Concomitant coumarin-NSAID therapy and risk for bleeding

Shared Decision-Making for Drug-Drug Interactions: Formative Evaluation of an Anticoagulant Drug Interaction

Background

Warnings about drug-drug interactions (DDIs) between warfarin and nonsteroidal anti-inflammatory drugs (NSAIDs) within electronic health records indicate potential harm but fail to account for contextual factors and preferences. We developed a tool called DDInteract to enhance and support shared decision-making (SDM) between patients and physicians when both warfarin and NSAIDs are used concurrently. DDInteract was designed to be integrated into electronic health records using interoperability standards.

Objective

The purpose of this study was to conduct a formative evaluation of a DDInteract that incorporates patient and product contextual factors to estimate the risk of bleeding.

Methods

A randomized formative evaluation was conducted to compare DDInteract to usual care (UC) using physician-patient dyads. Using case vignettes, physicians and patients on warfarin participated in simulated virtual clinical encounters where they discussed the use of taking ibuprofen and warfarin concurrently and determined an appropriate therapeutic plan based on the patient’s individualized risk. Dyads were randomized to either DDInteract or UC. Participants completed a postsession interview and survey of the SDM process. This included the 9-item Shared Decision-Making Questionnaire (SDM-Q-9), tool usability and workload National Aeronautics and Space Administration (NASA) Task Load Index, Unified Theory of Acceptance and Use of Technology (UTAUT), Perceived Behavioral Control (PBC) scale, System Usability Scale (SUS), and Decision Conflict Scale (DCS). They also were interviewed after the session to obtain perceptions on DDInteract and UC resources for DDIs.

Results

Twelve dyad encounters were performed using virtual software. Most (n=11, 91.7%) patients were over 50 years of age, and 9 (75%) had been taking warfarin for more than 2 years (75%). Regarding scores on the SDM-Q-9, participants rated DDInteract higher than UC for questions pertaining to helping patients clarify the decision (P=.03), involving patients in the decision (P=.01), displaying treatment options (P<.001), identifying advantages and disadvantages (P=.01), and facilitating patient understanding (P=.01) and discussion of preferences (P=.01). Five of the 8 UTAUT constructs showed differences between the 2 groups, favoring DDInteract (P<.05). Usability ratings from the SUS were significantly higher (P<.05) for physicians using DDInteract compared to those in the UC group but showed no differences from the patient’s perspective. No differences in patient responses were observed between groups using the DCS. During the session debrief, physicians indicated little concern for the additional time or workload entailed by DDInteract use. Both clinicians and patients indicated that the tool was beneficial in simulated encounters to understand and mitigate the risk of harm from this DDI.

Conclusions

Overall, DDInteract may improve encounters where there is a risk of bleeding due to a potential drug-drug interaction involving anticoagulants. Participants rated DDInteract as logical and useful for enhancing SDM. They reported that they would be willing to use the tool for an interaction involving warfarin and NSAIDs.

Development and Challenges of Diclofenac-Based Novel Therapeutics: Targeting Cancer and Complex Diseases

Simple Summary

Diclofenac is a widely used drug for its anti-inflammatory and pain alleviating properties. This review summarizes the current understanding about the drug diclofenac. The potential applications of diclofenac beyond its well-known anti-inflammatory properties for other diseases such as cancer are discussed, along with existing limitations.

Abstract

Diclofenac is a highly prescribed non-steroidal anti-inflammatory drug (NSAID) that relieves inflammation, pain, fever, and aches, used at different doses depending on clinical conditions. This drug inhibits cyclooxygenase-1 and cyclooxygenase-2 enzymes, which are responsible for the generation of prostaglandin synthesis. To improve current diclofenac-based therapies, we require new molecular systematic therapeutic approaches to reduce complex multifactorial effects. However, the critical challenge that appears with diclofenac and other drugs of the same class is their side effects, such as signs of stomach injuries, kidney problems, cardiovascular issues, hepatic issues, and diarrhea. In this article, we discuss why defining diclofenac-based mechanisms, pharmacological features, and its medicinal properties are needed to direct future drug development against neurodegeneration and imperfect ageing and to improve cancer therapy. In addition, we describe various advance molecular mechanisms and fundamental aspects linked with diclofenac which can strengthen and enable the better designing of new derivatives of diclofenac to overcome critical challenges and improve their applications.

Management of patients receiving novel antithrombotic treatment in endodontic practice: Review and clinical recommendations

Cardiovascular diseases are a major component of non-communicable diseases and death, with thrombosis constituting the most common underlying pathosis of the three major cardiovascular disorders: ischaemic heart disease (acute coronary syndrome), stroke and venous thromboembolism (VTE). The introduction of direct oral anticoagulants (DOACs) in recent years has necessitated a more complex approach to periprocedural and perioperative anticoagulation management and the need for revised management strategies and protocols. Currently, patients taking classic oral anticoagulants are advised to stop taking the drugs and have their INR values checked 72 h prior to dental surgery (e.g., apical surgery, tooth extraction, and periodontal surgery) and checked again 24 h prior to the procedure to ensure it is within the therapeutic range. However, the current incorporation of these novel DOACs in routine medical practice requires changes in the way patients are managed preoperatively in dentistry, and specifically in endodontic surgery. The methodology applied in this review included searching for relevant articles in the PubMed database using keywords listed in the Entree Terms databases. Articles published on human blood clotting mechanism, antithrombotic drugs, as well as treatment guidelines and recommendations for dentistry were retrieved. In addition, textbooks and guidelines that may not have surfaced in the online search were searched manually. The aim of this paper was to review the mechanisms of action of classic and novel antithrombotic medications and their impact on endodontic treatment and the management of local haemostasis in endodontics.

Postoperative Bleeding and Acute Kidney Injury in Esophageal Cancer Patients Receiving Ketorolac

BACKGROUND

As strategies promoting enhanced recovery protocols and opioid minimization techniques are increasingly prioritized, use of nonsteroidal antiinflammatory drugs continues to rise. Whether this prevalent use poses increased risk for bleeding or renal dysfunction in surgical populations after extensive dissection and fluid shifts is unclear.

METHODS

We reviewed records of patients undergoing esophagectomy for a diagnosis of esophageal adenocarcinoma at a single institution from 2006 to 2018 for ketorolac administration during the postoperative hospital admission, as well as the occurrence of postoperative events, defined as the need for blood product transfusion and/or acute kidney injury.

RESULTS

We identified 1019 patients, 123 of whom experienced postoperative events (12%). Ketorolac was administered to 686 (67%). Furthermore, ketorolac use steadily increased over the study period; 36 of 72 patients received this medication in 2006 (49%), and 76 of 83 in 2018 (92%). Multivariable logistic regression failed to identify a relationship between ketorolac administration (assessed as a binary covariate) and postoperative events (P = .657). Additional examination for a dose-response relationship using the cumulative total dose from the time of surgery to discharge also did not demonstrate a relationship with postoperative events (P = .829). In an effort to evaluate a more homogeneous population, we performed a subgroup analysis using only patients treated with trimodality therapy, which showed similar findings.

CONCLUSIONS

Ketorolac has become a staple of multimodal postesophagectomy analgesic regimens. Importantly, this medication does not pose risk for acute kidney injury or bleeding after surgery.

Risk factors associated with nonsteroidal anti-inflammatory drugs (NSAIDs)-induced gastrointestinal bleeding resulting on people over 60 years old in Beijing

Gastrointestinal (GI) bleeding is an unwanted side effect common to all chemical types of nonsteroidal anti-inflammatory drugs (NSAIDs), particularly in elderly people. However, the risk factors of GI bleeding associated with NSAIDs for elderly people remain unknown. This study aims to evaluate the risks of GI bleeding associated with NSAIDs in 4728 elderly people over 60 years old based on database from a hospital in Beijing.This retrospective hospital-based study included 4728 patients over 60 years old prescribed with NSAIDs, of which 928 patients had GI bleeding and 3800 did not have. Odds ratios (OR) for the risk of GI bleeding associated with NSAIDs were determined by logistic regression analysis. Mean Decrease Gini (MDG) involved in random forest algorithm was used to rank the associated factors with GI bleeding.In multivariate analysis, family history of GI bleeding (OR, 3.348; P = .000), history of peptic ulcers (OR, 4.068; P = .000), history of cardiovascular and cerebrovascular disease (OR, 1.476; P = .001), diabetes mellitus (OR, 1.408; P = .000), antiplatelet drugs (OR, 3.106; P = .000), Helicobacter pylori infection (OR, 1.312; P = .001), cholesterol level (OR, 0.516; P = .000), upper abdominal discomfort (OR, 3.467; P = .000), anorexia (OR, 2.038; P = .000), and NSAIDs used for 0.5 to 3 months (OR, 0.780; P = .000) were associated with GI bleeding. After ranked the MDG of each factor, the top 5 ranked factors associated with GI bleeding were melena, hematemesis, antiplatelet drugs, cholesterol level, and upper abdominal discomfort.We found that family history of GI bleeding, history of peptic ulcers, history of cardiovascular and cerebrovascular disease, diabetes mellitus, antiplatelet drugs, Helicobacter pylori infection, hypocholesterolemia, and NSAIDs used for 0.5 to 3 months were independent risk factors for GI bleeding on people over 60 years old. Meanwhile, upper abdominal discomfort might be the predictor of GI bleeding associated with NSAIDs elderly users.

Should patients prescribed long-term low-dose aspirin receive proton pump inhibitors? A systematic review and meta-analysis

BACKGROUND

Several clinical guidelines recommend the use of proton pump inhibitors (PPIs) in patients taking low-dose aspirin but report no or limited supporting data. We conducted a systematic review and meta-analysis to examine the effects of co-administration of PPIs in patients taking low-dose aspirin on the risks of adverse gastrointestinal (GI) and cardiovascular (CV) events, and on patient adherence to aspirin.

METHODS

We searched PUBMED, EMBASE and Cochrane Central Register of Controlled Trials databases for relevant articles published through November 2013. We included randomised controlled trials (RCTs) and observational studies in patients taking low-dose aspirin with and without PPIs. Risk of bias was assessed using the Cochrane Collaboration's tool (for RCTs) and the Newcastle-Ottawa Scale (for observational studies). Pooled risk ratios (RRs) were computed using a random-effects model.

RESULTS

We included 13 studies, of which 12 (2 RCTs and 10 observational studies) reported on GI events, and one (cohort study) on both GI bleeding and CV events. No study reported on adherence to aspirin. Co-administration of PPIs in patients receiving low-dose aspirin was associated with risk reductions of 73% (RR 0.27, 95% CI 0.17-0.42) and 50% (RR 0.50, 95% CI 0.32-0.80) in the occurrence of peptic ulcer and GI bleeding respectively. There was evidence of bias in publications reporting on the GI events.

CONCLUSIONS

The practice of co-prescribing PPIs in patients taking low-dose aspirin is supported by some data, but the evidence is rather weak. It currently remains unclear whether the benefits of co-administration of PPIs in users of low-dose aspirin outweigh their potential harms.

Drug-drug interactions and risk of bleeding among inpatients on warfarin therapy: a prospective observational study

Background

Warfarin is known for its interaction with many drugs, resulting in undesired treatment outcomes such as bleeding. The study aimed to assess the prevalence of drug-drug interactions and determinants of bleeding among inpatients on warfarin therapy.

Methods

A cohort of inpatients on warfarin treatment was prospectively followed from date of admission until discharge. The study was carried out from January to October 2013 in Ayder Referral Hospital, Northern Ethiopia. Patients on warfarin therapy during the study period and willing to participate were included as study subjects. Each concurrent medication was collected and checked for drug-drug interactions using Micromedex® online drug reference. Data were analyzed using statistical software, SPSS for windows version 16. The relationship between bleeding complications and independent variables (age, sex, residence, type and number of co-medications, dose and duration of warfarin treatment, INR value) was assessed using binary logistic regression analysis (Odds ratio, 95% confidence interval).

Results

Of the total 133 patients enrolled in the study, 78 (58.9%) were females. The mean age of the study participants was 40.81 ± 17.6 years. The prevalence of drug-drug interactions was 99.2%. Among these, 65 (49.2%) patients had at least one major while the others had moderate level of drug-drug interaction. Twenty two (16.5%) patients have developed bleeding complications. Increase in international normalized ratio value was found to be strongly associated with risk of bleeding (P value = 0.00; OR = 0.03 (0.00-0.46)).

Conclusion

Drug-drug interactions with warfarin were prevalent in the study hospital. Bleeding complications due to warfarin were also high. Thus, clinicians should be aware of potential interactions and monitor patients’ international normalized ratio closely.

Risk factors associated with NSAID-induced upper gastrointestinal bleeding resulting in hospital admissions: A cross-sectional, retrospective, case series analysis in valencia, spain

Abstract.

BACKGROUND

NSAIDs are a significant cause of drug-related hospital admissions and deaths. The therapeutic effects of NSAIDs have been associated with the risk for developing adverse events, mainly in the gastrointestinal tract.

OBJECTIVES

The focus of this study was to identify the most common risk factors associated with NSAID-induced upper gastrointestinal bleeding (UGIB) resulting in hospital admissions. A secondary end point was the relationship between use of gastroprotective treatment and relevant risk factors to NSAID-induced UGIB in the selected population.

METHODS

This study was a cross-sectional, retrospective, case-series analysis of NSAID-induced UGIB resulting in hospital admission to the Requena General Hospital, Valencia, Spain, occurring from 1997 to 2005. International Classification of Diseases, Ninth Revision, Clinical Modification codes were used to identify UGIB admissions associated with NSAIDs. To estimate the probability of association between UGIB and the use of NSAIDs, the Naranjo adverse drug reaction probability was used. Patients were categorized as high-risk to develop UGIB if they met ≥1 of the following risk criteria (relevant risk factors): aged ≥65 years (age risk factor); peptic ulcer disease or NSAID gastropathy occurring in the year before their hospital admission (history risk factor); and concomitant use of other NSAIDs, systemic corticoids, oral anticoagulants, or platelet aggregation inhibitors (concomitant medication risk factor). Patients were categorized as candidates to use gastroprotections if they met ≥1 of the relevant risk factors. Patients were categorized as users of gastroprotective treatment if they used proton pump inhibitors, histamine H2-receptor antagonists, or misoprostol at hospital admission.

RESULTS

This study comprised 209 cases of NSAID-induced UGIB (129 men, 80 women: mean [SD] age, 71.5 [13.8] years; 128 [61.2%] receiving acetyl salicylic acid [ASA], with 72 [34.4%] receiving low-dose [80-325 mg] ASA). Prevalence of relevant risk factors for UGIB were as follows: age, 158 (75.6%) patients; history, 37 (17.7%); and concomitant medication, 35 (16.7%). One hundred seventy-eight (85.2%) patients met ≥1 criterion for using a gastroprotective agent; 28 (15.6%) were actually using one. Only the history risk factor was significantly associated with the use of gastroprotective treatment (P = 0.007; odds ratio = 3.17).

CONCLUSIONS

In this study of NSAID-induced UGIB resulting in hospital admission, age was the most common risk factor. However, this criterion was not associated with the use of gastroprotective agents. A large number of cases were associated with the use of ASA, primarily in those receiving low doses. A significant lack of gastroprotective agent use was observed in patients who met the criteria to use them.

Effect of multiple pharmacy use on medication adherence and drug-drug interactions in older adults with Medicare Part D

OBJECTIVES

To assess the association between multiple pharmacy use and medication adherence and potential drug-drug interactions (DDIs) in older adults.

DESIGN

Cross-sectional propensity score-weighted analysis.

SETTING

2009 claims data.

PARTICIPANTS

A nationally representative sample of 926,956 Medicare Part D beneficiaries aged 65 and older continuously enrolled in fee-for-service Medicare and Part D that year who filled one or more prescriptions at a community retail or mail order pharmacy.

MEASUREMENTS

Multiple pharmacy use was defined as concurrent (overlapping time periods) or sequential use (non-overlapping time periods) of ≥ 2 pharmacies in the year. Medication adherence was calculated using a proportion of days covered of 0.80 or greater for eight therapeutic categories (beta-blockers, renin angiotensin system antagonists, calcium channel blockers, statins, sulfonylureas, biguanides (metformin), thiazolidinediones, and dipeptidyl peptidase-IV inhibitors). Potential DDIs arising from use of certain drugs across a broad set of classes were defined as the concurrent filling of two interacting drugs.

RESULTS

Overall, 38.1% of the sample used multiple pharmacies. Those using multiple pharmacies (concurrently or sequentially) consistently had higher adjusted odds of nonadherence (ranging from 1.10 to 1.31, P < .001) across all chronic medication classes assessed after controlling for sociodemographic, health status, and access to care factors than single pharmacy users. The adjusted predicted probability of exposure to a DDI was also slightly higher for those using multiple pharmacies concurrently (3.6%) than for single pharmacy users (3.2%, adjusted odds ratio (AOR) = 1.11, 95% confidence interval (CI) = 1.08-1.15) but lower in individuals using multiple pharmacies sequentially (2.8%, AOR = 0.85, 95% CI = 0.81-0.91).

CONCLUSIONS

Filling prescriptions at multiple pharmacies was associated with lower medication adherence across multiple chronic medications and a small but statistically significant greater likelihood of DDIs in concurrent pharmacy users.

Safe prescription recommendations for non steroidal anti-inflammatory drugs: consensus document ellaborated by nominated experts of three scientific associations (SER-SEC-AEG)

This article outlines key recommendations for the appropriate prescription of non steroidal anti-inflammatory drugs to patients with different musculoskeletal problems. These recommendations are based on current scientific evidence, and takes into consideration gastrointestinal and cardiovascular safety issues. The recommendations have been agreed on by experts from three scientific societies (Spanish Society of Rheumatology [SER], Spanish Association of Gastroenterology [AEG] and Spanish Society of Cardiology [SEC]), following a two-round Delphi methodology. Areas that have been taken into account encompass: efficiency, cardiovascular risk, gastrointestinal risk, liver risk, renal risk, inflammatory bowel disease, anemia, post-operative pain, and prevention strategies. We propose a patient management algorithm that summarizes the main aspects of the recommendations.

Evidence-based management of anticoagulant therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

High-quality anticoagulation management is required to keep these narrow therapeutic index medications as effective and safe as possible. This article focuses on the common important management questions for which, at a minimum, low-quality published evidence is available to guide best practices.

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

Most practical clinical questions regarding the management of anticoagulation, both oral and parenteral, have not been adequately addressed by randomized trials. We found sufficient evidence for summaries of recommendations for 23 questions, of which only two are strong rather than weak recommendations. Strong recommendations include targeting an international normalized ratio of 2.0 to 3.0 for patients on vitamin K antagonist therapy (Grade 1B) and not routinely using pharmacogenetic testing for guiding doses of vitamin K antagonist (Grade 1B). Weak recommendations deal with such issues as loading doses, initiation overlap, monitoring frequency, vitamin K supplementation, patient self-management, weight and renal function adjustment of doses, dosing decision support, drug interactions to avoid, and prevention and management of bleeding complications. We also address anticoagulation management services and intensive patient education.

CONCLUSIONS

We offer guidance for many common anticoagulation-related management problems. Most anticoagulation management questions have not been adequately studied.

Major bleeding risk associated with warfarin and co-medications in the elderly population

PURPOSE

Warfarin management in the elderly population is complex as medicines prescribed for concomitant diseases may further increase the risk of major bleeding associated with warfarin use. We aimed to quantify the excess risk of bleeding-related hospitalisation when warfarin was co-dispensed with potentially interacting medicines.

METHODS

A retrospective cohort study was undertaken over a 4-year period from July 2002 to June 2006 to examine bleeding risk associated with medications co-administered in patients taking warfarin using an administrative claims database from the Australian Department of Veterans' Affairs. All veterans aged 65 years and over who were new users of warfarin were followed until death or study end. Risk of bleeding was assessed using a Poisson GEE model adjusting for age, gender, socioeconomic status, co-morbidity index, previous bleeding related hospitalisations and indicators of health service use.

RESULTS

Overall, 17661 veterans who used warfarin at any time during the study period were included. The overall incidence rate of bleeding-related hospitalisations was 4.1 (95% CI 3.7-4.6) per 100 person-years in veterans who were not receiving potentially interacting medicines. Bleeding-related hospitalisation rates were significantly increased when warfarin was co-prescribed with low-dose aspirin (Adjusted rate ratio (AdjRR) 1.44, 95% CI 1.00-2.07), clopidogrel (AdjRR 2.23, 95% CI 1.48–3.36), clopidogrel with aspirin (AdjRR 3.44, 95% CI 1.28-9.23), amiodarone (AdjRR 3.33, 95% CI 1.38–8.00) and antibiotics (AdjRR 2.34, 95% CI 1.55-3.54).

CONCLUSIONS

Models assessing bleeding risk with warfarin should take account of the range of potentially harmful medicine combinations used in elderly people with comorbid conditions.

Potentially serious drug-drug interactions among community-dwelling older adult dental patients

OBJECTIVES

Reducing adverse drug events, including those resulting from drug-drug interactions, will be a health safety issue of increasing importance for dental practitioners in the coming decades as greater numbers of older adults seek oral health care. The purpose of this study was to identify prescription drugs with the potential for serious interactions and estimate prevalent use among older adults visiting the dentist.

STUDY DESIGN

The Medicare Current Beneficiary Survey is an ongoing series of nationally representative surveys of Medicare beneficiaries. Potentially serious drug interactions were selected with the use of published work by Partnership to Prevent Drug-Drug Interactions. Drug interactions were identified and prevalence estimates made for community-dwelling older adults visiting the dentist. Analyses were completed to test associations between sociodemographic and health-related variables and the use of prescription drugs with the potential for serious interactions.

RESULTS

Overall, 3.4% of those visiting the dentist were estimated to have been prescribed drugs with the potential for a serious drug interaction. Drugs commonly prescribed in dentistry with the potential for serious interactions include the benzodiazepines, macrolide antibiotics, and nonsteroidal antiinflammatory analgesics.

CONCLUSIONS

Understanding potentially harmful drug combinations, their clinical consequences, and the frequency with which implicated drugs are being prescribed will assist practitioners in clinically managing patients and avoiding inappropriate prescribing.

Drug interactions with phenprocoumon and the risk of serious haemorrhage: a nested case-control study in a large population-based German database

PURPOSE

Phenprocoumon is the most frequently used vitamin K antagonist in Germany. The aim of this study was to estimate the risk of serious bleeding as a result of the use of drugs with potential interaction with phenprocoumon.

METHODS

We conducted a nested case-control study in a cohort of 246,220 phenprocoumon users in the German Pharmacoepidemiological Research Database. Cases were patients hospitalised for haemorrhage of different kinds. Ten controls were matched to each case by health insurance, birth year and sex using incidence density sampling. Odds ratios (OR) with 95% confidence intervals (CI) of the risk of serious bleeding associated with combined use of phenprocoumon and potentially interacting drugs versus phenprocoumon alone were estimated using conditional logistic regression analysis. Our analyses considered multiple risk factors, such as bleeding history, other comorbidities or co-medication.

RESULTS

Our study included 2,553 cases and 25,348 matched controls. An increased risk of bleeding was observed for the combined use of phenprocoumon and clopidogrel vs phenprocoumon use alone (OR: 1.83, 95% CI: 1.41-2.36). Antibiotic drugs associated with an increased risk of haemorrhage in the population of phenprocoumon users included the group of quinolones with ORs ranging from 2.74 (95% CI: 1.80-4.18) for ciprofloxacin to 4.40 (95% CI: 2.45-7.89) for levofloxacin, amoxicillin plus clavulanic acid (OR: 2.99, 95% CI: 1.39-6.42) and cotrimoxazole (OR 3.57, 95% CI: 2.36-5.40). Among non-steroidal anti-inflammatory drugs (NSAIDs), ketoprofen and naproxen were associated with the highest risks.

CONCLUSION

Significantly elevated risks of major bleeding were mainly observed for drugs with known pharmacodynamic interaction with phenprocoumon, and less for drugs with possible pharmacokinetic interaction.

A drug-drug interaction knowledge assessment instrument for health professional students: a Rasch analysis of validity evidence

BACKGROUND

It is essential that current and future health professionals be able to evaluate for possible clinically significant drug-drug interactions (DDIs) and when detected, determine appropriate management strategies to prevent patient harm.

OBJECTIVE

Assess the validity of a DDI knowledge assessment instrument in a health professional student population.

METHODS

This study recruited health professional students (medical, nurse practitioner, and pharmacy) beginning experiential training at the University of Arizona. Students were given a knowledge assessment instrument that included 15 medication pairings selected on the basis of clinical importance and were asked to select the most appropriate DDI management strategy for each pair by selecting "avoid combination," "usually avoid combination," "take precautions," or "no special precautions." Data were analyzed in 2 ways because of the subjective nature of classifying DDIs into specific management categories. In the first analysis, respondents were given credit for a correct item only if they selected the management strategy deemed appropriate (management strategy analysis). In another analysis, students were given credit for an item only if they correctly identified specific DDIs (DDI recognition analysis). Rasch analysis was used to assess the validity of the knowledge instrument.

RESULTS

A total of 165 of the 226 eligible health professional students completed the DDI knowledge assessment (73% response rate). The mean score for management strategy analysis was 3.82 out of 15, whereas DDI recognition analysis produced a higher average (mean=6.55). Good reliability was demonstrated in both strategies, and no ceiling or floor effects were observed. Some construct underrepresentation occurred with both scoring strategies, and some mistargeting was identified when analyzing the management strategy.

CONCLUSIONS

Although improvements in construct representation may be beneficial, the instrument used demonstrated good reliability and validity and could be used by educators to assess and improve DDI knowledge. The ability of the participants to identify DDIs and select an appropriate management strategy was low. These results support the need for additional DDI education in this institution's health curricula.

Risk factors of drug interaction between warfarin and nonsteroidal anti-inflammatory drugs in practical setting

Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to interact with the oral anticoagulant warfarin and can cause a serious bleeding complication. In this study, we evaluated the risk factors for international normalized ratio (INR) increase, which is a surrogate marker of bleeding, after addition of an NSAID in a total of 98 patients who used warfarin. Patient age, sex, body mass index, maintenance warfarin dose, baseline INR, coadministered medications, underlying diseases, and liver and kidney functions were evaluated for possible risk factors with INR increase > or =15.0% as the primary end-point. Of the 98 patients, 39 (39.8%) showed an INR elevation of > or =15.0% after adding a NSAID to warfarin therapy. Multivariate analysis showed that high maintenance dose (>40 mg/week) of warfarin (P=0.001), the presence of coadministered medications (P=0.024), the use of meloxicam (P=0.025) and low baseline INR value (P=0.03) were the risk factors for INR increase in respect to NSAID-warfarin interaction. In conclusion, special caution is required when an NSAID is administered to warfarin users if patients are taking warfarin >40 mg/week and other medications interacting with warfarin.

Gastrointestinal safety of nonsteroidal antiinflammatory drugs and selective cyclooxygenase-2 inhibitors in patients on warfarin

BACKGROUND

The interaction between warfarin and nonsteroidal antiinflammatory drugs (NSAIDs) is well known. However, warfarin and NSAIDs are still commonly prescribed together. Selective cyclooxygenase-2 (COX-2) inhibitors, a newer class of NSAID, offer potential advantages over the nonselective NSAIDs in patients treated with warfarin.

OBJECTIVE

To study the rates of hospitalization for gastrointestinal (GI) bleeding events in 3 groups of patients: those taking warfarin only, those taking warfarin plus a nonselective NSAID, and those taking warfarin plus a selective COX-2 inhibitor.

METHODS

This was a retrospective cohort analysis in a large nonprofit health maintenance organization. All warfarin users from January 1, 2000, to December 31, 2005, were eligible for inclusion in the study. Eligible patients were grouped by their exposure time to warfarin only, warfarin plus nonselective NSAIDs, or warfarin plus selective COX-2 inhibitor. The study endpoint was hospitalization for a GI bleed. Patients were matched using a propensity scoring methodology. A multivariate Cox proportional hazards model was used to estimate the hazard ratio for GI bleeding between patient cohorts, controlling for age, sex, baseline medical conditions, prior history of GI bleeding, and prescription drug use.

RESULTS

The eligible population consisted of 35,548 patients undergoing 46,214 courses of warfarin therapy. The adjusted hazard ratio for hospital-associated GI bleeding in the warfarin plus nonselective NSAID group versus warfarin alone was 3.58 (95% CI 2.31 to 5.55; p < 0.01) and for warfarin plus selective COX-2 inhibitor versus warfarin alone was 1.71 (95% CI 0.60 to 4.84; p = 0.31). For nonselective NSAIDs plus warfarin versus selective COX-2 inhibitor plus warfarin, the adjusted hazard ratio was 3.69 (95% CI 1.42 to 9.60; p = 0.01).

CONCLUSIONS

In general, nonselective NSAIDs and selective COX-2 inhibitors should be avoided in patients taking warfarin. In situations where patients require NSAIDs and cannot be managed using other therapies, our results suggest that selective COX-2 inhibitors are associated with fewer hospitalizations for GI bleeding.

Pharmacy students' ability to identify potential drug-drug interactions

OBJECTIVE

To evaluate the ability of third- and fourth-year pharmacy students to identify clinically significant drug-drug interactions (DDIs)

METHODS

A questionnaire designed to measure DDI knowledge was disseminated to fourth-year pharmacy students in a school of pharmacy. A second questionnaire was distributed to third-year pharmacy students in 2 schools of pharmacy (schools A and B) and re-administered to students in 1 of the schools 1 year later.

RESULTS

Class of 2005 fourth-year pharmacy students correctly categorized an average of 52% +/- 13% DDI pairs on the first questionnaire. Third-year pharmacy students at schools A and B correctly categorized an average of 61% +/- 18% and 66% +/- 15% of DDI pairs, respectively. The average percentage of correct responses for fourth-year students from the class of 2007 was 65% (+/- 17%).

CONCLUSION

Pharmacy students' ability to identify important DDIs is far from optimal, even after completing experiential requirements.

[Appropriate use of non-steroidal anti-inflammatory drugs in rheumatology: guidelines from the Spanish Society of Rheumatology and the Mexican College of Rheumatology]

OBJECTIVE

To develop guidelines for the appropriate use of NSAIDs in rheumatology.

METHODS

We used a methodology modified from the one developed by RAND/UCLA. Two groups of panellists were selected, one by the CMR and another by the SER. Recommendations were proposed from nominal groups and the agreement to them was tested among rheumatologists from both societies by a tworound Delphi survey. The analysis of the second Delphi round supported the generation of the final set of recommendations and the assignment of a level of agreement to each of them. Systematic reviews of five recommendations in which the agreement was low or was divided were also carried out.

RESULTS

Here we present recommendations for the safe use of NSAIDs in rheumatic diseases, based on the best available evidence, expert opinion, the agreement among rheumatologists, and literature review. The trend is to reduce the frequency, duration and dose of NSAIDs in favour of non-pharmacological measures, analgesic drugs or disease modifying drugs. In addition, the recommendations help to identify profiles for increased toxicity, with an emphasis on gastrointestinal and cardiovascular risks. The recommendations deal with the course of action and monitoring in different risk groups and in patients using antiplatelet or anticoagulant drugs. The overall level of agreement is high.

CONCLUSIONS

The NSAIDs are safe and effective drugs for the treatment of rheumatic diseases. However, it is necessary to individualize its use according to their risk profile.

The potential for interaction between warfarin and coprescribed medication: a retrospective study in primary care

BACKGROUND AND OBJECTIVE

Warfarin is commonly involved in drug-related hospital admissions. The drug is most commonly prescribed to elderly patients in whom polypharmacy is common and, when administered in combination with other drugs such as NSAIDs, aspirin (acetylsalicylic acid) or macrolide antibacterials, is associated with increased bleeding risk. The aim of this study was to investigate the prevalence of prescriptions that might give rise to clinically relevant drug-drug interactions in a warfarinized population.

METHODS

Primary care prescribing of warfarin and potentially interacting medicines was assessed between 1 April 2005 and 31 March 2006 using computerized prescribing data retrieved from 321 primary care practices in Scotland.

RESULTS

A total of 17,861 registered patients were prescribed warfarin in the study year, of whom 68% (n=12,107) were concomitantly issued with a prescription for at least one potentially interacting medicine. For short-term use, 'one-off' prescriptions for antibacterials (sulfonamides, ciprofloxacin, and macrolides), nonselective NSAIDs and antithrombotics (fibrinolytics) were the most frequently prescribed drug groups with potential for interaction, being prescribed to 12.7%, 5.3%, and 1.4% of warfarinized patients, respectively. Macrolide antibacterials were prescribed in significantly fewer warfaranized patients than standardized population (3.84% vs 4.41%; p<0.001). For long-term use, nonselective NSAIDs and antithrombotics were the most frequently prescribed drug groups, being prescribed to 21.0% and 21.1% of warfarinized patients, respectively. When compared with a standardized population, NSAIDs and antithrombotics were prescribed to a significantly smaller proportion of the warfarin population, whereas selective cyclo-oxygenase 2 inhibitors were prescribed to a significantly greater proportion. Nevertheless for the whole warfarinized population 26.3% were prescribed nonselective NSAIDs and 22.5% antithrombotic agents.

CONCLUSIONS

The lower 'one off' use of macrolide antibacterials and long-term use of antithrombotics and NSAIDs in warfarinized patients observed in this study might suggest awareness among general practitioners of the increased risks for bleeding associated with concomitant use of these agents with warfarin therapy. However, despite this, the majority of warfarinized patients in this study were issued with a repeat prescription for at least one potentially interacting medicine.

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.

Prevalence and predictors of potential drug-drug interactions in Regione Emilia-Romagna, Italy

BACKGROUND AND OBJECTIVE

Drug-drug interactions (DDIs) are preventable medication errors associated with potentially serious adverse events and death. Several studies have examined the prevalence of potential DDIs among ambulatory patients in various countries. Limited recent data on the prevalence of potential DDIs in Italy are available in the medical literature. The objective of this study was to estimate the prevalence of clinically important potential DDIs among the approximately 4 million residents of Regione Emilia-Romagna (RER), Italy, and to examine possible predictors of potential DDI exposure.

METHODS

A retrospective follow-up study of 2004 outpatient prescription data from RER was conducted. A previously published list of clinically important potential DDIs was refined to include only pairs of drugs in which both drugs were reimbursed by the 2004 Italian National Formulary. A potential DDI was defined as the presence of a minimum 5-day overlap in days supply for drugs in an interacting pair. The 1-year period prevalence of each potential DDI was quantified. A logistic regression analysis was conducted to examine patient characteristics as predictors of potential DDIs.

RESULTS AND DISCUSSION

The list of clinically important potential DDIs included 12 drug pairs that could be captured using the RER database. These 12 potential DDIs occurred 8894 times in the RER population in 2004. The most commonly identified potentially interacting medication pairs were warfarin and non-steroidal anti-inflammatory drugs (6824 cases), theophylline/aminophylline and ciprofloxacin/fluvoxamine (930), and warfarin and barbiturates (567). Odds of exposure were highest among those aged 65 years or older, males, and those with more chronic conditions. Odds of exposure increased 1.39 times with each addition of a prescription medication.

CONCLUSION

A substantial number of clinically important potential DDIs were identified, particularly among warfarin users. Awareness of the most prevalent potential DDIs can help practitioners prevent concomitant use of these dangerous medication combinations.

Allele variants of the cytochrome P450 2C9 genotype in white subjects from the netherlands with serious gastroduodenal ulcers attributable to the use of NSAIDs

BACKGROUND

The most common serious adverse effects (AEs) associated with NSAID therapy are bleeding and perforated gastroduodenal ulcers. These AEs are dose related, and reduced oral clearance of NSAIDs associated with polymorphisms of cytochrome P450 (CYP) would, theoretically, increase the risk for AEs.

OBJECTIVE

The purpose of this study was to determine whether polymorphisms of the CYP2C9 genotype are associated with the development of serious complications of NSAID-related ulcers.

METHODS

We examined the records of patients with complications of serious NSAID-related ulcers who were hospitalized from November 2001 to December 2003. Diagnosis was confirmed by endoscopy or abdominal surgery, and a group of consecutive subjects was identified for genetic analysis. CYP2C9 allele frequencies were determined and compared with those in a matched cohort of subjects receiving stable weekly maintenance doses of oral coumarin anticoagulants. Allele frequencies also were compared with those in matched cohorts from earlier studies.

RESULTS

All 26 subjects with serious NSAID-related ulcers were white, 15 (58%) were female, and the median age was 74.5 years (range, 32-96 years). All 87 subjects in the reference group were white, 24 (28%) were female, and the median age was 69 years (range, 48-81 years). CYP2C9 genotype frequencies did not differ significantly between subjects with serious complications of NSAID-related ulcers and subjects using oral coumarin anticoagulants. The genotype frequencies in both groups were similar to those reported in previous studies in white subjects.

CONCLUSION

The CYP2C9 genotype was not a significant or clinically relevant risk factor in the development of serious NSAID-related ulcers in this group of subjects.

Drug-associated disease: cytochrome P450 interactions

Critically ill patients generally are older, frequently have organ failure, and commonly receive multiple medications, all of which make them susceptible to adverse effects of drugs. Drug interactions are a common adverse effect, and many are predictable based on understanding the mechanisms that underlie drug interactions. This article identifies commonly used medications in critically ill patients and the associated drug interactions that may occur with emphasis on the cytochrome P450 enzyme system.

Assessment of potential drug–drug interactions with a prescription claims database

PURPOSE

The prevalence of 25 clinically important potential drug-drug interactions (DDIs) in a population represented by the drug claims database of a pharmacy benefit management company (PBM) was studied.

METHODS

A retrospective cross-sectional analysis of pharmaceutical claims for almost 46 million participants in a PBM was conducted to determine the frequency of 25 DDIs previously identified as clinically important. A DDI was counted when drugs in potentially interacting combinations were dispensed within 30 days of each other during a 25-month period between April 2000 and June 2002.

RESULTS

The number of DDIs ranged from 37 for pimozide and an azole antifungal to 127,684 for warfarin and a nonsteroidal antiinflammatory drug (NSAID). The highest prevalence (278.56 per 100,000 persons) and highest case-exposure rate (242.7 per 1,000 warfarin recipients) occurred with the warfarin-NSAID combination. The combination with the lowest overall prevalence (cyclosporine and a rifamycin, 0.10/100,000) differed from the combination with the lowest case-exposure rate (pimozide and an azole antifungal, 0.028 per 1,000 azole antifungal recipients). Number of cases, prevalence, and case-exposure rates for both sexes generally increased with age. An estimated 374,000 plan participants were exposed to a clinically important DDI during a 25-month period. Between 20% and 46% of prescription drug claims were reversed (canceled) for a medication with a drug interaction when a warning about the interaction was sent to the pharmacy.

CONCLUSION

Analysis of prescription claims data from a major PBM found that 374,000 of 46 million plan participants had been exposed to a potential DDI of clinical importance.

Selecting nonprescription analgesics

Worldwide, there has been an emerging patient demand for access to efficient drugs without consulting a doctor and obtaining a prescription. As a result, there has been an expanding movement of prescription-only drugs to over-the-counter (OTC) status. An increasing number of drugs are becoming available OTC, empowering patients to treat themselves. Where the principle of empowering individuals to treat themselves can fail is when consumers lack the knowledge to do so safely. This potentially applies to the self-selection of analgesic drugs by consumers. When used inappropriately, these drugs pose significant risks. The nonsteroidal antiinflammatory drugs (NSAIDs) are associated with many adverse reactions, interactions, and contraindications in a number of patient groups, even at OTC doses. In particular, in the elderly, the high incidence of cardiovascular and gastrointestinal disease, coupled with age-related decline in renal function and multiple medication use, all warrant extra caution with the use of NSAIDs and make paracetamol the simple analgesic drug of first choice. Despite the possibility of hepatotoxicity in overdose, paracetamol represents a better all-round option for most patients requiring OTC analgesic therapy.

Incremental cost-effectiveness of cyclooxygenase 2-selective versus nonselective nonsteroidal anti-inflammatory drugs in a cohort of coumarin users: a pharmacoeconomic analysis linked to a case-control study

BACKGROUND

A previous case-control study involving concomitant users of coumarin and nonsteroidal anti-inflammatory drugs (NSAIDs) found that cyclooxygenase 2 (COX-2)-selective NSAIDs were associated with fewer bleeding complications than nonselective NSAIDs.

OBJECTIVE

The goal of this study was to determine the incremental cost-effectiveness of COX-2-selective versus nonselective NSAIDs in relation to the occurrence of bleeding complications in a cohort of concomitant coumarin users.

METHODS

The pharmacoeconomic evaluation was linked to a case-control analysis (patients with and without bleeding complications) based on data from the earlier study in users of concomitant coumarin and NSAIDs. Medical costs associated with NSAID use and bleeding complications were estimated according to Dutch guidelines for pharmacoeconomic analyses, based on Dutch drug prices and national averages for health care costs. Rofecoxib, meloxicam, and nabumetone were considered COX-2 selective. Total costs were calculated and compared for 2 hypothetical scenarios in which patients used either COX-2-selective or nonselective NSAIDs. Sensitivity analyses were performed in which both the odds ratios (ORs) and the costs of NSAIDs and bleeding episodes were varied.

RESULTS

A total of 1,491 bleeding complications occurred in 4400 coumarin users: among the 221 (15%) NSAID users with a bleeding episode, 96% used a nonselective NSAID and 4% used a COX-2-selective NSAID. The adjusted OR of a bleeding episode for nonselective compared with COX-2-selective NSAIDs was 3.07 (95% CI, 1.18-8.03). The estimated mean cost of a bleeding episode was 478 per patient. Factoring in the excess cost of a COX-2-selective NSAID compared with a nonselective NSAID, as well as the cost savings in averted bleeding episodes, it was determined that there would be net medical cost savings of 53,800 and 162 averted bleeding episodes if the entire patient group received COX-2-selective NSAIDs rather than nonselective NSAIDs. The sensitivity analysis showed these results to be robust.

CONCLUSION

In this study population of concomitant coumarin and NSAID users, the reduction in bleeding complications with the use of more expensive COX-2-selective inhibitors was associated with net medical cost savings compared with nonselective NSAIDs.

Hemorrhagic Complications of Anticoagulant Treatment

This chapter about hemorrhagic complications of anticoagulant treatment is part of the seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Bleeding is the major complication of anticoagulant therapy. The criteria for defining the severity of bleeding varies considerably between studies, accounting in part for the variation in the rates of bleeding reported. The major determinants of vitamin K antagonist-induced bleeding are the intensity of the anticoagulant effect, underlying patient characteristics, and the length of therapy. There is good evidence that vitamin K antagonist therapy, targeted international normalized ratio (INR) of 2.5 (range, 2.0 to 3.0), is associated with a lower risk of bleeding than therapy targeted at an INR > 3.0. The risk of bleeding associated with IV unfractionated heparin (UFH) in patients with acute venous thromboembolism (VTE) is < 3% in recent trials. This bleeding risk may increase with increasing heparin dosages and age (> 70 years). Low molecular weight heparin (LMWH) is associated with less major bleeding compared with UFH in acute VTE. UFH and LMWH are not associated with an increase in major bleeding in ischemic coronary syndromes, but are associated with an increase in major bleeding in ischemic stroke. Information on bleeding associated with the newer generation of antithrombotic agents has begun to emerge. In terms of treatment decision making for anticoagulant therapy, bleeding risk cannot be considered alone, ie, the potential decrease in thromboembolism must be balanced against the potential increased bleeding risk.

Identification of Serious Drug–Drug Interactions: Results of the Partnership to Prevent Drug–Drug Interactions

OBJECTIVE

To develop a list of clinically important drug-drug interactions (DDIs) likely to be encountered in community and ambulatory pharmacy settings and detected by a computerized pharmacy system.

DESIGN

Cross-sectional, one-time evaluation.

SETTING

United States in fall 2001.

PARTICIPANTS

An expert panel comprising two physicians, two clinical pharmacists, and an expert on DDIs.

INTERVENTIONS

Systematic review of drug interaction compendia and published literature, ratings (on a 1 to 10 scale) of various clinical aspects of DDIs (e.g., clinical importance, quality and quantity of evidence, causal relationship, risk of morbidity and mortality), and a modified Delphi consensus-building process.

MAIN OUTCOME MEASURE

Panelists' opinions about clinical importance of DDIs.

RESULTS

The expert panel considered 56 DDIs. Of these, 28 had a mean clinical importance score of 8.0 or more. The ratings for clinical importance ranged from 3.2 to 9.6, with a mean +/- SD of 7.5 +/- 1.5 across the combinations examined. The mean score for the quality of literature suggesting the interaction exists ranged from 1.0 to 9.6, with a mean +/- SD of 5.8 +/- 2.5. In terms of substantiation of the interactions evaluated, the mean +/- SD rating was 6.3 +/- 2.2, with a range from 1.4 to 9.2. Through the modified Delphi process, the panel determined that 25 interactions were clinically important.

CONCLUSION

Using an expert panel and a standard evaluation tool, 25 clinically important drug interactions that are likely to occur in the community and ambulatory pharmacy settings were identified. Pharmacists should take steps to prevent patients from receiving these interacting medications, and computer software vendors should focus interaction alerts on these and similarly important DDIs.

The influence of cyclo-oxygenase specificity of non-steroidal anti-inflammatory drugs on bleeding complications in concomitant coumarine users

BACKGROUND

Concomitant use of coumarines and non-steroidal anti-inflammatory drugs (NSAIDs) may induce bleeding complications, due to the inhibition of both coagulant factors and platelet function. Unlike non-selective NSAIDs, cyclo-oxygenase-2 (COX-2)-selective NSAIDs interfere very little with platelet aggregation.

AIM

To determine whether COX-2-selective NSAIDs are associated with less bleeding complications in coumarine users, compared with non-selective NSAIDs.

DESIGN

Prospective, nested case-control study.

METHODS

We studied concomitant coumarine and NSAID users over two years. Patients with bleeding (cases), and frequency-matched patients without bleeding (controls), were sent questionnaires regarding possible risk factors for bleeding. International normalized ratio (INR) values were recorded. Univariate and multivariate analyses were used to detect factors contributing to bleeding.

RESULTS

There were 1491 reported bleeds. NSAIDs were involved in 14.8%; 3.9% involving COX-2-selective NSAIDs. In non-bleeders, 2601 prescriptions with a coumarine/NSAID combination were detected; 9.7% were COX-2-selective. Adjusted ORs (95% CI) for a bleeding complication were 3.07 (1.18-8.03) for non-selective NSAID use, 3.01 (1.42-6.37) for NSAID use > 1 month, and 1.89 (1.03-3.49) for INR > or = 4.0.

DISCUSSION

In coumarine users, COX-2-selective NSAIDs are associated with less bleeding complications than non-selective NSAIDs are. Duration of NSAID use, as well as intensity of coumarine treatment, plays an important additional role. When the coumarine-NSAID combination is inevitable in an individual patient, a COX-2-selective NSAID may be preferred, with careful monitoring of the INR.