Lara Magro

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.

Identifying Adverse Drug Reactions Associated with Drug-Drug Interactions: Data Mining of a Spontaneous Reporting Database in Italy

AbstractBackground: Drug-drug interactions (DDIs) are an important cause of adverse drug reactions (ADRs). Many studies have recently considered this issue, but most of them focus only on potential interactions and are often related to the hospital setting. A spontaneous reporting database could be a valuable resource for detection of ADRs associated with DDIs; however, data in the literature are limited. Objective: To detect those patients treated with potentially interacting drugs and the cases where reported adverse reactions are a possible consequence of DDIs, using an Italian spontaneous reporting database. Methods: The data were obtained from a database containing all reports of suspected ADRs from five Italian regions (January 1990 to December 2007) that are the main contributors to the Italian spontaneous reporting system. All reports containing at least two drugs, reported as being suspected of causing the ADR or as concomitant medication, were selected and a list of drug pairs was drawn up. We performed a search to verify which drug pairs are considered a potential DDI, using the Internet version of the DRUGDEX® system. For each report containing a potential DDI, we verified whether the description of the adverse reaction corresponded to the interaction effect. Results: The database contained 45 315 reports, of which 17 700 (39.1%) had at least two reported drugs. We identified 5345 (30.2%) reports with potential DDIs, and in 1159 (21.7%) of these reports a related ADR was reported. The percentage of reports with potential DDIs increased in relation to the number of concomitantly administered drugs, ranging from 9.8% for two drugs to 88.3% for eight or more drugs. The percentages of serious or fatal reports of ADRs associated with a DDI were significantly higher than other reports analysed. The mean age, percentage of male patients and the mean number of drugs were also significantly higher in reports with DDIs than in other reports. In 235 of 1159 reports (20.3%), both interacting drugs were recognized as suspect by the reporter. This percentage varies in relation to the drugs involved, ranging from 2% to about 65%. The most frequently reported interaction was digoxin and diuretics, but no fatal ADRs were reported with this combination. The combination of anticoagulant and antiplatelet agents was responsible for the greatest number of serious reactions and deaths. Conclusions: This study validates that spontaneous reporting, despite its limitations, can be an important resource for detecting ADRs associated with the concomitant use of interacting drugs. Moreover, our data confirm that DDIs could be a real problem in clinical practice, showing that more than one in five patients exposed to a potential DDI experienced a related ADR.

Stronger association of drug-induced progressive multifocal leukoencephalopathy (PML) with biological immunomodulating agents

AimThe aim of the present study was to collect and compare cases of drug-induced PML in order to contribute to the debate about the role of the underlying diseases and/or drug immunosuppression in PML occurrence.MethodsWe searched for drug-induced PML cases in two international spontaneous adverse drug reaction (ADR) report databases, FDA-AERS and WHO-VigiBase. From MEDLINE, we retrieved case reports and case series containing the MESH term “leukoencephalopathy, progressive multifocal/chemically induced”. In order to assess the PML-drug relationship, we analysed drug-reaction pairs in terms of the patients’ underlying diseases and co-suspected drugs.ResultsOverall, 214 cases in FDA-AERS, 118 in WHO-VigiBase and 140 in MEDLINE were collected. Therapeutic groups more frequently involved in PML cases were monoclonal antibodies (MAbs), conventional immunosuppressive drugs and anti-HIV drugs. The most frequent underlying diseases were lymphoproliferative diseases (28%), autoimmune disorders (20%) and transplants (10%). MAbs were more often reported in cases where they were the only suspected drugs, whereas for the other therapeutic groups, concomitant drugs were reported.ConclusionsWe found a strong relationship between PML and MAbs, especially when used in autoimmune diseases. PML is becoming a crucial issue of MAbs, since they can cause severe ADRs through the imbalance of the immune system. Based on these results, patients treated with MAbs should be carefully monitored for early signs and symptoms of PML.

Improvement of patient adverse drug reaction reporting through a community pharmacist-based intervention in the Campania region of Italy

Objective: Adverse drug reaction (ADR) reporting by patients has a fundamental role in pharmacovigilance. The main objectives of the present study were to assess the impact of a pharmacist-based intervention in promoting direct patient reporting, to evaluate patient ability to identify and report ADRs and to determine their pattern. Research design and methods: The study involved 96 pharmacists in the Campania region of Italy, who interviewed their customers and asked them whether they had experienced an ADR. Patients who had experienced an ADR were invited to complete an ADR reporting form. The quality of completed ADR reporting forms was evaluated before their entry into the Italian Spontaneous Reporting System (Rete Nazionale di Farmacovigilanza [RNF]) and, once entered, their pattern was determined. Results: A total of 18,677 patients were interviewed, and 10.88% had experienced an ADR. After quality control, 54.32% of all reporting forms were entered into the RNF so that patient contribution to spontaneous reporting, null over the years, reached ∼7%. Patients reported mainly non-serious (91.28%) and expected (94.62%) ADRs, and NSAIDs or antibiotics were the most frequently reported drugs. Conclusions: The study shows that pharmacists can have an important role in promoting patient reporting and adds new information on how a patient reporting form should be structured.

Fluvastatin and Hepatic Reactions A Signal From Spontaneous Reporting in Italy

AbstractBackground: Signal detection is a crucial element in recognising new adverse drug reactions (ADRs) as soon as possible. HMG-CoA reductase inhibitors (‘statins’), the most potent cholesterol-lowering drugs, are generally well tolerated but can occasionally lead to liver toxicity. Pre- and postmarketing studies on statins revealed an incidence of 0.1–3% elevation in hepatic transaminase levels. However, these elevations are asymptomatic, reversible, dose related or probably due to other causes. Postmarketing studies clearly showed the lack of evidence of hepatotoxicity from statins, apart from some isolated case reports of serious hepatic damage described in the literature. It is still unclear whether serious hepatic reactions are dose related and more frequent than the expected rate in the general population. Objective: In this study, the hypothesis that fluvastatin could cause serious liver injuries more than the other statins is investigated, in the light of a quantitative and qualitative signal analysis, drug consumption data and evidence from the literature. Methods: The Italian Interregional Group of Pharmacovigilance (Gruppo Interregional di Farmacovigilanza; GIF) is an example of signal detection within the Italian spontaneous ADR reporting system. The GIF database holds reports of suspected ADRs submitted by five Italian pharmacovigilance regional centres. In the GIF database, all reports of suspected ADRs are classified according to the WHO criteria for causality assessment. The reactions are coded according to the WHO Adverse Reaction Terminology and classified as serious or non-serious events on the basis of the WHO Critical Term List. Every 6 months the GIF database is analysed to extract potential signals through a qualitative case-by-case analysis and using a quantitative methodology called proportional reporting ratio (PRR). This methodology permitted us to identify the potential signal ‘fluvastatin and hepatic reactions’. Results: At 31 December 2004, the GIF database contained 35 757 reports with an annual reporting rate of 170 reports per million inhabitants. We found a total of 1260 reports of ADRs related to statins, including 178 of hepatic reactions. Sixty-nine reports were attributed to fluvastatin, which showed the highest PRR in comparison with the other statins. Fluvastatin was associated with 33 serious reactions, mainly hepatitis and cholestatic hepatitis. The number of reports of severe hepatotoxicity associated with fluvastatin started to increase from 2002. About half of them did not report other suspected or concomitant drugs and in one third the hepatotoxicity occurred after <1 month of therapy. Twenty-seven out of 33 patients were female, and fluvastatin was administered at 80 mg/day in 81% of cases reporting complete data on drug dosage. Conclusion: In the literature, serious hepatic reactions are rarely described in patients taking statins; however, data gathered by GIF suggest that cases of hepatotoxicity are reported more often than expected. In addition, GIF data seem to reveal that fluvastatin is more likely to cause hepatic reactions than the other statins. However, this is a preliminary signal and future evaluations are certainly needed to confirm it and to quantify this possible risk.

Use and safety profile of antiepileptic drugs in Italy

ObjectiveTo analyse and discuss the use and the safety profile of individual antiepileptic drugs (AEDs) in Italy.MethodsThe AED safety data referred to the period January 1988–June 2005 and were obtained from the database of the Italian Interregional Group of Pharmacovigilance (GIF). This database collects all spontaneous reports of suspected adverse drug reactions (ADRs) from six Italian regions which are the main contributors to the Italian spontaneous reporting system. Individual AED consumption data (defined daily dose/1,000 inhabitants per day) in the GIF area and in the whole of Italy referred to the period January 2003-June 2005 and were derived from drug sales data (Institute for Medical Statistics Health).ResultsPhenobarbital was the most frequently used AED in the GIF area (4.26 DDD/1,000 inhabitants per day) followed by carbamazepine (1.97), valproic acid (1.33) and gabapentin (1.10). AED consumption in the whole of Italy showed a similar pattern. Gabapentin was the most frequently used AED among newer AEDs. In the GIF database 37,906 reports (up to June 2005) were present; 666 of them (1.76%) were associated with at least one AED (Anatomical Therapeutic Chemical code N03A). The AED with the highest number of reports was carbamazepine (208 reports) followed by phenobarbital (98), gabapentin (80), phenytoin (56), valproic acid (55), lamotrigine (51), oxcarbazepine (43) and vigabatrin (35). Use and toxicity profile were evaluated only for AEDs associated with at least 30 reports. Skin reactions were the most frequently reported ADRs, followed by haematological, general condition, hepatic, neurological and gastrointestinal adverse reactions. Phenobarbital, lamotrigine, carbamazepine and phenytoin had the highest percentage of skin reactions (69, 67, 60 and 54%, respectively). Many haematological reactions were reported for each AED; the highest percentage was related to valproic acid (25%). Vigabatrin was associated with the highest percentage of reactions related to hearing, vision and other senses (97%). Phenytoin and valproic acid had the highest percentage of hepatic reactions (30 and 20%), whereas gabapentin of nervous system, psychiatric, gastrointestinal and urinary reactions (26, 21, 21 and 14%, respectively) and phenobarbital of musculoskeletal reactions (13%).ConclusionsIn Italy antiepileptic drug therapy appears to be still dominated by traditional drugs. Our analysis showed a different safety profile related to each AED. Some of the drug-adverse reaction associations discussed are not included in the Italian drug leaflets or have not been reported before in the literature.

Non-traumatic Haemorrhagic Adverse Events: A Cross-sectional Study in Emergency Departments

Objectives: The aims of this cross-sectional study were to describe the incidence of haemorrhages and adverse drug events related to different classes of drugs as cause of emergency department admission. Methods: Adult patients (≥ 18 years) visiting two emergency departments of the University Hospital in Verona (Italy) over a twelve-month period in 2015-2016 were included. The study takes into consideration non-traumatic haemorrhages defined through an International Classification of Diseases, Clinical Modification (ICD-9 CM) diagnosis code and classified into five groups (cerebral haemorrhage, gastrointestinal bleeding, epistaxis, haematuria and other haemorrhages). Demographic data, clinical data and outcome of hospitalization were extrapolated from computerized medical records. Drugs were grouped into six categories and linked to the prescription data of the Verona population during the study period. Results: Overall, 117,019 admissions to emergency departments related to 101,053 patients occurred. According to selection criteria, 1,614 admissions for bleeding, which concerned 1,391 patients (1.4% of the total patients, 59.6% male, 45.7% ≥ 75 years old) were analysed. Out of 1,391 patients, 873 had taken at least one drug (62.8%). Patients were admitted more frequently for epistaxis and gastrointestinal bleeding (27.5% and 23.9%, respectively), and the most reported drugs were antiplatelet (38.8% and 37.7%, respectively) followed by anticoagulants (23.5%), heparins (8.4%), corticosteroids (6.2%), SSRI (5.6%) and NSAIDs (3.0%). About 37% of the visiting patients were subsequently hospitalized, and death was the outcome in 4.2% of cases. Conclusion: In emergency department about 1.4% of admitted patients had an haemorrhage, of these 37% have been hospitalized and 4.2% died during hospitalization. About one third of patients with haemorrhages did not use any drugs. The majority of hospitalized patients had gastrointestinal bleedings and cerebral haemorrhages. To the best of our knowledge, this study is new in the literature, since it takes into consideration all non-traumatic bleedings, and also all drugs known to be associated with haemorrhagic events mentioned on the clinical records.

What Future Healthcare Professionals Need to Know About Pharmacovigilance: Introduction of the WHO PV Core Curriculum for University Teaching with Focus on Clinical Aspects

Adverse drug reactions (ADRs) can cause serious health problems, as shown in studies about drug-related hospitalizations. To build knowledge of and raise awareness about ADRs among healthcare professionals, more education in the field of ADRs and pharmacovigilance (PV) is needed. No standard exists for teaching PV at universities for medical, pharmacy, dentistry and nursing students, so a core curriculum needs to be developed to teach important aspects of PV to students. In September 2016, a stakeholders’ meeting was initiated on behalf of the World Health Organization (WHO) and organized by the Netherlands Pharmacovigilance Centre Lareb. This meeting addressed and agreed on the PV competencies students need to develop and what key aspects of the subject should be taught. Five key aspects were identified: understanding the importance of PV in the context of pharmacotherapy, and preventing, recognizing, managing and reporting ADRs. Since time and resources for PV education are limited, elements of the WHO PV core curriculum for university teaching were designed to be integrated into existing courses but can be used as a stand-alone programme. The basis of and outline for the WHO PV core curriculum for university teaching are addressed in this paper. It is expected that PV competencies for students are vital for their contribution to safe use of medicines in the future. In addition, this article aims to stimulate discussion on this subject and promote collaboration between universities, national PV centres and other stakeholders to integrate key aspects of PV in their educational programmes.

Chapter 27 – Lormetazepam Addiction

Lormetazepam is a benzodiazepine (BDZ) mainly used as sedative-hypnotic. It has some specific pharmacological properties that differentiate it from other BDZs. Over the past few years, it has become the most commonly used BDZ in Italy. Abuse, dependence, and addiction may appear after prolonged treatment with lormetazepam. To our knowledge, there is limited evidence of specific addictive properties of lormetazepam in the scientific literature. In the Italian pharmacovigilance database reports of abuse/dependence/addiction caused by lormetazepam account for about 50% of the total BDZ abuse/dependence/addiction reports. In our experience, lormetazepam addiction in Italy was concerned almost exclusively with drop formulation. The lack of data about lormetazepam addiction in the literature is probably because drop solution exists only in Italy and Spain. Research shows that combining medications for addiction treatment (e.g., flumazenil) with behavioral therapy is the best way to ensure success for most patients.

Italian monitoring registries: a tool for a safer use of innovative drugs? Data from the national pharmacovigilance system

ABSTRACT Objectives: Our aim was to investigate the ADR reports of drugs with a monitoring registry (MR drugs), in particular those related to abuse/misuse, medication error, overdose, which might indicate an unsafe use. We compared these reports with those of similar drugs without a registry (non-MR drugs), thus verifying whether the registries could be useful tools for a safer use of innovative drugs. Methods: All ADR reports included in the Italian Pharmacovigilance Network database from January 1st 2013 to December 31st 2015 (vaccines and literature cases excluded) were analysed. We compared the ADR reports of MR and non-MR drugs with the same ATC class at III level. Results: The percentage of ADR reports with a completed ‘Section 7’ was significantly lower for MR compared to non-MR drugs (2.0 versus 6.2, p < 0.001). The difference concerned in particular the ADR reports related to abuse/misuse, medication errors and overdose. These reports, more strictly related to inappropriate use, were less frequent for MR drugs in all the considered ATC classes. Conclusions: Our study suggests that monitoring registries could be a useful tool for the reduction of frequency of ADRs related to inappropriate use, besides the control of pharmaceutical budget.