Drug-drug (DDIs) and herb-drug interactions (HDIs) are common among patients with cancer and can have important clinical ramifications, according to a study published in the Journal of Oncology Practice.1

Patients with cancer frequently use other medications and herbal supplements with their antineoplastic agents and are therefore at high risk of DDIs and HDIs. The aim of this study was to determine the rates and effects of DDIs and HDIs in a prospective setting.

The prospective study enrolled 149 patients with solid tumors who were starting a new antineoplastic agent. Patients completed a questionnaire that inquired about over-the-counter (OTC) medication and herbal supplement use.

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Lexi-Interact software was used to identify potential DDIs. Potentially clinically relevant findings resulted in notification of the oncologist for potential intervention.

The median age at baseline was 57.5 and 28.9% of patients were male. Comorbidities were present in 54.4% of patients, including hypertension, diabetes, hypothyroidism, and dyslipidemia.

The median number of concomitant drugs was 3 (range, 0 to 13), and the majority were for lowering blood pressure or were non-steroidal anti-inflammatory drugs, proton-pump inhibitors, opioids, antidepressants, and steroids.

More than 16% of patients reported using OTC medications; 36 potentially relevant DDIs were identified among 17.4% (95% CI, 11.3-23.5%). These include pharmacokinetic (86.1%) and pharmacodynamic (13.9%).

The DDI severity was rated as C, D, and X in 23, 11, and 2 patients, respectively. Clinical consequences potentially occurred as a result of the DDI among 2.7% of patients (95% CI, 0.1-5.3%).

Herbal supplements were used by 56.4% of patients with a median number of 4 (range, 0 to 8), including allium sativum, aloe barbadensis/capensis, gingko biloba, spirulina sp., and panax ginseng.

A possible 121 HDIs were identified among 50.3% of patients (95% CI, 42.3-58.3%). The severity was rated as mild in 2.5% and moderate in 61.4%, and 36.1% were not graded due to lack of clinical data.  

There were no reported clinical consequences resulting from an HDI.

The authors wrote that these findings “showed that a program of medication surveillance in patients with cancer led by clinical pharmacists could prevent a relatively high proportion of patients from experiencing potentially adverse clinical consequences of DDIs and HDIs.”


  1. Ramos-Esquivel A, Víquez-Jaikel A, Fernández C. Potential drug-drug and herb-drug interactions in patients with cancer: a prospective study of medication surveillance. J Oncol Pract. 2017 Jun 19. doi: 10.1200/JOP.2016.2017.020859 [Epub ahead of print]