Assessment of potential drug–drug interactions in an oncology unit of a tertiary care teaching hospital

The Prevalence of Drug-Drug Interactions and Reported Therapy Related Side Effects in Oncology Out-Patients

Objective: The use of multiple medications in cancer patients is unavoidable; thus, adverse drug-drug interactions are frequent. This study aims to assess the prevalence of potential drug interactions in oncology patients visiting the outpatient chemotherapy unit. Method: Demographic and health-related information of patients visiting an outpatient chemotherapy unit was recorded using a pre-prepared form. A comprehensive list of all concurrently used medications was compiled and checked for interactions with the Micromedex online drug interaction tool. Results: A total of 179 adult patients were included. We recorded an average of 9.3 drugs per patient with 79 patients using more than 10 drugs. A total of 1671 drugs including 303 chemotherapeutic agents were assessed for drug-drug interactions. A total of 374 interactions, of which 203 were significant, were recorded in 118 (65.9%) patients with an average of 3.2 interactions per patient. Only 46 major interactions were recorded for anticancer agents. Cyclophosphamide (n=13) and cisplatin (n=12) were involved in most interactions. The number of interactions correlated with the number of drugs used (p=.001) and the presence of comorbidities (p=.002). The presence of comorbidities increased the risk of interaction by 1.21 (p=.04). Recorded side effects were not correlated to drug interactions. Conclusion: Medication review in cancer patients is essential in establishing all medications used by patients. Routine assessment in terms of potential drug interactions and evaluation of these interactions by a qualified pharmacist may help in optimizing patient outcomes.

Evaluation of potential drug-drug interactions in cancer patients at a tertiary care hospital in Pakistan

BACKGROUND

Despite harboring a high burden of cancer patients who are at high risk of potential drug-drug interactions (pDDIs), there is scarcity of published information about pDDIs in cancer patients from Pakistan.

OBJECTIVE

To evaluate frequency, pattern, mechanism and factors associated with pDDIs in cancer patients treated at a tertiary care hospital in Pakistan.

METHODS

In this cross-sectional analytical study, a total of 253 eligible ambulatory cancer patients treated at Center for Nuclear Medicine and Radiotherapy Hospital Quetta were evaluated for pDDIs using IBM Micromedex® Drug Interactions. SPSS (version 26) was used for conducting multivariate analysis to find factors associated with the presence pDDIs. A p-value <0.05 was considered statistically significant.

RESULTS

A total of 141/253 (55.7%) patients were exposed to at-least one pDDI. A total of 251 pDDIs were noted with a median of one pDDI/per patient (interquartile range:1-2) Majority interactions were of major severity (72.9%), pharmacodynamic (49.8%) and had fair documentation level (64.1%). Anti-cancer drugs were involved in 73.0% pDDIs with doxorubicin as the most commonly involved (40.0%) anti-cancer followed by cyclophosphamide (27.6%) and cisplatin (13.5%). Potential cardiac adverse events made the bulk (33.8%) of predicted events. Receiving >2 anti-cancer (OR = 5.19, p-value = 0.001) and >6 ancillary drugs (OR = 4.16, p-value = 0.033) emerged as the risk factors of pDDIs.

CONCLUSIONS

The prevalence of pDDIs was within the range reported in published literature. Solid medication review, availability of DDI detecting tools and clinical pharmacist, and paying special attention to the high-risk patients may reduce the frequency of pDDIs at the study site.

Drug-drug interactions in patients undergoing chemoradiotherapy and the impact of an expert team intervention

Background Several studies have examined the drug-drug interaction patterns in different patient populations and treatment settings; however, there is a need, particularly in the field of oncology and radiotherapy, for evaluating methods targeted towards preventing potential drug-drug interactions. One of the measures proposed is identifying potential interactions using computer programs and their evaluation by pharmacologists or clinical pharmacists, thereby providing clinically relevant information to the treating physician regarding the required prescription changes. Objective To determine the prevalence of potential drug-drug interactions in patients receiving chemoradiotherapy and assess the usefulness of expert team recommendations in minimizing interactions. Setting Patients admitted to the radiotherapy and oncology ward of a tertiary care teaching hospital in Karnataka, India. Method We conducted a prospective, cross-sectional study of prescriptions written for patients receiving chemoradiotherapy. Prescriptions containing two or more drugs, at least one of the drugs being an anticancer drug, were analyzed. They were screened for potential drug-drug interactions using the Lexicomp® drug interaction software. The interactions were classified as X, drug combination to be avoided; D, modification of therapy to be considered; and C, therapy to be monitored, as per the Lexicomp criteria. Main outcome measure The number of drug-drug interactions detected that were accepted by the treating radio-oncologist as requiring prescription change before and after the prescription review by an expert team. Results Two hundred twenty-three prescriptions were screened for the presence of drug-drug interactions; 106 prescriptions (47.53%) containing 620 drugs and 211 drug-drug interactions were identified. Of the 211 interactions identified, 6.64% (14/211), 18.48% (39/211), and 74.88% (158/211) drug-drug interactions belonged to category X, D, and C, respectively. Twenty-seven (50.94%) of the 53 category X and D interactions identified were accepted the oncologist as requiring a change in the prescription; an additional 13 (24.53%) interactions were identified as significant by the expert team, and 11 (84.62%) of these were accepted by the oncologist. Conclusion A system of alerting the treating physician to a potential drug-drug interaction leads to avoidance of prescription of the interacting drug combination, and the assistance by an expert team adds significantly to avoidance of clinically relevant drug interactions.