Potential Interactions of Medication Prescribed in Discharge Letters from a Clinic for Hematology and Oncology.

BACKGROUND: As there are few data worldwide concerning the frequency and relevance of interactions of prescribed drugs in hemato-oncology, we analyzed the medication prescribed to patients at a clinic within a comprehensive cancer center.

METHODS: Details of the medication prescribed for all patients in 2011 were extracted from their discharge letters. All potential medication combinations were assess with respect to the risk of interaction using 3 specialized websites.

RESULTS: The files of 202 patients receiving 275 drugs were extracted; 4,303 drug combinations were created. Overall, 88% of these combinations were found to be harmless with an interaction value (IV) of 1. However 10% showed potential risk of probable interaction (IV 2 + 3). 47% of the patients had at least 1 drug combination with a risk of interaction. A maximum of 29 drugs with 15 probable and possible interactions were found.

CONCLUSION: Awareness for this topic should be raised in physicians and patients. An important step for avoiding risks of interactions is a systematic check of all drugs prescribed. There is urgent need for reliable data on clinically relevant interactions and for a better network in which physicians and pharmacists can exchange data about relevant interactions.