Important drug-drug interactions in the elderly

Genetic and Epigenetic Host-Virus Network to Investigate Pathogenesis and Identify Biomarkers for Drug Repurposing of Human Respiratory Syncytial Virus via Real-World Two-Side RNA-Seq Data: Systems Biology and Deep-Learning Approach

Human respiratory syncytial virus (hRSV) affects more than 33 million people each year, but there are currently no effective drugs or vaccines approved. In this study, we first constructed a candidate host-pathogen interspecies genome-wide genetic and epigenetic network (HPI-GWGEN) via big-data mining. Then, we employed reversed dynamic methods via two-side host-pathogen RNA-seq time-profile data to prune false positives in candidate HPI-GWGEN to obtain the real HPI-GWGEN. With the aid of principal-network projection and the annotation of KEGG pathways, we can extract core signaling pathways during hRSV infection to investigate the pathogenic mechanism of hRSV infection and select the corresponding significant biomarkers as drug targets, i.e., TRAF6, STAT3, IRF3, TYK2, and MAVS. Finally, in order to discover potential molecular drugs, we trained a DNN-based DTI model by drug-target interaction databases to predict candidate molecular drugs for these drug targets. After screening these candidate molecular drugs by three drug design specifications simultaneously, i.e., regulation ability, sensitivity, and toxicity. We finally selected acitretin, RS-67333, and phenformin to combine as a potential multimolecule drug for the therapeutic treatment of hRSV infection.

Drug-Drug Interactions and the Risk of Emergency Hospitalizations: A Nationwide Population-Based Study

BACKGROUND

Several studies suggest a significant risk of hospitalization because of drug-drug interactions in the general population. However, to our knowledge, this risk has never been measured precisely in a large population.

OBJECTIVE

We aimed to estimate the risk of emergency hospitalization associated with exposure to the contraindicated concomitant use of interacting drugs in the general population.

METHODS

A self-controlled case-series analysis was carried out on a cohort of 150,000 subjects randomly selected from the French national health insurance database, between 01/01/2016 and 31/12/2016. Exposure to the contraindicated concomitant use of interacting drugs was defined as the overlapping period of dispensings of drugs contraindicated because of clinically meaningful drug-drug interactions. The main outcome, incidence rate ratios, comparing the incidence rate of emergency hospitalizations during each category of exposure time periods with that during the reference period, was estimated using the conditional Poisson regression model.

RESULTS

Over the study period, 967 subjects were exposed to at least one contraindicated concomitant use of interacting drug and 177 had been exposed and presented at least one emergency hospitalization. Compared to the unexposed follow-up time, the risk of emergency hospitalization increased during exposure to contraindicated concomitant use of interacting drug periods (incidence rate ratio: 2.41; 95% confidence interval 1.55-3.76). This could translate into 7200 (4500-8900) potentially preventable emergency hospitalizations yearly in France.

CONCLUSIONS

We evidenced an almost 2.5-fold increase in the risk of emergency hospitalizations during periods of exposure to contraindicated concomitant use of interacting drugs, with a potential public health impact exceeding 7000 preventable hospitalizations yearly in France. These results confirm the need to reinforce training in prescription practices and tools for prevention concerning contraindicated concomitant use of interacting drugs. These would especially concern drugs involved in an increase in long QT syndrome when associated such as citalopram, and highly prescribed drugs with a risk of overdose if co-prescribed with cytochrome P450 inhibitors, such as antigout and lipid-lowering drugs.

Sociodemographic and Health-Related Factors Influencing Drug Intake among the Elderly Population

Excessive drugs intake among the elderly population, including self-medication, constitutes an important public health problem. Polypharmacy may lead to numerous adverse health effects, which become more prevalent when combined with biological changes in seniors. In this cross-sectional study, 500 Polish adults aged ≥60 years (M = 67.9 ± 4.2) were asked to complete a questionnaire via telephone calls, allowing us to identify sociodemographic and health-related factors influencing the daily medications consumption. Our findings revealed that all of the participants were receiving medications; 60.2% of them receive at least 1 to 3 drugs per day (301/500). The most commonly used medications included antihypertensive drugs and analgesics (51.0% and 46.0%, respectively). Taking into account clinical conditions, independent predictors of receiving over 3 medications per day turned out to be (1) coronary artery disease (OR = 6.77; CI 95%, 2.86–16.1), (2) diabetes (OR = 3.23, CI 95%, 1.75–5.95), (3) asthma (OR = 4.87, CI 95%, 2.13–11.1), (4) heart failure (OR = 3.38, CI 95%, 1.59–7.19) and (5) gastroesophageal reflux disease (OR = 1.93, CI 95%, 1.03–3.62). Participants suffering from depression were more likely to take drugs for hypertension (OR = 1.70, CI 95%, 1.04–2.78), while those with anxiety and social loneliness took more painkillers (OR = 2.59, CI 95%, 1.58–4.26 and OR = 2.08, CI 95%, 1.38–3.13, respectively). The most significant sociodemographic factors increasing the drugs intake among the population included in our study were high body mass and subsequent increased BMI values (OR = 2.68, CI 95%, 1.50–4.77). Furthermore, living in a city with over 400,000 inhabitants increased the likelihood of taking antidepressants (OR = 2.18, CI 95%, 1.20–3.94). Our study revealed factors increasing the risk of excessive medications intake and hence, increased susceptibility to some iatrogenic diseases among the elderly population. These factors should be considered by primary care physicians while prescribing appropriate drugs to elderly patients.

Emergency room admissions induced by drug-drug interactions in the elderly: a cross-sectional study

The elderly people are increasingly exposed to polymedication and therefore to the risks of drug–drug interactions (DDIs). However, there are few data available on the clinical consequences of these drug combinations. We investigated the impact of the various DDIs classified as severe in terms of emergency admissions in the elderly. A cross‐sectional study was conducted using information from the emergency department admissions of Bordeaux University Hospital between September 2016 and August 2017. Events of interest were frequency of concomitant uses of interacting drugs that are contraindicated or warned against and frequency of emergency admissions due to contraindicated or warned against concomitant uses of interacting drugs. Five thousand, eight hundred sixty (5860) admissions to the emergency department were analyzed. A total of 375 (6.4%) contraindicated or warned against concomitant uses were identified, including 163 contraindicated (43.5%) and 212 warned against (56.5%). Reason for admission appeared likely related to the underlying DDI in 58 cases. Within these, 36 admissions were assessed as probably due to a DDI (0.6% of hospitalizations) and 22 as certainly (0.4% of hospitalizations). Of these, there were 24 (45%) admissions related to a long QT syndrome (LQTS), nine (16%) related to a drug overdose, and eight (14%) related to a hemorrhage. An antidepressant was involved in 22 of the 24 cases of LQTS. Seven of the eight cases of hemorrhage involved the antithrombotic agents / non‐steroidal anti‐inflammatory drugs combination. Elderly patients admitted to emergency departments are particularly exposed to high‐risk potential DDIs. These drug combinations lead mainly to LQTS and involve certain antidepressants.

Therapeutic Drug Monitoring of Second- and Third-Generation Antipsychotic Drugs-Influence of Smoking Behavior and Inflammation on Pharmacokinetics

Both inflammation and smoking can influence a drug’s pharmacokinetic properties, i.e., its liberation, absorption, distribution, metabolism, and elimination. Depending on, e.g., pharmacogenetics, these changes may alter treatment response or cause serious adverse drug reactions and are thus of clinical relevance. Antipsychotic drugs, used in the treatment of psychosis and schizophrenia, should be closely monitored due to multiple factors (e.g., the narrow therapeutic window of certain psychotropic drugs, the chronicity of most mental illnesses, and the common occurrence of polypharmacotherapy in psychiatry). Therapeutic drug monitoring (TDM) aids with drug titration by enabling the quantification of patients’ drug levels. Recommendations on the use of TDM during treatment with psychotropic drugs are presented in the Consensus Guidelines for Therapeutic Drug Monitoring in Neuropsychopharmacology; however, data on antipsychotic drug levels during inflammation or after changes in smoking behavior—both clinically relevant in psychiatry—that can aid clinical decision making are sparse. The following narrative review provides an overview of relevant literature regarding TDM in psychiatry, particularly in the context of second- and third-generation antipsychotic drugs, inflammation, and smoking behavior. It aims to spread awareness regarding TDM (most pronouncedly of clozapine and olanzapine) as a tool to optimize drug safety and provide patient-tailored treatment.

Therapeutic Drug Monitoring of Second- and Third-Generation Antipsychotic Drugs—Influence of Smoking Behavior and Inflammation on Pharmacokinetics

Both inflammation and smoking can influence a drug’s pharmacokinetic properties, i.e., its liberation, absorption, distribution, metabolism, and elimination. Depending on, e.g., pharmacogenetics, these changes may alter treatment response or cause serious adverse drug reactions and are thus of clinical relevance. Antipsychotic drugs, used in the treatment of psychosis and schizophrenia, should be closely monitored due to multiple factors (e.g., the narrow therapeutic window of certain psychotropic drugs, the chronicity of most mental illnesses, and the common occurrence of polypharmacotherapy in psychiatry). Therapeutic drug monitoring (TDM) aids with drug titration by enabling the quantification of patients’ drug levels. Recommendations on the use of TDM during treatment with psychotropic drugs are presented in the Consensus Guidelines for Therapeutic Drug Monitoring in Neuropsychopharmacology; however, data on antipsychotic drug levels during inflammation or after changes in smoking behavior—both clinically relevant in psychiatry—that can aid clinical decision making are sparse. The following narrative review provides an overview of relevant literature regarding TDM in psychiatry, particularly in the context of second- and third-generation antipsychotic drugs, inflammation, and smoking behavior. It aims to spread awareness regarding TDM (most pronouncedly of clozapine and olanzapine) as a tool to optimize drug safety and provide patient-tailored treatment.

Therapeutic Drug Monitoring of Second- and Third-Generation Antipsychotic Drugs-Influence of Smoking Behavior and Inflammation on Pharmacokinetics

Both inflammation and smoking can influence a drug's pharmacokinetic properties, i.e., its liberation, absorption, distribution, metabolism, and elimination. Depending on, e.g., pharmacogenetics, these changes may alter treatment response or cause serious adverse drug reactions and are thus of clinical relevance. Antipsychotic drugs, used in the treatment of psychosis and schizophrenia, should be closely monitored due to multiple factors (e.g., the narrow therapeutic window of certain psychotropic drugs, the chronicity of most mental illnesses, and the common occurrence of polypharmacotherapy in psychiatry). Therapeutic drug monitoring (TDM) aids with drug titration by enabling the quantification of patients' drug levels. Recommendations on the use of TDM during treatment with psychotropic drugs are presented in the Consensus Guidelines for Therapeutic Drug Monitoring in Neuropsychopharmacology; however, data on antipsychotic drug levels during inflammation or after changes in smoking behavior-both clinically relevant in psychiatry-that can aid clinical decision making are sparse. The following narrative review provides an overview of relevant literature regarding TDM in psychiatry, particularly in the context of second- and third-generation antipsychotic drugs, inflammation, and smoking behavior. It aims to spread awareness regarding TDM (most pronouncedly of clozapine and olanzapine) as a tool to optimize drug safety and provide patient-tailored treatment.

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.

Prevalence and sort of pharmacokinetic drug-drug interactions in hospitalized psychiatric patients

Psychiatric patients are high-risk patients for the development of pharmacokinetic drug-drug interactions (DDIs), leading to highly variable (victim) drug serum concentrations. Avoiding and targeting high-risk drug combinations could reduce preventable adverse drug reactions (ADRs). Pharmacokinetic cytochrome P450 (CYP)-mediated DDIs are often predictable and, therefore, preventable. The retrospective, longitudinal analysis used informations from a large pharmacovigilance study (Optimization of pharmacological treatment in hospitalized psychiatric patients study, study number 01VSF16009, 01/2017), conducted in 10 psychiatric hospitals in Germany. Medication data were examined for the co-prescription of clinically relevant CYP inhibitors or inducers and substrates of these enzymes (victim drugs). In total, data from 27,396 patient cases (45.6% female) with a mean (mean ± standard deviation (SD)) age of 47.3 ± 18.3 years were available for analysis. CYP inhibitors or inducers were at least once prescribed in 14.4% (n = 3946) of the cases. The most frequently prescribed CYP inhibitors were melperone (n = 2504, 28.1%) and duloxetine (n = 1324, 14.9%). Overall, 51.0% of the cases taking melperone were combined with a victim drug (n = 1288). Carbamazepine was the most frequently prescribed CYP inducer (n = 733, 88.8%). Combinations with victim drugs were detected for 58% (n = 427) of cases on medication with carbamazepine. Finally, a DDI was detected in 43.6% of the cases in which a CYP inhibitor or inducer was prescribed. The frequency of CYP-mediated DDI is considerably high in the psychiatric setting. Physicians should be aware of the CYP inhibitory and inducing potential of psychotropic and internistic drugs (especially, melperone).

Polypharmacy and drug-drug interactions among older and younger male prisoners in Switzerland

PURPOSE

The purpose of this paper is to determine the prevalence of polypharmacy and drug-drug interactions (DDIs) in older and younger prisoners, and compared if age group is associated with risks of polypharmacy and DDIs.

DESIGN/METHODOLOGY/APPROACH

For 380 prisoners from Switzerland (190 were 49 years and younger; 190 were 50 years and older), data concerning their medication use were gathered. MediQ identified if interactions of two or more substances could lead to potentially adverse DDI. Data were analysed using descriptive statistics and generalised linear mixed models.

FINDINGS

On average, older prisoners took 3.8 medications, while younger prisoners took 2.1 medications. Number of medications taken on one reference day was higher by a factor of 2.4 for older prisoners when compared to younger prisoners (p = 0.002). The odds of polypharmacy was significantly higher for older than for younger prisoners (>=5 medications: odds ratio = 5.52, p = 0.035). Age group analysis indicated that for potentially adverse DDI there was no significant difference (odds ratio = 0.94; p = 0.879). However, when controlling for the number of medication, the risk of adverse DDI was higher in younger than older prisoners, but the result was not significant.

ORIGINALITY/VALUE

Older prisoners are at a higher risk of polypharmacy but their risk for potentially adverse DDI is not significantly different from that of younger prisoners. Special clinical attention must be given to older prisoners who are at risk for polypharmacy. Careful medication management is also important for younger prisoners who are at risk of very complex drug therapies.

Atopic Keratoconjunctivitis: Pharmacotherapy for the Elderly

Among the different forms of allergic conjunctivitis, atopic keratoconjunctivitis has distinct characteristics, defined by a more common onset in late adolescence or early adulthood, but also affecting the elderly, and with a higher prevalence in male individuals. However, the prevalence of atopic keratoconjunctivitis is scarcely investigated, and the data are often uncertain because other allergic nasal or respiratory disorders occur concomitantly. Mast cells, eosinophils, basophils, and T cells are involved in the pathogenesis of atopic keratoconjunctivitis. Despite its denomination as atopic, negative responses to skin tests or in-vitro immunoglobulin E tests are common. In fact, atopic keratoconjunctivitis can be attributed to a combination of T-helper-1 and T-helper-2 responses, but a higher prominence for T-helper-1 cells was found. The most common symptoms of atopic keratoconjunctivitis are bilateral ocular itching, burning, and tearing with a perennial presentation, although some patients may have seasonal exacerbations in winter or summer. Other symptoms such as photophobia, blurred vision, and mucous chewy discharge, owing to the accumulation of cells and mucin, may occur. The diagnosis of atopic keratoconjunctivitis is mainly clinical, as accepted diagnostic criteria or laboratory tests are not available. The treatment of atopic keratoconjunctivitis is aimed at controlling symptoms, decreasing relapse and exacerbations, and reducing vision loss. Therapeutic options comprise topical ophthalmic drops, including cromones, antihistamines, corticosteroids, and calcineurin inhibitors. Topical ointments are also available for corticosteroids and calcineurin inhibitors. Severe forms may require systemic medications including antihistamines, corticosteroids, and calcineurin inhibitors. Atopic keratoconjunctivitis therapy in the elderly does not differ from the adult population, but the occurrence of multi-morbidities and concomitant drug treatment, which are common in this age group, requires a careful evaluation to determine appropriate and personalized treatment.

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.

Patient's lack of understanding producing insulin drug-interactions in Southeast Brazilian primary care clinics

Detrimental drug-drug interactions (DDIs) in Diabetic patients could be from the simultaneous use of multiple drugs, polypharmacy. Brazilian public health studies evaluating the practical knowledge about drug interactions are scarce. This study's objective is to identify drug interactions and prevalence of detrimental DDIs in diabetic patients attending Brazilian basic health system clinics.

METHODS

Patients using insulin between the age of 18-90 years were selected to complete the MedTake questionnaire, to evaluate the indication, dosage, regimen and drug interaction. The MedTake test was employed. For each medicine, the test was scored as the percentage of correct actions and compared with printed instructions one single researcher downloaded all the data was from the municipality's computerized system.

RESULTS

The median age of recruits was 60.2 ± 14.3 and MedTake test scores were low 60.3 ± 20. One hundred patients missed the correct dose question, 40 missed why they were prescribed the drug, indication and 65 missed the therapeutic regimen. These diabetes patients did not know the DDIs between insulin combined with other medicines. Drugs that had more interaction with insulin were: acetylsalicylic acid (40%), enalapril (18%), losartan (32%) and hydrochlorothiazide (23%).

CONCLUSIONS

Diabetes patients without practical knowledge about insulin interacting with other pharmaceutical drugs that can produce DDIs with other medicines illustrates a need to develop education programs for diabetics.

DMMS: A Decentralized Blockchain Ledger for the Management of Medication Histories

Background

Access to accurate and complete medication histories across healthcare institutions enables effective patient care. Histories across healthcare institutions currently rely on centralized systems for sharing medication data. However, there is a lack of efficient mechanisms to ensure that medication histories transferred from one institution to another are accurate, secure, and trustworthy.

Methods

In this article, we introduce a decentralized medication management system (DMMS) that leverages the advantages of blockchain to manage medication histories. DMMS is realized as a decentralized network under the hyperledger fabric framework. Based on the network, we designed an architecture, within which each prescriber can create prescriptions for each patient and perform queries about historical prescriptions accordingly. finally, we analyzed the advantages of DMMS over centralized systems in terms of accuracy, security, trustworthiness, and privacy.

Results

We developed a proof of concept to showcase DMMS. In this system, a prescriber prescribes medications for a patient and then encrypts the prescriptions via the patient's public keys. Patients can query their own prescriptions from different histories across healthcare institutions and then decrypt the prescriptions via their private keys. At the same time, a prescriber can query a patient's prescription records across healthcare institutions after approval from the patient. Analytic results show that DMMS can improve security, trustworthiness, and privacy in medication history sharing and exchanging across healthcare institutions. In addition, we discuss the potential for DMMS in e-prescribing markets.

Conclusions

This study shows that a distributed secure ledger can enable reliable, interoperable, and accurate medication history sharing.

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.

Clinically relevant drug-drug interactions among elderly people with dementia

Purpose

Increased numbers of drugs and changes in pharmacokinetic and pharmacodynamic parameters among elderly people contribute to increased prevalence of adverse drug reactions. Drug–drug interactions (DDIs) are an important reason for admission to hospital and elderly people with dementia are particularly vulnerable. The aims of the present study were to assess the occurrence and characteristics of clinically relevant DDIs and to investigate potential risk factors associated with DDIs among elderly people with dementia.

Methods

People ≥ 65 years with dementia, admitted to two hospitals in Northern Sweden, were included. The medical records of 458 patients were reviewed. Clinically relevant DDIs were identified using the Janusmed interactions database. Pharmacological classification was conducted using Stockley’s classification system.

Results

A total of 401 DDIs were identified among 43.2% of the study population, of which 98.5% had interactions that may require dose adjustment and 7.6% had drug combinations that should be avoided. Pharmacodynamic interactions were most common, of which furosemide–citalopram (n = 35) were most frequently observed. Omeprazol–citalopram (n = 25) was the most common drug combination among pharmacokinetic interactions. Citalopram and warfarin were the most commonly involved drug substances. An association was found between a higher number of medications being prescribed and having at least one DDI.

Conclusion

Clinically relevant drug–drug interactions are prevalent among elderly people with dementia living in Northern Sweden. Drug–drug interactions should be identified in order to manage and prevent adverse outcomes. This is particularly important among this group of people especially when multiple medications are being prescribed.

Phenobarbital Treatment at a Neonatal Age Results in Decreased Efficacy of Omeprazole in Adult Mice

Drug-drug interactions (DDIs) occur when the action of one drug interferes with or alters the activity of another drug taken concomitantly. This can lead to decreased drug efficacy or increased toxicity. Because of DDIs, physicians in the clinical practice attempt to avoid potential interactions when multiple drugs are coadministrated; however, there is still a large knowledge gap in understanding how drugs taken in the past can contribute to DDIs in the future. The goal of this study was to investigate the consequence of neonatal drug exposure on efficacy of other drugs administered up through adult life. We selected a mouse model to test phenobarbital exposure at a neonatal age and its impact on efficacy of omeprazole in adult life. The results of our experiment show an observed decrease in omeprazole's ability to raise gastric pH in adult mice that received single or multiple doses of phenobarbital at a neonatal age. This effect may be associated with the permanent induction of cytochrome P450 enzymes in adult liver after neonatal phenobarbital treatment. Our data indicates that DDIs may result from drugs administered in the past in an animal model and should prompt re-evaluation of how DDIs are viewed and how to avoid long-term DDIs in clinical practice.

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.

Long-Term Use of Cardiovascular Drugs: Challenges for Research and for Patient Care

Little is known about the benefits and risks of the long-term use of cardiovascular drugs. Evidence from randomized clinical trials (RCTs) rarely goes beyond a few years of follow-up, but patients are often given continuous treatment with multiple drugs well into old age. We focus on 4 commonly used cardiovascular drug classes: aspirin, statins, beta-blockers, and angiotensin-converting enzyme inhibitors given to patients after myocardial infarction. However, the issues raised apply more broadly to all long-term medications across cardiovascular diseases and the whole of medicine. The evidence and limitations of RCTs are addressed, as well as current practice in pre-licensing trials, the increasing problems of polypharmacy (especially in the elderly), the lack of trial evidence for withdrawal of drugs, the role of regulatory authorities and other stakeholders in this challenging situation, and the potential educational solutions for the medical profession. We conclude with a set of recommendations on how to improve the situation of long-term drug use.

Prevalence and impact of fall-risk-increasing drugs, polypharmacy, and drug-drug interactions in robust versus frail hospitalised falls patients: a prospective cohort study

BACKGROUND

Several measures of medication exposure are associated with adverse outcomes in older people. Exposure to and the clinical outcomes of these measures in robust versus frail older inpatients are not known.

OBJECTIVE

In older robust and frail patients admitted to hospital after a fall, we investigated the prevalence and clinical impact of fall-risk-increasing drugs (FRIDs), total number of medications, and drug-drug interactions (DDIs).

METHODS

Patients ≥60 years of age admitted with a fall to a tertiary referral teaching hospital in Sydney were recruited and frailty was assessed. Data were collected at admission, discharge, and 2 months after admission.

RESULTS

A total of 204 patients were recruited (mean age 80.5 ± 8.3 years), with 101 robust and 103 frail. On admission, compared with the robust, frail participants had significantly higher mean ± SD number of FRIDs (frail 3.4 ± 2.2 vs. robust 1.6 ± 1.5, P < 0.0001), total number of medications (9.8 ± 4.3 vs. 4.4 ± 3.3, P < 0.0001), and DDI exposure (35 vs. 5 %, P = 0.001). Number of FRIDs on discharge was significantly associated with recurrent falls [odds ratio (OR) 1.7 (95 % confidence interval [CI] 1.3-2.1)], which were most likely to occur with 1.5 FRIDs in the frail and 2.5 FRIDs in the robust. Number of medications on discharge was also associated with recurrent falls [OR 1.2 (1.0-1.3)], but DDIs were not.

CONCLUSION

Exposure to FRIDs and other measures of high-risk medication exposures is common in older people admitted with falls, especially the frail. Number of FRIDs and to a lesser extent total number of medicines at discharge were associated with recurrent falls.

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.

Actual drug-drug interactions in elderly patients discharged from internal medicine clinic: a prospective observational study

PURPOSE

The aim of the study was to evaluate the incidence and type of actual drug-drug interactions (DDIs) that result in adverse drug reactions (ADRs) or diminished therapeutic effect in elderly patients within 30 days of discharge from an internal medicine clinic.

METHODS

A prospective observational study was conducted at the Internal Medicine Clinic of University Hospital Dubrava, Zagreb, Croatia, between October and December 2011. Patients aged ≥ 65 years discharged from the Internal Medicine Clinic during the study period with a prescription for two or more medications were eligible for inclusion in the study. A total of 222 patients were ultimately enrolled in the study. For each patient, potential DDIs were identified using Lexi-Interact software. The follow-up visit was scheduled approximately 30 days after discharge. Causality between DDIs and ADRs or diminished therapeutic effect of drugs was assessed by two independent clinicians.

RESULTS

Potential DDIs were identified in 190 (85.6 %) patients. Actual DDIs were detected in 21 (9.5 %) patients. In 19 patients, DDIs resulted in an ADR. Diminished therapeutic effect resulting from DDIs was detected in two patients. Angiotensin-converting enzyme inhibitors were the drug class most frequently associated with DDI-related ADRs.

CONCLUSIONS

A significant incidence of actual DDIs suggests that DDIs play an important role in patient safety. Drug therapy should be initiated if absolutely necessary, and the number of drugs used to treat elderly patients should be minimized to reduce the incidence of DDI-related adverse patient outcomes.

Pharmacotherapy of heart failure in the elderly: adverse events

Aging is associated with numerous alterations in body composition and organ function that result in substantial changes in the absorption, distribution, metabolism, and elimination of virtually all drugs. In addition, older patients with heart failure (HF) almost invariably have multiple coexisting medical conditions for which they are receiving medications. This article reviews common adverse drug effects and drug interactions associated with HF therapy in older patients and discusses strategies for reducing the risk of adverse drug events. In order to minimize these risks, it is essential that clinicians avoid prescribing unnecessary medications, adjust medication dosages to optimally balance benefits and side effects, and remain ever vigilant to the potential for medications to cause or contribute to clinically important adverse events and impaired quality of life. In treating older HF patients, the oft-cited dictum "start low, go slow" clearly applies. Despite the inherent challenges, with careful management and close follow-up, most older HF patients can be successfully treated through the judicious use of guideline-recommended HF therapies.

Potential drug-drug interactions in prescriptions to patients over 45 years of age in primary care, southern Brazil

BACKGROUND

Few cross-sectional studies involving adults and elderly patients with major DDIs have been conducted in the primary care setting. The study aimed to investigate the prevalence of potential drug-drug interactions (DDIs) in patients treated in primary care.

METHODOLOGY/PRINCIPAL FINDINGS

A cross-sectional study involving patients aged 45 years or older was conducted at 25 Basic Health Units in the city of Maringá (southern Brazil) from May to December 2010. The data were collected from prescriptions at the pharmacy of the health unit at the time of the delivery of medication to the patient. After delivery, the researcher checked the electronic medical records of the patient. A total of 827 patients were investigated (mean age: 64.1; mean number of medications: 4.4). DDIs were identified in the Micromedex® database. The prevalence of potential DDIs and major DDIs was 63.0% and 12.1%, respectively. In both the univariate and multivariate analyses, the number of drugs prescribed was significantly associated with potential DDIs, with an increasing risk from three to five drugs (OR = 4.74; 95% CI: 2.90-7.73) to six or more drugs (OR = 23.03; 95% CI: 10.42-50.91). Forty drugs accounted for 122 pairs of major DDIs, the most frequent of which involved simvastatin (23.8%), captopril/enalapril (16.4%) and fluoxetine (16.4%).

CONCLUSIONS/SIGNIFICANCE

This is the first large-scale study on primary care carried out in Latin America. Based on the findings, the estimated prevalence of potential DDIs was high, whereas clinically significant DDIs occurred in a smaller proportion. Exposing patients to a greater number of prescription drugs, especially three or more, proved to be a significant predictor of DDIs. Prescribers should be more aware of potential DDIs. Future studies should assess potential DDIs in primary care over a longer period of time.

Anticholinergics in palliative medicine: an update

Anticholinergics, or antimuscarinic drugs, are drugs that competitively inhibit the action of acetylcholine at muscarinic receptors, leading to a blockade of the actions of the parasympathetic nervous system at sites where overactivity can lead to increased symptom burden. Successful blockade of the parasympathetic nervous system ultimately leads to decreased production of secretions in the salivary, bronchial, and gastrointestinal tracts. These effects are often used for several symptoms that originate due to parasympathetic nervous system overactivity, such as the "death rattle" and malignant bowel obstruction. Anticholinergic agents are divided into either tertiary amines or quaternary ammonium compounds, which differ in their ability to cross into the central nervous system. Quaternary compounds do not cross into the central nervous system and have a different adverse effect profile than the tertiary amines. The purpose of this review is to highlight anticholinergic agents, their pharmacology, and an evidence-based assessment of their role in palliative care.

Assessment of pharmacotherapeutic safety of medical prescriptions for elderly residents in a long-term care facility

The present study aimed to estimate the prevalence of elderly using potentially inappropriate medications (PIM) and with occurrence of potentially hazardous drug interactions (PHDI); to identify the risk factors for the prescription of PIM and to evaluate the impact of pharmaceutical intervention (PI) for the prescription of safer therapeutic alternatives. Therefore, a cross-sectional study was performed in a long-term care facility in São Paulo State, between December/2010 and January/2011. The medical records of the patients >60 years old who took any drugs were consulted to assess the pharmacotherapeutic safety of the medical prescriptions, in order to identify PIM and PHDI, according to the Beers (2003) and World Health Organization criteria, respectively. PI consisted of a guidance letter to the physician responsible for the institution, with the suggestions of safer equivalent therapeutics. Approximately 88% of the elderly took at least one drug, and for 30% of them the PIM had been prescribed. Most of the PIM identified (53.4%) act on the central nervous system. Among the 13 different DI detected, 6 are considered PHDI. Polypharmacy was detected as a risk factor for PIM prescription. After the PI there was no change in medical prescriptions of patients who had been prescribed PIM or PHDI. The data suggests that PI performed by letter, as the only interventional, method was ineffective. To contribute it a wide dissemination of PIM and PHDI among prescriber professionals is necessary for the selection of safer treatment for elderly. Additionally, a pharmacist should be part of the health care team in order to help promote rational use of medicines.

Interventions to improve anticoagulation with warfarin

INTRODUCTION

This study aimed to investigate potential drug-drug interactions (pDDIs) with warfarin to minimize them, assess the acceptability of pharmaceutical interventions by the medical team and the impact on the international normalized ratio (INR) results.

METHODS

This pertains to a prospective study involving inpatients who started warfarin therapy in a university hospital located in southern Brazil. The pDDIs with warfarin were identified using the interaction screening program Drug-Reax, Micromedex Healthcare Series 1.0.

RESULTS

Two hundred and two inpatients were monitored. The mean of 10 different drugs was prescribed for each patient (SD = 3.6). At least 1 major or moderate pDDIs with warfarin per patient was observed, the mean was 3.6 (SD = 1.6). The most common pDDIs with warfarin involved in the increase of anticoagulation effect were enoxaparin (32.2%), simvastatin (27.6%), omeprazole (22.5%), and tramadol (21.5%). For 32 patients (15.8%), interventions were rejected, and they had a higher risk (relative risk= 2.17; 95% confidence interval 1.10-4.27) for abnormal test results (INR > 5). Multivariate analysis showed that age, length of hospital stay, exposure to ≥4 major or moderate pDDIs, and refusal of pharmacist recommendations contribute significantly to the patient's INR result >5. Consequently, the risk of bleeding is increased.

CONCLUSIONS

Major and moderate pDDIs with warfarin are very common in inpatients and are associated with INR results outside the therapeutic range. Pharmaceutical interventions concerning the management of interactions by providing information to physicians can improve the patient safety.

Implementation of a personal medication record program in an independent living facility

OBJECTIVE

To describe the process of implementing a "Vial of Life" [Lifesaving Information for Emergencies] program in an independent living facility.

SETTING

An independent living facility in the Richmond, Virginia, area.

PRACTICE DESCRIPTION

The average age of the residents is 79.75 years, with 75% of the population being female. The facility offers social, cultural, and recreational activities, health and wellness programs, a salon, and outdoor activities.

PRACTICE INNOVATION

Implementing the Vial of Life Project into an independent living facility.

MAIN OUTCOME MEASUREMENTS

The number of patients who have participated in the Vial of Life Project; the implementation experience and student exposure to the implementation process.

RESULTS

There were 12 residents out of 83 total who elected to receive the service from a pharmacist. This resulted in a 14.45% participation rate. In addition, the faculty and students were exposed to the program and its implementation in an independent living facility.

CONCLUSION

The Vial of Life Project has allowed for increase in access to the pharmacist for education and medication reviews.

Aging and antihypertensive medication-related complications in the chronic kidney disease patient

PURPOSE OF REVIEW

We have reviewed the recent literature to describe the potential medication errors and adverse drug events (ADEs) associated with antihypertensives among older adults with chronic kidney disease (CKD).

RECENT FINDINGS

Overall, few studies have been published describing ADEs in older adults with CKD. Several examined hyperkalemia associated with angiotensin-converting enzyme (ACE)-inhibitor/angiotensin II receptor blocker (ARB), diuretic (potassium-sparing), and β-blocker use. Additional studies described acute kidney injury (AKI) most commonly with ACE-inhibitor/ARB therapy. Finally, orthostatic hypotension was evaluated in those taking ACE-inhibitor/ARB, β-blocker, or calcium-channel blocker therapy. In the absence of robust literature examining these events in this understudied population, one must consider age-related antihypertensive pharmacokinetic/pharmacodynamic profiles concomitantly with the patient's comorbidities and other medications in order to minimize the risk for potential medication errors, drug-drug interactions, and ADEs.

SUMMARY

Some of the most common ADEs associated with antihypertensive use in older adults with CKD include hyperkalemia, AKI, and orthostatic hypotension. Diligent monitoring of laboratory data, vital signs, and potential drug-drug interactions may mitigate serious ADEs caused by antihypertensives in this high-risk patient population.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Allergic diseases in the elderly

Demographic distribution of the population is progressively changing with the proportion of elderly persons increasing in most societies. This entails that there is a need to evaluate the impact of common diseases, such as asthma and other allergic conditions, in this age segment. Frailty, comorbidities and polymedication are some of the factors that condition management in geriatric patients. The objective of this review is to highlight the characteristics of allergic diseases in older age groups, from the influence of immunosenescence, to particular clinical implications and management issues, such as drug interactions or age-related side effects.

Delivering domiciliary pharmaceutical care from a health centre pharmacy

Aim

To develop and administer a pharmacist domiciliary visiting programme from a community pharmacy based in a health centre.

Design

Prospective cohort with peer professional intervention assessment and patient feedback questionnaires.

Subjects and setting

Total general practitioner surgery list (4,922 patients) in an urban residential area. Candidates were defined by three inclusion criteria: 65 years or older taking five or more repeat medicines (polypharmacy); any age plus polypharmacy plus significant disablement; 80 years or older taking three or more specified medications on repeat prescription.

Outcome measures

Interventions made during a programme of three visits for each patient; peer assessment of impact on patient care and cost by the three surgery GPs and three clinical pharmacists; patients' perceived worth of the service; cost of the service.

Results

One hundred patients (2 per cent) were visited over a period of six months; 74 completed the three-visit programme that involved a total of 256 visits. There were 160 interventions classified as: medicines management issues (88), health beliefs and concordance (41) or therapeutic problems, including adverse effects (31). Nineteen patients required specific and detailed collaboration with the patient's GP. There was good agreement on the utility of the pharmacist's interventions at this level with only four negative assessments out of a possible 114 (3.5 per cent). The programme was well received by patients. Talking to a pharmacist (as opposed to another health care professional) about their medicines was important to 70 of 74 patients. Sixty-one described their reaction to the visiting programme using one of three positive adjectives, “relieved,” “reassured” or “grateful”. Based on this cohort, the estimated costs to the pharmacy were £5,000 per annum, equivalent to 33 working days. Cost savings based on outcomes were not estimated.

Conclusions

This study demonstrated the feasibility of identifying candidates for domiciliary care from surgery records using carefully selected inclusion criteria. This is likely to encompass between 2 and 3 per cent of a surgery population. The visiting programme, which was well received by patients, had a favourable effect on patient care in the majority of the cohort and a very important impact in a minority (19 per cent). This success required the commitment of all members of the health centre team. It benefited from the proximity of the visiting pharmacist to medical records and prescribers.

Occurrence of potential drug-drug interactions in nursing home residents

Objective

It has been suggested that elderly people are at increased risk of drug-related problems such as drug-induced adverse effects, drug-drug interactions and drug-disease interactions. This is particularly the case for nursing home residents because of the often complicated and multiple co-morbidity that occurs in these people. The aim of this study was to develop prescribing indicators to assess systematically the occurrence and nature of potential drug-drug interactions (DDIs) in a cohort of Dutch nursing home residents.

Method

The study was conducted in residents aged 65 years and over in six nursing homes (n=2,355, two-year study period). Computerised medication data for the residents were evaluated with respect to co-prescribing of potentially interacting drugs. All DDIs that were classified as clinically relevant according to the Dutch National Drug Interaction Database were studied. DDIs were classified into three categories according to their pharmacological mechanism: 1 — pharmacokinetic interactions at the level of gastrointestinal (GI) absorption; 2 — pharmacokinetic interactions at the level of metabolism and excretion; and 3 — pharmacodynamic interactions.

Key findings

Thirty-two per cent (n=748) of all residents were exposed to one or more combinations of drugs that could lead to clinically adverse outcomes. The numbers of residents who received drug combinations with a mechanism of interaction from category 1, 2 or 3 were 73 (3 per cent), 164 (7 per cent) and 612 (26 per cent) respectively. The number of medications prescribed was significantly associated with the occurrence of a potential DDI (P&lt;0.05). Drugs most frequently involved were oral anticoagulants, antibiotics and theophylline.

Conclusion

During the two-year study period, about one-third of the residents were exposed to at least one drug interaction considered clinically relevant. Adequate surveillance systems are needed to enable better identification of these interactions with a view to preventing potential clinical problems. Using the prescribing indicators developed in this study, such surveillance could focus on detection and clinical aspects of potential DDIs and possible alternative treatments.

Gender differences, polypharmacy, and potential pharmacological interactions in the elderly

OBJECTIVE

This study aims to analyze pharmacological interactions among drugs taken by elderly patients and their age and gender differences in a population from Porto Alegre, Brazil.

METHODS

We retrospectively analyzed the database provided by the Institute of Geriatric and Gerontology, Porto Alegre, Brazil. The database was composed of 438 elderly and includes information about the patients' disease, therapy regimens, utilized drugs. All drugs reported by the elderly patients were classified using the Anatomical Therapeutic and Chemical Classification System. The drug-drug interactions and their severity were assessed using the Micromedex® Healthcare Series.

RESULTS

Of the 438 elderly patients in the data base, 376 (85.8%) used pharmacotherapy, 274 were female, and 90.4% of females used drugs. The average number of drugs used by each individual younger than 80 years was 3.2±2.6. Women younger than 80 years old used more drugs than men in the same age group whereas men older than 80 years increased their use of drugs in relation to other age groups. Therefore, 32.6% of men and 49.2% of women described at least one interaction, and 8.1% of men and 10.6% of women described four or more potential drug-drug interactions. Two-thirds of drug-drug interactions were moderate in both genders, and most of them involved angiotensin-converting enzyme inhibitor, non-steroidal anti-inflammatory, loop and thiazide diuretics, and β-blockers.

CONCLUSION

Elderly patients should be closely monitored, based on drug class, gender, age group and nutritional status.

Risk of potential drug-drug interactions among Brazilian elderly: a population-based, cross-sectional study

BACKGROUND

Drug-drug interactions (DDIs) are one of the main causes of adverse reactions related to medications, being responsible for up to 23% of hospital admissions. However, only a few studies have evaluated this problem in elderly Brazilians.

OBJECTIVES

To determine the prevalence of potential DDIs (PDDIs) in community-dwelling elderly people in Brazil, analyse these interactions with regard to severity and clinical implications, and identify associated factors.

METHODS

A population-based cross-sectional study was carried out involving 2143 elderly (aged >or=60 years) residents of the metropolitan area of Sao Paulo, Brazil. Data were obtained from the SABE (Saúde, Bem estar e Envelhecimento [Health, Well-Being, and Aging]) survey, which is a multicentre study carried out in seven countries of Latin America and the Caribbean, coordinated by the Pan-American Health Organization. PDDIs were analysed using a computerized program and categorized according to level of severity, onset, mechanism and documentation in the literature. The STATA software statistical package was used for data analysis, and logistic regression was conducted to determine whether variables were associated with PDDIs.

RESULTS

Analysis revealed that 568 (26.5%) of the elderly population included in the study were taking medications that could lead to a DDI. Almost two-thirds (64.4%) of the elderly population exposed to PDDIs were women, 50.7% were aged >or=75 years, 71.7% reported having fair or poor health and 65.8% took 2-5 medications. A total of 125 different PDDIs were identified; the treatment combination of an ACE inhibitor with a thiazide or loop diuretic (associated with hypotension) was the most frequent cause of PDDIs (n = 322 patients; 56.7% of individuals with PDDIs). Analysis of the PDDIs revealed that 70.4% were of moderate severity, 64.8% were supported by good quality evidence and 56.8% were considered of delayed onset. The multivariate analysis showed that the risk of a PDDI was significantly increased among elderly individuals using six or more medications (odds ratio [OR] 3.37) and in patients with hypertension (OR 2.56), diabetes mellitus (OR 1.73) or heart problems (OR 3.36).

CONCLUSIONS

Approximately one-quarter of the elderly population living in Sao Paulo could be taking two or more potentially interacting medicines. Polypharmacy predisposes elderly individuals to PDDIs. More than half of these drug combinations (57.6%, n = 72) were part of commonly employed treatment regimens and may be responsible for adverse reactions that compromise the safety of elderly individuals, especially at home. Educational initiatives are needed to avoid unnecessary risks.

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.