Interpreting and applying CYP450 genomic test results to psychotropic medications

Pharmacogenetics of Obsessive-Compulsive Disorder: An Evidence-Update

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

Lisdexamfetamine Dimesylate Effects on the Pharmacokinetics of Cytochrome P450 Substrates in Healthy Adults in an Open-Label, Randomized, Crossover Study

INTRODUCTION

This open-label, randomized, two-period drug interaction study assessed lisdexamfetamine dimesylate (LDX) effects on cytochrome P450 (CYP) enzyme (CYP1A2, CYP2D6, CYP2C19, and CYP3A) activity.

METHODS

Thirty healthy volunteers were administered the Cooperstown cocktail (CYP1A2 [caffeine 200 mg], CYP2D6 [dextromethorphan 30 mg], CYP2C19 [omeprazole 40 mg], and CYP3A [midazolam 0.025 mg/kg] substrates) or Cooperstown cocktail + oral LDX 70 mg. Blood samples for pharmacokinetic analysis were collected pre-dose and serially for 72 h post-dose. Treatment differences in the primary endpoints, maximum plasma concentration (C max) and area under the plasma concentration versus time curve from 0 to infinity (AUC0-∞), were assessed using geometric mean ratios with 90 % CIs.

RESULTS

Geometric least squares (LS) means (without versus with LDX) for C max (ng/mL) were 5370 versus 5246 for caffeine, 2.43 versus 2.87 for dextromethorphan, 35.23 versus 35.11 for midazolam, and 677.9 versus 466.9 for omeprazole; and for AUC0-∞ (ng · h/mL) were 56,207 versus 56,688 for caffeine, 34.85 versus 37.27 for dextromethorphan, 92.07 versus 93.04 for midazolam, and 1428 versus 1499 for omeprazole. Geometric LS mean ratios were within the standard bioequivalence testing range, except for omeprazole and dextromethorphan C max. Parent/metabolite C max and AUC0-∞ ratios were similar between treatments except for dextromethorphan/dextrorphan AUC0-∞ ratio, which was lower with LDX. No serious or severe treatment-emergent adverse events were reported.

CONCLUSIONS

LDX did not alter CYP1A2, CYP2D6, or CYP3A activity. A small C max reduction for omeprazole and its metabolite was observed, possibly reflecting an effect either on the activity of CYP2C19 or omeprazole absorption.

Pharmacogenetics of antidepressant treatment in obsessive–compulsive disorder: an update and implications for clinicians

Obsessive–compulsive disorder (OCD) is a chronic neuropsychiatric disorder with high genetic influence. Antidepressants such as serotonin reuptake inhibitors, are widely accepted as the first-line medications for OCD; however, approximately 50% of OCD patients show poor response. Personalized medicine utilizing genetic testing has recently received much attention because the variability of antidepressant response and tolerability are partly due to an individual’s genetic variations. This has led to researchers investigating the role of specific genetic factors on antidepressant response and utility of testing in the clinical realm. Genetic test panels are showing promise for guiding antidepressant treatment to improve outcomes in depression. This article will review the most recent findings in the pharmacogenetics of OCD and its related disorders. Promising results have been reported for several serotonergic and glutamatergic system genes and the cytochrome CYP450 liver enzyme genes, which appear to play an important role in OCD and antidepressant response.

Efficacy and safety of pharmacotherapy in cancer-related psychiatric disorders across the trajectory of cancer care: a review

At least 25-30% of patients with cancer and an even higher percentage of patients in an advanced phase of illness meet the criteria for a psychiatric diagnosis, including depression, anxiety, stress-related syndromes, adjustment disorders, sleep disorders and delirium. A number of studies have accumulated over the last 35 years on the use of psychotropic drugs as a pillar in the treatment of psychiatric disorders. Major advances in psycho-oncology research have also shown the efficacy of psychotropic drugs as adjuvant treatment of cancer-related symptoms, such as pain, hot flushes, pruritus, nausea and vomiting, fatigue, and cognitive impairment. The knowledge about pharmacokinetics and pharmacodynamics, clinical use, safety, side effects and efficacy of psychotropic drugs in cancer care is essential for an integrated and multidimensional approach to patients treated in different settings, including community-based centres, oncology, and palliative care. A search of the major databases (MEDLINE, Embase, PsycLIT, PsycINFO, the Cochrane Library) was conducted in order to summarize relevant data concerning the efficacy and safety of pharmacotherapy for cancer-related psychiatric disorders in cancer patients across the trajectory of the disease.