Risk Of Potential Drug-drug Interactions Research Articles

Risk of Potential Drug-Drug Interactions among Brazilian Elderly

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. 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. 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. 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). 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.

Potential drug–drug interactions and radiodiagnostic procedures: an in-hospital survey

To evaluate the type, frequency, severity and predictors of potential Drug-Drug Interactions (DDIs) in a cohort of patients undergoing radiodiagnostic procedures. Eight Radiology wards located in Tuscany (Italy). All participants exposed to at least two medications were included in the analysis. DDIs were grouped according to their severity as 'minor', 'moderate' or 'major'. A logistic model was used to estimate Odds Ratios and 95% Confidence Intervals for all predictors of potential DDI. Type and predictors of potential DDI in a cohort of patients undergoing radiodiagnostic procedures. One-thousand-and-two subjects (57.6% females; mean age: 67.3 +/- 12.2) entered the analysis, and 46.1% of them incurred in a potential DDI (78.9% 'moderate' in severity). The combination of allopurinol and ACE-inhibitors was the most frequent (21/153) among major potential DDIs, while steroids were involved in all cases of potential DDI due to premedication. Co-morbidity, number of co-medications, advanced age and premedication use increased the risk of potential DDI; a protective role was found for positive history of allergy. When the analysis was restricted to subjects with premedication (n = 93), only 12.9% of them reported a potential DDI directly attributable to premedication drugs. Among patients undergoing radiological examination, types and predictors of potential DDIs appeared in agreement with other kind of in-hospital populations. Premedication revealed to be a proxy predictor for potential DDIs. Considering the poor capability of the prescriber in recognizing interactions, their systematic evaluation (using an informatics tool) in patients undergoing radiological examination might be helpful in preventing the occurrence of clinically relevant DDIs.

Laboratory Tests in the Clinical Risk Management of Potential Drug-Drug Interactions

Patient safety and the life cycle of a drug are negatively influenced by the still increasing occurrence of potential drug-drug interactions (DDIs). Clinical risk management of potential DDIs is required in patients using drugs to influence the benefit-risk profile positively. Information about laboratory test results, in particular, may be useful in the assessment of potential DDIs for the individual patient. The objective of this study was to examine the frequency and nature of laboratory tests required for the assessment of the clinical relevance of potential DDIs in Dutch community pharmacies. In addition, the nature and clinical relevance of these potential DDIs is analysed. All patients from 100 Dutch community pharmacies using, according to dispensing information, two or more drugs concomitantly on a specified date (Wednesday, 4 April 2007), were included (n = 223,019). The anonymous dispensing data of the included patients were analysed against a list of DDIs requiring laboratory tests for the assessment of their clinical relevance. The number of patients at risk for these potential DDIs with severe adverse reactions was calculated. The frequency of potential DDIs requiring laboratory tests were stratified by age, sex and degree of polypharmacy. Of the included patients, 24.4% had one or more potential DDIs (n = 54,427). In 9.0% of the included patients, one or more laboratory tests for the assessment of clinical relevance of the potential DDI were required (n = 19,968). The frequency of DDIs requiring laboratory tests increased with increasing age and number of drugs, but was not related to sex. The most commonly required laboratory tests were for renal function (42.2%), electrolytes (20.1%) and coagulation (13.1%). The percentage of patients at risk for potential DDIs requiring laboratory tests with adverse reaction category F (serious, irrecoverable disablement or death) was 2.5%; category E (increased risk of failure of life-saving therapy) was 0.6%; and category D (inconvenience with residual symptom and failure of therapy concerning serious but non-fatal diseases) was 3.8%. A large number of patients in Dutch community pharmacies are at risk for potential DDIs requiring laboratory tests for the assessment of the clinical relevance of the interaction. There is a strong relationship between the frequency of DDIs requiring laboratory tests and age and the number of drugs concomitantly used. In the clinical risk management of potential DDIs, information about laboratory test results is of additional value. Future research is necessary in order to obtain more evidence on using laboratory tests in terms of which tests should be linked to pharmacy data, in which patients they should be done, how often and what actions should be taken when an abnormal value is found.

The Prevalence of Potential Drug-Drug Interactions in Patients with Heart Failure at Hospital Discharge

Pharmacotherapy for heart failure is complex and, due to polypharmacy, is associated with a large risk of potential drug-drug interactions (DDIs). The objective of the present study was to assess the prevalence of potential DDIs in the medication of hospitalised heart failure patients and to evaluate their clinical relevance. The medication of 400 patients was retrospectively analysed for potential DDIs at hospital admission and discharge using a computerised drug interaction program. Main inclusion criteria were the diagnosis of heart failure and a minimum of two drug prescriptions at discharge. In the study population of 400 heart failure patients (median age 79 years, 55.5% men), the median number of drugs per patient was lower at admission than at discharge (6 [interquartile range {IQR} 4-9] vs 8 [IQR 6-10]; p < 0.001). At hospital admission, a total of 863 potential DDIs were detected in 272 patients (68.0%; 95% CI 63.4, 72.6). At discharge, 1171 potential DDIs were detected in 355 patients (88.8%; 95% CI 85.7, 91.8). This corresponds with a significant increase in the median number of potential DDIs per patient from admission to discharge (1.5 [IQR 0-3] vs 3 [IQR 1-4]; p < 0.001). Of the 1171 potential DDIs at discharge, 432 (36.9%) were prevalent at admission and 739 (63.1%) resulted from a medication change during the hospital stay. Of these 739 new potential DDIs, the severity of the potential adverse effect was rated as 'major' in 190 (25.7%) patients, 'moderate' in 482 (65.2%) and 'minor' in 67 (9.1%). The 190 potential DDIs with major severity were recorded in a total of 145 patients (36.3%; 95% CI 31.5, 41.0%). Hyperkalaemia was the most prevalent potential adverse effect of major severity (n = 93) and the combination of an ACE inhibitor with a potassium-sparing diuretic was recorded in 64 (16.0%) patients. The study shows that hospitalisation of patients with heart failure results in an increase in the number of drugs prescribed per patient and, thereby, also in the number of potentially interacting drug combinations per patient. Although electronic drug interaction programs are a valuable tool to check for potential DDIs, the clinical relevance of most potential DDIs can only be judged by assessment of the individual patient.