Metabolic drug interactions with new psychotropic agents

New psychotropic drugs introduced in clinical practice in recent years include new antidepressants, such as selective serotonin reuptake inhibitors (SSRI) and 'third generation' antidepressants, and atypical antipsychotics, i.e. clozapine, risperidone, olanzapine, quetiapine, ziprasidone and amisulpride. These agents are extensively metabolized in the liver by cytochrome P450 (CYP) enzymes and are therefore susceptible to metabolically based drug interactions with other psychotropic medications or with compounds used for the treatment of concomitant somatic illnesses. New antidepressants differ in their potential for metabolic drug interactions. Fluoxetine and paroxetine are potent inhibitors of CYP2D6, fluvoxamine markedly inhibits CYP1A2 and CYP2C19, while nefazodone is a potent inhibitor of CYP3A4. These antidepressants may be involved in clinically significant interactions when coadministered with substrates of these isoforms, especially those with a narrow therapeutic index. Other new antidepressants including sertraline, citalopram, venlafaxine, mirtazapine and reboxetine are weak in vitro inhibitors of the different CYP isoforms and appear to have less propensity for important metabolic interactions. The new atypical antipsychotics do not affect significantly the activity of CYP isoenzymes and are not expected to impair the elimination of other medications. Conversely, coadministration of inhibitors or inducers of the CYP isoenzymes involved in metabolism of the various antipsychotic compounds may alter their plasma concentrations, possibly leading to clinically significant effects. The potential for metabolically based drug interactions of any new psychotropic agent may be anticipated on the basis of knowledge about the CYP enzymes responsible for its metabolism and about its effect on the activity of these enzymes. This information is essential for rational prescribing and may guide selection of an appropriate compound which is less likely to interact with already taken medication(s).     

Olanzapine in the treatment of depression with psychotic features: A prospective open-label study

Objective. Depression with psychotic features is a severe subtype of major depression associated with the presence of delusions, hallucinations and specific neurobiological features. Despite clinical consensus and guideline recommendations, data comparing the efficacy of combining antipsychotics with antidepressants compared to antidepressants alone remain inconclusive. The aim of the study was to investigate effectiveness and tolerability of the atypical antipsychotic olanzapine in acute depression with psychotic features. Methods. Seventeen inpatients with major depressive disorder with psychosis (MDDp) were treated with a combination of an antidepressant and olanzapine for 6 weeks in a prospective open-label study. Depressive and psychotic symptoms, extrapyramidal and general side effects were assessed every 2 weeks. Sixteen patients were eligible for final analysis. Results. The Brief Psychiatric Rating Scale (BPRS) showed a 30% symptom reduction after week 2, a 45% symptom reduction after week 4 and no considerable improvement thereafter. Depressive symptoms (Bech–Rafaelsen Melancholia Scale, BRMS) receded by 37% after week 2 and 50% after week 4. No extrapyramidal side effects occurred. Conclusion. Olanzapine is effective and tolerable in combination with an antidepressant in an MDDp inpatient sample. The results concur with data supporting good efficacy in negative and depressive symptoms of patients with schizophrenic and schizoaffective diseases.     

Pre-existing mental health disorders and pregnancy

Mental health conditions are independent risk factors for poor obstetric and neonatal outcomes therefore obstetricians need to be able to manage them well. This review will summarize the management of pre-existing mental health disorders in pregnancy. Explanations will be given as to which women are managed in primary care for their mental health conditions and which women are managed in specialist Perinatal Mental Health Services. When women should be referred to perinatal mental health services is described. The article provides recommendations on the obstetric management of these women as well as information on psychotropic medication in pregnancy and lactation.     

Antidepressant Drugs in the Elderly — Rôle of the Cytochrome P450 2D6

Depression, the most common mental health problem of the elderly, is often under-diagnosed and under-treated. As patients age, antidepressant pharmacological treatment becomes more complicated due to an increased risk of adverse drug events. These risks are associated with age-related physiological changes and individual variability in drug metabolism related to several factors, the most frequent of which is polymedication as a result of coexisting chronic illnesses.

Comedications induce drug interactions that depend on the patient's metabolic capacity, linked to the genetically determined cytochrome P450 enzyme (CYP450) function. The effect of some isoenzyme polymorphisms on the pharmacokinetics of many antidepressants and other psychotropic drugs is well characterized.

The author approaches successively the notions of the cytochrome P450 (2D6), its role in drug biotransformation, and the importance of knowing its substrates, inhibitors and inducers in order to predict drug interactions. The clinical significance of this notion, and the help that could be given by genotyping, and phenotyping are also explained. The author's experience on the relationship between drug side effects and patient metabolic status, and on the antidepressant interactions with fluoxetine, fluvoxamine and citalopram, is given in order to rationalize and individualize antidepressant choice in elderly.     

Combined paracetamol and amitriptyline adsorption to activated charcoal

Objectives. High-gram drug doses seen in multiple-drug poisonings might be close to the adsorption capacity of activated charcoal (AC). The aim was to determine the maximum adsorption capacities (Q_m) of amitriptyline and paracetamol, separately and in combination, to AC. Methods. ACs (Carbomix® and Norit Ready-To-Use) were tested in vitro. At pH 1.2 and pH 7.2, 0.250 g AC and paracetamol and/or amitriptyline were mixed and incubated. The AC?:?drug ratios were 10?:?1, 5?:?1, 3?:?1, 2?:?1, and 1?:?1. The mixed-drug adsorption vials contained the same AC?:?paracetamol ratios, but amitriptyline was added as fixed dose (0.080 g) to all samples. Drug concentrations in the liquid phase were analyzed using high-performance liquid chromatography (HPLC)/UV-detection. Results. Q_m, amitriptyline, were 0.49 g/g Carbomix® and 0.70 g/g Norit Ready-To-Use, and Q_m, paracetamol, were 0.63 g/g Carbomix® and 0.72 g/g Norit Ready-To-Use. The tested pH differences had minor effect on the adsorption. The mixed-drug adsorption showed about 40% Q_m reduction of each drug with increasing amounts of drug/g AC, but the total gram of drug adsorbed to AC was increased compared to one-drug conditions. Conclusion. The adsorption of the two compounds to AC seems to compete resulting in lower maximum adsorption capacity for both drugs when mixed. However, a great adsorptive capacity was noted and might be explained by adsorption of the drugs to different AC surface sites. Furthermore, the Norit Ready-To-Use preparation, with less volume and total weight for the same AC dose as Carbomix®, showed a higher Q_m. This might be clinically significant in terms of preventing nausea, vomiting, and subsequent aspiration.     

Risk of seizures associated with psychotropic medications: emphasis on new drugs and new findings

Psychotropic medications in the classes of antidepressants, antipsychotics and mood stabilisers have been recognised in the literature and clinical settings as having high epileptogenic potential. Among these three classes, clozapine, tricyclic antidepressants (TCAs) and lithium are agents that clinicians have historically recognised as precipitants of drug-induced seizures. There are few reports that review the epileptogenic risk of newer psychotropic agents; in this qualitative review, the authors provide an update on the most recently published reports on seizures associated with antidepressants, antipsychotics, mood stabilisers, anxiolytics and sedative-hypnotics. In general, the epileptogenic risks of the newer psychotropic agents appear to be quite low as long as dosing strategies are consistent with recommended guidelines. Whilst newer psychotropic medications appear to be safe in patients with epilepsy, few studies have specifically addressed this population. In addition, the potential for drug interactions between antiepileptic drugs and psychotropics may be substantial with certain agents. For example, many psychotropes are both substrates and inhibitors of cytochrome P450 (CYP450) isoenzymes, whilst many antiepileptic drugs are both substrates and inducers of CYP450 activity. Every attempt should be made to minimise potential interactions when these agents are concomitantly administered.     

Measuring the mind: assessing cognitive change in clinical drug trials

Genetic variation of SLC6A4, HTR1A, MAOA, COMT and BDNF has been associated with depression, variable antidepressant drug responses as well as impacts on brain regions of emotion processing that are modulated by antidepressants. Pharmacogenetic studies are using psychometric outcome measures of drug response and are hampered by small effect sizes that might be overcome by the use of intermediate endophenotypes of drug response, which are suggested by imaging studies. Such an approach will not only tighten the relationship between genes and drug response, but also yield new insights into the neurobiology of depression and individual drug responses. This article provides a comprehensive overview of pharmacogenetic, imaging genetics and drug response studies, utilizing imaging techniques within the context of antidepressive drug therapy.     

Pharmacological treatment of generalized anxiety disorder

Introduction: Generalized anxiety disorder (GAD) is a chronic, relapsing, debilitating disorder, associated with markedly impaired social and occupational functioning. Pharmacological treatment is considered standard care and several drug classes are now FDA approved for the treatment of GAD. While there are clear data for the efficacy of short-term acute treatment, long-term treatment and treatment-resistant GAD remain challenging.

Areas covered: This article describes current pharmacological treatment options for GAD, with focus on benzodiazepines, azapirones, antidepressants and anticonvulsant and antipsychotic drugs. Recent findings from placebo-controlled clinical trials are reviewed and evidence-based clinical implications are discussed. A PubMed search was completed using the terms: ‘generalized anxiety disorder AND treatment’ and ‘generalized anxiety disorder AND therapy’. Additional pivotal trials were included for a historical perspective (older landmark trials that established efficacy and safety for older drug classes in the treatment of GAD).

Expert opinion: Efficacy for treatment of GAD has been established for several different drug classes. At present, based on clear efficacy and good tolerability, first-line treatment with either a selective serotonin reuptake inhibitor (SSRI) or a serotonin-norepinephrine reuptake inhibitor (SNRI) is indicated. If an initial, at least moderate, clinical response is achieved under antidepressant therapy, treatment should be at least continued for 12 months.     

Roland Kuhn—100th Birthday of an Innovator of Clinical Psychopharmacology

On the occasion of his 100th birthday this letter is to pay tribute to Swiss psychiatrist and psychopharmacologist Roland Kuhn (1912–2005), who established the antidepressant effects of imipramine starting in 1956. Since until now only monoaminergic-based antidepressants such as this substance found their way into psychopharmacological therapy, one can say that Kuhn established the lead antidepressant substance and has hence fundamentally changed clinical psychiatry and care for the mentally ill.