The burden and management of cytochrome P450 2D6 (CYP2D6)-mediated drug-drug interaction (DDI): co-medication of metoprolol and paroxetine or fluoxetine in the elderly

Efficacy and tolerability of desvenlafaxine in the real-world treatment of patients with major depression: a narrative review and an expert opinion paper

INTRODUCTION

Major depressive disorder (MDD) is a common severe mental disorder, requiring a tailored and integrated treatment. Several approaches are available including different classes of antidepressants various psychotherapeutic approaches, and psychosocial interventions. The treatment plan for each patient with MDD should be differentiated on the basis of several clinical, personal, and contextual factors.

AREAS COVERED

Desvenlafaxine - a serotonine-noradrenergic reuptake inhibitor (SNRI) antidepressant - has been approved in the United States in 2008 for the treatment of MDD in adults, and has been recently rediscovered by clinicians due to its good side-effect profile and its clinical effectiveness. A narrative review on efficacy, tolerability and use of desvenlafaxine in clinical practice was carried out. The keywords: 'major depression', 'depression,' 'desvenlafaxine,' 'efficacy,' 'clinical efficacy,' 'side effects', 'tolerability,' 'elderly patients', 'consultation-liaison', 'menopausal', 'young people', 'adolescent' were entered in PubMed, ISI Web of Knowledge, Scopus and Medline. No time limit was fixed, the search strategy was implemented on May 10, 2023.

EXPERT OPINION

Desvenlafaxine should be listed among the optimal treatment strategies for managing people with MDD, whose main strengths are: 1) ease of dosing; 2) favorable safety and tolerability profile, 3) absence of sexual dysfunctions, weight gain and low rate of discontinuation symptoms; 4) low risk of drug-drug interactions.

Pharmacokinetic and Pharmacodynamic Drug-Drug Interactions: Research Methods and Applications

Because of the high research and development cost of new drugs, the long development process of new drugs, and the high failure rate at later stages, combining past drugs has gradually become a more economical and attractive alternative. However, the ensuing problem of drug-drug interactions (DDIs) urgently need to be solved, and combination has attracted a lot of attention from pharmaceutical researchers. At present, DDI is often evaluated and investigated from two perspectives: pharmacodynamics and pharmacokinetics. However, in some special cases, DDI cannot be accurately evaluated from a single perspective. Therefore, this review describes and compares the current DDI evaluation methods based on two aspects: pharmacokinetic interaction and pharmacodynamic interaction. The methods summarized in this paper mainly include probe drug cocktail methods, liver microsome and hepatocyte models, static models, physiologically based pharmacokinetic models, machine learning models, in vivo comparative efficacy studies, and in vitro static and dynamic tests. This review aims to serve as a useful guide for interested researchers to promote more scientific accuracy and clinical practical use of DDI studies.

Age-related modifications in CYP-dependent drug metabolism: role of stress

Accumulating clinical evidence indicates extensive inter-individual variations in the effectiveness and adverse effects of standard treatment protocols, which are largely attributed to the multifactorial regulation of the hepatic CYP-dependent drug metabolism that is connected with either transcriptional or post-translational modifications. Age and stress belong to the most important factors in CYP gene regulation. Alterations in neuroendocrine responses to stress, which are associated with modified hypothalamo-pituitary-adrenal axis function, usually accompany ageing. In this light, ageing followed by a decline of the functional integrity of organs, including liver, a failure in preserving homeostasis under stress, increased morbidity and susceptibility to stress, among others, holds a determinant role in the CYP-catalyzed drug metabolism and thus, in the outcome and toxicity of pharmacotherapy. Modifications in the drug metabolizing capacity of the liver with age have been reported and in particular, a decline in the activity of the main CYP isoforms in male senescent rats, indicating decreased metabolism and higher levels of the drug-substrates in their blood. These factors along with the restricted experience in the use of the most medicines in childhood and elderly, could explain at an extent the inter-individual variability in drug efficacy and toxicity outcomes, and underscore the necessity of designing the treatment protocols, accordingly.

Interaction alerts: A comparison of classifications and recommendations for clinical management between Janusmed and three other knowledge resources

Classifications of drug interaction alerts differ between knowledge resources, but agreement regarding recommendations for clinical management is less explored. Starting from the medication lists of 274 older patients with ≥2 drugs, all unique drug pairs that triggered a clinically significant interaction alert in Janusmed were included: 100 Category C (manageable by, e.g. dose adjustment) and nine Category D interactions (should be avoided). Out of 109 C/D alerts in Janusmed, 89 (82%), 75 (69%) and 45 (41%) drug pairs triggered an alert of similar clinical significance in Lexicomp, Micromedex® and Stockley's Drug Interactions/Checker (Stockley), respectively. Eight (7%), 20 (18%) and 10 (9%) drug pairs did not trigger any alert in these resources. For 81 (74%), 81 (74%) and 94 (86%) drug pairs, Lexicomp, Micromedex and Stockley provided at least one recommendation for clinical management similar to those provided by Janusmed. For 16 (15%), 9 (8%) and 21 (19%) drug pairs, these resources provided recommendation(s) entirely in agreement with Janusmed. Although many drug pairs elicit alerts of similar significance, and partly concordant recommendations, a non-negligible proportion do not. The findings encourage medical/pharmaceutical reflection by prescribing clinicians and dispensing pharmacists; recommendations provided by knowledge resources vary considerably and cannot be considered definite.

Determination of CYP450 activities in diabetes mellitus rats by a UHPLC-MS/MS method

In this study, we investigated the effect of type 1 diabetes mellitus on the modulation of the activities of CYP450s in dynamics by a UHPLC-MS/MS method. The diabetic rat model was constructed by an intraperitoneal single injection of streptozotocin. Fasting blood glucose levels > 16.7 mmol/L were considered as diabetic. The rats were given a cocktail of four probe drugs (10 mg/kg phenacetin, 1 mg/kg tolbutamide, 10 mg/kg metoprolol, and 10 mg/kg midazolam) by oral administration for the pharmacokinetic study. Thereafter, the metabolic ratio (MR) of the metabolites to probe substrates were determined. The results indicated that two weeks after diabetes was induced, diabetes increased the MRs of acetaminophen/phenacetin (CYP1A2) and 4-hydroxyl tolbutamide/tolbutamide (CYP2C9); however, it decreased the MRs of α-hydroxy metoprolol/metoprolol (CYP2D6) and 1-hydroxy midazolam/midazolam (CYP3A4). Two months after diabetes was induced, diabetes increased the MRs of acetaminophen/phenacetin and 4-hydroxyl tolbutamide/tolbutamide. The MR of α-hydroxy metoprolol/metoprolol was decreased and the MR of 1-hydroxy midazolam/midazolam was increased but the difference was not significant. According to the results, CYP1A2 and CYP2C9 activities were enhanced in the diabetic rats. and CYP2D6 activity was inhibited in a short period of diabetes; however, the decrease in CYP2D6 activity was not significant in the long period. CYP3A4 activity was decreased in a short period of diabetes and increased in a long period of diabetes but was not significant in the two periods. This study suggests the activity change rule of the CYP450 enzyme system in diabetes mellitus, which can provide a reference for precise clinical medication.

Co-prescription of metoprolol and CYP2D6-inhibiting antidepressants before and after implementation of an optimized drug interaction database in Norway

Purpose

To compare the co-prescription of metoprolol and potent CYP2D6-inhibiting antidepressants before and during a 10-year period after implementation of an optimized drug interaction database into clinical decision support systems in Norway.

Methods

The study was a retrospective, cross-sequential nationwide analysis of drug-dispensing data retrieved from the Norwegian Prescription Database over a 1-year period before (2007) and two 1-year periods after (2012 and 2017) implementation of a drug interaction database providing recommendations on non-interacting alternative medications. Primary outcome was changes in co-prescription rates of metoprolol and the potent CYP2D6-inhibiting antidepressants fluoxetine, paroxetine, or bupropion relative to alternative antidepressants with no or limited CYP2D6 inhibitory potential. To control for potential secular trend bias, a comparison group consisting of atenolol/bisoprolol users was included.

Results

The co-prescription rate of metoprolol with potent CYP2D6 inhibitors declined following implementation of the optimized database, by 21% (P < 0.001) after 5 years and by 40% (P < 0.001) after 10 years. Compared with atenolol/bisoprolol users, patients treated with metoprolol had significantly reduced likelihood of being prescribed a CYP2D6-inhibiting antidepressant in the two post-implementation periods (OR 0.61 (95% CI 0.54–0.69) and OR 0.45 (95% CI 0.40–0.51), respectively, versus OR 0.84 (95% CI 0.74–0.94) prior to implementation). Small and mostly insignificant differences in average daily metoprolol dosage were found between patients treated with the various antidepressants.

Conclusion

The present study suggests that implementation of a drug interaction database providing recommendations on non-interacting drug alternatives contributes to reduced co-prescribing of drug combinations associated with potentially serious adverse effects.

Impact of the CYP2D6 Genotype on Metoprolol Tolerance and Adverse Events in Elderly Chinese Patients With Cardiovascular Diseases

The latest consensus has changed CYP2D6 genotyping among Chinese population, while its impact on metoprolol tolerance and adverse events in elderly Chinese patients with cardiovascular diseases remains unclear. In this study, we prospectively included elderly patients who started metoprolol treatment for cardiovascular indications. According to the latest consensus on CYP2D6 genotype-to-phenotype translation, the patients were categorized as normal, intermediate, or poor metabolizers (NMs, IMs, or PMs, respectively) by detecting the presence of the CYP2D6*1, *2, *5, *10, and *14. Logistic regression model was used to analyze the correlation between the CYP2D6 phenotype and incidence of adverse events, which were assessed over a 12-week period. In this study, there were 651 (62.7%) NMs, 385 (37.1%) IMs, and 3 (0.3%) PMs. After 12 weeks of follow-up, compared with NMs, IMs had the lower maintenance dose [50.0 (25.0–50.0) mg/day vs. 25.0 (25.0–50.0) mg/day, p < 0.001] and lower weight-adjusted maintenance doses (0.52 ± 0.25 mg/day/kg vs. 0.42 ± 0.22 mg/day/kg, p < 0.001), and had higher incidence of postural hypotension (6.0% vs. 10.9%, p = 0.006), bradycardia (21.5% vs. 28.6%, p = 0.011), asystole (0.8% vs. 3.1%, p = 0.009) and syncope (2.0% vs. 6.2%, p = 0.001). In logistic regression model, the overall incidence of adverse events was 1.37-fold larger in IMs than in NMs (odds ratio = 1.37, 95% confidence interval = 1.05–1.79, p = 0.021). We conclude that IMs have lower tolerance and higher incidence of metoprolol-related adverse events than NMs in elderly Chinese patients with cardiovascular diseases. CYP2D6 genotyping is justifiable in elderly patients to minimize the risk of adverse events and ensure the benefits of metoprolol.

Impact of Drug-Gene-Interaction, Drug-Drug-Interaction, and Drug-Drug-Gene-Interaction on (es)Citalopram Therapy: The PharmLines Initiative

We explored the association between CYP2C19/3A4 mediated drug-gene-interaction (DGI), drug-drug-interaction (DDI) and drug-drug-gene-interaction (DDGI) and (es)citalopram dispensing course. A cohort study was conducted among adult Caucasians from the Lifelines cohort (167,729 participants) and linked dispensing data from the IADB.nl database as part of the PharmLines Initiative. Exposure groups were categorized into (es)citalopram starters with DGI, DDI and DDGI. The primary outcome was drug switching and/or dose adjustment, and the secondary was early discontinuation after the start of (es)citalopram. Logistic regression modeling was applied to estimate adjusted odd ratios with their confidence interval. We identified 316 (es)citalopram starters with complete CYP2C19/3A4 genetic information. The CYP2C19 IM/PM and CYP3A4 NM combination increased risks of switching and/or dose reduction (OR: 2.75, 95% CI: 1.03–7.29). The higher effect size was achieved by the CYP2C19 IM/PM and CYP3A4 IM combination (OR: 4.38, 95% CI: 1.22–15.69). CYP2C19/3A4 mediated DDIs and DDGIs showed trends towards increased risks of switching and/or dose reduction. In conclusion, a DGI involving predicted decreased CYP2C19 function increases the need for (es)citalopram switching and/or dose reduction which might be enhanced by co-presence of predicted decreased CYP3A4 function. For DDI and DDGI, no conclusions can be drawn from the results.

Development of Comprehensible Prescription Label Instructions: A Study Protocol for a Mixed-Methods Approach

Introduction

Patients receive information about their medication from different sources, including prescription labels. These labels are physically attached to each package dispensed to patients and contain the most important instructions on how to use the medication correctly. However, many patients experience difficulties in understanding and applying the instructions on these labels correctly, especially patients with limited health literacy. The aim of this study is to investigate the comprehensibility of prescription label instructions among patients with adequate and limited health literacy skills, and to implement improvements in primary health care.

Methods

We used a mixed-methods approach, which consisted of four phases. Phase 1 (desk research) was divided into a systematic literature review on the comprehensibility of prescription label instructions (1a) and a content analysis of the textual elements in Dutch prescription label instructions (1b). In phase 2 (patient studies), semi-structured interviews were conducted to investigate the comprehensibility of seven prescription labels among patients with different health literacy skills (2a), and a quantitative study in which the comprehensibility of six optimized prescription labels was compared among patients with different health literacy skills (2b). Patient studies were conducted in eight Dutch pharmacies. In phase 3 optimized prescription label instructions were implemented in national medication databases which has been supported by a guideline (3a), and education of pharmacy workers (3b). Phase 4 consists of evaluating the optimized prescription label instructions by experiences from patients and pharmacists.

Anticipated Results

This mixed-methods approach will result in scientific publications of the individual studies, and a guideline on how to compose comprehensible prescription label instructions to be put on medication packages. Optimized prescription label instructions will be implemented in national medication databases.

Discussion

This protocol describes a mixed-method research to compose and implement comprehensible prescription label instructions and will lead to knowledge about the comprehensibility of textual elements in these labels, with specific attention for patients with limited health literacy. Implementation of optimized prescription label instructions will lead to a better understanding of them, which may contribute to improved medication adherence. A limitation is that non-textual aspects of prescription labels are not investigated.

Improving antibacterial prescribing safety in the management of COPD exacerbations: systematic review of observational and clinical studies on potential drug interactions associated with frequently prescribed antibacterials among COPD patients

Background

Guidelines advise the use of antibacterials (ABs) in the management of COPD exacerbations. COPD patients often have multiple comorbidities, such as diabetes mellitus and cardiac diseases, leading to polypharmacy. Consequently, drug–drug interactions (DDIs) may frequently occur, and may cause serious adverse events and treatment failure.

Objectives

(i) To review DDIs related to frequently prescribed ABs among COPD patients from observational and clinical studies. (ii) To improve AB prescribing safety in clinical practice by structuring DDIs according to comorbidities of COPD.

Methods

We conducted a systematic review by searching PubMed and Embase up to 8 February 2018 for clinical trials, cohort and case–control studies reporting DDIs of ABs used for COPD. Study design, subjects, sample size, pharmacological mechanism of DDI and effect of interaction were extracted. We evaluated levels of DDIs and quality of evidence according to established criteria and structured the data by possible comorbidities.

Results

In all, 318 articles were eligible for review, describing a wide range of drugs used for comorbidities and their potential DDIs with ABs. DDIs between ABs and co-administered drugs could be subdivided into: (i) co-administered drugs altering the pharmacokinetics of ABs; and (ii) ABs interfering with the pharmacokinetics of co-administered drugs. The DDIs could lead to therapeutic failures or toxicities.

Conclusions

DDIs related to ABs with clinical significance may involve a wide range of indicated drugs to treat comorbidities in COPD. The evidence presented can support (computer-supported) decision-making by health practitioners when prescribing ABs during COPD exacerbations in the case of co-medication.

Combining Antidepressants with β-Blockers: Evidence of a Clinically Significant CYP2D6 Drug Interaction

BACKGROUND

The β-blockers and antidepressants are two of the most commonly prescribed drug classes in the United States. Several antidepressants are potent inhibitors of cytochrome P450 2D6 liver enzymes (CYP2D6) and can increase the plasma concentrations of certain β-blockers when administered concomitantly, potentially leading to serious medical consequences such as hypotension, bradycardia, and falls.

OBJECTIVE

The primary objective of this investigation was to determine whether initiating an antidepressant in patients receiving β-blockers increased the risk of hemodynamic adverse events. Our primary outcome was time to hospital admissions or emergency department (ED) visits for an International Classification of Diseases-9 diagnosis suggestive of excessive β-blockade.

METHODS

We conducted a survival analysis for adults continuously enrolled in the California Medicaid system (Medi-Cal) between 2004 and 2012. Eligible patients were required to be receiving β-blocker medications that are primarily CYP2D6 substrates (e.g., metoprolol, propranolol, or carvedilol). Univariate and multivariable analyses were performed for patients who concurrently received antidepressants with β-blockers. An additional multivariable analysis analyzed the association of this combination upon hospitalizations or ED visits for all causes.

RESULTS

A total of 21,292 beneficiaries met the inclusion criteria, and 4.3% of patients required hospitalization or ED visits within 30 days of co-medication. In multivariable analysis, patients receiving antidepressants with moderate to strong CYP2D6 inhibitory potential (fluoxetine, paroxetine, duloxetine, or bupropion) had a greater risk for hospitalization or ED visits for hemodynamic events than those initiated on antidepressants with weak CYP2D6 inhibition for 30 days or less when each was compared with patients receiving no antidepressants (hazard ratio [HR] 1.53, 95% confidence interval [CI] 1.03-2.81; p=0.04 vs HR 1.24; 95% CI 0.82-1.88; p=0.30). Other demographic variables associated with increased morbidity included advanced age, male sex, higher β-blocker doses, and African American race or Hispanic ethnicity.

CONCLUSIONS

Results of this analysis suggest that initiation of certain antidepressants was associated with an increased risk for serious medical sequelae among patients concurrently receiving β-blockers. Greater risk was observed with antidepressants that potently inhibit the CYP2D6 enzyme, implying that increased morbidity may be mediated by a metabolic drug interaction.

Prevalence and Accuracy of Information on CYP2D6, CYP2C19, and CYP2C9 Related Substrate and Inhibitor Co-Prescriptions in the General Population: A Cross-Sectional Descriptive Study as Part of the PharmLines Initiative

BACKGROUND

Drug-drug interaction (DDI) is one of the main contributors to adverse drug reactions and therefore, it is important to study its frequency in the population. We aimed to investigate frequency and concordance on CYP2D6, CYP2C19, and CYP2C9 (CYP2D6/2C19/2C9)-mediated potential DDIs at the Lifelines cohort and linked data from the pharmacy database IADB.nl.

METHODS

As part of the University of Groningen PharmLines Initiative, data were collected on CYP2D6/2C19/2C9-related substrate/inhibitors from entry questionnaires of Lifelines participants and linked information from the pharmacy database IADB.nl. CYP2D6/2C19/2C9 related co-prescriptions were divided based on the type of drugs i.e. chronically used medication (CM) or occasionally used medication (OM). This resulted in the combination of two chronically used drugs (CM-CM), chronically and occasionally used medication (CM-OM), and two occasionally used drugs (OM-OM). To measure the agreement level, cohen's kappa statistics and test characteristics were used. Results were stratified by time window, gender, and age.

RESULTS

Among 80,837 medicine users in the Lifelines, about 1-2 per hundred participants were exposed to a CYP2D6/2C19/2C9-mediated potential DDI. Overall, the overlapping time window of three months produced the highest mean kappa values between the databases i.e. 0.545 (95% CI:0.544-0.545), 0.512 (95% CI:0.511-0.512), and 0.374 (95% CI:0.373-0.375), respectively. CM-CM had a better level of agreement (good) than CM-OM (fair to moderate) and OM-OM combination (poor to moderate). The influence of gender on concordance values was different for different CYPs. Among older persons, agreement levels were higher than for the younger population.

CONCLUSIONS

CYP2D6/2C19/2C9-mediated potential DDIs were frequent and concordance of data varied by time window, type of combination, sex and age. Subsequent studies should rather use a combination of self-reported and pharmacy database information.

Sexual Dimorphism in Drug Metabolism and Pharmacokinetics

Background:

Sex and gender-based differences are observed well beyond the sex organs and affect several physiological and biochemical processes involved in the metabolism of drug molecules. It is essential to understand not only the sex and gender-based differences in the metabolism of the drug but also the molecular mechanisms involved in the regulation of drug metabolism for avoiding sex-related adverse effects of drugs in the human.

Method:

The articles on the sex and gender-based differences in the metabolism of drug molecules were retrieved from the Pub Med database. The articles were classified into the metabolism of the drug molecule, gene expression regulation of drug-metabolizing enzymes, the effect of sex hormones on the metabolism of drug, expression of drugmetabolizing enzymes, etc.

Result:

Several drug molecules are known, which are metabolized differently in males and females. These differences in metabolism may be due to the genomic and non-genomic action of sex hormones. Several other drug molecules still require further evaluation at the molecular level regarding the sex and gender-based differences in their metabolism. Attention is also required at the effect of signaling cascades associated with the metabolism of drug molecules.

Conclusion:

Sex and gender-based differences in the metabolism of drugs exist at various levels and it may be due to the genomic and non-genomic action of sex hormones. Detailed understanding of the effect of sex and related condition on the metabolism of drug molecules will help clinicians to determine the effective therapeutic doses of drugs dependingon the condition of patient and disease.

The impact of CYP2D6 mediated drug-drug interaction: a systematic review on a combination of metoprolol and paroxetine/fluoxetine

AIM

Metoprolol (a CYP2D6 substrate) is often co-prescribed with paroxetine/fluoxetine (a CYP2D6 inhibitor) because the clinical relevance of this drug-drug interaction (DDI) is still unclear. This review aimed to systematically evaluate the available evidence and quantify the clinical impact of the DDI.

METHOD

Pubmed, Web of Science, Cochrane Library and Embase were searched for studies reporting on the effect of the DDI among adults published until April 2018. Data on pharmacokinetics, pharmacodynamics and clinical outcomes from experimental, observational and case report studies were retrieved. The protocol of this study was registered in PROSPERO (CRD42018093087).

RESULTS

We found nine eligible articles that consisted of four experimental and two observational studies as well as three case reports. Experimental studies reported that paroxetine increased the AUC of metoprolol three to five times, and significantly decreased systolic blood pressure and heart rate of patients. Case reports concerned bradycardia and atrioventricular block due to the DDI. Results from observational studies were conflicting. A cohort study indicated that the DDI was significantly associated with the incidence of early discontinuation of metoprolol as an indicator of the emergence of metoprolol-related side effects. In a case-control study, the DDI was not significantly associated with bradycardia.

CONCLUSION

Despite the contradictory conclusions from the current literature, the majority of studies suggest that the DDI can lead to adverse clinical consequences. Since alternative antidepressants and beta-blockers with comparable efficacy are available, such DDIs can be avoided. Nonetheless, if prescribing the combination is unavoidable, a dose adjustment or close monitoring of the metoprolol-related side effects is necessary.

Discontinuation and dose adjustment of metoprolol after metoprolol-paroxetine/fluoxetine co-prescription in Dutch elderly

Purpose

Co‐prescription of paroxetine/fluoxetine (a strong CYP2D6 inhibitor) in metoprolol (a CYP2D6 substrate) users is common, but data on the clinical consequences of this drug‐drug interaction are limited and inconclusive. Therefore, we assessed the effect of paroxetine/fluoxetine initiation on the existing treatment with metoprolol on the discontinuation and dose adjustment of metoprolol among elderly.

Methods

We performed a cohort study using the University of Groningen IADB.nl prescription database (www.IADB.nl). We selected all elderly (≥60 years) who had ever been prescribed metoprolol and had a first co‐prescription of paroxetine/fluoxetine, citalopram (weak CYP2D6 inhibitor), or mirtazapine (negative control) from 1994 to 2015. The exposure group was metoprolol and paroxetine/fluoxetine co‐prescription, and the other groups acted as controls. The outcomes were early discontinuation and dose adjustment of metoprolol. Logistic regression was applied to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI).

Results

Combinations of metoprolol‐paroxetine/fluoxetine, metoprolol‐citalopram, and metoprolol‐mirtazapine were started in 528, 673, and 625 patients, respectively. Compared with metoprolol‐citalopram, metoprolol‐paroxetine/fluoxetine was not significantly associated with the early discontinuation and dose adjustment of metoprolol (OR = 1.07, 95% CI:0.77‐1.48; OR = 0.87, 95% CI:0.57‐1.33, respectively). In comparison with metoprolol‐mirtazapine, metoprolol‐paroxetine/fluoxetine was associated with a significant 43% relative increase in early discontinuation of metoprolol (OR = 1.43, 95% CI:1.01‐2.02) but no difference in the risk of dose adjustment. Stratified analysis by gender showed that women have a significantly high risk of metoprolol early discontinuation (OR = 1.62, 95% CI:1.03‐2.53).

Conclusion

Paroxetine/fluoxetine initiation in metoprolol prescriptions, especially for female older patients, is associated with the risk of early discontinuation of metoprolol.

Drug-drug interactions involving antidepressants: focus on desvenlafaxine

Psychiatric and physical conditions often coexist, and there is robust evidence that associates the frequency of depression with single and multiple physical conditions. More than half of patients with depression may have at least one chronic physical condition. Therefore, antidepressants are often used in cotherapy with other medications for the management of both psychiatric and chronic physical illnesses. The risk of drug-drug interactions (DDIs) is augmented by complex polypharmacy regimens and extended periods of treatment required, of which possible outcomes range from tolerability issues to lack of efficacy and serious adverse events. Optimal patient outcomes may be achieved through drug selection with minimal potential for DDIs. Desvenlafaxine is a serotonin-norepinephrine reuptake inhibitor approved for the treatment of adults with major depressive disorder. Pharmacokinetic studies of desvenlafaxine have shown a simple metabolic profile unique among antidepressants. This review examines the DDI profiles of antidepressants, particularly desvenlafaxine, in relation to drugs of different therapeutic areas. The summary and comparison of information available is meant to help clinicians in making informed decisions when using desvenlafaxine in patients with depression and comorbid chronic conditions.

Potential drug-drug interactions and polypharmacy in institutionalized elderly patients in a public hospital in Brazil

WHAT IS KNOWN ON THE SUBJECT?: Older individuals constitute an increasing proportion of the population, and therefore, are the major consumers of drugs. The elderly, especially those with mental disabilities, frequently develop chronic diseases and start using numerous drugs. Drug-drug interactions (DDIs) are a major clinical problem in the elderly population, and previous studies have focused only on antidepressants and others types of drugs used to treat mental health conditions. WHAT THIS ARTICLE ADDS TO EXISTING KNOWLEDGE?: This study shows that in hospitalized elderly patients with mental disorders (aged 60-69 years), polypharmacy (≥5 drugs) and the use of drugs that act on the cardiovascular, respiratory and nervous systems can lead to potential drug-drug interactions. Moreover, it was reported that the prevalence of drug-drug interactions in elderly patients with mental disorders was high during their hospitalization in a public hospital in Brazil. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: Nurses should know the factors associated with drug-drug interactions in hospitalized elderly patients with mental disorders to choose appropriate strategies for avoiding treatment failure and adverse events in patients.

ABSTRACT

Introduction Despite the impact on patient safety and the fact that prevalence is higher in older patients, previous research did not analyse drug-drug interactions (DDIs) in view of nursing care of elderly psychiatric patients. Aim To identify potential drug-drug interactions and polypharmacy in prescriptions of aged inpatients with psychiatric disorders and analyse associated factors. Methods In this retrospective cross-sectional study, we analysed the medical records of institutionalized patients diagnosed with psychiatric disorders (n = 94), aged >60 years, and prescribed multiple medications. Drug prescriptions were checked at admission, midway through and the last prescription. Factors associated with DDI occurrence were assessed using multivariable logistic regression analysis. Results A DDI prevalence potential of 67.0%, 74.5% and 80.8% occurred in patients at admission, midway through hospitalization and the last prescription, respectively. Most of the prescribed drugs were nervous system agents. A high percentage of serious and contraindicated potential DDIs occurred. Age between 60 and 69 years, use of cardiovascular and respiratory system drugs, and the number of medications contributed significantly to DDI. Implications for mental health nursing Knowledge on the factors associated with DDIs in patients with mental disorders can contribute to the improvement of effectiveness and safety of nursing care.