Background Detection of drugs that produce prolongation of the QT interval is very important.

Purpose Oncological patients have an associated risk for QT prolongation due to hydroelectrolyte disturbances associated with their pathologies and the treatment received for side-effects related to antineoplasic treatment.

To evaluate the prescription of drugs with a known risk for prolonging the QT interval in cancer patients. Propose treatment alternatives that improve patient safety.

Material and methods Oncological patients under treatment with a tyrosine kinase inhibitor (TKI) were included. We collected the following variables: sex, age, type of tumour, analytical disturbances, history of heart disease (through left ventricular ejection fraction (LVEF)) current oncological treatment and concomitant medication through Farmatools^®2.5, patient interview and electronic prescription registration (Selene^®).

Results A total of 48 patients were analysed: 29 (60.4%) males and 19 (39.6%) females, with a mean age of 60±12.9 years. Of the total number of patients, 12 (25%) were diagnosed with soft tissue sarcoma; five (10.4%) with colorectal cancer; seven (14.6%) with kidney cancer; one (2.1%) with thyroid cancer; sixteen (33.3%) with non-small cell lung cancer (NSCLC); one (2.1%) with non-Hodgkin’s lymphoma; four (8.3%) with breast cancer; and two (4.2%) with malignant melanoma.

Patient risk factors were: females (39.58%),age >65 years (45.8%; 9% were female), electrolyte disturbances (8.3%), hepatic and renal dysfunction (12.5% respectively) and a history of heart disease (14.6%).

All patients received oncologic treatment with some TKI (known risk of prolongation of the QT interval); 19 patients (39.6%) had concomitant treatment with a known risk drug; and 29 patients (60.4%) had treatment with a drug that interacted with the known risk drug. Twenty-four patients (82.7%) had potential interactions with other risk drugs, three (10.3%) had interaction with drugs that inhibited the metabolism of the known risk drug and two (6.9%) had both types of interaction.

The most commonly prescribed drugs were antiemetics (22.9%), neuroleptics (8.3%) and antidepressants (. 3%).

In compliance with the Oncology Department, therapeutic groups with a high risk for prolongation of the QT interval such as antidepressants, antiemetics and antipsychotics were changed to others with a lower risk of prolongation of the QT interval: in all patients taking citalopram the treatment was modified with venlafaxine, fluoxetine or sertraline (conditional risk). In all patients taking ondansetron, treatment was modified with granisetron (possible risk).

Conclusion Our results are similar to those of other published studies. The prevalence detected in the prescription of drugs that prolong the QT interval is relevant, taking into account that cancer patients have a higher risk factor.

Reference and/or Acknowledgements 1. NEnglJMed2004;350:1013. 22. https://www.crediblemeds.org

No conflict of interest