The Prevalence of Potential Drug-Drug Interactions in Patients with Heart Failure at Hospital Discharge

Impact of polypharmacy on clinical outcomes in patients with advanced heart failure undergoing cardiac resynchronization therapy

Background

The prevalence rates of heart failure (HF) and hyperpolypharmacy have increased with the aging population. While a negative impact of hyperpolypharmacy on HF clinical outcomes has already been reported, the effects of hyperpolypharmacy on patients with advanced HF with reduced ejection fraction (HFrEF) undergoing cardiac resynchronization therapy (CRT) remain unclear.

Methods

We retrospectively evaluated data from 147 patients with advanced HFrEF who underwent CRT between March 2004 and June 2020. Patients were divided into nonpolypharmacy (<5 medications) and polypharmacy (≥5 medications) groups, as well as nonhyperpolypharmacy (<10 medications) and hyperpolypharmacy (≥10 medications) groups.

Results

The mean age of the study population was 70.6 ± 9.7 years, and 90 patients (67.2%) were male. The median number of medications used was 10 (interquartile range: 7-13, range: 2-24); Kaplan-Meier survival analysis revealed that the hyperpolypharmacy group had a significantly worse long-term survival rate in terms of major adverse cardiovascular events (MACE; p = 0.004) and all-cause mortality (p = 0.005). Long-term survival in terms of MACE and all-cause mortality was not significantly different between the polypharmacy with cardiovascular medication and nonpolypharmacy with cardiovascular medication groups. By contrast, the polypharmacy with noncardiovascular medication group had a significantly worse long-term survival rate in terms of MACE (p = 0.006) and all-cause mortality (p = 0.003) than the nonpolypharmacy with noncardiovascular medication group.

Conclusions

Hyperpolypharmacy was significantly associated with adverse cardiovascular outcomes in patients with advanced HFrEF who underwent CRT. Noncardiovascular polypharmacy may underlie the harmful effects of hyperpolypharmacy.

Risk Factors and Patterns of Drug-Drug Interactions in Two Categories of Level-3 Hospitals in Dhaka: A Cross-Sectional Study

Background and Aims

Drug-drug interactions (DDIs) are a significant health issue that may adversely affect the health and well-being of patients. This study assesses and compares potential DDI (pDDI) patterns, severity, and associated risk factors in government and private hospitals in Dhaka, Bangladesh.

Methods

A total of 188 and 206 prescriptions were collected from various government and private hospitals' outdoor departments, respectively, by capturing pictures of the prescriptions. Bivariate analyses were performed through STATA 15. MedScape drug interaction checker was applied to identify pDDIs, while their consequences were obtained from DrugBank and MedScape.

Results

Private hospitals had more pDDIs containing prescriptions than government hospitals (62.62% and 57.97%, respectively). The mean pDDIs cases were 3.29 in the private hospitals, while at government hospitals they were 3.02. Among the detected pDDIs, pharmacodynamic pDDIs were predominat, accounting for 63.32% and 66.23% of total events in government and private hospitals, respectively. Severity-wise, both types of hospitals had almost equal amounts of serious (10.34% vs. 9.18%), moderate (68.96% vs. 59.61%), and minor (20.06% vs. 21.79%) pDDIs. Polypharmacy was crucial in pDDI cases, responsible for 70.21% and 81.83% of pDDIs in government and private hospitals, respectively. Multiple comorbidities with pDDIs were more common in private hospitals (24.46% vs. 18.93%), while government hospitals displayed a higher frequency of pDDIs with one comorbidity (24.75% vs. 17.55%). Non-mention of comorbidities was correlated with both types of hospitals (p ≤ 0.01) in pDDIs cases. Furthermore, considerable amounts of pDDIs in prescription error categories were detected. Both types of hospitals had a prevalence of antihypertensive, antidiabetic, psychotic, and antiplatelet-related pDDIs.

Conclusion

The two kinds of hospitals exhibited similar pDDI patterns, while their associations were random with the risk variables. When prescribing pharmacokinetics and pharmacodynamics pDDIs, physicians should evaluate the risk-benefit ratio.

Drug-Drug Interactions in Hospitalized Urological Patients: A Retrospective Cohort Study

INTRODUCTION

Exposure to potential drug-drug interactions (pDDIs) can be a notable source of avoidable drug-related harm that requires adequate management to prevent medical errors. We aimed to evaluate pDDIs and associated factors in hospitalized urological patients on admission, during hospitalization, and on discharge.

METHODS

A retrospective cohort study was conducted at the Clinic of Urology of the University Clinical Centre Kragujevac, Serbia. To detect pDDIs, we used Lexicomp, which categorizes pDDIs as follows: X (avoid combination), D (consider therapy modification), C (monitor therapy), B (no action needed), and A (no known interaction). Multiple linear regression analysis was used to identify factors associated with the number of pDDIs.

RESULTS

More than half of the 220 included patients had at least one pDDI on admission and discharge (57.3% and 63.6%, respectively), whereas 95.0% had at least one pDDI during hospitalization. The total number and number of X, D, C, and B categories of pDDIs were the highest during hospitalization and the lowest on admission. Duration of hospitalization, arrhythmias, dementia, renal failure, cancer, surgery during hospitalization, number of prescribed drugs, and various pharmacological drug classes were risk factors for a higher number of pDDIs, while age, ischemic heart disease, hypertension, and development of infection during hospitalization were protective factors in at least one of the stages. The impact of renal colic depended on the stage and category of pDDI.

CONCLUSION

More than half of the urological patients were exposed to at least one pDDIs at all stages. Medical professionals should regularly screen for pDDIs, particularly in patients with risk factors.

Prevalence and factors associated with potential drug-drug interactions in prescriptions presented at private pharmacies in Mbarara city, southwestern Uganda

BACKGROUND

Drug-drug interactions (DDIs) influence the effectiveness of medication and thus determine the treatment outcomes of diseases managed with pharmacotherapy. This study aimed to determine the prevalence, severity, and factors associated with potential drug-drug interactions in prescriptions presented at private pharmacies in Mbarara city.

METHODS

DDIs were identified and classified basing on risk and severity using Lexicomp drug interaction database. STATA version 13 was used to analyze the collected data. Descriptive statistics were used to summarize the severity of potential DDIs identified. Bivariate and multivariate logistic regression was employed to identify different factors associated with the presence of potential DDIs.

RESULTS

A total of 295 prescriptions from 18 private pharmacies were studied and the prevalence of clinically significant potential DDIs was 37.6%. About half (149, 50.5%) of the patients were females, the majority (199, 67.5%) were adults 18-59 years of age whereas most (208, 70.5%) had a comorbid condition. Over one half (162, 54.9%) of the prescriptions were received from hospitals and majority of the prescriptions had 4 drugs prescribed (n = 175, 59.32%). Having one or more comorbidities and prescribing of therapeutic drug categories including anti-fungal, antihypertensives, analgesics, or corticosteroids were significantly associated with potential DDIs.

CONCLUSIONS

The prevalence of potential drug-drug interactions in outpatient setting in Mbarara city was high and majority of the potential DDIs were of moderate severity. Having 1 or more comorbidities and prescribing of therapeutic drug categories including antifungals, antihypertensives, analgesics, or corticosteroids were significantly associated with potential DDIs.

Assessment of risk factors associated with potential drug-drug interactions among patients suffering from chronic disorders

Patients suffering from chronic diseases are more likely to experience pDDIs due to older age, prolonged treatment, severe illness and greater number of prescribed drugs. The objective of the current study was to assess the prevalence of pDDIs and risk factors associated with occurrence of pDDIs in chronic disease patients attending outpatient clinics for regular check-ups. Patients suffering from diabetes, chronic obstructive pulmonary disease (COPD), stroke and osteoporosis were included in the study. This study was a cross sectional, observational, prospective study that included 337 patients from outpatient clinics of respiratory ward, cardiac ward and orthopedic ward of Nishter Hospital Multan, Pakistan. The mean number of interactions per patient was 1.68. A greater risk for occurrence of pDDI was associated with older age ≥ 60 years (OR = 1.95, 95% CI = 1.44-2.37, p<0.001); polypharmacy (≥ 5 drugs) (OR = 3.74, 95% CI 2.32-4.54, p<0.001); overburden (OR = 2.23, 95% CI = 1.64-3.16, p<0.01); CCI score (OR = 1.28, 95% CI = 1.04-1.84, p<0.001); multiple prescribers to one patient (OR = 1.18, 95% CI = 1.06-1.41, p<0.01); and trainee practitioner (OR = 1.09, 95% CI = 1.01-1.28, p<0.01). Old age, polypharmacy, overburden healthcare system, higher comorbidity index, multiple prescribers to one patient and trainee practitioner were associated with increased risk of occurrence of pDDIs in chronic disease patients.

Advanced Medication Alert System Decreased Hospital-Based Outpatient Duplicated Medications: A Longitudinal Hospital Cohort Study

OBJECTIVES

This study aimed to examine the associations between adoption of an advanced medication alert system and decreases in hospital-based outpatient duplicated medication rates in Taiwan.

METHODS

The unit of analysis was the hospital. We merged the hospital medication alert system adoption survey data and Taiwan National Health Insurance outpatient claims data. The observation time was 1998 to 2011, divided into 5 periods (T1-T5). The analysis included 216 hospitals, and outcome variable was hospital-based outpatient duplicated medication rates. The system adoption time frame, hospital accreditation level, and number of drugs per prescription were defined as predicted variables. A generalized estimating equation regression model was used.

RESULTS

Adoption of the advanced medication alert system gradually increased, such that 100% of medical centers and 84% of regional hospitals, but less than 50% of district hospitals, had systems by T5. The hospital-based outpatient duplicated medication rate continually decreased, from 29.8% to 11.2%. The generalized estimating equation model showed rates of duplicated medications of b = -8.44 at T2 and b = -17.88 at T5 (P < 0.001) compared with T1. Medical centers and regional hospitals demonstrated much lower duplication rates (b = -13.71, b = -6.82; P < 0.001) compared with district hospitals. Hospitals with more medications per prescription had higher duplication rates than did hospitals with fewer items.

CONCLUSIONS

Hospitals accredited at higher levels tended to have advanced medication alert systems. Hospitals that implemented advanced systems decreased hospital-based outpatient duplicated medications, avoiding a potential risk due to inappropriate medication use.

Evaluation of Potential Drug Interactions with AiDKlinik® in a Random Population Sample

Purpose

Undesirable drug interactions are frequent, they endanger the success of therapy, and they lead to adverse drug reactions. The present study aimed to evaluate statistically potentially drug interactions in a locally circumscribed, random sample population.

Patients and Methods

In a random sample population of 264 patients taking medications, we performed analyses with the drug information system AiDKlinik^®. Statistical analysis was performed using SAS version 9.4.

Results

Statistically potentially drug interactions were recorded in 82/264 (31.1%) subjects, including 39/82 (47.56%) men, and 43/82 (52.43%) women (χ²= 0.081; p = 0.776). The average number of potential possible interactions detected per person was 1.60 ± 1.21. The regression model with the variables age, body-mass-index and number of long-term-medications shows a significant association between the number of long-term medications taken and the number of moderately severe and severe reactions to drug interactions (F(3.239) = 28.67, p < 0.0001; (t(239) 8.28; p < 0.0001)). After backward elimination, the regression model showed a significant interaction with the number of long-term medications (t (240) = 8.73, p < 0.0001) and body-mass-index (t (240) = 2.02, p = 0.0442). In descriptive analysis, the highest percentages of potential drug interactions occurred in 42/82 (51.22%) subjects with body mass indices (BMIs) >25 kg/m² and in 28/82 (34.15%) subjects aged 61–70 years.

Conclusion

Number of long-term medications use, age, and obesity may lead to increased drug–drug interactions in a random population sample.

Drug interactions in hospital prescriptions in Denmark: Prevalence and associations with adverse outcomes

Purpose

While the beneficial effects of medications are numerous, drug–drug interactions may lead to adverse drug reactions that are preventable causes of morbidity and mortality. Our goal was to quantify the prevalence of potential drug–drug interactions in drug prescriptions at Danish hospitals, estimate the risk of adverse outcomes associated with discouraged drug combinations, and highlight the patient types (defined by the primary diagnosis of the admission) that appear to be more affected.

Methods

This cross‐sectional (descriptive part) and cohort study (adverse outcomes part) used hospital electronic health records from two Danish regions (~2.5 million people) from January 2008 through June 2016. We included all inpatients receiving two or more medications during their admission and considered concomitant prescriptions of potentially interacting drugs as per the Danish Drug Interaction Database. We measured the prevalence of potential drug–drug interactions in general and discouraged drug pairs in particular during admissions and associations with adverse outcomes: post‐discharge all‐cause mortality rate, readmission rate and length‐of‐stay.

Results

Among 2 886 227 hospital admissions (945 475 patients; median age 62 years [IQR: 41–74]; 54% female; median number of drugs 7 [IQR: 4–11]), patients in 1 836 170 admissions were exposed to at least one potential drug–drug interaction (659 525 patients; median age 65 years [IQR: 49–77]; 54% female; median number of drugs 9 [IQR: 6–13]) and in 27 605 admissions to a discouraged drug pair (18 192 patients; median age 68 years [IQR: 58–77]; female 46%; median number of drugs 16 [IQR: 11–22]). Meropenem‐valproic acid (HR: 1.5, 95% CI: 1.1–1.9), domperidone‐fluconazole (HR: 2.5, 95% CI: 2.1–3.1), imipramine‐terbinafine (HR: 3.8, 95% CI: 1.2–12), agomelatine‐ciprofloxacin (HR: 2.6, 95% CI: 1.3–5.5), clarithromycin‐quetiapine (HR: 1.7, 95% CI: 1.1–2.7) and piroxicam‐warfarin (HR: 3.4, 95% CI: 1–11.4) were associated with elevated mortality. Confidence interval bounds of pairs associated with readmission were close to 1; length‐of‐stay results were inconclusive.

Conclusions

Well‐described potential drug–drug interactions are still missed and alerts at point of prescription may reduce the risk of harming patients; prescribing clinicians should be alert when using strong inhibitor/inducer drugs (i.e. clarithromycin, valproic acid, terbinafine) and prevalent anticoagulants (i.e. warfarin and non‐steroidal anti‐inflammatory drugs ‐ NSAIDs) due to their great potential for dangerous interactions. The most prominent CYP isoenzyme involved in mortality and readmission rates was 3A4.

Predictors of drug-drug interactions of medications prescribed to patients admitted due to suicidal behavior

INTRODUCTION

Drug-drug interactions among people with suicidal behavior is a challenging topic, considering the harm it poses for patients already vulnerable and the lack of literature on the thematic. This aspect must not be neglected in research and clinical practice, and thus requires thorough investigation.

OBJECTIVE

to investigate predictors of drug-drug interaction of prescribed drugs and the prescription of two or more drugs for people admitted due to suicidal behavior in a psychiatric emergency department (short-stay hospital ward).

METHOD

A cross-sectional study with retrospective approach, carried out in a Brazilian psychiatric emergency unit in 2015. Data about first and last medical prescriptions were collected from 127 patients' files. Descriptive statistics and the Zero Adjusted Logarithmic Distribution (ZALG) model were adopted, with the significance level α = 0.05.

RESULTS

Potential drug-drug interactions were found in most of the first and last prescriptions. The sample majority were female, with previous suicide attempts, being discharged from the hospital with three drugs (or more) prescribed, and without referral to any health service. Age and comorbidities were predictors of more drug prescriptions and the amount of prescribed drugs was the most important predictor of drug-drug interactions (quantity and severity).

CONCLUSIONS

the variables associated with drug-drug interactions and prescription of two or more drugs among people with suicidal behavior needs to be investigated in different contexts and addressed in interventions with the aim to promote patient safety.

Risk Factors for the Occurrence of Potential Drug-Drug Interactions in Surgical Patients

Background: Drug-drug interactions are defined as modifications of the drug action that result from the simultaneous administration of another individual drug or several drugs. Nowadays, potential drug-drug interactions (DDIs) are most frequently detected and analyzed using personal digital assistant software programs (online interaction checker tools).

Objective: To determine the risk factors for the emergence of all drug-drug interactions in surgical patients with particular emphasis on clinically significant interactions.

Patients and methods: This was a retrospective cohort analysis of patients treated at the Surgical Clinic of the Clinical Center Kragujevac. Three interaction checkers were used to reveal drug-drug interactions: Medscape, Epocrates and Micromedex.

Results: The study included total of 200 patients, aged 58.54±17.08 years. Average number of drug-drug interactions per patient was between 10.50±9.10 (Micromedex) and 18.75±17.14 (Epocrates). Number of prescribed drugs, antidepressive therapy, antiarrhythmic therapy, number of pharmacological/therapeutic subgroups (2nd level of ATC classification) prescribed, delirium or dementia, diabetes, heart failure, and number of physicians who prescribed drugs to single patient were identified as risk factors for drug-drug interactions while length of hospitalization in days and age of patient in years emerged as protective factors.

Conclusion: Drug-drug interactions are relatively common in surgical patients and predisposed by factors such as number of prescribed drugs or drug group per patient, number of physicians who prescribed drugs, antidepressive therapy, antiarrhythmic therapy, presence of delirium or dementia, diabetes and heart failure. On the other hand, prolonged hospitalization and higher age are factors that reduce the risk of interactions in surgical patients.

Potential Drug-Drug Interactions in Hospitalized Medical Patients: Data From Low Resource Settings

Introduction

Adverse events related to Drug-Drug Interactions (DDIs) are among the few common reasons for hospitalization worldwide; however, they can be prevented with an efficient patient-centered system. Different mechanisms have successfully limited the prevalence of DDIs in developed countries. There are limited data regarding DDIs from limited-resource settings. Furthermore, there is no cost-effective system that has shown promising results in preventing them in this setting. This study aims to assess the frequency of potential DDIs in a low-resource setting and to check its association with different factors such as poly-pharmacy and demographics.

Methods

Through this cross-sectional study, drug charts of patients admitted to a medical unit in November 2019 were analyzed using a structured questionnaire. A list of drugs co-prescribed to each patient was entered into the Medscape Drug Interaction checker to calculate the frequency and severity of potential DDIs.

Results

The mean age of patients was 49 years, and on average, seven drugs were prescribed to each patient. Among 100 analyzed prescriptions, 400 potential DDIs were identified with a mean of 4±5.42 per patient. According to Medscape interaction checker classification, 2 DDIs were contraindicated, 28 were serious, 246 required close monitoring, and 124 were minor. The most frequently encountered drug interaction was "spironolactone with furosemide." There was a significant correlation of the occurrence of potential DDIs with increased numbers of prescribed drugs.

Conclusion

Our patient population was prescribed more drugs per patient than calculated in other settings. Poly-pharmacy is an independent risk factor for DDIs. Lastly, advancing age exposes patients to poly-pharmacy, and therefore, they are at a higher risk of developing DDIs.

Identifying and Characterizing Serious Adverse Drug Reactions Associated With Drug-Drug Interactions in a Spontaneous Reporting Database

Background: Drug-drug interactions (DDIs) are an important cause of adverse drug reactions (ADRs). In literature most of studies focus only on potential DDIs, while detailed data on serious ADRs associated with DDIs are limited. Our aim is to identify and characterize serious ADRs caused by DDIs using a spontaneous reporting database.

Methods: All serious ADR reports, not related to vaccines and with a “definite”, “probable” or “possible” causality assessment, inserted into the National Pharmacovigilance database from Veneto Region (January 1, 2015 to May 31, 2020) were analyzed. A list of drug pairs was created by selecting the reports containing at least two suspected or concomitant drugs. We verified which drug pairs potentially interacted according to the online version of DRUGDEX^® system. For each potential DDI we controlled whether the ADR description in the report corresponded to the interaction effect as described in Micromedex. A detailed characterization of all serious reports containing an occurring DDI was performed.

Results: In the study period a total of 31,604 reports of suspected ADRs from the Veneto Region were identified, of which 2,195 serious reports (6.9% of all ADR reports) containing at least two suspected or concomitant drugs were analyzed. We identified 1,208 ADR reports with at least one potential DDI (55.0% of 2,195) and 381 reports (17.4% of 2,195 reports) with an occurring ADR associated with a DDI. The median age of patients and the number of contraindicated or major DDIs were significantly higher in reports with an occurring DDI. Warfarin was the most frequently reported interacting drug and the most common ADRs were gastrointestinal or cerebral hemorrhagic events. The proton pump inhibitors/warfarin, followed by platelet aggregation inhibitors/warfarin were the drug-drug combinations most frequently involved in ADRs caused by DDIs. The highest proportion of fatal reports was observed with platelet aggregation inhibitors/warfarin and antidepressants/warfarin.

Conclusion: Our findings showed that about one-third of patients exposed to a potential DDI actually experienced a serious ADR. Furthermore, our study confirms that a spontaneous reporting database could be a valuable resource for identifying and characterizing ADRs caused by DDIs and the drugs leading to serious ADRs and deaths.

The role of the clinical pharmacist in the prevention of potential drug interactions in geriatric heart failure patients

Background The treatment of heart failure patients is very complex and includes lifestyle modification as well as different pharmacological therapies. Polypharmacy is very common in such patients and they are at increased risk of potential drug-drug interactions and associated effects such as poor adherence, compliance and adverse events. Objective The aim of the present study is to investigate retrospectively the prescribed pharmacotherapy of the hospital discharged heart failure patients for possible drug interactions. Settings Clinic for Cardiology of the "Saint Marina" University Hospital in Varna, Bulgaria. Method Lexicomp^® Drug interaction software was used for screening potential drug-drug interactions. Logistic regression was applied to determine the odds ratio for the association between the age and number of drugs taken and the number of potential drug-drug interactions. Main outcome measure Incidence and type of pDDIs in geriatric heart failure patients. Results A retrospective study was conducted by reviewing the medical records of 248 selected heart failure patients for the prescribed medicines for a 1-year period (January 2015-December 2015). The total number of potential drug-drug interactions was 1532, or approximately 6.28 (± 4.72 SD) per one person. The range of prescribed drugs was between three and fourteen, 92% of them have been taking more than five medicines, an average of 7.12 (± 2.07 SD) per patient. The average age was 72.35 (± 10.16 SD). The results have shown stronger association between the number of drugs taken (more than 7) and the occurrence of potential drug-drug interactions (more than 10)-37.84 (95% CI 9.012-158.896, P ≤ 0.001). No statistically significant differences were found between age and occurrence of potential drug-drug interactions (more than 10)-1.008 (95% CI 0.441-2.308, P = 0.848). Conclusion The incidence of drug-drug interactions in heart failure patients is high. The clinical pharmacist, as a part of the multidisciplinary team, could reduce medication-related problems, such as drug interactions, and to optimize drug therapy by checking the treatment prescribed at the discharge of these patients.

Potential Drug-Drug Interactions in Patients With Urinary Tract Infections: A Contributing Factor in Patient and Medication Safety

Introduction: Hospitalized patients with urinary tract infections (UTIs) often present with comorbid illnesses and are subsequently prescribed multiple medications, which increases the likelihood of drug-drug interactions. Therefore, this study aimed to explore the prevalence, levels, risk factors, and clinical relevance of potential drug-drug interactions (pDDIs) in hospitalized patients with UTIs. Secondly, we aimed to develop management guidelines and identify monitoring parameters for the most frequent interactions.

Methods: A retrospective cross-sectional study was conducted in internal medicine wards of two tertiary care hospitals in Peshawar, Khyber Pakhtunkhwa, Pakistan. The clinical profiles of 422 patients with UTIs were reviewed for pDDIs using the Micromedex Drug-Reax^®. Logistic regression was applied to assess the association of pDDIs with various risk factors. The clinical relevance of frequent pDDIs was identified by assessing the potential adverse outcomes of pDDIs including patients’ signs, symptoms, and abnormal laboratory findings.

Results: Of 422 patients, at least one pDDI was identified in 62.3% patients, while 40% patients had at least one major pDDI. A total of 1,086 pDDIs were identified, of which 53.4% and 39.3% were of moderate and major severity, respectively. Patients with most frequent pDDIs were presented with hypoglycemia, hepatotoxicity, nephrotoxicity, hypertension, and decreased therapeutic response. These adverse events were more prevalent in patients taking higher doses of interacting drugs. Multivariate regression analysis revealed significant association of pDDIs with six or more medicines (p < 0.001), diabetes mellitus (p < 0.001), ischemic heart disease (p = 0.02), and congestive cardiac failure (p = 0.04).

Conclusions: Patients with UTIs present with a considerable number of clinically important pDDIs. Polypharmacy, diabetes mellitus, ischemic heart disease, and congestive cardiac failure increase the risk of pDDIs. Knowledge about the most frequent pDDIs will enable healthcare professionals to implement optimized monitoring and management strategies regarding associated adverse consequences in order to ensure patient safety. Most of the interactions can be managed by considering alternative therapy and dose reduction.

Are patients with a nasally placed feeding tube at risk of potential drug-drug interactions? A multicentre cross-sectional study

Aims

The primary aims were to determine the rate of potential drug-drug interactions (pDDIs) in patients with nasally placed feeding tubes (NPFT) and the factors significantly associated with pDDIs. The secondary aim was to assess the change in pDDIs for patients between admission and discharge.

Material and methods

This multicentre study applied a cross-sectional design and was conducted in six Brazilian hospitals, from October 2016 to July 2018. Data from patients with NPFT were collected through electronic forms. All regular medications prescribed were recorded. Medications were classified according to the World Health Organization (WHO) Anatomical Therapeutic Chemical code. Drug-drug interaction screening software was used to screen patients’ medications for pDDIs. Negative binomial regression was used to account for the over dispersed nature of the pDDI count. Since the number of pDDIs was closely related to the number of prescribed medications, we modelled the rate of pDDIs with the count of pDDIs as the numerator and the number of prescribed medications as the denominator; six variables were considered for inclusion: time (admission or discharge), patient age, patient gender, age-adjusted Charlson Comorbidity Index (CCI) score, type of prescription (electronic or handwritten) and patient care complexity. To account for correlation within the two time points (admission and discharge) for each patient a generalised estimating equations approach was used to adjust the standard error estimates. To test the change in pDDI rate between admission and discharge a full model of six variables was fitted to generate an adjusted estimate.

Results

In this study, 327 patients were included. At least one pDDI was found in more than 91% of patients on admission and discharge and most of these pDDIs were classified as major severity. Three factors were significantly associated with the rate of pDDIs per medication: patient age, patient care complexity and prescription type (handwritten vs electronic). There was no evidence of a difference in pDDI rate between admission and discharge.

Conclusion

Patients with a NPFT are at high risk of pDDIs. Drug interaction screening tools and computerized clinical decision support systems could be effective risk mitigation strategies for this patient group.

Potential drug-drug interactions in outpatient department of a tertiary care hospital in Pakistan: a cross-sectional study

BACKGROUND

Potential drug-drug interactions (pDDIs) are one of the preventable drug related problems having the risk of serious adverse events or therapeutic failure. In developing countries like Pakistan, this issue remains poorly addressed. The objective of this study was to explore prevalence of pDDIs in the Outpatient Department (OPD) of a tertiary care hospital in Pakistan. The secondary aim was to describe the levels of reported pDDIs and develop a list of widespread clinically relevant interactions.

METHODS

Prescriptions of 2400 OPD patients were analyzed for pDDIs through Micromedex Drug-Reax®. Prevalence, severity- and documentation-levels and widespread clinically relevant interactions were reported.

RESULTS

Of total 2400 prescriptions, pDDIs were present in 22.3%. Whereas, moderate- and major-pDDIs were found in 377 (15.7%) and 225 (9.4%), respectively. PDDIs were more prevalent in Medicine (9.2%) and Cardiology (2.6%) as compared with other OPD specialties. Total 942 pDDIs were identified, of which, the majority were either moderate- (61.9%) or major-pDDIs (32.1%). Some of the most common interactions were ibuprofen + levofloxacin (n = 50), ciprofloxacin + diclofenac (32), aspirin + atenolol (24), and diclofenac + levofloxacin (19). The potential adverse outcomes of widespread interactions were seizures, bleeding, QT-interval prolongation, arrhythmias, tendon rupture, hypoglycemia/hyperglycemia, serotonin syndrome, drug toxicity, and decreased therapeutic response.

CONCLUSIONS

OPD patients were at risk to pDDIs, particularly to major- and moderate-pDDIs. Screening of prescriptions for pDDIs and monitoring of pharmacotherapy in terms of response and associated adverse drug events will contribute to patient safety.

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.

Assessment of Drug-Drug Interaction in Ayder Comprehensive Specialized Hospital, Mekelle, Northern Ethiopia: A Retrospective Study

Introduction

Adverse drug interaction is a major cause of morbidity and mortality. Its occurrence is influenced by a multitude of factors. The influences of drug-drug interactions (DDIs) can be minimized through creation of awareness to health care professionals.

Objective

The objective of this study was to assess DDIs in Ayder Comprehensive Specialized Hospital (ACSH).

Methodology

A retrospective study design was employed on patient prescriptions available in the outpatient department of pharmacy and filled from September 2016 to February 2017 in ACSH.

Result

From the 600 prescription records assessed, the average number of drugs on single prescription was 2.73. Regarding the interaction observed 34 (9.63%) prescriptions with major drug-drug interaction, 210 (59.5%) moderate, 87 (24.65%) minor, and 22 (6.22%) unknown were identified. Age category showed significant association to affect the occurrence of DDIs and polypharmacy had statistically significant association with DDIs in bivariate analysis which was lost in adjusted OR.

Conclusion

From the current study it can be concluded that nearly half of the prescription ordered in ACSH contained DDIs and from the prescription with interacting medications majority of them had moderate DDIs.

A Prospective Analysis of Drug Interactions in Patients of Intensive Cardiac Care Unit

INTRODUCTION

Drug-Drug Interaction (DDI) is a serious concern in cardiac patients due to polypharmacy.

AIM

The present study was aimed to identify the potential DDI among hospitalized cardiac patients and evaluate the mechanism and severity of such interactions.

MATERIALS AND METHODS

A prospective observational study was conducted in intensive cardiac care unit of a tertiary care hospital for six months. Patients aged 18 years and above and taking two or more drugs were included in the study. Medscape drug interaction checker was used to identify and analyze the pattern of potential DDI.

RESULTS

Out of 500 patients, most of the patients were male (78.4%) in the age group of 50-60 years (31%). The most common diagnosis was acute coronary syndrome (57.2%). Out of total 2849 DDI, 2194 (77.01%) were pharmacodynamic, 586 (20.57%) were pharmacokinetic in nature while 69 (2.42%) drug pairs interacted by unknown mechanism. Majority of drug interactions were significant {2031 (71.29%)} in nature followed by minor {725(25.45%)} while serious drug interactions were observed in only 93 (3.26%) drug pairs. A positive correlation was observed between patient's age and number of drugs prescribed (r=0.178, p<0.001), number of drugs prescribed and potential Drug-Drug Interaction (pDDI) (r= 0.788, p<0.001) and between patient's age and pDDI (r=0.338, p<0.001).

CONCLUSION

The risk of pDDI was more commonly observed in elderly male patients particularly with antiplatelet drugs like low dose aspirin and clopidogrel.

Psychocardiology in the elderly

The population is rapidly aging worldwide and the burden of chronic disease follows along. Frequently, diseases go hand in hand and cardiovascular disease and mental health problems are no exception. Symptoms of depression in the elderly are often overlooked and untreated because they coincide with other problems encountered by the elderly. Older adults with depressive symptoms have poorer functioning compared to those with chronic medical conditions. The burden of cardiovascular disease also remains a leading cause of morbidity and mortality. Bidirectional associations between depression and cardiovascular diseases are described with a focus on psychosocial factors affecting cardiac functioning and disease outcome.

Identification of Drug-Drug Interactions In Vitro: A Case Study Evaluating the Effects of Sofosbuvir and Amiodarone on hiPSC-Derived Cardiomyocytes

Drug-drug interactions pose a difficult drug safety problem, given the increasing number of individuals taking multiple medications and the relative complexity of assessing the potential for interactions. For example, sofosbuvir-based drug treatments have significantly advanced care for hepatitis C virus-infected patients, yet recent reports suggest interactions with amiodarone may cause severe symptomatic bradycardia and thus limit an otherwise extremely effective treatment. Here, we evaluated the ability of human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) to recapitulate the interaction between sofosbuvir and amiodarone in vitro, and more generally assessed the feasibility of hiPSC-CMs as a model system for drug-drug interactions. Sofosbuvir alone had negligible effects on cardiomyocyte electrophysiology, whereas the sofosbuvir-amiodarone combination produced dose-dependent effects beyond that of amiodarone alone. By comparison, GS-331007, the primary circulating metabolite of sofosbuvir, had no effect alone or in combination with amiodarone. Further mechanistic studies revealed that the sofosbuvir-amiodarone combination disrupted intracellular calcium (Ca²⁺) handling and cellular electrophysiology at pharmacologically relevant concentrations, and mechanical activity at supra-pharmacological (30x C_max) concentrations. These effects were independent of the common mechanisms of direct ion channel block and P-glycoprotein activity. These results support hiPSC-CMs as a comprehensive, yet scalable model system for the identification and evaluation of cardioactive pharmacodynamic drug-drug interactions.

Assessment of potential drug-drug interactions and its associated factors in the hospitalized cardiac patients

Drug-drug interactions (DDIs) may result in the alteration of therapeutic response. Sometimes they may increase the untoward effects of many drugs. Hospitalized cardiac patients need more attention regarding drug-drug interactions due to complexity of their disease and therapeutic regimen. This research was performed to find out types, prevalence and association between various predictors of potential drug-drug interactions (pDDIs) in the Department of Cardiology and to report common interactions. This study was performed in the hospitalized cardiac patients at Ayub Teaching Hospital, Abbottabad, Pakistan. Patient charts of 2342 patients were assessed for pDDIs using Micromedex® Drug Information. Logistic regression was applied to find predictors of pDDIs. The main outcome measure in the study was the association of the potential drug-drug interactions with various factors such as age, gender, polypharmacy, and hospital stay of the patients. We identified 53 interacting-combinations that were present in total 5109 pDDIs with median number of 02 pDDIs per patient. Overall, 91.6% patients had at least one pDDI; 86.3% were having at least one major pDDI, and 84.5% patients had at least one moderate pDDI. Among 5109 identified pDDIs, most were of moderate (55%) or major severity (45%); established (24.2%), theoretical (18.8%) or probable (57%) type of scientific evidence. Top 10 common pDDIs included 3 major and 7 moderate interactions. Results obtained by multivariate logistic regression revealed a significant association of the occurrence of pDDIs in patient with age of 60 years or more (p < 0.001), hospital stay of 7 days or longer (p < 0.001) and taking 7 or more drugs (p < 0.001). We found a high prevalence for pDDIs in the Department of Cardiology, most of which were of moderate severity. Older patients, patients with longer hospital stay and with elevated number of prescribed drugs were at higher risk of pDDIs.

Clinical-pharmacist intervention reduces clinically relevant drug-drug interactions in patients with heart failure: A randomized, double-blind, controlled trial

BACKGROUND

Incidence of drug-drug interactions (DDIs) increases with complexity of treatment and comorbidities, as in heart failure (HF). This randomized, double-blind study evaluated the intervention of the pharmacist on prevalence of clinically relevant DDIs (NCT01855165).

METHODS

Patients admitted with HF were screened for clinically relevant DDIs, and randomized to control or intervention. All attending physicians received standard advice about pharmacological therapy; those in the intervention group also received alerts about clinically relevant DDIs. Primary endpoint was DDI at discharge and secondary were re-hospitalization or death during follow-up.

RESULTS

Of 213 patients, 51 (mean age, 79 ± 6 years; male, 47%) showed 66 clinically relevant DDIs and were randomized. For intervention (n=26) versus control (n=25), the number of patients with and the number of DDIs were significantly lower at discharge: 8 vs. 18 and 10 vs. 31; p=0.003 and 0.0049, respectively. Over a 6 month follow-up period, 11 control and 9 intervention patients were re-hospitalized or died (p>0.2 for all). No significant differences were seen between control and intervention for patients with eGFR <60 mL/min/1.73 m(2) (78%) for re-hospitalization or death (10 vs. 7; p=0.74).

CONCLUSIONS

Pharmacist intervention significantly reduces the number of patients with clinically relevant DDIs, but not clinical endpoints 6 months from discharge.

Drug-drug interaction software in clinical practice: a systematic review

PURPOSE

Several electronic databases which report the prevalence of drug-drug interactions (DDIs) are used as a tool for evaluation of potentially harmful DDIs. The aim of our review was to evaluate the usability and appropriateness of commercially available electronic databases which assess the prevalence of potential DDIs.

METHODS

The systematic electronic literature search was conducted with the following search terms: "database" AND "software," and "drug-drug interactions" AND "database," and the inclusion and exclusion criteria were applied in order to identify the publications of interest.

RESULTS

A total of 3766 papers were identified by systematic search. After applying inclusion and exclusion criteria, 38 publications were included in the analysis. The most commonly used software in the included studies was Micromedex® Drug-Reax, for which some authors argue to be the most reliable due to highest sensitivity. It gives information about clinical consequences of DDIs, classifies underlying mechanism and onset of the adverse outcome (either rapid, or delayed) as well as severity (such as minor, moderate, or major), and provides the level of evidence which supports this information. This data is also provided by Drug Interaction Facts®, Lexi-Interact®, and Pharmavista®. A small number of studies which compared assessment of DDIs with electronic database and the clinician's assessment showed large discrepancy in number and relevance of detected DDIs. The overlap was in some cases as low as 11 %.

CONCLUSION

The deficiency of clinical relevance of detected DDIs should be addressed in the upcoming research as it would provide more relevant information to the prescribers' in clinical practice.

Potential drug-drug interactions in hospitalized patients with chronic heart failure and chronic obstructive pulmonary disease

INTRODUCTION

Polypharmacy is common in patients with chronic heart failure (HF) and/or chronic obstructive pulmonary disease (COPD), but little is known about the prevalence and significance of drug-drug interactions (DDIs). This study evaluates DDIs in hospitalized patients.

MATERIAL AND METHODS

We retrospectively screened medical charts over a 6-month period for diagnosis of chronic HF and/or COPD. Potential DDIs were evaluated using Lexi-Interact software.

RESULTS

Seven hundred and seventy-eight patients were included in the study (median age 75 years, 61% men). The median number of drugs on admission and discharge was 6 (interquartile range (IQR) 4-9) and 7 (IQR 5-), respectively (p = 0.10). We recorded 6.5 ±5.7 potential DDIs per patient on admission and 7.2 ±5.6 on discharge (p = 0.2). From admission to discharge, type-C and type-X potential DDIs increased (p < 0.05 for both). Type X interactions were rare (< 1%), with the combination of a β-blocker and a β2 agonist being the most common (64%). There were significantly more type-C and type-D potential DDIs in patients with chronic HF as compared to patients with COPD (p < 0.001). Patients with concomitant chronic HF and COPD had more type-C and type-X potential DDIs when compared to those with individual disease (p < 0.005). An aldosterone antagonist and ACE inhibitor/ARB were prescribed to 3% of chronic HF patients with estimated glomerular filtration rate < 30 ml/(min × 1.73 m(2)).

CONCLUSIONS

The DDIs are common in patients with chronic HF and/or COPD, but only a few appear to be of clinical significance. The increase in potential DDIs from admission to discharge may reflect better guideline implementation rather than poor clinical practice.

Drug-drug interactions in inpatient and outpatient settings in Iran: a systematic review of the literature

Drug-drug interactions (DDIs) are an important type of adverse drug events. Yet overall incidence and pattern of DDIs in Iran has not been well documented and little information is available about the strategies that have been used for their prevention. The purpose of this study was to systematically review the literature on the incidence and pattern of DDIs in Iran as well as the used strategies for their prevention. PubMed, Scopus, electronic Persian databases, and Google Scholar were searched to identify published studies on DDIs in Iran. Additionally, the reference lists of all retrieved articles were reviewed to identify additional relevant articles. Eligible studies were those that analyzed original data on the incidence of DDIs in inpatient or outpatient settings in Iran. Articles about one specific DDI and drug interactions with herbs, diseases, and nutrients were excluded. The quality of included studies was assessed using quality assessment criteria. Database searches yielded 1053 potentially eligible citations. After removing duplicates, screening titles and abstracts, and reading full texts, 34 articles were found to be relevant. The quality assessment of the included studies showed a relatively poor quality. In terms of study setting, 18 and 16 studies have been conducted in inpatient and outpatient settings, respectively. All studies focused on potential DDIs while no study assessed actual DDIs. The median incidence of potential DDIs in outpatient settings was 8.5% per prescription while it was 19.2% in inpatient settings. The most indicated factor influencing DDIs incidence was patient age. The most involved drug classes in DDIs were beta blockers, angiotensin-converting-enzyme inhibitors (ACEIs), diuretic agents, and non-steroidal anti-inflammatory drugs (NSAIDs). Thirty-one studies were observational and three were experimental in which the strategies to reduce DDIs were applied. Although almost all studies concluded that the incidence of potential DDIs in Iran in both inpatient and outpatient settings was relatively high, there is still no evidence of the incidence of actual DDIs. More extensive research is needed to identify and minimize factors associated with incidence of DDIs, and to evaluate the effects of preventive interventions especially those that utilize information technology.

Can medications be safely withdrawn in patients with stable chronic heart failure? systematic review and meta-analysis

BACKGROUND

Heart failure (HF) therapy involves use of multiple medications. There is little guidance on the safety and impact on clinical outcomes of stopping HF medications.

METHODS AND RESULTS

A comprehensive systematic search for studies of drug therapy withdrawal in HF was performed. Meta-analysis of the risk ratio (RR) was performed with the use of the Mantel-Haenszel random effects model for all-cause mortality and cardiovascular outcomes. Twenty-six studies met the inclusion criteria. Studies on withdrawal of renin-angiotensin-aldosterone system (RAAS) inhibitors and beta-blockers in HF are scarce and small, yet show relatively convincingly that such withdrawals have untoward effects on cardiac structure, symptoms, and major outcomes. Meta-analysis of 7 studies of digoxin withdrawal (2,987 participants) without background beta-blocker showed increased HF hospitalizations (RR 1.30, 95% confidence interval [CI] 1.16-1.46; P < .0001), but no impact on all-cause mortality (RR 1.00, 95% CI 0.90-1.12; P = .06) nor reduction in all-cause hospitalization (RR 1.03, 95% CI 0.98-1.09; P = .27). Diuretic withdrawal trials demonstrated an ongoing need for these agents in chronic HF. Studies in peripartum cardiomyopathy showed that medications could be successfully withdrawn after recovery.

CONCLUSION

Current evidence discourages any attempt to discontinue RAAS inhibitors or beta-blockers in patients with stable HF, regardless of clinical and/or echocardiographic status. Formal withdrawal trials of other classes are needed.

Older people's experiences of medicine changes on leaving hospital

BACKGROUND

Few qualitative studies have explored older patients' perspectives on medicine changes that resulted from a stay in hospital.

OBJECTIVE

To explore how older people aged ≥75 years, who had recently been discharged from hospital to their own home, understood and managed any changes to their medicines.

METHODS

Forty people aged ≥75 years were recruited from two internal medicine wards. Participants were included if they took four or more prescription medicines at admission, experienced a medicine change and were discharged to their own home. Participants were interviewed in person at home. Interviews were semi-structured and were recorded, transcribed verbatim, coded using NVivo, and analyzed thematically.

RESULTS

Participants experienced a median of four medicine changes per person and sixteen participants were unaware of the exact changes and the reasons for them. Some participants had concerns about their medicine changes. Twenty-nine participants could not recall anyone talking about their medicine changes just prior to them being discharged. The majority of participants trusted the decisions the hospital doctors made regarding their medicines and many participants spoke as if it was not their place to question doctors about their medicines.

CONCLUSION

Clear and understandable explanations of medicine changes are needed for older people on discharge from hospital. Health professionals should also be aware that older patients might not think it is acceptable for them to ask direct questions of staff members.

Prevalence of drug interactions in hospital healthcare

AIM OF THE REVIEW

To study the prevalence of drug interactions in hospital healthcare by reviewing literature.

METHOD

A review was carried out of studies written in Spanish and English on the prevalence of drug interactions in hospital care published in Pubmed between January 1990 and September 2008. The search strategy combined free text and MeSH terms, using the following keywords: "Drug interaction", "prevalence" and "hospital". For each article, we classified independent variables (pathology, age of population, whether patients were hospitalized or not, geographical location, etc.) and dependent variables (number of interactions per 100 patients studied, prevalence of patients with interactions, most common drug interactions, and others).

RESULTS

The search generated 436 articles. Finally, 47 articles were selected for the study, 3 provided results about drug interactions with real clinical consequences, 42 about potential interactions, and 2 described both. The prevalence of patients with interactions was between 15 and 45 % and the number of interactions per 100 patients was between 37 and 106, depending on the group of studies analyzed. There was a considerable increase in these rates in patients with heart diseases and elderly persons.

CONCLUSION

There is a large number of studies on the prevalence of drug interactions in hospitals but they report widely varying results. The prevalence is higher in patients with heart diseases and elderly people.

[Influence of hospitalisation on drug prescription in arterial hypertension and chronic conditions]

OBJECTIVES

To evaluate the influence of hospitalization on drug prescription in chronic conditions.

METHODS

Admission and discharge prescriptions from 92 patients consecutively admitted in a specialized department of the Assistance Publique-Hôpitaux de Paris hospital were recorded in a prospective two-month study. A Qualitative Therapeutical Score (QTS) was calculated as an estimation of qualitative modifications in the prescription.

RESULTS

Patients admitted for an hospital stay of over 24h have more lines of prescription than patients admitted for an hospitalization shorter than 24h (5.7±4.2/d vs 2.9±2.5/d, P<0.01). For all the patients enrolled, the hospital stay is not associated with any change in the global number of treatments. However, in patients treated with antihyperstensive drug, the number of drug intakes decreases (2.6±1.5/d vs 1.9±1.4/d, P<0.05) as a consequence of an increase in the prescription of fixed-dose combinations. In patients with cardiovascular diseases, the QTS is higher and qualitative modifications are more often found in patients admitted for an hospital stay of over 24h than for those admitted for a an hospitalization shorter than 24h (0.57 vs 0.11; P<0.01 and 31% vs 11%; P<0.05 respectively). Antihypertensive drugs are the most represented drugs within these qualitative modifications.

CONCLUSION

In patients with drug treatments for arterial hypertension or chronic conditions, hospitalization is not associated with quantitative but with qualitative modifications, especially for an over 24h hospital stay.

Adverse drug reactions caused by drug-drug interactions reported to Croatian Agency for Medicinal Products and Medical Devices: a retrospective observational study

Aim

To analyze potential and actual drug-drug interactions reported to the Spontaneous Reporting Database of the Croatian Agency for Medicinal Products and Medical Devices (HALMED) and determine their incidence.

Methods

In this retrospective observational study performed from March 2005 to December 2008, we detected potential and actual drug-drug interactions using interaction programs and analyzed them.

Results

HALMED received 1209 reports involving at least two drugs. There were 468 (38.7%) reports on potential drug-drug interactions, 94 of which (7.8% of total reports) were actual drug-drug interactions. Among actual drug-drug interaction reports, the proportion of serious adverse drug reactions (53 out of 94) and the number of drugs (n = 4) was significantly higher (P < 0.001) than among the remaining reports (580 out of 1982; n = 2, respectively). Actual drug-drug interactions most frequently involved nervous system agents (34.0%), and interactions caused by antiplatelet, anticoagulant, and non-steroidal anti-inflammatory drugs were in most cases serious. In only 12 out of 94 reports, actual drug-drug interactions were recognized by the reporter.

Conclusion

The study confirmed that the Spontaneous Reporting Database was a valuable resource for detecting actual drug-drug interactions. Also, it identified drugs leading to serious adverse drug reactions and deaths, thus indicating the areas which should be in the focus of health care education.

Polypharmacy and food-drug interactions among older persons: a review

Polypharmacy is generally defined as the use of 5 or more prescription medications on a regular basis. The average number of prescribed and over-the-counter medications used by community-dwelling older adults per day in the United States is 6 medications, and the number used by institutionalized older persons is 9 medications. Almost all medications affect nutriture, either directly or indirectly, and nutriture affects drug disposition and effect. This review will highlight the issues surrounding polypharmacy, food-drug interactions, and the consequences of these interactions for the older adult.

Epidemiology and characteristics of adverse drug reactions caused by drug-drug interactions

INTRODUCTION

Drug-drug interactions (DDIs) arise in numerous different ways, involving pharmacokinetic or pharmacodynamic mechanisms. Adverse drug reactions are a possible consequence of DDIs and health operators are often unaware of the clinical risks of certain drug combinations. Many papers on drug interactions have been published in recent years, but most of them focused on potential DDIs while few studies have been conducted on actual interactions.

AREAS COVERED

This paper reviews the epidemiology of actual DDIs in outpatients as well as in hospital settings and in spontaneous reporting databases. The incidence of actual DDIs is consistently lower than that of potential DDIs. However, the absolute number of patients involved is high, representing a significant proportion of adverse drug reactions. The importance of risk factors such as age, polypharmacy and genetic polymorphisms is also evaluated. The relevance and efficacy of tools for recognizing and preventing DDIs are discussed.

EXPERT OPINION

Potential DDIs far outnumber actual drug interactions. The potential for an adverse interaction to occur is often theoretical, and clinically important adverse effects occur only in the presence of specific risk factors. Several studies have shown the efficacy of computers in early detection of DDIs. However, a correct risk-benefit evaluation by the prescribing physician, together with a careful clinical, physiological and biochemical monitoring of patients, is essential. Future directions of drug interaction research include the increasing importance of pharmacogenetics in preventing DDIs and the evaluation of interactions with biological drugs.

Polypharmacy, aging and potential drug-drug interactions in outpatients in Taiwan: a retrospective computerized screening study

BACKGROUND

Polypharmacy is common in outpatients and has been identified as a major risk factor for drug-drug interactions (DDIs), which are an important cause of adverse drug reactions. There has been a rapid increase in the number of elderly patients worldwide. However, there have been few studies quantifying the impact of both patient age and the number of concomitant drugs prescribed on the probability of potential DDIs per person in general outpatients.

OBJECTIVE

To assess the extent to which polypharmacy and aging are associated with potential DDIs in outpatients at a medical centre in Taiwan.

METHODS

The medications of 81,650 outpatients who visited a medical centre in Taiwan between January 2004 and March 2004 were retrospectively screened for potential DDIs using a computerized drug-interaction program. The main inclusion criteria were a minimum of two drug prescriptions and duration of use of 14 or more days. We also analysed the DDI pattern, which included severity, level of documentation and onset of potential DDIs, and assessed the impact of the number of drugs prescribed and of aging on the prevalence of potential DDIs per person.

RESULTS

The prevalence of potential DDIs was 25.6% (20,902 of 81,650). The mean ± SD age of the 20,902 patients with potential DDIs was 57.5 ± 16.5 years, and 47.6% of these patients were male. The mean ± SD number of prescribed drugs in patients with potential DDIs was 5.8 ± 2.4, and 67.7% of these patients were prescribed more than four drugs. The majority (55.7%) of DDIs were of the C2 pattern (severity: moderate; documentation: probable). The prevalence of potential DDIs increased in a linear mode with increasing age (p < 0.001) and with the number of drugs prescribed (p < 0.001); furthermore, in addition to being independently associated with potential DDIs, these two factors interacted to increase the risk further.

CONCLUSIONS

This study showed that approximately one-quarter of 81,650 outpatients who visited a medical centre in Taiwan over a period of 3 months in 2004 had potential DDIs. We observed independent increases in potential DDIs per person in association with aging and increasing number of prescribed drugs. Furthermore, a significant interaction between these two factors was observed: the effect of aging on the prevalence of potential DDIs increased as the number of prescribed drugs increased. Potential DDIs in outpatients can be reduced by minimizing the number of drugs prescribed following careful consideration of both their benefits and risks, particularly in the aging population.

Potential drug interactions in patients admitted to cardiology wards of a south Indian teaching hospital

BACKGROUND

The potential drug-drug interaction (pDDI) increases as the number of concomitant medications increases. Patients with cardiovascular disorders are at higher risk for drug- drug interactions because of the types and number of drugs they receive. While drug interactions are reported to be common, there is no published report of the prevalence of such interactions among Indian cardiac patients. The aim of the present study was to identify the pattern of pDDI and document any observed interaction. It was also planned to evaluate the demography of patients and correlate it with the drug-drug interactions.

METHOD

A prospective observational study from Oct 2007 to Apr 2008 was carried out in 'cardiology department' of a hospital in South India. Those patients who were taking at least two drugs and had a hospital stay of at least 48 hours were included in the study. The medications of the patients were analyzed for possible interactions. Factors associated with pDDI were studied. The actual interactions that were observed during the hospital stay in the study subjects were documented.

RESULTS

A total of 812 patients were included in the study. 388 pDDIs were identified among 249 patients. The incidence of pDDI was 30.67%. The most common potential interactions were between aspirin & heparin (29.38%), and clopidogrel & heparin (7.21%). Drug classes most commonly involved were antiplatelets, anticoagulants and diuretics. Majority of interactions were of moderate severity, delayed onset, and pharmacodynamic in nature. Total 68 actual interactions were observed in the observed cases.

CONCLUSION

The present study identified pDDIs and also documented interactions in cardiovascular patients. Factors which had correlation with adverse drug interactions were identified. This study highlights the need for screening prescriptions of cardiovascular patients for pDDIs and proactive monitoring of patients who have identified risk factors; this helps in detection and prevention of possible adverse drug interactions.

Prevalence of potentially hazardous drug interactions amongst Australian veterans

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT * Up to 21% of adverse drug event related hospital admissions are due to drug interactions. Clinical significance of drug interactions varies. * Studies which only identified drug interactions of potentially major clinical significance found lower prevalence, of between 2 and 16%. * Prevalence of drug interactions defined 'potentially hazardous' has had limited study, with no publications identified for the Australian population. WHAT THIS STUDY ADDS * In the study population of 287 074, 1.5% of subjects were dispensed potentially hazardous interacting drug pairs. * However, limited to populations on specific medicines, it was found that for patients dispensed verapamil, methotrexate, amiodarone, lithium, warfarin, cyclosporin and itraconazole, potentially hazardous interactions occurred at a rate greater than 5%. * These patients should be the focus of medication review programmes to avoid potentially serious adverse drug events. BACKGROUND Up to 21% of adverse drug event-related hospital admissions are due to drug interactions. Clinical significance of drug interactions varies, and drug interactions defined 'potentially hazardous' are more likely to contribute to morbidity and mortality. AIM The aim of this study was to assess the prevalence of potentially hazardous drug interactions in an elderly Australian veteran population. METHODS This study assessed the prevalence of potentially hazardous drug interactions, where hazardous was defined in three or more international drug interaction references, using Repatriation Pharmaceutical Benefits Scheme pharmacy claims data. Analysis was limited to patients who received regular concurrent dispensings of potentially hazardous interacting medicines. RESULTS Of the 287 074 subjects included in the study, 1.5% were dispensed potentially hazardous interacting drug pairs. For patients dispensed cyclosporin, concomitant use of a statin was common (47%); as was statin use with those dispensed itraconazole (31%). Of those dispensed methotrexate, 24% also received a non-steroidal anti-inflammatory drug; of those on lithium, 18% also received an ACE inhibitor or angiotensin 2 receptor blocker; of those on warfarin, 7.2% and 5.9% were co-dispensed an non-steroidal anti-inflammatory drugs or antiplatelets respectively; for those on verapamil, 5.3% were co-dispensed a beta-blocker, while for those on amiodarone 6.2% were co-dispensed digoxin. CONCLUSIONS Overall prevalence of potentially serious drug interactions appears to be low in the Australian veteran population. However, patients taking cyclosporine, itraconazole, methotrexate, lithium, warfarin, verapamil and amiodarone appear to be most at risk and their medicine use should be regularly reviewed to prevent potentially hazardous drug interactions.

Prevalence of potential drug interactions in patients in an intensive care unit of a university hospital in Brazil

OBJECTIVES

To investigate the prevalence of potential drug interactions at the intensive care unit of a university hospital in Brazil and to analyze their clinical significance.

METHODS

This cross-sectional retrospective study included 299 patients who had been hospitalized in the intensive care unit of the hospital. The drugs administered during the first 24 hours of hospitalization, in the 50th length-ofstay percentile and at the time of discharge were analyzed to identify potential drug-drug and drug-enteral nutrition interactions using DRUG-REAXH software. The drugs were classified according to the anatomical therapeutic chemical classification.

RESULTS

The median number of medications per patient was smaller at the time of discharge than in the 50th length-of-stay percentile and in the first 24 hours of hospitalization. There was a 70% prevalence of potential drug interactions at the intensive care unit at the studied time points of hospitalization. Most of the drug interactions were either severe or moderate, and the scientific evidence for the interactions was, in general, either good or excellent. Pharmacodynamic interactions presented a subtle predominance in relation to pharmacokinetic interactions. The occurrence of potential drug interactions was associated with the number of medications administered and the length of stay. Medications that induced cytochrome P450, drugs that prolong the QT interval and cardiovascular drugs were pharmacotherapy factors associated with potential drug interactions.

CONCLUSION

The study showed that potential drug interactions were prevalent in the intensive care unit due to the complexity of the pharmacotherapies administered. The interactions were associated with the number of drugs, the length of stay and the characteristics of the administered medications.

The incidence of potential drug-drug interactions in elderly patients with arterial hypertension

OBJECTIVE

To assess the incidence and type of potential, clinically significant drug-drug interactions in elderly outpatients with arterial hypertension.

SETTING

Three community pharmacies in Croatia.

METHOD

Eligible patients were aged 65 or older, treated for arterial hypertension and received 2 or more drugs. Potential interactions were identified by Lexi-Interact software. The software categorized each potential interaction according to clinical significance in five groups: (A) No known interaction; (B) Specified agents may interact, but there is little to no evidence of clinical concern; (C) Specified agents may interact in a clinically significant manner. Monitoring therapy is suggested; (D) The two medications may interact in a clinically significant manner. Modification of therapy is suggested; (X) Contraindicated combination. Interactions of level C, D and X were considered clinically significant.

MAIN OUTCOME MEASURE

The incidence and type of potential drug-drug interactions.

RESULTS

There were 265 patients included in the study. Potential, clinically significant drug interactions were identified in 240 (90.6%) patients, out of which 97.9% had interactions with clinical significance C, 20.4% D, and 0.8% X. The median number of drug interactions per patient was 4. We identified 215 drug combinations with the potential to cause clinically significant interaction, out of which 83.3% had clinical significance C, 16.3% clinical significance D, and 0.4% clinical significance X.

CONCLUSION

Drug-drug interactions are common in elderly hypertensive patients. Computer-based screening could help pharmacists and physicians to recognize potential, clinically significant interactions.

[Drug-drug interactions in multicentre polypathological polymedicated patients]

OBJECTIVE

To determine the prevalence of relevant drug-drug interactions (DDIs) and associated predictor factors in a sample of patients with multiple complex chronic diseases (polypathological patients) receiving multiple drug therapy. Our secondary objective was to determine the acceptance of a drug interaction reporting program with recommendations addressed to the prescribing physicians.

SUBJECTS AND METHODS

A cross-sectional study performed in three primary care centres assigned to a teaching hospital. All patients with 2 or more chronic diseases and treated simultaneously with 5 or more drugs were recruited in the study. DDIs were detected by using Drug-Reax System((R)) (Micromedex) program, the Drug Data Base (Bot) Spanish General Council of Official Colleges of Pharmacists or literature search when needed. Those DDIs which, according to the opinion of the pharmacist investigators, required any intervention were considered relevant. Acceptance of the reported DDI recommendations was evaluated by means of a survey addressed by primary care physicians ("acceptable," pertinent recommendation to modify treatment).

RESULTS

A total of 283 polypathological polymedicated patients were included. Mean age was 74.5 years (range 43-100 years). Mean number of diseases per patient was 2.5 and prescriptions 9.7). Out of a total of 2748 drug prescriptions, 1053 DDIs in 250 patients (96.5%) were identified. Of these, 45% were filtered as relevant DDIs. The presence of ischemic heart disease, two or more hospital admissions and having received 7 or more prescriptions were associated with the presence of DDIs. 177 informs containing 473 recommendations about DDIs were sent to primary care physicians from our Pharmacy Department. 339 recommendations were answered by primary care physicians, and 84% were favourably accepted.

CONCLUSIONS

Almost every polypathological polymedicated patient is exposed to at least one DDI and about a 60% would require any intervention. Appropriate filtering and personalising recommendations in a collaborative way may represent an adequate manner to improve the risk-benefit ratio of the drug prescriptions.

Drug interactions and adverse events associated with antimycotic drugs used for invasive aspergillosis in hematopoietic SCT

The aim of this study was to assess the frequency of potential drug-drug interactions (pDDIs) and adverse drug events (ADEs) associated with antimycotics in hospitalized patients with hematopoietic SCT (HSCT). Of the 120 HSCT recipients evaluated, 36 received antimycotics. A total of 124 ADEs were recorded in 32 of the 36 patients treated, with 54 ADEs being possibly and 9 probably related to antimycotics. Of the treatments with amphotericin B, 93% were associated with one or more possible and 36% with probable ADEs. The corresponding figures for lipid-based amphotericin B were 100% and 7%, for voriconazole 68% and 11% and for caspofungin 70% and 0%. A total of 57 potentially severe DDIs associated with antimycotics were detected in 31 of the 36 patients. Of these, 14 DDIs were a possible cause of an ADE and 5 (4 times a combination of voriconazole with CYA and once a combination of CYA with conventional amphotericin B) were probably related. Although the prevalence of pDDIs and ADEs is high in HSCT patients, ADEs related with a high probability to treatment with antimycotics are rare. Regarding the high prevalence of pDDIs, our findings underscore the importance of close monitoring of laboratory and clinical parameters, as well as dose adjustment for critical drugs, in patients with HSCT.

Heart failure and adverse drug reactions among hospitalized older adults

The aim of this study was to assess whether heart failure (HF) could be a risk factor for adverse drug reactions (ADRs) among hospitalized older adults. This study included 19,496 patients admitted to community- and university-based hospitals in Italy (mean age 70 +/- 14 years; 49.7% female). ADRs were identified in 207 of the 2,413 (8.6%) patients with HF and in 855 (5.0%) of the 17,083 patients without HF (P < 0.001). After adjusting for potential confounders, HF was shown to be associated with an increased likelihood of experiencing an ADR (odds ratio (OR) 1.29; 95% confidence interval (CI) 1.06-1.56). After stratifying the sample by gender, the association continued to be seen in the women (OR 1.58; 95% CI 1.22-2.05) but not in the men (OR 0.99; 95% CI 0.74-1.34). In conclusion, HF appears to be associated with a higher rate of ADRs among hospitalized patients. Gender may influence the effect of HF on the risk of ADRs.

Prevalence of drug-drug interactions at hospital entry and during hospital stay of patients in internal medicine

OBJECTIVE

The aim of this study was to assess potential drug-drug interactions (pDDIs) at hospital admission, during hospitalization and at discharge and to evaluate the number of pDDIs created during hospitalization.

METHODS

The medication of 851 patients was screened for pDDIs (major and moderate severity) using the screening program Pharmavista. The frequency of pDDIs per patient, per number of drugs and drug pairs was estimated.

RESULTS

During hospitalization, the frequency of major and moderate pDDIs per patient was 1.11, which was higher compared to hospital admission (0.59) or to hospital discharge (0.60). The frequency of major and moderate pDDIs per drug prescribed (13.7% vs. 9.1%) or per drug pairs analyzed (4.5% vs. 2.3%) was higher at hospital admission compared to hospital discharge. 47% of all major and moderate pDDIs at discharge were due to a medication change during hospitalization.

CONCLUSIONS

Although the number of major and moderate pDDIs per patient did not increase from hospital admission to discharge, it is important to realize that 47% of all major and moderate DDIs at hospital discharge were created during hospitalization. Prescribing drugs with a low risk for pDDIs as well as careful monitoring for adverse drug reactions are important measures to minimize harm associated with DDIs.

Drug-drug interactions in a geriatric outpatient cohort: prevalence and relevance

BACKGROUND

The prevalence of drug-drug interactions (DDIs) in a geriatric population may be high because of polypharmacy. However, wide variance in the clinical relevance of these interactions has been shown.

OBJECTIVES

To explore whether adverse drug reactions (ADRs) as a result of DDIs can be identified by clinical evaluation, to describe the prevalence of ADRs and diminished drug effectiveness as a result of DDIs and to verify whether the top ten most frequent potential DDIs known to public pharmacies are of primary importance in geriatric outpatients in the Netherlands.

METHOD

All adverse events classified by the Naranjo algorithm as being a possible ADR and drug combinations resulting in diminished drug effectiveness were identified prospectively in 807 geriatric outpatients (mean age 81 years) at their first visit. The setting was a diagnostic day clinic. The Medication Appropriateness Index (MAI) and Beers criteria were used to evaluate drug use and identify possible DDIs. The ten most frequent potential interactions, according to a 1997 national database of public pharmacies ('Top Ten') in the Netherlands, and possible adverse events as a result of other interactions, were described. The effects of changes in medication regimen were recorded by checking the medical records.

RESULTS

In 300 patients (44.5% of the 674 patients taking more than one drug), 398 potential DDIs were identified. In 172 (25.5%) of patients taking more than one drug, drug combinations were identified that were responsible for at least one ADR or which possibly resulted in reduced effectiveness of therapy. Eighty-four of the 158 possible ADRs resulting from enhanced action of drugs forming combinations listed in the 'Top Ten' were seen in 73 patients. Only four DDIs resulting in less effective therapy that involved drug combinations in the 'Top Ten' were identified. Changes in drug regimens pertaining to possible interactions were proposed or put into effect in 111 of the 172 (65%) patients with possible DDIs. Sixty-one (55%) of these patients returned for follow-up. Of these, 49 (80%) were shown to have improved after changes were made to their medication regimen.

CONCLUSION

In this study, nearly half of the geriatric outpatients attending a diagnostic day clinic who were taking more than one drug were candidates for DDIs. One-quarter of these patients were found to have possible adverse events or diminished treatment effectiveness that may have been at least partly caused by these DDIs. These potential interactions can be identified through clinical evaluation. In the majority of patients (99 of 172) the potential interactions resulting in possible ADRs or diminished effectiveness were not present in the 'Top Ten' interactions described by a national database of public pharmacies, a finding that emphasizes that the particular characteristics of geriatric patients (e.g. frequent psychiatric co-morbidities) need to be considered when evaluating their drug use. At least 7% of all patients taking more than one drug, and 80% of those with possible drug interactions whose drug regimen was adjusted, benefited from changes made to their drug regimens.