Background Cancer patients are usually polymedicated, therefore one of the objectives of pharmaceutical care in cancer patients is to identify drug interactions.

Purpose To identify potential drug interactions with oral antineoplastic agents and risk factors in order to design a medicines reconciliation programme in an oncology outpatient clinic.

Material and methods The study was undertaken at an oncology outpatient clinic during July 2014 in patients taking oral antineoplastic agents. The information regarding patient demographics and drug treatments was collected retrospectively from Hospital and Outpatients records. Potential drug interactions were identified selecting clinically relevant interactions. Drug interactions were assessed by using Micromedex, the summaries of product characteristics of the oral antineoplastic agents and a published interactions guide.¹

Results 174 patients were included: median 65 years old (range: 27–84), 52% female.

41 patients (23.6%) showed 50 potential drug interactions, averaging 1.2 interactions per patient. Of this group of patients, 22 (53.6%) were male. Their age range was 34–83 years (median 64) and they received 1 to 24 concomitant drugs (median 9).

20 oral antineoplastic agents were identified in the patient records, of which 14 had potential interactions, most commonly seen in erlotinib 14 (28%), dabrafenib 6 (12%) and gefitinib 5 (10%).

According to the severity the interactions found were: contraindicated 1 (2%); severe 29 (58%).

Recommendations in the literature were: avoid the drug combination, 3; adjust posology/administration, 25 and monitor, 22.

Conclusion A large number of patients treated with oral antineoplastic agents had potential drug interactions, especially with the new drugs. However, many of those interactions are predictable and therefore preventable.

It would be helpful to implement a medicines reconciliation programme in polymedicated oncology outpatients.

Reference

1. González-Carrascosa T, Sierra Sánchez JF, Martinez Bautista MJ, et al. Conciliación en el Paciente Oncológico. Guía de Interacciones, 1st ed. 2013

ReferenceNo conflict of interest.