx) results received by diagnostic odyssey patients as secondary findings during clinical whole exome sequencing (WES) testing as a part of their care in Mayo Clinic's Individualized Medicine Clinic to determine the potential benefits and limitations to this cohort.MethodsWES results on 94 patients included a subset of PGx variants in CYP2C19, CYP2C9, and VKORC1 if identified in the patient. Demographic, phenotypic, and medication usage information was abstracted from patient medical data. A pharmacist interpreted the PGx results in the context of the patients’ current medication use and made therapeutic recommendations.ResultsThe majority was young with a median age of 10 years old, had neurological involvement in the disease presentation (71%), and was currently taking medications (90%). Of the 94 PGx‐evaluated patients, 91% had at least one variant allele reported and 20% had potential immediate implications on current medication use.ConclusionDue to the disease complexity and medication needs of diagnostic odyssey patients, there may be immediate benefit obtained from early life PGx testing for many and most will likely find benefit in the future. These results require conscientious interpretation and management to be actionable for all prescribing physicians throughout the lifetime of the patient.