Phenotypic Assessment of Drug Metabolic Pathways and P-Glycoprotein in Patients Treated With Antidepressants in an Ambulatory Setting.

OBJECTIVE: Drug-metabolizing enzymes (DMEs), such as cytochrome P450 (CYP) enzymes, and transporters have emerged as major determinants of variability in drug metabolism and response. This study investigated the association between CYP and P-glycoprotein activities and plasma antidepressant concentration in an outpatient clinical setting. Secondary outcomes were antidepressant efficacy and tolerance. We also describe phenotypes in patients treated with antidepressants and evaluate the tolerance of a minimally invasive phenotyping approach. METHODS: From January 2015 to August 2015, 64 patients on a stable antidepressant regimen underwent a simultaneous assessment of steady-state antidepressant concentration and DME (CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A) and P-glycoprotein transporter activity using a cocktail phenotyping approach. Psychiatric diagnoses were in accordance with DSM-5. RESULTS: We observed a high proportion of subjects (> 20%) with reduced activity of CYP2C19, CYP2D6, CYP3A4, and P-glycoprotein. As expected, higher CYP activity for major metabolic pathways was associated with lower concentration of the parent compound (CYP2C19 and escitalopram, P = .025; CYP2D6 and fluoxetine, P < .001; CYP2C19 and sertraline, P = .001), higher concentration of the metabolite (CYP2D6 and O-desmethylvenlafaxine, P = .007), and higher metabolite-to-parent drug ratio (CYP2C19 and escitalopram, P = .03; CYP2D6 and fluoxetine, P < .001; CYP2C19 and sertraline, P = .048; CYP2B6 and sertraline, P = .006). Phenotyping also highlighted the relevance of a minor metabolic pathway for venlafaxine (CYP3A4). Insufficient response and adverse reactions to antidepressants were not significantly associated with plasma antidepressant concentration, DME, or P-glycoprotein activity. Tolerance of the phenotypic test in ambulatory settings was found to be excellent. CONCLUSIONS: The phenotypic assessment of DMEs and a transporter is a valuable, well-tolerated method to explore the interindividual variability in drug disposition in clinical settings. The method is able to account for the inhibitory activity of antidepressants themselves and for polymedication, which is frequent in this population of refractory depressed patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02438072.

Exploring venlafaxine pharmacokinetic variability with a phenotyping approach, a multicentric french-swiss study (MARVEL study).

BACKGROUND: It is well known that the standard doses of a given drug may not have equivalent effects in all patients. To date, the management of depression remains mainly empirical and often poorly evaluated. The development of a personalized medicine in psychiatry may reduce treatment failure, intolerance or resistance, and hence the burden and costs of mood depressive disorders. The Geneva Cocktail Phenotypic approach presents several advantages including the "in vivo" measure of different cytochromes and transporter P-gp activities, their simultaneous determination in a single test, avoiding the influence of variability over time on phenotyping results, the administration of low dose substrates, a limited sampling strategy with an analytical method developed on DBS analysis. The goal of this project is to explore the relationship between the activity of drug-metabolizing enzymes (DME), assessed by a phenotypic approach, and the concentrations of Venlafaxine (VLX) + O-demethyl-venlafaxine (ODV), the efficacy and tolerance of VLX. METHODS/DESIGN: This study is a multicentre prospective non-randomized open trial. Eligible patients present a major depressive episode, MADRS over or equal to 20, treatment with VLX regardless of the dose during at least 4 weeks. The Phenotype Visit includes VLX and ODV concentration measurement. Following the oral absorption of low doses of omeprazole, midazolam, dextromethorphan, and fexofenadine, drug metabolizing enzymes activity is assessed by specific metabolite/probe concentration ratios from a sample taken 2 h after cocktail administration for CYP2C19, CYP3A4, CYP2D6; and by the determination of the limited area under the curve from the capillary blood samples taken 2-3 and 6 h after cocktail administration for CYP2C19 and P-gp. Two follow-up visits will take place between 25 and 40 days and 50-70 days after inclusion. They include assessment of efficacy, tolerance and observance. Eleven french centres are involved in recruitment, expected to be completed within approximately 2 years with 205 patients. Metabolic ratios are determined in Geneva, Switzerland. DISCUSSION: By showing an association between drug metabolism and VLX concentrations, efficacy and tolerance, there is a hope that testing drug metabolism pathways with a phenotypical approach would help physicians in selecting and dosing antidepressants. The MARVEL study will provide an important contribution to increasing the knowledge of VLX variability and in optimizing the use of methods of personalized therapy in psychiatric settings. TRIAL REGISTRATION: ClinicalTrials.gov NCT02590185 (10/27/2015). This study is currently recruiting participants.

Markers of Individual Drug Metabolism: Towards the Development of a Personalized Antidepressant Prescription.

The development of a personalized psychopharmacotherapy could potentially reduce treatment failure associated with drug intolerance or resistance, and therefore the burden and costs of affective disorders. An important challenge in realising this potential will be to identify suitable markers of an individual's metabolic response to specific pharmaceuticals. In the absence of suitable markers related directly to drug mechanism, the drug-metabolizing enzymes and transporters have emerged as major determinants of variability in drug metabolism and response. In keeping with this emergent general pharmacological trend, numerous studies concerning the relationship between antidepressants, their metabolism, transport, pharmacokinetic properties, efficacy and tolerability have now been published. These studies are reviewed in this article. The studies considered here frequently support a link between enzyme/transporter activity and/or the pharmacokinetic parameters of antidepressants. However, the majority of studies explored the variability of tricyclic antidepressants, which are less often prescribed today. Furthermore only a few studies have been conducted in naturalistic clinical conditions, seeking to determine whether the systematic assessment of the variability may improve the management of 'real-world' patients. Nonetheless recent studies have yielded promising results regarding the potential benefits of determining drug metabolism variability which might encourage additional large-scale prospective systematic studies be set up to assess the relevance of this approach in everyday practice.

Treating mood disorders in patients with a history of intestinal surgery: a systematic review.

Bariatric surgery is increasingly being performed, with the intended benefits of significant and durable weight loss. Radical surgical resection can result in short bowel syndrome (SBS), a rare and devastating condition. Psychological distress is common in these patients. Relevant articles were identified by searching Pubmed and EMBASE databases with the following keywords: 'Bariatrics'[Mesh] OR 'Short Bowel Syndrome' AND 'Antidepressive Agents' OR 'Psychotropic Drugs'[Mesh]. One in-vitro study, four clinical studies and six relevant case reports were identified. Most clinical studies on antidepressant focused on the Roux-en-Y gastric bypass (RYGB); these results are somewhat conflicting for a variety of reasons including different methodologies and small sample sizes. One month after RYGB, in patients receiving serotonin or serotonin/noradrenaline reuptake inhibitors, antidepressant levels decrease to 50% of preoperative levels and return to baseline (or greater) by 6 months in almost all patients. Other pharmacokinetic studies have shown that, 1 year after RYGB, duloxetine and sertraline levels are significantly reduced in comparison with the control population. Paradoxically, in patients with SBS and a few years after surgery, high concentration to dose ratios have been reported for citalopram and escitalopram; this may be because of an intestinal adaptation. Surgery of the intestine is likely to modify absorption and first-pass metabolism of drugs; managing the treatment of depression and anxiety in bariatric and SBS patients therefore presents a major challenge. Close clinical follow-up, associated with therapeutic drug monitoring when available, should enable the optimization of treatment response and modulate the risk of adverse events.

Surface expression of Fc epsilon RI on Langerhans' cells of clinically uninvolved skin is associated with disease activity in atopic dermatitis, allergic asthma, and rhinitis.

BACKGROUND: Fc epsilon RI expressed on the surface of human epidermal Langerhans' cells facilitates uptake of IgE-associated allergens and plays a pivotal role in the pathogenesis of atopic dermatitis. Seminal results from studies investigating Langerhans' cell Fc epsilon RI in skin biopsy sections or epidermal cell suspensions demonstrate the highest receptor expression in lesional skin of patients with active atopic dermatitis. OBJECTIVE: We sought to investigate and localize Fc epsilon RI expression on Langerhans' cells within a minimally disturbed tissue environment in clinically uninvolved skin and to compare receptor expression between healthy donors and patients with atopic dermatitis or other allergic diseases. METHODS: Intact epidermal sheets from skin suction blisters, immunofluorescently stained with Langerhans' cell markers and anti-Fc epsilon RI alpha (mAbs 15E5 and 22E7) or anti-IgE, were examined by means of confocal microscopy. Samples incubated with anti-Fc epsilon RI alpha before or after cell fixation-permeabilization were compared to discriminate between cytoplasmic and membrane localization. RESULTS: Cytoplasmic Fc epsilon RI alpha chain was found in Langerhans' cells from all donors, irrespective of atopic status. Surface Fc epsilon RI-bound IgE was detected in the skin of individuals with active atopic dermatitis and in the skin of those with active asthma or rhinitis. No surface Fc epsilon RI was expressed in the skin of patients with a clinical history of atopic dermatitis, asthma, or rhinitis whose disease was in remission or in the skin of nonatopic individuals. CONCLUSION: In clinically uninvolved skin, Langerhans' cell-surface Fc epsilon RI expression is not only linked to atopic dermatitis but is also generally associated with allergic disease. This supports the concept of a systemic regulatory mechanism associated with active allergic disease, which is further aggravated by local inflammation in atopic skin lesions.