A literature search on pharmacokinetic drug interactions of statins and analysis of how such interactions are reflected in package inserts in Japan

Pharmacokinetic Study of Coadministration with Cefuroxime Sodium for Injection Influencing ReDuNing Injection-Derived Seven Phytochemicals and Nine Metabolites in Rats

According to the sixth edition of China's "New Coronavirus Diagnosis and Treatment Plan (NCDTP)," ReDuNing injection (RDN) was firstly introduced to treat severe and critical COVID-19, whereas its combination with broad-spectrum antibiotics was suggested to take with extreme caution and full reasons. Therefore, we aim to describe the pharmacokinetics of seven active phytochemicals and semiquantification of nine relevant metabolites in ReDuNing injection (RDN) after combining with cefuroxime sodium (CNa) for injection in rat plasma. Male Sprague-Dawley rats were randomly assigned to six groups, and they were intravenously administered, respectively, with different prescriptions of RDN (2 mL/kg) and CNa (225 mg/kg). At different time points (0.03, 0.08, 0.17, 0.24, 0.33, 0.50, 0.67, 1, and 6 h) after administration, the drug concentrations of iridoids glycosides, organic acids, and metabolites in rat plasma were determined using ultrahigh-pressure liquid chromatography coupled with linear ion rap-orbitrap tandem mass spectrometry (UHPLC-LTQ-Orbitrap-MS), and main pharmacokinetic parameters were estimated by noncompartment model. The results showed that there were differences in pharmacokinetic parameters, AUC_(0-t), T_1/2, C _max, CL of iridoids glycosides, and organic acids, after the intravenous administration of the different combinations of RDN and CNa. Moreover, different combinations of the injections also resulted in different curves of relative changes of each metabolite. The obtained results suggested that RDN and CNa existed pharmacokinetic drug-herb interactions in rats. The findings not only lay the foundation for evaluating the safety of RDN injection combined with CNa but also make contributions to clinically applying RDN injection combined with CNa, which works potentially against severe forms of COVID-19.

High-Intensity Statin vs. Low-Density Lipoprotein Cholesterol Target for Patients Undergoing Percutaneous Coronary Intervention: Insights From a Territory-Wide Cohort Study in Hong Kong

Background: Different guidelines recommend different approaches to lipid management in patients with atherosclerotic cardiovascular disease. We aim to determine the best strategy for lipid management in Asian patients undergoing percutaneous coronary intervention (PCI).

Method: This was a retrospective cohort study conducted in patients who underwent first-ever PCI from 14 hospitals in Hong Kong. All participants either achieved low-density lipoprotein cholesterol (LDL-C) target of <55 mg/dl with ≥50% reduction from baseline (group 1), or received high-intensity statin (group 2), or both (group 3) within 1 yr after PCI. The primary endpoint was a composite outcome of all-cause mortality, myocardial infarction, stroke, and any unplanned coronary revascularization between 1 and 5 yr after PCI.

Results: A total of 8,650 patients were analyzed with a median follow-up period of 4.2 yr. After the adjustment of baseline characteristics, complexity of PCI and medications prescribed and the risks of the primary outcome were significantly lower in group 2 (hazard ratio [HR], 0.82; 95% confidence interval [CI], 0.74–0.93, P = 0.003) and group 3 (HR, 0.75; 95% CI, 0.62–0.90; P = 0.002). The primary outcome occurred at similar rates between group 2 and group 3.

Conclusions: Use of high intensity statin, with or without the attainment of guidelines recommended LDL-C target, was associated with a lower adjusted risk of MACE at 5 yr, compared with patients who attained LDL-C target without high intensity statin.

Treatment patterns of lipid-lowering therapies and possible statin intolerance among statin users with clinical atherosclerotic cardiovascular disease (ASCVD) or diabetes mellitus (DM) in Taiwan

OBJECTIVES

To assess treatment patterns of statin and/or ezetimibe and possible statin intolerance among patients initiating statin or statin plus ezetimibe and with clinical atherosclerotic cardiovascular disease (ASCVD) or diabetes mellitus (DM) in Taiwan.

METHODS

A retrospective cohort study using Taiwan's 2005 to 2013 National Health Insurance Research Database (NHIRD) was conducted. Patients with history of clinical ASCVD or DM (without previous clinical ASCVD) and initiating statin or statin plus ezetimibe therapy during 2006 to 2012 were identified. The treatment initiation date was defined as index date. Treatment patterns (including discontinuation, reinitiation, subtraction, switching, and augmentation), adherence (medication possession ratio [MPR]), persistence (gap no greater than 60 d) of statin and/or ezetimibe, and possible statin intolerance during 12-month follow-up from the index date were examined.

RESULTS

Among patients initiating statin or statin plus ezetimibe, 11 092 patients with history of clinical ASCVD and 31 100 patients with DM but without clinical ASCVD were analysed. The discontinuation, reinitiation, and switching rates among patients with clinical ASCVD were 54.0%, 11.3%, and 25.7% during 12-month follow-up period, respectively. Among patients with DM, the rates were 57.5%, 14.2%, and 28.5%. The MPRs of statin among clinical ASCVD and DM cohorts were 0.62 and 0.60, respectively. As for ezetimibe, the MPRs were 0.56 and 0.59. Persistence to statin treatment was 46.1% among ASCVD patients and 42.6% among DM patients. Among the ASCVD and DM cohorts, possible statin intolerance was observed among 19.9% and 21.4% of patients, respectively.

CONCLUSIONS

Large number of patients with either ASCVD or DM discontinued lipid-lowering therapies with suboptimal adherence and persistence among Taiwanese population. There is a large unmet medical need to provide safe and more effective therapies, which can be used in combination with statins or alone, to reduce the risk of CV events and improve outcomes in high-risk patients.

Effect of moderate-intensity statin therapy on plaque inflammation in patients with acute coronary syndrome: A prospective interventional study evaluated by 18F-FDG PET/CT of the carotid artery

BACKGROUND

Asian patients with acute coronary syndrome (ACS) are frequently prescribed moderate- -intensity statin in real practice, even during the early stage of ACS. Under assessment herein was the effect of moderate-intensity statin therapy on the resolution of plaque inflammation during the first month after ACS, a period with highest recurrent ischemic events, using dual time point 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT).

METHODS

This prospective study included statin-naïve patients with ACS and non-calcified carotid plaques (≥ 3 mm on ultrasound images). Baseline FDG PET/CT images of the carotid arteries of the patients were obtained. Then, all patients received atorvastatin (20 mg/day); follow-up FDG PET/CT images of the carotid arteries were then obtained after 1 month of therapy. The primary endpoint measurement was the change in the target-to-background ratio (TBR) of the carotid artery between the initial and follow-up FDG PET/CT scans.

RESULTS

Thirteen ACS patients completed the initial and follow-up FDG PET/CT scans. Moderate-intensity statin therapy failed to reduce plaque inflammation at 1 month after ACS (TBR 1.60 ± 0.20 at baseline vs. 1.50 ± 0.40 after therapy; p = 0.422) but significantly reduced serum low-density lipoprotein cholesterol (LDL-C) levels (mean LDL-C 101.2 ± 21.1 mg/dL at baseline vs. 70.7 ± 12.4 mg/dL after therapy; p < 0.001). Changes in the TBR and serum LDL-C levels were not correlated (r = -0.27, p = 0.243).

CONCLUSIONS

Dual time point FDG PET/CT imaging demonstrates that moderate-intensity statin therapy was insufficient in suppressed plaque inflammation within the first month after ACS in Asian patients, even though achieving target LDL levels.

An evaluation of the completeness of drug-drug interaction-related information in package inserts

PURPOSE

The project aimed to evaluate the completeness of drug-drug interaction (DDI)-related information in package inserts (PIs) and develop a systematic approach to conduct the evaluation.

METHODS

DDI-related information in the branded PIs of statins, macrolides, protease inhibitors and selected drugs of narrow therapeutic index (DNTI) were evaluated against the criteria distilled from the Food and Drug Administration (FDA) labelling recommendation guidance document. Decision trees were crafted and employed in the evaluation process. Scores were computed to give each PI an overall completeness score and individual criterion completeness score. The Kruskal-Wallis test and Dunn's multiple comparison test were used to assess the differences in the completeness scores.

RESULTS

The mean overall completeness score of the 21 PIs was 35.7 ± 13.4 % (range 12.2-62 %). Eight out of the 11 individual evaluation criterion had a mean completeness score below 50 %. A subclass analysis conducted revealed that PIs from the different drug classes differed in the type of DDI-related information, such that they are more complete or less complete.

CONCLUSION

The completeness score of DDI-related information in the PIs varied extensively amongst and within drug classes. A consensus between the authorities and drug companies on the type and quality of DDI-related information to be included could improve their completeness in PIs and make PIs a valuable source of DDI reference. Decision trees, albeit not validated yet, lay the groundwork for a valuable tool to evaluate DDI-related or other drug information.

Differences between the United States and Japan in labels of oncological drugs

PURPOSE

Our study addresses how the information in the labels differed between United States (US) and Japan, what factors were associated with the decision to place the boxed warning on the label, and the relation of both countries in terms of drug label policy.

METHODS

We investigated adverse drug reactions (ADRs) in boxed warnings for 44 oncological drug labels approved from 2004 to 2014 in both Japan and the US. We applied conditional logistic regression to examine how likely it was for each ADR to be included in a boxed warning.

RESULTS

There were substantial differences in all sections of the labels. The concordance rate between US and Japanese labels was 44.1% for serious adverse reactions and 30.5% for boxed warnings. Our regression analysis indicated that deaths and/or terminations related to specific ADRs reported in clinical trials were significantly associated with inclusion of the ADR in boxed warnings in Japan, but not in the US. The boxed warnings of similar drugs seemed to affect those of follow-on drugs in both countries. US drug labels were likely to influence Japanese labels, but not vice versa.

CONCLUSION

This study suggests that the observed differences are not solely due to differences in clinical outcomes between the two countries, but rather due to differences in regulatory considerations and historical factors in both local and global contexts. Further research is needed to examine the impact of these differences on public health and to determine how and to what extent we should intervene with this status quo. Copyright © 2016 John Wiley & Sons, Ltd.

Prevalence of statin-drug interactions in older people: a systematic review

PURPOSE

Statins are among the most frequently prescribed medications internationally. Older people are commonly prescribed multiple medications and are at an increased risk of drug-drug interactions, including statin-drug interactions. The aim of this study was to conduct a systematic review of current evidence on the prevalence of statin-drug interactions in older people.

METHODS

A systematic search of observational studies in Embase, Medline, and PubMed was conducted. Articles were included if they were published in English during the period July 2000-July 2014 and reported on the prevalence of statin-drug interactions in people over 65 years of age. Two reviewers independently assessed the articles for eligibility and extracted the data.

RESULTS

The search returned 1556 eligible articles. A total of 19 articles met the inclusion criteria. In studies (n = 7) that focused on statin users only, the prevalence of potential statin-drug interactions assessed using different measures ranged from 0.19 to 33.0 %. In studies that examined drug interactions across a population of both statin users and non-users (n = 12), the prevalence of potential statin-drug interactions ranged from 0.1 to 7.1 % (n = 8), and the prevalence of clinically relevant statin-drug interactions ranged from 1.5 to 4 % (n = 4).

CONCLUSIONS

Current published evidence suggests substantial variations in the prevalence of statin-drug interactions and their clinical relevance. Further studies are necessary to provide a better understanding of the prevalence of clinically significant statin-drug interactions, the medications most frequently contributing to statin-drug interactions, and impact on relevant clinical outcomes in older people.

Assessment of statin-associated muscle toxicity in Japan: a cohort study conducted using claims database and laboratory information

OBJECTIVE

To estimate the incidence of muscle toxicity in patients receiving statin therapy by examining study populations, drug exposure status and outcome definitions.

DESIGN

A retrospective cohort study.

SETTING

16 medical facilities in Japan providing information on laboratory tests performed in and claims received by their facilities between 1 April 2004 and 31 December 2010.

PARTICIPANTS

A database representing a cohort of 35 903 adult statin (atorvastatin, fluvastatin, pitavastatin, pravastatin, rosuvastatin and simvastatin) users was studied. Use of interacting drugs (fibrates, triazoles, macrolides, amiodarone and ciclosporin) by these patients was determined.

MAIN OUTCOME MEASURE

Statin-associated muscle toxicity (the 'event') was identified based on a diagnosis of muscle-related disorders (myopathy or rhabdomyolysis) and/or abnormal elevation of creatine kinase (CK) concentrations. Events were excluded if the patients had CK elevation-related conditions other than muscle toxicity. Incidence rates for muscle toxicity were determined per 1000 person-years, with 95% CI determined by Poisson regression.

RESULTS

A total of 18 036 patients accounted for 42 193 person-years of statin therapy, and 43 events were identified. The incidence of muscle toxicity in the patients treated with statins was 1.02 (95% CI 0.76 to 1.37)/1000 person-years. The estimates varied when outcome definitions were modified from 0.09/1000 person-years, which met both diagnosis and CK 10× greater than the upper limit of normal range (ULN) criteria, to 2.06/1000 person-years, which met diagnosis or CK 5× ULN criterion. The incidence of muscle toxicity was also influenced by the statin therapies selected, but no significant differences were observed. Among 2430 patients (13.5%) received interacting drugs with statins, only three muscle toxicity cases were observed (incidence: 1.69/1000 person-years).

CONCLUSIONS

This database study suggested that statin use is generally well tolerated and safe; however, the risk of muscle toxicity related to the use of interacting drugs requires further exploration.

A review of statin use in patients with acute coronary syndrome in Western and Japanese populations

Early high-dose statin therapy to reduce low-density lipoprotein cholesterol (LDL-C) is associated with improved cardiovascular outcomes in Western patients with stable coronary heart disease or acute coronary syndromes (ACS), but many patients remain undertreated and do not attain LDL-C treatment goals. Early statin therapy has also been shown to improve cardiovascular outcomes in Japanese patients with ACS, and pretreatment with high-dose statin prior to percutaneous coronary intervention has been shown to reduce cardiovascular events in these patients. As is the case in Western populations, many Japanese patients may be undertreated and a residual cardiovascular risk remains. While differences in treatment practice, dosing and genetic factors exist between Japan and Western countries, similarities are also evident when Japanese statin studies are compared with those performed in Western populations. With the increasing prevalence of cardiovascular risk factors in Japan, aggressive statin treatment may be beneficial in achieving optimal cardiovascular outcomes.

Systemic exposure to atorvastatin between Asian and Caucasian subjects: a combined analysis of 22 studies

The aim of the present study was to determine whether there is a differing pattern of systemic exposure to atorvastatin in Asian versus Caucasian subjects by comparison of data obtained from completed pharmacokinetic studies. Pharmacokinetic data were analyzed from completed single-dose (10-80 mg) studies in Asian and Caucasian subjects. Dose normalized area under the concentration-time curve (AUC) and maximum observed concentration (Cmax) (AUC(dn) and Cmax(dn)) were obtained by dividing each value by the administered dose. Dose-per-bodyweight normalized AUC and Cmax (AUC(dn,wt) and Cmax,(dn,wt)) were obtained by dividing each value by the administered dose per unit bodyweight. Mean difference and 90% confidence intervals for Asian versus Caucasian comparisons were calculated for atorvastatin pharmacokinetic values based on the t statistic and expressed as ratios using Caucasians as the reference. Data were analyzed from 310 Asians and 579 Caucasians from 22 studies. AUC(dn) (Asian = 2.35, Caucasian = 2.06 [ng·hr·mL(-1)]/mg) and Cmax(dn) (Asian = 0.39, Caucasian = 0.40 Cmax(dn,wt)) and the equivalent dose-per-bodyweight normalized values for atorvastatin (AUC(dn,wt): Asian = 157.5, Caucasian = 156.4 [ng·hr·mL(-1)]/[mg·kg(-1)]; Cmax(dn,wt): Asian = 26.2, Caucasian = 30.3 [ng·mL(-1)]/[mg·kg(-1)]) were similar in both ethnic groups. Mean differences and 90% confidence interval for the differences fell within the limits (0.8-1.25) except for Cmax(dn,wt), for which the lower limit was slightly below 80%. No differences were noted in the systemic exposure to atorvastatin between Asian and Caucasian subjects. These data therefore demonstrate that dosing considerations in the current labels for atorvastatin are similar for Asian compared with Caucasian subjects.

Statin dose in Asians: is pharmacogenetics relevant?

Historically the efficacy and safety of statins has mostly been studied in western populations. Few such studies have been carried out in Asians until recent years. These studies revealed interesting similarities and differences for statin use between Asians and Caucasians. One clinically important question subsequently raised is whether Asians need lower statin doses compared with Caucasians. Many practicing physicians believe that statin doses are lower in Asians because of the generally lower bodyweight and BMI. Whether this belief is based on sound scientific evidence needs to be reviewed. Furthermore, since the decision of optimal dose is based on both efficacy and safety, both of which may be impacted by genetic factors, one may ask whether pharmacogenetics plays a role in the dose difference, if such a difference exists. There is a clinical need to critically and comprehensively article the literature to answer these questions, and summarize future directions of research in the field. This article serves the above purpose.

Prediction of pharmacokinetic drug-drug interaction caused by changes in cytochrome P450 activity using in vivo information

The aim of the present paper was to present an overview of the current status of the methods used to predict the magnitude of pharmacokinetic drug-drug interactions (DDIs) which are caused by apparent changes in cytochrome P450 (CYP) activity with an emphasis on a method using in vivo information. In addition, more than a hundred representative CYP substrates, inhibitor and inducer drugs involved in significant pharmacokinetic DDIs were selected from the literature and are listed. Although the magnitude of DDIs has been conventionally predicted based on in vitro experiments, their predictability is restricted occasionally due to several difficulties, including a precise determination of the unbound inhibitor concentrations at the enzyme site and a reliable in vitro measurement of the inhibition constant (K(i)). Alternatively, a simple method has been recently proposed for the prediction of the magnitude of DDIs based on information fully available from in vivo clinical studies. The new in vivo-based method would be applicable to the adjustment of dose regimens in actual pharmacotherapy situations although it requires a prior clinical study for the prediction. In this review, theoretical and quantitative relationships between the in vivo- and the in vitro-based prediction methods are considered. One of the interesting outcomes of the consideration is that the K(i)-normalized dose (dose/in vitro K(i)) of larger than approximately 20L (2-200L, when variability is considered) may be a pragmatic index which predicts significant in vivo DDIs. In the last part of the article, the relevance of the inclusion of the in vivo-based method into the process of new drug development is discussed for good prediction of in vivo DDIs.

Adverse events caused by drug interactions involving glucuronoconjugates of zidovudine, valproic acid and lamotrigine, and analysis of how such potential events are discussed in package inserts of Japan, UK and USA

BACKGROUND AND OBJECTIVE

As pharmacokinetic drug interactions frequently cause adverse events, it is important that the relevant information is given in package inserts (PIs). We previously analysed the provision of PIs for HMG-CoA reductase inhibitors and Ca antagonists, for which metabolism by cytochrome P450 could be a major interaction mechanism. In this article, we focus on interactions involving glucuronoconjugates because many drugs and their metabolites undergo this conjugation.

METHODS

We reviewed clinical drug interactions related to glucuronoconjugates, focusing on reports of adverse events. Then, we picked out three important drugs (zidovudine, valproic acid and lamotrigine), and examined how the literature information is reflected in the relevant PIs in Japan, UK and USA.

RESULTS AND DISCUSSION

Pharmacokinetic interactions related to glucuronoconjugates were found with 33 drug combinations. Of these, five combinations induced clear adverse events: (i) severe anaemia due to zidovudine and caused by interaction with valproic acid, (ii) recurrence/increased frequency of seizure or increased manic states from a reduction in therapeutic effects of valproic acid caused by panipenem, (iii) meropenem or (iv) ritonavir and (v) of lamotrigine caused by oral contraceptives. Analysis of PIs showed a lack of description of the interaction of zidovudine with valproic acid in the Japanese PI. The UK PI mentioned this interaction without quantitative data, whereas full information was given in the US PI. A lack of description was also present on the interaction between valproic acid with ritonavir, reported in 2006, in the PIs of all three countries. For the interactions involving valproic acid and panipenem or meropenem, even though marked reduction of blood valproic acid level has been reported, no quantitative data were provided in any of the PIs.

CONCLUSION

Five combinations were identified to cause severe adverse events because of interactions related to glucuronoconjugates. This information, including quantitative data, is not always properly provided in the relevant PIs in Japan, UK or USA. PIs should be improved to better inform healthcare providers and thereby help them and their patients.

Safety and efficacy of statins in Asians

Asian patients frequently have heightened responses to therapeutic drugs. As a consequence, the recommended drug doses are often lower in Asian countries than in Western countries. This practice extends to the use of cardiovascular drugs, including statins for the treatment of dyslipidemia. Pharmacokinetic investigations have noted higher plasma levels of statins in Asians compared with Caucasians, although postmarketing data for all statins have not identified any particular safety issues, even when statins are given at equivalent doses. The potential mechanisms of heightened response to statins in Asians are related to genetically based differences in the metabolism of statins at the level of hepatic enzymes and drug transporters. Studies indicate that lower statin doses achieve lipid improvements in Asian patients comparable with those observed with higher doses in Caucasians. In conclusion, prescribing lower starting doses of statins in Asians appears warranted while research on this subject continues.

Analysis of Pharmacokinetic Data Provided in Japanese Package Inserts and Interview Forms Focusing on Urinary Excretion of Pharmacologically Active Species

In optimizing oral pharmacotherapy for patients with renal failure, information on actual urinary excretion ratio of the unchanged drug, which is obtained by dividing a urinary excretion ratio by a bioavailability after oral dose, is quite helpful. In addition, urinary excretion ratio of the active species is sometimes equally important where metabolites have a pharmacological potency. In the present study, we conducted a survey of Japanese package inserts and interview forms of drugs, which is being prescribed at the University of Tokyo Hospital, on pharmacokinetic data that enables an estimation of actual urinary excretion ratio. The total urinary excretion of a drug was documented in 70.1% of package inserts and 84.5% of interview forms, respectively. The total urinary excretion is often measured by radioactivity and thus includes its metabolites and degradation products. However, inclusion of degradation products/metabolites was described explicitly for 43.7% and 66.2%, and the absolute fraction of the unchanged drug or degradation product/metabolite was given only for 29.0% and 48.9% in package inserts and interview forms, respectively. The pharmacological activity of metabolite(s) was documented for 19.8% and 54.3%, and the oral bioavailability was described only for 5.7% and 30.6% in respective documents. For some drugs, the time period for the urine collection was too short to evaluate the urinary excretion ratio. With regard to 65 drugs (38.7%), more detailed information on urinary excretion was found in published books, but not provided in the package inserts or interview forms. It is hoped that more distinct and sufficient descriptions on the urinary excretion and bioavailability will be associated to the package inserts and the interview forms in future, for safe and efficient use of prescription drugs.

Predicting in vivo drug interactions from in vitro drug discovery data

In vitro screening for drugs that inhibit cytochrome P450 enzymes is well established as a means for predicting potential metabolism-mediated drug interactions in vivo. Given that these predictions are based on enzyme kinetic parameters observed from in vitro experiments, the miscalculation of the inhibitory potency of a compound can lead to an inaccurate prediction of an in vivo drug interaction, potentially precluding a safe drug from advancing in development or allowing a potent inhibitor to 'slip' into the patient population. Here, we describe the principles underlying the generation of in vitro drug metabolism data and highlight commonly encountered uncertainties and sources of bias and error that can affect extrapolation of drug-drug interaction information to the clinical setting.

Statin-macrolide interaction risk: a population-based study throughout a general practice database

INTRODUCTION

The myopathy risk associated with statin use increases in case of concomitant prescription of certain drugs, such as cytochrome P(450) (CYP) system inhibitors (i.e., macrolides). The aim of this study was to assess whether concurrent statin/macrolide prescriptions at high interaction risk are commonly written in a general practice setting.

METHODS

For this study, 156 general practitioners (GPs) with a patient population of almost 200,000 individuals, and participating in the Arianna database set up by "Caserta-1" Local health-Service Agency (ASL), were recruited. Within such a study sample, subjects receiving at least one statin/macrolide concomitant prescription during the year 2003 were identified. Sensitivity analysis was performed to assess the time distribution of high-risk macrolide prescriptions written within +/-10 days from the statin prescription date.

RESULTS

Among 190,124 patients included in the study, 7,176 (3.8%) received at least one statin prescription during the observation period. Of these, 228 (3.2%) were occasionally co-prescribed with any macrolide on the same date, in 153 cases (2.1% of statin users) the macrolide being of high interaction risk. In particular, 2.1% (55) of simvastatin users and 2.2% (64) of patients on atorvastatin were prescribed with high-risk macrolide on the same date versus 0.6% and 1.8% of patients prescribed with fluvastatin and pravastatin, respectively. Concerning GPs, 99 (63.5%) co-administered statin and macrolide at high interaction risk at least once.

CONCLUSIONS

Most GPs occasionally prescribed statin/macrolide at high interaction risk on the same date, despite the availability of therapeutic alternatives. Prevention strategies targeted to increase awareness of health professionals about the interaction risks of widely prescribed drugs are needed.