CPC-106 Pharmacokinetic Drug-Drug Interactions Due to Treatment with Amiodarone – a Practical Approach

Background The drug amiodarone has a complex pharmacokinetic profile and can be a challenge to use due to the high potential for drug-drug interactions. Purpose To identify and submit proposals for handling drug-drug interactions for patients treated with amiodarone. In addition we would like to highlight the fact that drug interactions can occur even if amiodarone is administered as only a single IV dose, and the effect on further treatment. The purpose was also to prepare proposals for management and follow ups of interactions in the clinic. Materials and Methods Before the ward round the pharmacist carried out medicines reviews for the 25 patients who were included. They were all treated with amiodarone at admission or during hospitalisation. Input was given on the clinically significant interactions identified. For patients treated with warfarin in addition to IV amiodarone the INR values were observed through the entire hospital stay for any signs of a drug-drug interaction. Results The pharmacist had 54 inputs referring to interactions with amiodarone, of which 41 were taken into account. The inputs led to dose reductions, changes of drugs and monitoring of blood values. Case reports showed that interactions do occur after IV amiodarone treatment and these lead to uncertain and variable drug efficacy over time. Conclusions Based on results from the study and a literature search, general advice for handling interactions due to amiodarone and further treatment were prepared. The recommendations were endorsed by the consultant Cardiologist. No conflict of interest.