Prevalence of the coprescription of clinically important interacting drug combinations involving oral anticancer agents in Singapore: a retrospective database study.

There has been a recent increase in the availability and use of oral anticancer agents (OAAs). Drug-drug interactions (DDIs) involving OAAs pose a major concern in oncology practice due to these drugs' narrow therapeutic indices and potential for compromised efficacy and fatal adverse events. To assess the prevalence of the coprescription of potentially interacting drug combinations involving OAAs in Singapore. A retrospective review of physicians' electronic prescription records between the years 2007 and 2009 was performed in the largest cancer center in Singapore. An overall prevalence rate of potential DDIs and a prevalence rate for each individual DDI pair were calculated. Logistic regression was used to identify risk factors for potential DDIs. Fifty-eight clinically significant DDIs were selected for evaluation from Drug Interaction Facts and Micromedex DrugDex. A total of 39,772 OAA prescriptions prescribed to 8837 patients were reviewed. Potential DDI coprescription was found in 5.4% of the patients on OAAs and in 4.7% of the OAA prescriptions. The drug pair prescribed to the largest number of patients was prednisolone and aspirin. About half (53.3%) of the observed DDIs were found on the same prescription. On multivariate analysis, older patients, males, and those taking prednisolone had a higher risk for potential DDIs. Although limited by the data available, the analysis of prescription records found that ∼5% of patients taking OAAs in Singapore were exposed to ≥1 potentially interacting drug combination.

Ko Y ，Tan SL ，Chan A ，Wong YP ，Yong WP ，Ng RC ，Lim SW ，Salim A ... -  《-》

Clinically significant drug-drug interactions between oral anticancer agents and nonanticancer agents: a Delphi survey of oncology pharmacists.

Drug-drug interactions (DDIs) can lead to adverse clinical outcomes, particularly in oncology, because of the narrow therapeutic index of chemotherapeutic agents and because patients with cancer are at a high risk due to polypharmacy and age-related organ dysfunction. In a previously published study, drug profiles were developed based on primary and tertiary literature reviews for a list of clinically significant DDIs involving 28 oral anticancer agents (OAAs). This study was based on a Delphi survey of oncology pharmacists; the survey results were used to develop a consensus list of clinically significant DDIs involving OAAs and nonanticancer agents. In this study, the DDI profiles previously developed were updated, and the DDI pairs that were listed both in the 2009 Drug Interaction Facts (DIF) and the Thomson Micromedex DrugDex System compendia and that also met the predetermined criteria for clinical significance were selected for further evaluation. In a 2-round, electronically administered Delphi survey of oncology pharmacists, a 5-point Likert scale (1-5, where 1 = strongly agree and 5 = strongly disagree) was used to evaluate the DDI pairs based on 8 clinical aspects (clinical importance; irreversible morbidity and mortality; quality of data; quantity of data; patient's organ functions; comorbid conditions; awareness of interaction; and management burden). International pharmacists who specialized in oncology pharmacy practice and had > or =5 years of practice experience were eligible to participate. Nine of the 23 surveyed pharmacists responded, giving a response rate of 39.1%. A total of 37 DDI pairs were selected from DIF and DrugDex and evaluated by the survey respondents, resulting in the identification, via consensus, of 12 clinically significant DDI pairs. The clinical aspects with the most DDIs that reached consensus of agreement were clinical importance (82.9%) and awareness of interaction (73.2%). An expert panel identified 12 clinically significant DDIs involving OAAs.

Chan A ，Tan SH ，Wong CM ，Yap KY ，Ko Y ... -  《-》

Electronic database to detect drug-drug interactions between antidepressants and oral anticancer drugs from a cancer center in Singapore: implications to clinicians.

Electronic drug interaction databases are often utilized in clinical practice to detect for possible drug-drug interactions between drug pairs. It is uncertain, however, whether most of these detections interactions are clinically important in practice. To demonstrate these issues, this study utilized a comprehensive drug-drug interaction (DDI) electronic database to elucidate the prevalence of DDIs at a cancer centre between antidepressants and oral anticancer drugs (ACDs). Drug utilization reports were retrieved to determine the patients who were prescribed with antidepressants oral ACDs between 2006 and 2009 at a cancer center. Medication records of these patients were retrospectively examined using OncoRx, an internet-based oncology-specific database that allows the identification of DDIs. Out of 910 users of antidepressants, about one-third (281 patients, 30.9%) used an oral ACD and an antidepressant concomitantly. From these patients, about one-fifth (21.0%) had potential DDIs. These patients were users of 17 potentially interacting drug pairs. Ten out of the 17 drug pairs could potentially cause pharmacokinetic interactions, and the rest were pharmacodynamic interactions, with only three out of the 17 drug pairs were clinically documented to cause interacting events. The lack of screening conditions may have led to an over detection of DDI combinations by electronic DDI databases. Many of the detected interactions may not deem high significance in clinical practice. This study exposed a major weakness of current electronic DDI databases for detecting oral ACDs and antidepressants DDIs.

Chan A ，Yap KY ，Koh D ，Low XH ，Cheung YT ，Onco-Informatics (onco-informatics.com) Group ... -  《-》

Prevalence and predictors of potential drug-drug interactions in Regione Emilia-Romagna, Italy.

Gagne JJ ，Maio V ，Rabinowitz C 《-》

Clinically important potential drug-drug interactions in outpatient settings.

Aparasu R ，Baer R ，Aparasu A 《Research in Social & Administrative Pharmacy》