IntroductionAlthough combination therapies are generally used to achieve better therapeutic results, drug-drug interactions (DDIs) can lead to life-threatening adverse reactions (ADRs) or therapeutic failure by changing the therapeutic efficacy of drugs. DDIs have been reported to cause 4% of drug-related emergency visits (1). Changes in the pharmacokinetic properties of drugs may produce adverse drug reactions or therapeutic failure. The pharmacodynamics of DDIs can produce additive, synergistic, or antagonistic pharmacological effects (2).ADRs can be considered an important public health problem, particularly in the elderly patients (3). Polypharmacy and DDIs play critical roles in the production of ADRs and are related to an increased risk of mortality (4,5). Among identified adverse drug events, preventable adverse drug events have been reported to be 27% in primary care and 42% in long-term care, where prescribing and monitoring stages of pharmaceutical care were emphasized for prevention of adverse drug events (6,7). Potentially inappropriate medications have been identified in Beers Criteria (8), which aimed to prevent poor outcomes in elderly patients such as ADRs, hospitalization, morbidity, or mortality (8). In the elderly population DDIs can be diagnosed as severe adverse outcomes (9). Increased sensitivity to DDIs in elderly patients and the most frequent ADRs experienced by this age group have been shown in many studies (10-12). Elderly patients exposed to polypharmacy are at high risk of DDIs that depend on agerelated changes in pharmacokinetics or pharmacodynamics of drugs, and multiple co-morbidities.Another important factor for the increased vulnerability of elderly patients to DDIs can be poor compliance, underuse, overuse, or misuse of the medications (13). Moreover, elderly patients who will undergo surgical treatment or treatment in an intensive care unit have been reported to have a high risk for the occurrence of DDIs ( 14). Although there are publications investigating the use of inappropriate drugs in Turkish elderly patients (15,16), there are no data evaluating potential DDIs in Turkish elderly patients.Background/aim: Elderly patients are at high risk from drug-drug interactions (DDIs). This study evaluates the potential DDIs in Turkish elderly patients at a primary health care outpatient clinic.
Materials and methods:Online database systems were used to examine DDIs on the prescriptions of patients (n = 1206). The clinical severity of DDIs was classified by the Lexi-Interact Online database.Results: Of the 5059 prescriptions, 33% were found to have DDIs. We detected 29 (0.9%) A, 380 (11.8%) B, 2494 (77.7%) C, 289 (9%) D, and 18 (0.6%) X risk rating category DDIs among the prescriptions. Prescriptions of female patients and patients aged between 65 and 72 years showed significantly higher number of DDIs. The frequency of DDIs increased both with the number of drugs and combined preparations per prescription. Acetylsalicylic acid and salbutamol were the most frequently prescribed drugs ...