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

A descriptive analysis of drug-drug interactions and corresponding adverse drug reactions in multimorbid older inpatients: findings from the SENATOR trial

PURPOSE

Drug-drug interactions (DDIs) are prevalent among multimorbid and polymedicated older adults and can increase the risk of adverse drug reactions (ADRs), hospital admissions, and mortality. This study describes the incidence and prevalence of 66 clinically relevant DDIs and analyses the occurrence of 12 corresponding predefined ADRs in older inpatients enrolled in the SENATOR trial.

METHODS

The sub-study of the SENATOR trial that involved 1537 multimorbid older inpatients, recruited from 2016 to 2018 in six academic teaching hospitals in Belgium, Iceland, Ireland, Italy, Scotland, and Spain respectively, and analysed 66 potentially clinically significant DDIs. Descriptive analysis determined DDI and corresponding ADR prevalence/incidence.

RESULTS

At baseline (median age: 78 [72, 84], 52.8% male), the prevalence of patients with DDIs was high (50.9%), increased during hospitalisation (55.2%) and reduced to 49.7% after 12 weeks. The most common DDIs were: ≥ 2 potassium reducing drugs (17.1%), ≥ 3 centrally acting drugs (9.0%), and SSRI + loop/thiazide diuretic (7.2%). Of all participants, one-third experienced a prevalent (36.6%)/incident (35.8%) ADR. Major serum electrolyte disturbance had the highest incidence (10.7%)/prevalence (11.5%). Incident ADRs were more common in patients with DDIs (p = 0.013). A higher prevalence of new onset falls (p = 0.013), major constipation (p = 0.004), and major serum electrolyte disturbances (p = 0.006) was observed in patients with related and thus potentially causal DDIs.

CONCLUSIONS

Clinicians should, be aware of DDIs and the involved drug classes that can lead to an increased rate of ADRs in older multimorbid inpatients. Regularly reevaluating the appropriateness of the frequently prescribed drug classes and initiating judicious deprescribing is recommended.

CYP2D6 Substrate Dispensing Among Patients Dispensed Mirabegron: An Administrative Claims Analysis

BACKGROUND

Overactive bladder (OAB) is characterized by the presence of bothersome urinary symptoms. Pharmacologic treatment options for OAB include anticholinergics and β3-adrenergic agonists. Use of β3-adrenergic agonists may result in similar treatment efficacy with a decreased side effect profile compared with anticholinergics because high anticholinergic burden is associated with cardiovascular and neurologic side effects. However, the β3-adrenergic agonist mirabegron, one of two approved drugs within this class, is a moderate cytochrome P450 (CYP) 2D6 inhibitor, and coadministration of drugs that are CYP2D6 substrates with mirabegron may lead to adverse drug effects.

OBJECTIVE

The aim of this study was to quantify how often CYP2D6 substrates were dispensed in patients receiving mirabegron among adults of any age and among those ≥ 65 years of age.

METHODS

In this retrospective descriptive analysis, a deidentified administrative claims database in the United States, IQVIA PharMetrics® Plus, was used to identify dispensing claims for CYP2D6 substrates and mirabegron from November 2012 to September 2019. Prevalence of CYP2D6 substrate dispensing was assessed in patients dispensed mirabegron among all adults ≥ 18 years old and additionally among a cohort of those ≥ 65 years old. Patient baseline profiles at the time of mirabegron and CYP2D6 substrate codispensing and at the time of mirabegron dispensing were compared. CYP2D6 substrates were categorized as those with the potential for increased risk of QT prolongation, with anticholinergic properties, with narrow therapeutic index (NTI), contraindicated or having a black box warning when used with CYP2D6 inhibitors, or used for depression or other psychiatric disease. Dispensing data and patient profiles were summarized descriptively.

RESULTS

Overall, 68.5% of adults ≥ 18 years old dispensed mirabegron had overlapping dispensings for one or more CYP2D6 substrate; 60.6% and 53.6% had overlapping dispensings for CYP2D6 substrates with anticholinergic properties or risk of QT prolongation, respectively. CYP2D6 substrates with NTI, contraindicated with CYP2D6 inhibitors, or for psychiatric use were codispensed in 17.7%, 16.6%, and 38.0% of adult mirabegron users, respectively. Mirabegron users receiving one or more concurrent CYP2D6 substrate were more likely to be older, have more comorbidities and baseline polypharmacy, and have increased healthcare resource utilization compared with those without concurrent CYP2D6 substrates. Commonly codispensed CYP2D6 substrates included hydrocodone, oxycodone, tramadol, metoprolol, and tamsulosin. Findings were similar for patients in the older cohort (≥ 65 years old), with 72.1% receiving overlapping CYP2D6 substrates.

CONCLUSIONS

Codispensing of CYP2D6 substrates, especially those with anticholinergic properties or risk of QT prolongation, was common among adults and older adults receiving mirabegron. Results highlight the need for improved awareness of CYP2D6 substrate prescribing among patients receiving pharmacologic treatment for OAB that inhibits the CYP2D6 pathway.

Drug-Drug-Gene Interactions in Cardiovascular Medicine

Cardiovascular disease remains a leading cause of both morbidity and mortality worldwide. It is widely accepted that both concomitant medications (drug-drug interactions, DDIs) and genomic factors (drug-gene interactions, DGIs) can influence cardiovascular drug-related efficacy and safety outcomes. Although thousands of DDI and DGI (aka pharmacogenomic) studies have been published to date, the literature on drug-drug-gene interactions (DDGIs, cumulative effects of DDIs and DGIs) remains scarce. Moreover, multimorbidity is common in cardiovascular disease patients and is often associated with polypharmacy, which increases the likelihood of clinically relevant drug-related interactions. These, in turn, can lead to reduced drug efficacy, medication-related harm (adverse drug reactions, longer hospitalizations, mortality) and increased healthcare costs. To examine the extent to which DDGIs and other interactions influence efficacy and safety outcomes in the field of cardiovascular medicine, we review current evidence in the field. We describe the different categories of DDIs and DGIs before illustrating how these two interact to produce DDGIs and other complex interactions. We provide examples of studies that have reported the prevalence of clinically relevant interactions and the most implicated cardiovascular medicines before outlining the challenges associated with dealing with these interactions in clinical practice. Finally, we provide recommendations on how to manage the challenges including but not limited to expanding the scope of drug information compendia, interaction databases and clinical implementation guidelines (to include clinically relevant DDGIs and other complex interactions) and work towards their harmonization; better use of electronic decision support tools; using big data and novel computational techniques; using clinically relevant endpoints, preemptive genotyping; ensuring ethnic diversity; and upskilling of clinicians in pharmacogenomics and personalized medicine.

Effectiveness of the MULTIPAP Plus intervention in youngest-old patients with multimorbidity and polypharmacy aimed at improving prescribing practices in primary care: study protocol of a cluster randomized trial

BACKGROUND

The progressive ageing of the population is leading to an increase in multimorbidity and polypharmacy, which in turn may increase the risk of hospitalization and mortality. The enhancement of care with information and communications technology (ICT) can facilitate the use of prescription evaluation tools and support system for decision-making (DSS) with the potential of optimizing the healthcare delivery process.

OBJECTIVE

To assess the effectiveness and cost-effectiveness of the complex intervention MULTIPAP Plus, compared to usual care, in improving prescriptions for young-old patients (65-74 years old) with multimorbidity and polypharmacy in primary care.

METHODS/DESIGN

This is a pragmatic cluster-randomized clinical trial with a follow-up of 18 months in health centres of the Spanish National Health System. Unit of randomization: family physician. Unit of analysis: patient.

POPULATION

Patients aged 65-74 years with multimorbidity (≥ 3 chronic diseases) and polypharmacy (≥ 5 drugs) during the previous 3 months were included.

SAMPLE SIZE

n = 1148 patients (574 per study arm).

INTERVENTION

Complex intervention based on the ARIADNE principles with three components: (1) family physician (FP) training, (2) FP-patient interview, and (3) decision-making support system.

OUTCOMES

The primary outcome is a composite endpoint of hospital admission or death during the observation period measured as a binary outcome, and the secondary outcomes are number of hospital admission, all-cause mortality, use of health services, quality of life (EQ-5D-5L), functionality (WHODAS), falls, hip fractures, prescriptions and adherence to treatment. Clinical and sociodemographic factors will be explanatory variables.

STATISTICAL ANALYSIS

The main result is the difference in percentages in the final composite endpoint variable at 18 months, with its corresponding 95% CI. Adjustments by the main confounding and prognostic factors will be performed through a multilevel analysis. All analyses will be carried out in accordance to the intention-to-treat principle.

DISCUSSION

It is important to prevent the cascade of negative health and health care impacts attributable to the multimorbidity-polypharmacy binomial. ICT-enhanced routine clinical practice could improve the prescription process in patient care.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04147130 . Registered on 22 October 2019.

ASCP's 2021 Choosing Wisely® Recommendations: A Proud Accomplishment

Choosing Wisely® (CW) is a campaign to engage physicians and patients in conversations about unnecessary tests, treatments, and procedures. The campaign began in the United States in 2012 and in Canada in 2014, and now many countries around the world are adapting the campaign and implementing it. Currently, approximately 80 societies in the United States have published CW recommendations. Each recommendation is supported by clinical guidelines (when necessary), evidence-based ratinale, including information about when these tests or procedures may be appropriate. A deprescribing task force led by Chair Beier was created by ASCP in November 2018 after several conversations between ASCP leadership (notably, President J. Hirshfield) and Beier. Task force members comprise pharmacists practicing in academia, community, and long-term care settings. The chair also invited pharmacists from international countries (Canada and Australia) where deprescribing initiatives have a strong focus and scientific literature base. One of the primary goals for Chair Beier was to add ASCP's voice to the ABIM CW Campaign. Because ASCP is a membership association that represents pharmacists, health care professionals, and students serving the unique medication needs of older patients, by adding its name to the list of supporting partners, the organization makes a compelling argument to address deprescribing initiatives, tools, scientific literature, and resources to assist in initiating deprescribing conversations and their subsequent implementation.

Drug–drug interactions among hospitalized elderly in patients at medical wards of Northwest Ethiopia’s Comprehensive Specialized Hospitals: A multicenter observational study

Objective:

Drug–drug interactions are of major concern due to links to untoward drug effects, hospitalizations, and serious health impacts. Elderly patients are more predisposed to drug interactions than younger patients. The present study aimed to find out the prevalence of drug–drug interactions at North West Ethiopian compressive specialized hospitals’ Internal Medicine wards.

Methods:

From 30 April to 30 July 2021 GC, a multicenter prospective observational study was conducted at north Ethiopian specialized hospitals. Data was collected by using a structured questionnaire adapted from different literature and medical records at the North West Ethiopian Comprehensive Specialized Hospitals’ Internal Medicine wards during the study period. Thereafter checked the completeness of the collected data was checked drug–drug interactions by using Medscape. Epi data version 4.6.2 software was used as data clearance and STATA version 14.1 was used for further data analysis.

Result:

A total of 389 subjects participated in the study of which more than half (55.53%) of them were female with a mean (SD) age of 68.9 ± 7.46 years. A total of 641 drug–drug interactions were detected in this investigation of which, 225(35.1%) were major, 299(46.6%) were significant interactions, and 117(18.3%) were minor interactions. Hospital stay (AOR = 5.95 CI: 3.49–10.12), retire (AOR = 6.71 CI: 1.26–35.78), 5–9 drugs (AOR = 5.30 CI: 2.91–9.67) and more than 10 drugs (AOR = 8.03 CI: 2.47–26.07) were important risk factors for drug–drug interactions.

Conclusion:

The findings of this study suggest that drug–drug interactions were high among hospitalized elderly patients. The presence of polypharmacy, to be retired, and hospital stayed were all found to be strongly linked with drug–drug interactions.

Prevalence of potentially harmful multidrug interactions on medication lists of elderly ambulatory patients

Background

It has been hypothesized that polypharmacy may increase the frequency of multidrug interactions (MDIs) where one drug interacts with two or more other drugs, amplifying the risk of associated adverse drug events (ADEs). The main objective of this study was to determine the prevalence of MDIs in medication lists of elderly ambulatory patients and to identify the medications most commonly involved in MDIs that amplify the risk of ADEs.

Methods

Medication lists stored in the electronic health record (EHR) of 6,545 outpatients ≥60 years old were extracted from the enterprise data warehouse. Network analysis identified patients with three or more interacting medications from their medication lists. Potentially harmful interactions were identified from the enterprise drug-drug interaction alerting system. MDIs were considered to amplify the risk if interactions could increase the probability of ADEs.

Results

MDIs were identified in 1.3 % of the medication lists, the majority of which involved three interacting drugs (75.6 %) while the remainder involved four (15.6 %) or five or more (8.9 %) interacting drugs. The average number of medications on the lists was 3.1 ± 2.3 in patients with no drug interactions and 8.6 ± 3.4 in patients with MDIs. The prevalence of MDIs on medication lists was greater than 10 % in patients prescribed bupropion, tramadol, trazodone, cyclobenzaprine, fluoxetine, ondansetron, or quetiapine and greater than 20 % in patients prescribed amiodarone or methotrexate. All MDIs were potentially risk-amplifying due to pharmacodynamic interactions, where three or more medications were associated with the same ADE, or pharmacokinetic, where two or more drugs reduced the metabolism of a third drug. The most common drugs involved in MDIs were psychotropic, comprising 35.1 % of all drugs involved. The most common serious potential ADEs associated with the interactions were serotonin syndrome, seizures, prolonged QT interval and bleeding.

Conclusions

An identifiable number of medications, the majority of which are psychotropic, may be involved in MDIs in elderly ambulatory patients which may amplify the risk of serious ADEs. To mitigate the risk, providers will need to pay special attention to the overlapping drug-drug interactions which result in MDIs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02594-z.

Prevalence of drug-drug interactions in older people before and after hospital admission: analysis from the OPERAM trial

Background

Drug-drug interactions (DDIs) are highly prevalent in older patients but little is known about prevalence of DDIs over time. Our main objective was to assess changes in the prevalence and characteristics of drug-drug interactions (DDIs) during a one-year period after hospital admission in older people, and associated risk factors.

Methods

We conducted a sub-study of the European OPERAM trial (OPtimising thERapy to prevent Avoidable hospital admissions in Multimorbid older people), which assessed the effects of a structured medication review (experimental arm) compared to usual care (control arm) on reducing drug-related hospital readmissions. All OPERAM patients (≥70 years, with multimorbidity and polypharmacy, hospitalized in four centers in Bern, Brussels, Cork and Utrecht between December 2016 and October 2018, followed over 1 year) who were alive at hospital discharge and had full medication data during the index hospitalization (at baseline i.e., enrolment at admission, and at discharge) were included. DDIs were assessed using an international consensus list of potentially clinically significant DDIs in older people. The point-prevalence of DDIs was evaluated at baseline, discharge, and at 2, 6 and 12 months after hospitalization. Logistic regression models were performed to assess independent variables associated with changes in DDIs 2 months after baseline.

Results

Of the 1950 patients (median age 79 years) included, 1045 (54%) had at least one potentially clinically significant DDI at baseline; point-prevalence rates were 58, 57, 56 and 57% at discharge, and 2, 6 and 12 months, respectively. The prevalence increased significantly from baseline to discharge (P < .001 [significant only in the control group]), then remained stable over time (P for trend .31). The five most common DDIs –all pharmacodynamic in nature– accounted for 80% of all DDIs and involved drugs that affect potassium concentrations, centrally-acting drugs and antithrombotics. At 2 months, DDIs had increased in 459 (27%) patients and decreased in 331 (19%). The main factor predictive of a change in the prevalence of DDIs was hyperpolypharmacy (≥10 medications).

Conclusions

DDIs were very common; their prevalence increased during hospitalization and tended to remain stable thereafter. Medication review may help control this increase and minimize the risk of adverse drug events.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02532-z.

Efficacy and safety of statins in ethnic differences: a lesson for application in Indigenous Australian patient care

Although statins are effective in treating high cholesterol, adverse effects do occur with their use. Efficacy and tolerability vary among statins in different ethnic groups. Indigenous Australians have a high risk for cardiovascular and kidney diseases. Prescribing statins to Indigenous Australians with multi-morbidity requires different strategies to increase efficacy and reduce their toxicity. Previous studies have reported that Indigenous Australians are more susceptible to severe statin-induced myopathies. However, there is a lack of evidence in the underlying genetic factors in this population. This review aims to identify: inter-ethnic differences in the efficacy and safety of statins; major contributing factors accounting for any identified differences; and provide an overview of statin-induced adverse effects in Indigenous Australians.

[A case of elderly myxedema coma patient with end-stage renal failure]

CASE

84-year-old woman had been diagnosed hypothyroidism before, but she did not take tablets of thyroid hormone prescribed. Anorexia and decreased consciousness level were discovered by workers of the facility. Her family doctor found thyroid function abnormality as a cause, and she was introduced to our hospital to treat because the whole body condition was bad. Her physical examination was observed that JCS was 3-10. Laboratory examination showed that TSH 562.81 μIU/mL, fT4 0.40 ng/mL, pH 7.33, and Na 124 mEq/L. It was not a contradictory finding with the diagnostic criteria of mucus edema coma. Blood and peritoneal dialysis is denied, although her data indicated eGFR 8-10 ml/min/1.73 m2. Her hospitalization was long-term, but exhibited finally good clinical course. After three months of hospitalization, she was discharged from the hospital. The problems were as follows. The clear guideline of myxedema coma with end-stage renal failure state and many complications was not found. She and her family did not hope dialysis under this condition.We treated a case of myxedema coma in a case of an elderly person with terminal renal failure who did not hope dialysis. In addition to myxedema coma as a rare disease, there are many basic diseases in the elderly. Although it was a difficult case, it is important to repeatedly confirm the explanation and the intention of the person and the family with regard to the selection of the treatment policy.

Microvascular decompression for trigeminal neuralgia in the elderly: efficacy and safety

OBJECTIVE

The safety and efficacy of surgical microvascular decompression (MVD) in elderly patients with trigeminal neuralgia (TN) is controversially discussed in the literature. A widespread reluctance to expose this cohort to major intracranial surgery persists. Our aim was to compare the efficacy and safety between older and younger patients with TN.

METHODS

In this cross-sectional study, 139 MVD procedures (103 patients < 70 and 36 patients ≥ 70) were included. Surgical fitness was assessed by the American Society of Anesthesiology (ASA) grade. The pain-free interval was evaluated using Kaplan-Meier analysis only in patients with a recent follow-up visit. Independent risk factors for recurrence in patients with a minimum 12-month follow-up were determined.

RESULTS

Patients ≥ 70 showed a significantly higher number of comorbidities. Pain intensity, affection of trigeminal branches and symptom duration was similar between groups. No significant difference in treatment associated complications and permanent neurological deficits was shown. There was no treatment-related mortality. A tendency towards a lower recurrence rate in patients < 70 did not reach statistical significance (17.6% vs. 28.6%, P = 0.274). Pain-free interval was not different between both cohorts (78.7 vs. 73.5 months, P = 0.391).

CONCLUSION

Despite a higher prevalence of comorbidities in elderly patients, complication rates and neurological deficits after MVD were comparable to younger patients. Rates of immediate and long-term pain relief compared favorably to previous studies and were similar between elderly and younger patients. These data endorse MVD as a safe and effective first-line surgical procedure for elderly patients with TN and neurovascular conflict on MRI.

Characteristics of Older Adults Who Were Early Adopters of Medical Cannabis in the Florida Medical Marijuana Use Registry

Use of medical marijuana is increasing in the United States and older adults are the fastest growing user group. There is little information about the characteristics and outcomes related to medical marijuana use. This study is a descriptive analysis of older adults (aged ≥50 years old) who were early adopters of a medical marijuana program in the U.S. state of Florida. Per state legislation, initial and follow-up treatment plans were submitted to the University of Florida College of Pharmacy. Data collection included demographics, clinical history, medical conditions, substance use history, prescription history, and health status. Follow-up treatment plans noted changes in the chief complaint and actions taken since the initial visit. Of the state's 7548 registered users between August 2016 and July 2017, N = 4447 (58.9%) were older adults. Patients utilized cannabidiol (CBD)-only preparations (45%), preparations that had both tetrahydrocannabinol (THC) and CBD (33.3%) or were recorded to use both CBD-only and THC + CBD products (21.7%). The chief complaints indicating medical cannabis treatment were musculoskeletal disorders and spasms (48.4%) and chronic pain (45.4%). Among other prescription medications, patients utilized antidepressants (23.8%), anxiolytics and benzodiazepines (23.5%), opioids (28.6%), and cardiovascular agents (27.9%). Among all drug classes with potential sedating effects, 44.8% of the cohort were exposed to at least one. Patients with follow-up visits (27.5%) exhibited marked improvement as assessed by the authorizing physicians. However, the patient registry lacked detailed records and linkable information to other data resources to achieve complete follow up in order to assess safety or efficacy. Future improvements to registries are needed to more adequately capture patient information to fill knowledge gaps related to the safety and effectiveness of medical marijuana, particularly in the older adult population.

Potential and clinical relevant drug-drug interactions among elderly from nursing homes: a multicentre study in Murcia, Spain

This study purposes to determine the prevalence of potential and clinical relevant Drug-Drug-Interactions (pDDIs) in institutionalized older adults and to identify the pertinent factors associated. We conduct an observational, multicenter and cross-sectional study during the last quarter of 2010. We selected a sample of 275 subjects (aged ≥ 65 years) from 10 nursing homes of Murcia (Spain) by a two-stage complex sampling. pDDIs were identified using the College of Pharmacists Database. We only considered pDDIs of clinical relevance, and thereafter the relevant factors were identified through uni-level and multi-level regression analyses. A total of 210 pDDIs were identified, 120 of which were considered clinically relevant (57.1%), affecting a total of 70 elderly (25.8%). Eight pharmacological groups made up 70.2% of the clinically relevant pDDIs. More clinically relevant DDIs were found in people suffering several pathologies (OR = 2.3; 95%CI = 1.4-4.5), and also in people who take ten or more drugs daily (OR = 9.6; 95%CI = 4.8-19.1), and people who take anti-inflammatory drugs (OR = 3.9; 95%CI = 1.4-10.4). This study reveals that clinically relevant pDDIs are very common in institutionalized elderly people, and that caregivers should aim at improving their practice in order to reduce the prevalence of this phenomenon.

Risk of Drug-Drug Interactions in Out-Hospital Drug Dispensings in France: Results From the DRUG-Drug Interaction Prevalence Study

Introduction: Drug interactions could account for 1% of hospitalizations in the general population and 2-5% of hospital admissions in the elderly. However, few data are available on the drugs concerned and the potential severity of the interactions encountered. We thus first aimed to estimate the prevalence of dispensings including drugs Contraindicated or Discommended because of Interactions (CDI codispensings) and to identify the most frequently involved drug pairs. Second, we aimed to investigate whether the frequency of CDI codispensings appeared higher or lower than the expected for the drugs involved. Methods: We carried out a study using a random sample of all drugs dispensings registered in a database of the French Health Insurance System between 2010 and 2015. The distribution of the drugs involved was described considering active principles, detailing the 20 most frequent ones for both contraindicated or discommended codispensings (DCs). To investigate whether the frequency of CDI codispensings appeared higher or lower than the expected for the drugs involved, we developed a specific indicator, the Drug-drug interaction prevalence study-score (DIPS-score), that compares for each drug pair the observed frequency of codispensing to its expected probability. The latter is determined considering the frequencies of dispensings of the individual drugs constituting a pair of interest. Results: We analyzed 6,908,910 dispensings: 13,196 (0.2%) involved contraindicated codispensings (CCs), and 95,410 (1.4%) DCs. For CCS, the most frequently involved drug pair was "bisoprolol+flecainide" (n = 5,036); four out of five of the most represented pairs involved cardiovascular drugs. For DCS, the most frequently involved drug pair was "ramipril+spironolactone" (n = 4,741); all of the five most represented pairs involved cardiovascular drugs. The drug pair involved in the CC with the highest score value was "citalopram+hydroxyzine" (DIPS-score: 3.7; 2.9-4.6); that with the lowest score was "clarithromycin+simvastatin" (DIPS-score: 0.2; 0.2-0.3). DIPS-score median value was 0.4 for CCs and 0.6 for DCs. Conclusion: This high prevalence of CDI codispensings enforces the need for further risk-prevention actions regarding drug-drug interactions (DDIs), especially for arrhythmogenic or anti-arrhythmic drugs. In this perspective, the DIPS-score we develop could ease identifying the interactions that are poorly considered by clinicians/pharmacists and targeting interventions.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Evaluation of Potential Drug-Drug Interactions with Medications Prescribed to Geriatric Patients in a Tertiary Care Hospital

BACKGROUND AND OBJECTIVES

The drugs most commonly implicated in major potential interactions are those used in the day-to-day clinical management of elderly patients with chronic diseases. This study is planned to evaluate the profile of drug-drug interactions in the medications prescribed to elderly population and also to identify the possible predictors for potential drug-drug interactions in the elderly.

METHODS

This cross-sectional study included patients aged above 60 years with a minimum of two drugs in the prescriptions. Data were collected from medical prescriptions and patients' medical records. The data collected included demographic characteristics such as age, gender, height, weight, educational status, socioeconomic status, medical history, and medications prescribed. The prescriptions were analyzed for the potential drug interactions using Lexi-Interact™ Online, an online software to check drug-drug interactions.

RESULTS

A total of 209 patients were included in the study, among them 104 (49.8%) were males and 105 (50.2%) were females. The mean number of medications received was 6.53 ± 2.15 per prescription. Around 138 (66%) patients received more than six medications. The mean number of potential drug interactions seen in the prescription of these patients was 3.17 ± 2.78. Around 18.2% patients had more than five drug interactions. Major drug interactions were observed in 21.42% of cases. Around 3.02% of drug interactions belonged to risk category X, i.e., to be avoided. Logistic regression analysis showed that age above 70 years was associated with the presence of drug interactions. Increased number of medication was independently associated with the occurrence of drug interactions. The presence of drug interactions was not associated with increased number of comorbidities.

CONCLUSION

A significant number of potential drug-drug interactions were seen in the prescriptions of elderly patients. Increasing age and polypharmacy were identified as the predictors of potential drug interactions.

Potential Drug-Drug Interactions in a Cohort of Elderly, Polymedicated Primary Care Patients on Antithrombotic Treatment

INTRODUCTION

Drug-drug interactions (DDIs) are an important risk factor for adverse drug reactions. Older, polymedicated patients are particularly affected. Although antithrombotics have been detected as high-risk drugs for DDIs, data on older patients exposed to them are scarce.

METHODS

Baseline data of 365 IDrug study outpatients (≥ 60 years, use of an antithrombotic and one or more additional long-term drug) were analyzed regarding potential drug-drug interactions (pDDIs) with a clinical decision support system. Data included prescription and self-medication drugs.

RESULTS

The prevalence of having one or more pDDI was 85.2%. The median number of alerts per patient was three (range 0-17). For 58.4% of the patients, potential severe/contraindicated interactions were detected. Antiplatelets and non-steroidal anti-inflammatory drugs (NSAIDs) showed the highest number of average pDDI alert involvements per use (2.9 and 2.2, respectively). For NSAIDs, also the highest average number of severe/contraindicated alert involvements per use (1.2) was observed. 91.8% of all pDDI involvements concerned the 25 most frequently used drug classes. 97.5% of the severe/contraindicated pDDIs were attributed to only nine different potential clinical manifestations. The most common management recommendation for severe/contraindicated pDDIs was to intensify monitoring. Number of drugs was the only detected factor significantly associated with increased number of pDDIs (p < 0.001).

CONCLUSION

The findings indicate a high risk for pDDIs in older, polymedicated patients on antithrombotics. As a consequence of patients' frequently similar drug regimens, the variety of potential clinical manifestations was small. Awareness of these pDDI symptoms and the triggering drugs as well as patients' self-medication use may contribute to increased patient safety.

Collaborative intervention between pharmacists and physicians on elderly patients: a randomized controlled trial

Background

The elderly population is the largest consumer of medications as this age group is at high risk for developing chronic diseases. However, medication use among elderly people is complicated by an increased risk of drug-related problems. Therefore, the present study was conducted to investigate the effects of collaborative interventions between pharmacists and physicians on health-related outcomes of elderly patients.

Patients and methods

This was a randomized controlled trial (RCT) conducted on elderly outpatients who sought treatment in the Medical Outpatient Department of a public tertiary hospital in Malaysia and who were taking at least five medications. The participants were randomly allocated to the intervention and control groups. The intervention group received pharmaceutical care from a pharmacist in collaboration with physicians and was followed-up for 6 months, while the control group received usual care in the outpatient pharmacy.

Results

A total of 73 participants in the intervention group and 79 participants in the control group completed the study. Participants in the intervention group had significantly better medication adherence (median =7.0 vs 5.0, U=1224.5, p<0.001, r=0.503) and better Medication Appropriateness Index (MAI) score (median =8.0 vs 20.0, U=749.5, p<0.001, r=0.639).

Conclusion

Collaborative interventions between pharmacists and physicians improved medication adherence and MAI scores of the elderly patients. Therefore, such services should be implemented in all hospitals, especially in countries where pharmacists are still not playing a substantial role in patient care.

Trial registration

NMRR-12-958-13020.

Compatibility of medication with PRISCUS criteria and identification of drug interactions in a large cohort of patients with COPD

Patients with COPD are often of advanced age and have a high number of medications due to their lung disease and comorbidities. Thus they are at risk for unwanted effects from drugs, either due to age or due to interactions between drugs. These issues are not clarified. We therefore assessed the number of medications and potential adverse effects in a large cohort of patients with COPD. The analysis was performed in 2741 patients of the German COPD cohort COSYCONET, using baseline data (visit 1) and follow-up data after about 1.5 years (visit 3). Spirometric GOLD grades 1-4 were found in 8/35/32/9% of patients and GOLD groups ABCD in 7/25/4/48% of patients, while the remaining patients (n = 450, 16.4%) could not be classified according to GOLD criteria. The compatibility of medication with age was evaluated via the PRISCUS list, drug interactions via the AiD clinic system, whereby only drug combinations occurring in at least 10 patients were considered (nine unwanted interactions, one wanted interaction). The median numbers of medications were 5 or more in all patient categories, among them 3 or more non-respiratory medications. In the total population there were 153 patients (10.2%) aged ≥65 years who had any medication of the PRISCUS list with intermediate or low risk. Serious adverse combinations of drugs according to AiD occurred in 114 patients (4.2%), while the number of unwanted but only potentially clinically relevant combinations was 175 (6.4%). The number of wanted combinations was 219 (8.0%). These numbers did not markedly change when restricting the analysis to patients of GOLD grades 1-4. Moreover, the results were similar for visit 1 and visit 3. We conclude that in a large cohort of COPD patients about 10% of patients aged at least 65 years had medications that could interfere with their age and that the proportions of patients with either unwanted or wanted drug interactions were both in the range of 8-10%. These results suggest that problems arising from the high number of medications were not very frequent in the COPD cohort analysed.

Clinically relevant potential drug-drug interactions among outpatients: A nationwide database study

BACKGROUND

Adverse drug events due to drug-drug interactions (DDIs) represent a considerable public health burden, also in Slovenia. A better understanding of the most frequently occurring potential DDIs may enable safer pharmacotherapy and minimize drug-related problems.

OBJECTIVES

The aim of this study was to evaluate the prevalence and predictors of potential DDIs among outpatients in Slovenia.

METHODS

An analysis of potential DDIs was performed using health claims data on prescription drugs from a nationwide database. The Lexi-Interact Module was used as the reference source of interactions. The influence of patient-specific predictors on the risk of potential clinically relevant DDIs was evaluated using logistic regression model.

RESULTS

The study population included 1,179,803 outpatients who received 15,811,979 prescriptions. The total number of potential DDI cases identified was 3,974,994, of which 15.6% were potentially clinically relevant. Altogether, 9.3% (N = 191,213) of the total population in Slovenia is exposed to clinically relevant potential DDIs, and the proportion is higher among women and the elderly. After adjustment for cofactors, higher number of medications and older age are associated with higher odds of clinically relevant potential DDIs. The burden of DDIs is highest with drug combinations that increase risk of bleeding, enhance CNS depression or anticholinergic effects or cause cardiovascular complications.

CONCLUSION

The current study revealed that 1 in 10 individuals in the total Slovenian population is exposed to clinically relevant potential DDIs yearly. Taking into account the literature based conservative estimate that approximately 1% of potential DDIs result in negative health outcomes, roughly 1800 individuals in Slovenia experience an adverse health outcome each year as a result of clinically relevant potential interactions alone.

Cytochrome P450 interactions are common and consequential in Massachusetts hospital discharges

Despite the recognition that drug-drug interactions contribute substantially to preventable health-care costs, the prevalence of such interactions related to the cytochrome P450 system in clinical practice remains poorly characterized. This study drew retrospective hospital discharge cohorts from a large health claims data set and a large health system data set. For every hospital discharge, frequency of co-occurrence of substrates and inducers or inhibitors at cytochrome P450 2D6, 2C19, 3A4 and 1A2 were determined. A total of 124 520 individuals in the state of Massachusetts (health claims cohort) and 77 026 individuals in two large academic medical centers (electronic health record (EHR) cohort) were examined. In the claims cohort, 35 157 (28.2%) exhibited at least one CYP450 drug-drug interaction at hospital discharge, whereas in the EHR cohort, 36 750 (47.7%) had at least one interaction. The most commonly affected CYP450 systems were 2C19 and 2D6, with putative interactions observed in at least 10% of individuals at discharge in each cohort. Odds of hospital readmission within 90 days among those discharged with at least one interaction were 10-16% greater, with mean health-care cost $574/month greater over the subsequent year, after adjusting for age, sex, insurance type, total number of medications prescribed, Charlson comorbidity score and presence or absence of a psychiatric diagnosis. These two distinct clinical data types show that CYP450 drug-drug interactions are prevalent and associated with greater probability of early hospital readmission and greater health-care cost, despite the widespread availability and application of drug-drug interaction checking software.

A New Computer-Based Tool to Reduce Potentially Inappropriate Prescriptions in Hospitalized Geriatric Patients

BACKGROUND

Potentially inappropriate prescriptions (PIPs), associated with adverse drug reactions, hospitalization, and wasteful healthcare spending, are common in elderly patients with comorbidities and multiple drugs.

OBJECTIVE

Our objective was to develop and validate a new tool to reduce PIPs in a hospitalized geriatric population.

METHODS

This was an observational cohort study of two cohorts (development [n = 100 subjects] and validation [n = 449 subjects]) of consecutive patients aged ≥65 years admitted to geriatric wards from April to December 2012. In the development phase, data on clinical and demographic characteristics, Multidimensional Prognostic Index (MPI), and prescribed drugs before hospital admission were collected and processed using a tool that integrates the Screening Tool of Older Persons' Potentially Inappropriate Prescriptions (STOPP) criteria and the Micromedex™ Drug-Reax System, a drug-management platform. This tool generated a report that was provided to the treating physicians. The weight of the PIPs, as defined by the Medication Appropriateness Index (MAI), was assessed on admission and on discharge. Similar procedures were followed in the validation cohort.

RESULTS

PIPs were independently associated with polypharmacy and with prescribing of antithrombotics, sedatives and antidepressants in both cohorts. The use of the tool led to a significant reduction of the MAI score, both in the development (median score 4 [interquartile range; IQR 1-5] vs. 2 [IQR 0-4], p < 0.001) and in the validation cohorts (median 3 [IQR 1-5] vs. 2 [IQR 0-4], p < 0.001).

CONCLUSION

This tool significantly reduced PIPs, as defined by the MAI score, in a hospitalized geriatric population. This strategy might be useful to minimize inappropriate medication exposure in this group.

Drug-drug interactions in the intensive care unit: Do they really matter?

PURPOSE

To describe prevalence and patterns of potential drug-drug interactions (pDDIs) in the intensive care unit (ICU), occurrence of adverse drug events (ADEs), and agreement between different compendia and intensivists' perceptions.

METHODS

A cross-sectional study. Drug profiles of all adult patients from 2 academic ICUs were screened on day 3 upon admission. We identified pDDIs using 3 compendia (Stockley's, Micromedex, and Epocrates) and documented their mechanism of action, clinical consequences, severity, level of evidence, and management. Medical records were searched to identify ADEs potentially related to major pDDIs. Agreement between information sources (compendia, intensivists) was evaluated.

RESULTS

We identified 1120 pDDIs among 275 patients. Median number of pDDIs per patient was 3.0 (interquartile range, 1-6), with 79% of patients presenting with at least 1 pDDI. Major pDDIs were detected in 18% of patients, with potentially related to ADEs in 4% of patients. Only 13% of all pDDIs were documented simultaneously in all 3 compendia. Different information sources (compendia, clinicians) showed "no" to "fair" agreement.

CONCLUSIONS

Potential drug-drug interactions occurred in most ICU patients, contrasting with low rates of potentially related ADEs, which may have been underestimated. Sources of information are inconsistent, challenging the identification of pDDIs.

Potential drug-drug interactions among elderly patients admitted to medical ward of Ayder Referral Hospital, Northern Ethiopia: a cross sectional study

BACKGROUND

The elderly are considered as special population, as they differ from younger adults in terms of comorbidity, polypharmacy, pharmacokinetics, vulnerability to drug-drug interactions and adverse drug reactions. Despite the fact that the elderly patients are at high risk of having drug interaction and potential adverse outcomes, studies in this regard are scarce in resource limited settings like Ethiopia. The aim of this study was to assess the prevalence and determinants of potential drug-drug interaction in elderly patients admitted to medical ward of Ayder Referral Hospital in Northern Ethiopia.

METHODS

A cross sectional study was conducted among elderly inpatients aged 60 years and above. The study was conducted from February to May 2014. Prescribed drugs being taken concurrently for at least 24 h were included and checked for drug-drug interaction using Micromedex® 2.0 online drug reference. Data were analyzed using statistical software, statistical package for social sciences for windows version 20. Logistic regression model was used to analyze factors associated with occurrence of drug interaction. P value of <0.05 was considered statistically significant.

RESULTS

A total of 140 patients were participated in the study. The mean age (±standard deviation) of participants was 68 (±7) years. Majority (61.4 %) of patients were diagnosed with cardiovascular and/or renal diseases. A total of 814 drugs were prescribed with a mean of 6 (±4) medications per patient during a 13 (±9) days of hospital stay. About two-third (62.2 %) of the respondents were exposed to at least one potential drug-drug interaction. Among these 3.6, 32.9 and 25.7 % of patients had taken contraindicated drug combination, at least one major and at least one moderate drug-drug interaction, respectively. Patients with five or more prescribed medications were four times at risk of having drug-drug interaction (P = 0.00; adjusted odds ratio 4.047; 95 % confidence interval 1.867-8.775).

CONCLUSION

Drug-drug interaction in elderly patients was common in this resource limited set-up. Awareness creation and clinical pharmacist involvement in minimizing the risk associated with potentially harmful drug combinations are needed.

Pharmaceutical Management of Trigeminal Neuralgia in the Elderly

Classical trigeminal neuralgia (CTN) is a severe neuropathic pain in the distribution of one or more branches of the trigeminal nerve, which occurs in recurrent episodes, causing deterioration in quality of life, affecting everyday habits and inducing severe disability. The aim of this review is to give an overview of the current literature on pharmaceutical treatment options for CTN in the elderly. The first-line treatment for the management of CTN in adults is an antiepileptic—carbamazepine or oxcarbazepine. There is a lack of research on the use of antiepileptics in the elderly. This is a deficiency, as the use of antiepileptics raises a number of problems due to the polypharmacotherapy common in older patients. This can induce drug interactions due to co-morbidities and changes in pharmacokinetics and pharmacodynamics. Furthermore, the side effects of carbamazepine include central nervous system disturbances, such as a lack of balance, dizziness, somnolence, renal dysfunction and cardiac arrhythmias, which are poorly tolerated by the elderly. Unfortunately, the efficacy and safety of alternative treatment options have not been systematically evaluated. On the basis of the current literature, it is not possible to give an evidence-based recommendation for first-line pharmaceutical management of CTN specifically for the elderly.

Potential drug-drug interactions in a medical intensive care unit of a university hospital

BACKGROUND/AIM

Drug-drug interactions (DDIs) can impact patient safety. Occurrence of clinically important DDIs is higher for intensive care unit (ICU) patients. This observational study aimed to evaluate the potential DDIs in medical ICU patients of a university hospital.

MATERIALS AND METHODS

The Medical Pharmacology Department organized consultation reports for ICU patients in order to detect the DDIs. To focus on clinically important DDIs, interactions in the C, D, or X risk rating categories of the Lexi-Interact online database were analyzed. Frequency and clinical risk rating categories of DDIs were detected. Relationship between number of prescriptions and DDIs were assessed. The most frequent drug/drug groups were identified.

RESULTS

Of 101 ICU patients, 45.5% were found to have DDIs. We detected 125 C (72.2%), 37 D (21.4%), and 11 X (6.4%) risk category interactions. A statistically significant increase in the number of DDIs was shown with the number of prescriptions (P = 0.002). The most frequent DDIs were between agents acting on the cardiovascular system and corticosteroids (12.8%).

CONCLUSION

Results of this study show that pharmacological consultation plays a critical role in the recognition of DDIs for improvement of medication management and effective therapeutic endpoints without any adverse or toxic reactions.

Inappropriate Medication Use Among Underserved Elderly African Americans

OBJECTIVE

The goal of this study is to identify correlates and the prevalence of potentially inappropriate medication (PIM) use among underserved elderly African Americans.

METHOD

This cross-sectional study recruited 400 elderly African Americans living in South Los Angeles, and used structured, face-to-face surveys. These elicited data pertaining to the type, frequency, dosage, and indications of all medications used by participants.

RESULTS

Seventy percent of participants engaged in PIM use and used at least one medication that was classified as "Avoid" (27%) and "Use Conditionally" (43%) through Beers Criteria. Significant correlations emerged between PIM use and the number of autonomic and central nervous system, neurological and psychotherapeutic medications, medication duplications, and drug-drug interactions.

DISCUSSION

Our findings point to the need for multidisciplinary team programs of health care providers that include primary and specialist physicians, pharmacists, nurses, and social workers. Together, they can improve health outcomes, enhance the quality of life, and reduce morbidity and mortality due to inappropriate medication use.

Clinically important drug-drug interactions in poly-treated elderly outpatients: a campaign to improve appropriateness in general practice

AIMS

The aim was to assess the impact of a campaign for general practitioners (GPs) to reduce clinically-important drug-drug interactions (DDIs) in poly-treated elderly patients.

METHODS

We compiled a list of 53 DDIs and analyzed reimbursed prescriptions dispensed to poly-treated (≥four drugs) elderly (>65 years) patients in the Emilia Romagna region during January 2011-June 2011 (first pre-intervention period), January 2012-June 2012 (second pre-intervention period) and January 2013-June 2013 (post-intervention period). Educational initiatives to GPs were completed in July 2012-December 2012. Pre-test/post-test analysis (2013 vs. 2012) was performed, also using predicted 2013 data (P < 0.01 for statistical significance).

RESULTS

Despite the slight increase in poly-therapy rate (16% in 2013, +1.5% from 2011), we found a stable or slightly declining number of potential DDIs for each elderly poly-treated patient (~1.5). In 2013, 11 DDIs exceeded 5% of prevalence rate: antidiabetics-β-adrenoceptor blockers ranked first (20.3%), followed by ACE Inhibitors (ACEIs)/sartans-non steroidal anti-inflammatory drugs (NSAIDs) (16.4%), diuretics-NSAIDs (13.6%), selective serotonin re-uptake inhibitors (SSRIs)-NSAIDs/acetyl salicylic acid (ASA) (12.7%) and corticosteroids-NSAIDs/ASA (9.7%). A remarkable reduction emerged for NSAID-related DDIs (diuretics-NSAIDs peaked -14.5%; P < 0.01), whereas prevalence of antidiabetics-β-adrenoceptor blockers increased (+7.9%; P < 0.01). When using predicted values, the statistical significance disappeared for antidiabetics-β-adrenoceptor blockers (+1.3%; P = 0.04), whereas it persisted for almost all NSAIDs-related DDIs: ACEIs/sartans-NSAIDs (-3.0%), diuretics-NSAIDs (-6.0%), SSRIs-NSAIDs/ASA (-5.9%).

CONCLUSIONS

This campaign contained the burden of DDIs in poly-treated elderly patients by 1) reducing most prevalent DDIs, especially NSAIDs-related DDIs and 2) balancing the observed rise in poly-therapy rate with stable rate in overall prescriptions of potentially interacting drugs per patient.

Optimizing pharmacotherapy in elderly patients: the role of pharmacists

As the world's population ages, global health care systems will face the burden of chronic diseases and polypharmacy use among older adults. The traditional tasks of medication dispensing and provision of basic education by pharmacists have evolved to active engagement in direct patient care and collaborative team-based care. The care of older patients is an especially fitting mission for pharmacists, since the key to geriatric care often lies with management of chronic diseases and polypharmacy use, and preventing harmful consequences of both. Because most chronic conditions are treated with medications, pharmacists, with their extensive training in pharmacotherapy and pharmacokinetics, are in a unique and critical position in the management of them. Pharmacists have the expertise to detect, resolve, and prevent medication errors and drug-related problems, such as overtreatment, undertreatment, adverse drug events, and nonadherence. Pharmacists are also competent in critically reviewing and applying clinical guidelines to the care of individual patients, and in some instances confront the lack of data (common in older adults) to provide the best possible patient-centered care. The current review aimed to depict the evidence of geriatric pharmacy care, demonstrate current impact of pharmacists' interventions on older patients, survey the tools used by pharmacists to provide effective care, and explore their role in pharmacotherapy optimization in elders. The findings of the current review strongly support previous studies that showed positive impact of pharmacists' interventions on older patients' health-related outcomes. There is a clear role for pharmacists working directly or collaboratively to improve medication use and management in older populations. Therefore, in global health care systems, teams caring for elders should involve pharmacists to optimize pharmacotherapy.

[Potential drug-drug interactions among elderly using antihypertensives from the Brazilian List of Essential Medicines]

The aim of this study was to estimate the prevalence of potential interactions between antihypertensives and other drugs. A household survey was conducted with individuals 60 years or older residing in Rio de Janeiro, Brazil. Potential moderately or very severe drug-drug interactions with antihypertensives, documented as suspected, probable or established, were identified. A total of 577 elderly were interviewed (mean age = 72 years), 45.2% of whom were using antihypertensives, of which 31.0% were subject to potential drug-drug interactions. Most of the interactions were moderately severe. Compared to the other elderly, those with potential drug-drug interactions showed more than fourfold odds of using five or more medicines and more than twofold odds of having been hospitalized in the previous year. Among the most frequent pairs of interactions, 75% cause a reduction in the hypotensive effect (65/87), which can result in low effectiveness of blood pressure control, prescribing of more drugs, and risk of other adverse events and interactions.

Analysis of drug interactions at the end of life

BACKGROUND

As death approaches, patients are at their most frail, but an increasing symptom burden often necessitates an increase in medications, putting them at higher risk for drug-drug interactions.

OBJECTIVES

To assess the potential for drug-drug interactions in routine prescribing at the end of life.

METHODS

An Australian retrospective multicentre case-note review of 266 consecutive adult patients who were referred to specialist palliative care, with data available on 166. Medications used in the last 2 weeks of life were screened for potential interactions using the 'Stockley's Drug Interactions' software.

RESULTS

The mean number of medications prescribed was 10.8, median 9 (IQR 6-14); all patients received at least one medication. In this study, 72% of patients were at risk of 1 or more potential drug-drug interaction. The mean number of potential interactions was 4.4, with a median of 2.5 (IQR 0-7) per patient. There were only 4/166 (2.4%) prescribed medications with an associated clinical record of an adverse drug reaction.

CONCLUSIONS

Potential drug-drug interactions are common for this group of patients. Some interactions may be recognised as an acceptable risk when the prescription is written. Further research is necessary to determine the best way to improve recognition of potential drug-drug interactions and the rates of morbidity or accelerated mortality associated with this. It is likely that palliative care services will need to implement multiple strategies including greater use of computerised prescribing software, and greater closer liaison with clinical pharmacists.

How common are drug and gene interactions? Prevalence in a sample of 1143 patients with CYP2C9, CYP2C19 and CYP2D6 genotyping

AIM

Drug-drug interactions (DDIs) are a widely recognized major cause of adverse drug reactions, but two other newly described important types of interactions also exist: drug-gene interactions (DGIs) and drug-drug-gene interactions (DDGIs). A drug-gene interaction occurs when a patient's genetic CYP450 type (e.g., CYP2D6 poor metabolizer) affects that patient's ability to clear a drug. A drug-drug-gene interaction occurs when the patient's CYP450 genotype and another drug in the patient's regimen (e.g., a CYP2D6 inhibitor) affect that individual's ability to clear a drug. Their prevalence has not been previously described. This pilot study investigates the frequency of DDIs, DGIs and DDGIs in a sample of CYP450 tested individuals.

MATERIALS & METHODS

The investigators conducted a retrospective analysis of 1143 individuals with known CYP2D6, CYP2C19 and CYP2C9 genotypes. Using the individuals' medication lists and YouScript(®), a software tool to analyze cumulative DDIs and DGIs, the prevalence of DDI, DGI and DDGIs was analyzed.

RESULTS

A total of 1053 potential major or substantial interactions were identified in 501 individuals. DDIs accounted for 66.1% of the total interactions. The remaining 33.9% of interactions were DGIs (14.7%) and DDGIs (19.2%). When compared with DDIs alone, DGIs and DDGIs increased the total number of potentially clinically significant interactions by 51.3%.

CONCLUSION

In the future, identifying DGIs and DDGIs may lead to a more comprehensive method of identifying individuals who are at risk for adverse drug reactions.

Impact of specific Beers Criteria medications on associations between drug exposure and unplanned hospitalisation in elderly patients taking high-risk drugs: a case-time-control study in Western Australia

BACKGROUND

Certain broad medication classes have previously been associated with high rates of hospitalisation due to related adverse events in elderly Western Australians, based on clinical coding recorded on inpatient summaries. Similarly, some medications from the Beers Criteria, considered potentially inappropriate in older people, have been linked with an increased risk of unplanned hospitalisation in this population.

OBJECTIVE

Our objective was to determine whether risk estimates of drug-related hospitalisations are altered in elderly patients taking 'high-risk drugs' (HRDs) when specific Beers potentially inappropriate medications (PIMS) are taken into consideration.

METHODS

Using the pharmaceutical claims of 251,305 Western Australians aged ≥65 years (1993-2005) linked with other health data, we applied a case-time-control design to estimate odds ratios (ORs) for unplanned hospitalisations associated with anticoagulants, antirheumatics, opioids, corticosteroids and four major cardiovascular drug groups, from which attributable fractions (AFs), number and proportion of drug-related admissions were derived. The analysis was repeated, taking into account exposure to eight specific PIMs, and results were compared.

RESULTS

A total of 1,899,699 index hospitalisations were involved. Of index subjects, 12-57 % were exposed to each HRD at the time of admission, although the proportions taking both an HRD and one of the selected PIMs were much lower (generally ≤2 %, but as high as 8 % for combinations involving temazepam and for most PIMs combined with hypertension drugs). Included PIMs (indomethacin, naproxen, temazepam, oxazepam, diazepam, digoxin, amiodarone and ferrous sulphate) all tended to increase ORs, AFs and drug-related hospitalisation estimates in HRD combinations, although this was less evident for opioids and corticosteroids. Indomethacin had the greatest overall impact on HRD ORs/AFs. Indomethacin (OR 1.40; 95 % confidence interval [CI] 1.27-1.54) and naproxen (OR 1.22; 1.14-1.31) were associated with higher risks of unplanned hospitalisation than other antirheumatics (overall OR 1.09; 1.06-1.12). Similarly, among cardiac rhythm regulators, amiodarone (OR 1.22; 1.13-1.32) was riskier than digoxin (OR 1.08; 1.04-1.13). For comparisons of drug-related hospitalisation estimates, temazepam yielded the greatest absolute increases, especially with hypertension drugs.

CONCLUSIONS

Indomethacin and temazepam should be prescribed cautiously in elderly patients, especially in drug combinations. Furthermore, it appears other antirheumatics should be favoured over indomethacin/naproxen and, in situations where both drugs may be appropriate, digoxin over amiodarone. Our methodology may help assess the safety of new medications in drug combinations in preliminary pharmacovigilance investigations.

The role of clinical decision support in pharmacist response to drug-interaction alerts

BACKGROUND

With over 100,000 different types of drug-drug interactions health care professionals rely heavily on automated drug-interaction alerts. Substantial variance in drug-interaction alerts yields opportunities for the use of clinical decision support (CDS) as a potential benefit to pharmacists.

OBJECTIVE

The purpose of this research was to determine whether decision support during dispensing impacts pharmacist response to drug-interaction alerts.

METHODS

A brief survey was administered to pharmacists in the community consisting of three patient cases, each containing three drug-drug interactions of varying severity. For each interaction, pharmacists were asked how they would respond, one group of pharmacists was randomly assigned to receive CDS while the other group did not.

RESULTS

There were no significant differences in pharmacist response to alerts between the two groups. The control group did appear to be more likely to consult a drug reference, but this difference was not significant. While this study did not demonstrate a significant difference, drug-interaction alerts are still an area where improvements could be made. Advancements have the potential to reduce risk to patients and limit unnecessary hospital admissions.

CONCLUSION

This study suggests that this level of clinical decision support has limited impact, but may prove beneficial by reducing the need to consult additional references.

Severity and management of drug-drug interactions in acute geriatric patients

BACKGROUND

Previous studies have investigated the prevalence of drug-drug interactions (DDIs) among the elderly in different care settings, but data describing the frequency and management of DDIs among acute geriatric patients appear to be absent.

OBJECTIVE

The aim of this study was to investigate the severity and interdisciplinary management of DDIs in patients admitted to an acute geriatric ward.

METHODS

The study was conducted at Oslo University Hospital, Norway, over a period of 19 weeks in 2010/11. On admission and daily during the hospital stay, prescribed medications were reviewed by pharmacists to identify DDIs with the aid of web-based databases. DDIs defined to be of potential clinical relevance, i.e., those classified as "major" (generally avoid) or "moderate" (precautions recommended), were following assessments by pharmacists presented at interdisciplinary meetings with geriatricians and nurses, and discussed in relation to the possible implementation of monitoring actions or changes in prescribing. The odds for prescribing changes were compared in relation to DDI type ("pharmacokinetic" vs. "pharmacodynamic") and severity ("major" vs. "moderate"). The project group retrospectively assessed the possible causal relationships between hospitalizations and DDIs.

RESULTS

The pharmacists identified 245 DDIs of major (n = 13) or moderate (n = 232) severity in 80 (63.5 %) of the 126 patients included on admission and/or during hospitalization. In 94 of 162 cases where the pharmacists alerted the geriatricians (58.0 %), prescribing changes or monitoring actions were implemented. Prescribing changes (n = 38) were performed significantly more often for major than for moderate DDIs [odds ratio (OR) 3.8; 95 % confidence interval (CI) 1.2-12.2, p = 0.03], and significantly more often for pharmacokinetic than for pharmacodynamic DDIs (OR 4.9; 95 % CI 2.2-10.9, p < 0.01). For 28 of 126 patients (22.2 %), a causal relationship between hospitalizations and DDIs was assessed as "possible".

CONCLUSIONS

The present study shows that acute geriatric patients are frequently exposed to DDIs for which active management is recommended in order to avoid unfavorable clinical outcomes. The integration of pharmacists into interdisciplinary teams could prevent potentially severe DDIs in the elderly.

Options for treating postherpetic neuralgia in the medically complicated patient

Patients with postherpetic neuralgia (PHN) are often of advanced age or immunocompromised and likely to have ≥1 comorbid medical condition for which they receive ≥1 medication (polypharmacy). Comorbidities affecting renal or hepatic function can alter pharmacokinetics, thereby impacting the efficacy or tolerability of PHN analgesic therapies. Cardiovascular, cerebrovascular, or psychiatric comorbidities may increase patient vulnerability to potential adverse events associated with some PHN analgesic therapies. Because PHN is a localized condition, localized therapy with a topical analgesic (lidocaine patch 5% and capsaicin 8% patch or cream) may provide adequate efficacy while mitigating the risk of systemic adverse events compared with oral analgesics (eg, tricyclic antidepressants, anticonvulsants, opioids). However, combined therapy with a topical and an oral analgesic or with >1 oral analgesic may be needed for optimal pain management in some patients. This review summarizes how comorbidities and concomitant medications should be taken into account when selecting among available pharmacotherapies for PHN and provides recommendations for the selection of therapies that will provide analgesia while minimizing the risk of adverse events.

Estimating renal function to reduce the risk of adverse drug reactions

The aging process is characterized by relevant changes in pharmacokinetics. Renal function is known to decline with aging. However, as a result of reduced muscle mass, older individuals frequently have a depressed glomerular filtration rate (GFR) despite normal serum creatinine, and such a concealed renal insufficiency may impact significantly on the clearance of hydrosoluble drugs, as well as the risk of adverse drug reactions (ADRs) from hydrosoluble drugs. The assessment of renal function should thus be a mandatory item in the global examination of patient characteristics. Equations for estimating GFR have become very popular in recent years. However, different equations may yield significantly different estimated glomerular filtration rate (eGFR) values, which have important implications in dosing drugs cleared by the kidney. Current knowledge suggests that eGFR based on the Chronic Kidney Disease-Epidemiological Collaboration (CKD-EPI) study equation outperformed eGFR based on the Modification of Diet in Renal Disease (MDRD) study equation and creatinine clearance estimate based on the Cockcroft-Gault formula as a predictor of ADRs from kidney cleared drugs. More recently, the combined creatinine-cystatin C equation was shown to perform better than equations based on either of these markers alone in diagnosing CKD, even in older patients. However, its accuracy in predicting ADRs and usefulness in drug dosing is still to be investigated.