Prevalence Of Potential Drug Interactions Research Articles

The Prevalence of Drug-Drug Interactions and Reported Therapy Related Side Effects in Oncology Out-Patients

Objective: The use of multiple medications in cancer patients is unavoidable; thus, adverse drug-drug interactions are frequent. This study aims to assess the prevalence of potential drug interactions in oncology patients visiting the outpatient chemotherapy unit.
 Method: Demographic and health-related information of patients visiting an outpatient chemotherapy unit was recorded using a pre-prepared form. A comprehensive list of all concurrently used medications was compiled and checked for interactions with the Micromedex online drug interaction tool.
 Results: A total of 179 adult patients were included. We recorded an average of 9.3 drugs per patient with 79 patients using more than 10 drugs. A total of 1671 drugs including 303 chemotherapeutic agents were assessed for drug-drug interactions. A total of 374 interactions, of which 203 were significant, were recorded in 118 (65.9%) patients with an average of 3.2 interactions per patient. Only 46 major interactions were recorded for anticancer agents. Cyclophosphamide (n=13) and cisplatin (n=12) were involved in most interactions. The number of interactions correlated with the number of drugs used (p=.001) and the presence of comorbidities (p=.002). The presence of comorbidities increased the risk of interaction by 1.21 (p=.04). Recorded side effects were not correlated to drug interactions.
 Conclusion: Medication review in cancer patients is essential in establishing all medications used by patients. Routine assessment in terms of potential drug interactions and evaluation of these interactions by a qualified pharmacist may help in optimizing patient outcomes.

Prevalence of Potential Drug-Drug Interactions Among Hypertensive Pregnant Women Admitted to a Tertiary Care Hospital.

The aim is to determine the frequency of potential drug-drug interactions (pDDIs) and to analyze the clinically relevant drug interactions among hypertensive pregnant women. This was an observational, cross-sectional study conducted at a tertiary care hospital. The prescriptions of the hypertensive pregnant women admitted to the hospital from June 2021 to December 2021 were analyzed for potential drug-drug interactions using the database from Lexicomp ® Solutions android mobile application version 7.5.4(Wolters Kluwer, The Netherlands). A total of 127 patients were evaluated during the study period of 6 months, of which 70 (55.12%) had pDDIs. The total number of pDDIs was 85, of which 70 (82.35 %) were clinically relevant interactions with the majority of them having moderate severity (81.17%) followed by minor severity (17.65%) and major severity (1.18%). The most frequently interacting pDDIs were between Labetalol and Lornoxicam (42.35%), followed by Labetalol and Diclofenac (22.35%). This study highlights the high prevalence of potential drug interactions among hypertensive pregnant women and the need for rational drug use and strict vigilance in their monitoring.

Prevalence of potential drug interactions among outpatients’ prescriptions of community pharmacies in Nineveh Governorate, Iraq

Context: Management of chronic diseases requires the use of various drugs and dietary supplements. Their use is a potential source of drug interactions that interfere with therapeutic responses. Aims: To determine the prevalence of potential drug interactions, severity levels, and related risk factors in outpatient prescriptions submitted to community pharmacies. Methods: A cross-sectional study was conducted using convenience sampling. From August to December 2021, outpatient prescription data were collected from 16 community pharmacies within the Nineveh Governorate-Iraq. Recorded data included age (≥18 years), gender, and prescribed drugs and/or dietary supplements. Two online software programs were used for assessing drug interactions: Medscape.com and Drugs.com. Potential drug interactions were classified as minor, moderate/significant, or major/serious. Results: Among the 1000 prescriptions, the total interactions were 1373. More than half of the prescriptions (57.6%, 576/1000) had potential drug interactions. These interactions were mainly observed among the drugs (89.9%, 518/576). The severity of the interactions was mostly (50%) moderate/significant. A significant association (p0.001) was reported for numerous prescribed items with the occurrence of potential interactions. Nonsteroidal anti-inflammatory drugs/aspirin (44%), and calcium/magnesium-containing products (approximately 20%) contributed to the most frequent potential drug interactions. Conclusions: A high prevalence of potential drug interactions, mostly of moderate severity, was reported among outpatient prescriptions. These interactions are significantly associated with the number of prescribed items. The vital role of pharmacists in adopting strategies for monitoring potential drug interactions is essential for ensuring safe therapeutic regimens for patients.

Potential Drug Interactions in Adults Living in Manaus: A Real-World Comparison of Two Databases, 2019.

Drug information systems are commonly used by professionals to assist in the identification of drug interactions and to ensure the safe use of medications. Real-world evidence about the comparison of different drug interaction sources is scarce. We aimed to compare two drug interaction databases to identify interactions in a population-based survey. This is a cross-sectional study based on a previous survey performed in the city of Manaus, Brazil, in 2019. We included adults aged 18 years and over, who used two or more medicines 15 days before the interview. To assess potential drug interactions, we searched Micromedex and UpToDate databases. The primary outcome was the prevalence of potential drug interactions in each database. Weighted Kappa statistics were calculated to assess agreement on the presence of drug interaction, documentation and severity. A total of 752 participants were included in the study. The prevalence of drug interactions was 43.8% [95% confidence interval (CI): 40.2, 47.3%] in UpToDate and 30.2% (95% CI: 26.9, 33.5%), in Micromedex. The agreement related to drug interactions between the two databases was fair (Kappa: 0.631). For severity (Kappa: 0.398) and documentation (Kappa: 0.311), the agreement was poor. Agreement among compared databases was sub-optimal. Better quality and transparency of evidence available in drug interaction sources are needed to support informed healthcare professionals' decision.

Potential drug interactions in adults living in the Brazilian Amazon: A population-based case-control study, 2019

BackgroundDrug interactions are important causes of adverse events. Assessments of pharmacological interactions outside healthcare services settings are scarce. ObjectiveTo assess the frequency and factors associated with these potential interactions in adults living in Manaus, Amazonas, Brazil. MethodsWe conducted a case-control study in 2019 with residents who had taken two or more medicines two weeks before the interview. The cases involved people with potential drug interaction, according to Micromedex™, and adults without drug interactions formed the control group. The factors associated with interaction were identified by multivariate logistic regression. Results752 adults out of 2321 interviewed were using two or more medicines and were included. The prevalence of potential drug interactions was 30.2% (95% CI: 26.9; 33.5%). We identified 457 drug interactions, more frequently one interaction per person (49.7%), of major severity (61.9%), and with fair documentation (61.7%); three individuals were using contraindicated associations. Individuals aged 45–59 years (OR 1.88, 95% CI 1.03–3.42), using 3 or more drugs simultaneously (p-value<0.001), had higher chance of drug interactions. ConclusionDrug interaction was common in among adults living in Manaus, mostly of major severity. The odds of interaction increased with age and number of concomitantly medicines.

THE PREDICTORS OF POTENTIAL DRUG-DRUG INTERACTIONS AMONG DIABETIC HYPERTENSIVE ADULT OUTPATIENTS IN A KENYAN REFERRAL HOSPITAL

Objective: To characterize the predictors of potential drug-drug interactions among adult diabetic hypertensive outpatients at Kenyatta National Hospital.&#x0D; Methods: This cross-sectional study collected and analyzed data on potential drug interactions from 104 diabetic hypertensive outpatients (aged ≥18 y) at the Department of Endocrinology Outpatient Clinic of Kenyatta National Hospital from 1st May 2019 to 31st August 2019. The main outcome measure was the prevalence of potential drug-drug interactions and their predictors among the study population.&#x0D; Results: There was a female preponderance (70.2%). The mean age of the study participants was 61.6 y (SD±10.8). The prevalence of potential drug interactions was high at 57.7%. The average number of drug interactions was one interacting pair per patient, with a majority of the prescriptions (81.0%) having moderate drug-drug interactions. Patients receiving&gt;2 drugs were almost three times more likely to have drug-drug interaction compared to those prescribed ≤ 2 drugs (AOR=2.79; 95% CI: 1.11-7.28); p=0.029). Participants who were at stage 4 of hypertension were 2.5 times more likely to have a drug-drug interaction compared to the other stages of hypertension (AOR=2.52; 95% CI 1.31-4.89; p=0.007).&#x0D; Conclusion: Polypharmacy and stage 4 hypertension are independently associated with drug-drug interactions among patients with both diabetes and hypertension. Future studies should characterize the specific type of drug interactions and possible targets of minimization of drug-drug interactions.

Prevalence of Drug Interaction in Severely Obese Individuals and Associated Factors: Baseline Results from a Clinical Trial

The prevalence of obesity is increasing worldwide and is commonly associated with comorbidities. The use of several drugs is often necessary, which leads to Potential Drug Interactions (PDI) that may increase the morbidity and mortality. This study aimed to analyze the prevalence of drug interaction and its association with socio-demographics, health status, and drug use in severely obese individuals. Baseline data from a randomized clinical trial registered at Clinicaltrial.gov (NCT02463435) were used. A total of 150 individuals aged 18–65 years with a body mass index of 35 kg/m2 were included. The outcome variable was the presence of PDI, and the explanatory variables were divided into the following four levels: socio-demographic, lifestyle, health, and medication use. The prevalence of PDI was 50% (n = 75) (95% CI 41–58). The variables associated with drug–drug interactions in the multiple analyses were arterial hypertension (PR 1.83, 95%, CI 1.10–3.04), polypharmacy (PR 3.12, 95%, CI 2.17–4.50), and diabetes mellitus (PR 0.60, 95%, CI 0.45–0.81). The risk factors for the occurrence of drug interaction were the presence of diabetes mellitus, hypertension, and polypharmacy.

Evolution of Drug Interactions With Antiretroviral Medication in People With HIV.

BackgroundPolypharmacy and drug interactions are important issues for HIV-infected individuals. The number and nature of those interactions are continuously evolving with the use of new antiretroviral drugs and the aging of HIV-infected individuals. We aimed to analyze this evolution over time. MethodsThis retrospective cohort study was conducted in the University Hospital of Liège (Belgium). Treatments of HIV-infected outpatients attending Liège University Hospital were collected and analyzed in 2012 and 2016. The University of Liverpool HIV drug interactions database was used to determine drug interactions. ResultsWe included 1038 patients in 2016, of whom 78% had 1 comedication. Polypharmacy was seen in 20% of the cohort. Four percent of the patients presented red flag interactions, and 38% had orange flag interactions. Nonantiretroviral (non-ARV) therapeutic classes involved in drug interactions were mostly cardiovascular and central nervous system drugs. They were followed by hormone drugs and dietary supplements for orange flag interactions. Two factors significantly contributed to both red and orange flag interactions: the number of non-ARV comedications and protease inhibitor–based ARV regimens. The proportion of patients with red or orange flag interactions remained stable from 2012 to 2016. ConclusionsThis study highlights the persistence of an alarming number of contraindicated drug interactions and a high prevalence of potential drug interactions over time. Identification, prevention, and management of drug interactions remain a key priority in HIV care.

Prevalence of potential drug interactions in Thai patients receiving simvastatin: The causality assessment of musculoskeletal adverse events induced by statin interaction

Drug-drug interactions are one of the major risk factors associated with statin-induced myopathy. Although simvastatin is widely used in Thailand, studies investigating the prevalence of potential simvastatin-drug interactions (SDIs) and its clinical relevance in Thai population are still limited. We aimed to investigate the prevalence of potential SDIs (phase 1 study) and musculoskeletal adverse effects (AEs) associated with those interactions (phase 2 study). A phase 1 study was retrospectively conducted with outpatients at a 60-bed hospital who received simvastatin between July 1, 2012 and June 30, 2013. In phase 2, study was cross-sectionally conducted in outpatients whose prescriptions contain potential SDIs. Musculoskeletal AEs were evaluated by using symptom checklist questionnaires and measuring plasma creatinine kinase (CK). The causal relationship between the AEs and the potential SDIs was assessed using a Drug Interaction Probability Scale.Out of 3447 simvastatin users, potential SDIs were found in 314 patients (9.1%). The prevalence of prescriptions containing potential SDIs was in the range of 4.7–6.0%. Two-thirds of the potential SDIs were rated to be highly significant while more than 70% were in contraindication list. The most common precipitant drugs were gemfibrozil (382 prescriptions), colchicine (171 prescriptions) and amlodipine (152 prescriptions). Of 49 patients recruited into phase 2 study, we found that 31 patients (63.3%) had myopathy. Myalgia was the most frequently identified AEs (n=18, 58.1%), followed by asymptomatic rising CK (n=8, 25.8%), and myositis (n=5, 16.1%). Musculoskeletal AEs associated with SDIs were found in 16 patients (51.6%). Of these, we found 50.0%, 31.3% and 18.8% had asymptomatic rising CK, myalgia, and myositis, respectively. Precipitant drugs associated with myopathy were amlodipine (2 possible cases), colchicine (3 possible cases), gemfibrozil (8 possible and 1 probable cases), nevirapine (1 possible case), and nicotinic acid (1 possible case).Potential SDIs have been found in the Thai population with a prevalence that is consistent with previous reports. Half of the musculoskeletal AEs identified were associated with SDIs. Systematic screening and management with interdisciplinary co-operation are needed to increase awareness of potential SDIs.

Prevalence of potential drug interactions with azithromycin in Colombia, 2012-2013

Objective To determine the prevalence of potential drug interactions between azithromycin and different IA and III antiarrhythmic groups in a national database of drug prescriptions in 2012-2013. Methods Retrospective study based on a population database of medicine dispensation. Data from patients who received azithromycin between January 1, 2012 and June 30, 2013 were extracted along with data from patients who received azithromycin in combination with other medications shown to cause heart arrhythmias when used concomitantly. Frequencies and proportions were established. Results 13 859 patients receiving azithromycin alone or in combination with other drugs were identified. The average time of use was 4.5 ± 0.9 days. A total of 702 patients (5.1 %) received azithromycin plus 19 other potentially risky drugs. The most frequently associated were loratadine (77.1 %), diphenhydramine (16.5 %) and amitriptyline (8.1 %). Combinations with a single drug were the most frequent (n=533, 75.9 %), predominantly azithromycin+loratadine. The maximum number of combined drugs was six (n=2, 0.3 %). Conclusions Identification of drug prescriptions through population databases is an effective way to find potential drug interactions. The frequency of potential interactions between azithromycin and other drugs is common in Colombian patients. Future research should assess the risk of occurrence of adverse cardiac events.

Prevalência e fatores associados a potenciais interações medicamentosas entre idosos em um estudo de base populacional

Objetivo: Determinar a prevalência de potenciais interações medicamentosas e os fatores a elas associados entre idosos cadastrados nas equipes da Estratégia Saúde da Família (ESF) do município de Timóteo, MG. Métodos: Estudo transversal, utilizando amostragem aleatória estratificada. Foram realizadas 273 entrevistas domiciliares, com indivíduos de 60 anos ou mais de idade, por meio de formulário que continha perguntas de identificação, sociodemográficas e questões relacionadas às condições de saúde do idoso e ao consumo de medicamentos. As interações medicamentosas foram identificadas e classificadas de acordo com o software Micromedex®. Resultados: A prevalência de potenciais interações medicamentosas foi de 55,6%, perfazendo um total de 466 ocorrências, das quais 5,6% eram leves, 81,6% eram moderadas e 12,8% eram de maior gravidade. As classes terapêuticas mais frequentemente envolvidas foram anti-inflamatórios e, principalmente, fármacos utilizados em doenças cardiovasculares. A ausência de internação hospitalar nos últimos 4 meses associou-se significativamente a uma menor chance de interações graves, e a maior parte dos pacientes que não tiveram nenhum tipo de interação moderada utilizava apenas medicamentos prescritos por médicos. Conclusões: A prevalência de interações medicamentosas encontrada foi semelhante à descrita na literatura, demonstrando alta frequência entre idosos. A ausência de internação hospitalar prévia e a prescrição de medicamentos por profissionais médicos associaram-se a uma menor frequência desse fenômeno. A prescrição de múltiplos medicamentos simultaneamente aos idosos pode comprometer a segurança e a saúde dessa população, requerendo, por parte dos cuidadores, observação atenta quanto à ocorrência de interações medicamentosas.

Potential drug interactions in patients with a history of cancer.

Cancer survivors (css) are frequently exposed to polypharmacy, which might increase their risk of drug interactions. Our study aimed to determine the relative prevalence of potential drug interactions (pdis) among css compared with non-cancer respondents (ncrs). Self-reported prescription data from 4975 patients were extracted from the U.S. National Health and Nutrition Examination Survey and screened for pdis using iFacts: Drug Interaction Facts (Facts and Comparisons, St. Louis, MO, U.S.A.). The clinical significance of each pdi was graded on a 5-point scale based on the severity of the interaction and the level of evidence documenting the interaction. Summary statistics and logistic regression models were used to assess the impact of cancer history on the risk of pdis. Of patients eligible for the analyses, the css (n = 302) indicated using 4.4 ± 0.22 prescriptions on average, and the ncrs (n = 908), 3.8 ± 0.09. Nearly half of both cohorts (40% of css, 43% of ncrs) had at least 1 pdi. In both cohorts, 12% were at risk for fatal or permanently debilitating effects. In multivariate analyses, css were significantly less likely than ncrs to be at risk for any pdis (odds ratio: 0.65; 95% confidence interval: 0.46 to 0.92; p = 0.02). Advanced age and low household income were associated with pdis among css. Medications most commonly prescribed to css with a pdi included metoprolol (15.6%), levothyroxine (13.6%), and furosemide (11.9%). Although css appear to be less susceptible than ncrs to pdis, the prevalence of pdis among css remains suboptimal. Specific subgroups of css may be particularly prone to pdis, underscoring the importance of increased vigilance.

High prevalence of potential drug interactions affecting mycophenolic acid pharmacokinetics in nonmyeloablative hematopoietic stem cell transplant recipients

Objective: Mycophenolic acid (MPA) exposure is associated with clinical outcomes in hematopoietic cell transplant (HCT) recipients. Various drug interaction studies, predominantly in healthy volunteers or solid organ transplant recipients, have identified medications which impact MPA pharmacokinetics. Recipients of nonmyeloablative HCT, however, have an increased burden of comorbidities, potentially increasing the number of concomitant medications and potential drug interactions (PDI) affecting MPA exposure. Thus, we sought to be the first to characterize these PDI in nonmyeloablative HCT recipients. Materials and methods: We compiled PDI affecting MPA pharmacokinetics and characterized the prevalence of PDI in nonmyeloablative HCT recipients. A comprehensive literature evaluation of four databases and PubMed was conducted to identify medications with PDI affecting MPA pharmacokinetics. Subsequently, a retrospective medication review was conducted to characterize the cumulative PDI burden, defined as the number of PDI for an individual patient over the first 21 days after allogeneic graft infusion, in 84 nonmyeloablative HCT recipients. Results: Of the 187 concomitant medications, 11 (5.9%) had a PDI affecting MPA pharmacokinetics. 87% of 84 patients had one PDI, with a median cumulative PDI burden of 2 (range 0 – 4). The most common PDI, in descending order, were cyclosporine, omeprazole and pantoprazole. Conclusion: Only a minority of medications (5.9%) have a PDI affecting MPA pharmacokinetics. However, the majority of nonmyeloablative HCT recipients had a PDI, with cyclosporine and the proton pump inhibitors being the most common. A better understanding of PDI and their management should lead to safer medication regimens for nonmyeloablative HCT recipients.

P04.25. Complementary medicine use and potential adverse reactions amongst HIV-positive people

Purpose Relatively little is known about the patterns of complementary medicine (CM) use by HIV-positive people in the last decade, since the introduction of contemporary antiretroviral therapy (ART), or their information requirements. As ART use has evolved, CM use is likely to have also changed over time, however this has yet to be established. This is of relevance to health care providers, partly because of potential risks including drug interactions, but also to understand reasons for use and intended benefits, such as managing antiretroviral therapy (ART) side effects and/or addressing existing disease symptoms. The primary aim of this study is to establish the current patterns of use of CMs by HIV-positive people in Australia. Secondary aims are to identify their main information sources and the prevalence of potential drug interactions and suspected adverse reactions to CMs.

Prevalence of potential drug interactions in an Iranian general hospital

The hazards of prescribing many drugs, including side-effects, drug-drug interactions and difficulties of compliance have long been recognized as particular problems when prescribing. This study estimates the rate and factors associated with potential drug-drug interactions in prescriptions from wards of An Iranian General Hospital. Data were retrieved from the pharmacy of a general hospital (200 beds) during one year period 2010. Potential drug-drug interaction were identified using a computerized drug-drug interaction database system (Prescription Analyzer 2000, Sara Rayane Co., Iran). Patients of both genders and 15 years-old or more were included in this study. Prescriptions with two or more drugs prescribed were selected during one year period 2010. Gender number of drugs and therapeutic drug classes on prescriptions were explored as associated factors to drug-drug interaction. The overall prevalence of potential drug-drug interaction was 20.3%. The risks of severe potential drug interactions were relatively high and the rate of potential drug-drug interaction was significantly higher in women (60.6%) and the patients aged over 60 years old (57.1%). The frequency of the potentially severe drug-drug interaction was 10.8% with digoxin-furosemide as the most common interacting pair (5.91%). A positive correlation was found between drug-drug interaction, patient's age, number of drugs and drugs acting on cardiovascular system. So cardiology women inpatients, age more then 60 years old, and patients prescribed digoxin and angiotensin-converting enzyme inhibitors should be closely monitored for adverse outcomes from drug-drug interaction.

Potential drug interactions in cancer therapy: a prevalence study using an advanced screening method

BackgroundIn cancer patients, drug interactions may intensify adverse events or reduce antitumour effects. We assessed the prevalence of potential drug interactions (PDIs) among ambulatory cancer patients on i.v. treatment using an advanced screening method. Patients and methodsData on drugs used for comorbidities, anticancer agents, over-the-counter (OTC) drugs, and comorbidities were collected by means of a structured interview among the patients and review of medical charts. PDIs were identified using electronic (Drug Interaction Facts software, version 4.0) and manual screening methods (peer-reviewed reports). ResultsIn this study, 278 patients were enrolled. We identified 348 PDIs. Of all patients, 161 (58%) had at least one PDI. Of all PDIs, 34% was classified as major and 60% as moderate. Coumarins, quinolones, antiepileptics, and hydrochlorothiazide were frequently part of a PDI. Interactions that potentially cause QT interval prolongation, gastrointestinal toxicity, and central nervous system depression were also common. In multivariate analysis, an increasing number of drugs [odds ratio (OR) = 1.4, confidence interval (CI) 1.23–1.52; P < 0.001] and the use of an OTC drug (OR = 0.56, CI 0.32–0.97; P = 0.045) were risk factors. ConclusionsPDIs are common in patients treated for an (haemato-) oncological disease. Screening for potential interactions should take place routinely before administering chemotherapy.

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‐of‐stay percentile and at the time of discharge were analyzed to identify potential drug‐drug and drug‐enteral nutrition interactions using DRUG‐REAX® 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.

Potential drug interactions and duplicate prescriptions among ambulatory cancer patients: a prevalence study using an advanced screening method

BackgroundThe pharmacotherapeutic treatment of patients with cancer is generally associated with multiple side-effects. Drug interactions and duplicate prescriptions between anti-cancer drugs or interactions with medication to treat comorbidity can reinforce or intensify side-effects.The aim of the present study is to gain more insight into the prevalence of drug interactions and duplicate prescriptions among patients being treated in the outpatient day care departments for oncology and hematological illnesses. For the first time the prevalence of drug interactions with OTC-drugs in cancer patients will be studied. Possible risk factors for the occurrence of these drug-related problems will also be studied.Methods/DesignA multicenter cross-sectional observational study of the epidemiology of drug interactions and duplicate prescriptions is performed among all oncology and hemato-oncology patients treated with systemic anti-cancer drugs at the oncology and hematology outpatient day care department of the VU University medical center and the Zaans Medical Center.DiscussionIn this article the prevalence of potential drug interactions in outpatient day-care patients treated with anti-cancer agents is studied using a novel more extensive screening method. If this study shows a high prevalence of drug interactions clinical pharmacists and oncologists must collaborate to develop a pharmaceutical screening programme, including an automated electronic warning system, to support drug prescribing for ambulatory cancer patient. This programme could minimize the occurrence of drug related problems such as drug interactions and duplicate prescriptions, thereby increasing quality of life.Trial registrationThis study is registered, number NTR2238.

Prevalence and patient awareness of selected potential drug interactions with self-medication

In community pharmacies potential drug interactions between prescription only medicines (POM) and over-the-counter (OTC) drugs purchased for self-medication arise mainly in two situations: (i) if an OTC drug is purchased by a passer-by customer whose prescribed drug therapy is not known; or (ii) if a POM or an OTC drug is requested by a regular customer whose prescribed drug therapy is usually recorded. With this study we aimed to assess the prevalence of potential drug interactions with selected POM and OTC drugs in passer-by and regular customers as well as their awareness of these potential drug interactions. Data were collected in 14 community pharmacies in the region of Basel, Switzerland by observation of customer contacts and interviews with passer-by customers purchasing selected OTC drugs, and telephone-interviews with regular customers treated with selected POMs identified in community pharmacies' databases. The selected POMs and OTC drugs are drugs which could lead to clinically relevant drug interactions of varying severity but manageable through different interventions such as adjustment of dose and its timing and/or monitoring of the therapy, and avoidance of the combination by choosing an alternative treatment. Of 1183 passer-by customers observed, 164 (14 x 4%) purchased at least one of the selected OTC drugs. One hundred and two (62 x 2%) of those subjects were interviewed. Forty-three (42 x 2%) mentioned taking prescribed drugs, and three of them were exposed to potential drug interactions of moderate severity. Out of 592 regular customers selected from the community pharmacy database, 434 (73 x 3%) could be interviewed. Sixty-nine (15 x 9%) of them were exposed to a potential drug interaction between purchased OTC drug for self-medication and their POM. Furthermore, 116 (26 x 7%) regular customers were exposed to potential drug interactions within their prescribed drugs and in 28 (6 x 5%) multiple (>or=2) potential drug interactions were found. Two hundred and three (46 x 8%) regular customers were aware of potential drug interactions between their POM and OTC drugs. Ninety-six (47 x 3%) of them were informed by their prescribing physician and 52 (25 x 6%) by their community pharmacist. Awareness of potential drug interaction was higher in younger customers [odds ratio (OR) 0 x 95; 95% confidence intervals (CI) 0 x 93, 0 x 97, P<0 x 0001] and higher for drug interactions classified as 'severe' [OR 1 x 79; 95% CI 1 x 16, 2 x 77, P=0 x 009]. Efforts to increase awareness of potential drug interactions is needed. Although community pharmacies are adequately equipped with computerized drug interaction surveillance systems this is often not applied to self-medication. Vigilance for potential interactions of all drugs, including those sold over the counter, should be increased.

A longitudinal analysis of antihypertensive drug interactions in a Medicaid population

Background Drug interactions are a frequent cause of adverse drug events. We evaluated whether the frequency of previously reported antihypertensive drug–drug interactions could be reduced by pharmaceutical case management. Methods Patients >30 years of age with hypertension who were enrolled in the Iowa Pharmaceutical Case Management (PCM) program were evaluated. All prescription claims for patients were obtained on their date of eligibility and again 9 months later. A drug interaction database was developed to examine potential drug interactions in each patient's regimen. Results Antihypertensive drugs were taken by 1377 patients at baseline and at 9-month follow-up. Highly significant antihypertensive drug interactions were observed at baseline in 35% of patients (0.47 per patient), and interaction prevalence did not change over time. Decreases in the number of drug interactions tended to occur more commonly among patients of pharmacies that provided the highest intensity of service (11.5% in high-intensity pharmacies v 9% in low- or zero-intensity pharmacies, but this did not achieve statistical significance). Nearly 75% of patients had an interaction of any significance level, and the total number of interactions increased over time ( P = .0067). Conclusions This Medicaid population with hypertension had a very high prevalence of potential drug interactions. The prevalence of interactions did not change, but the mean number of all interactions actually increased over time. There was some suggestion that higher-intensity pharmacies might be more successful in minimizing the risk of clinically significant drug interactions when compared with lower-intensity pharmacies.