Background Atrial fibrillation (AF) is one of the most common sustained cardiac arrhythmia. It is associated with significant morbidity, mortality and poor quality of life. This is the reason why it is very important to closely follow its treatment. Amiodarone is one of the most frequently used antiarrhythmic drugs in patients with AF both in prophylaxis and treatment. However, the treatment with this drug results in high healthcare resource use and costs due to its poor safety profile.

Purpose The objective of this study was to assess the plasmatic concentration of amiodarone in patients with AF and also to identify possible factors that could influence it. The results were correlated with used doses, with concomitantly administered drugs, renal and liver function.

Material and methods A prospective observational study was conducted in 27 consecutive patients treated with amiodarone from May to July 2017 in a Clinical University Hospital. The patients included met our inclusion criteria. HPLC-MS was the device used to determine the plasma concentration of amiodarone.

Results The mean age of those 27 included patients was 65/6±11 years, 44.4% females. The used doses were 200 mg or 400 mg/day. In our patients, plasmatic concentration was given in a therapeutic interval (500–2,500 ng/ml) to 51.8%. In the patients with lower plasmatic concentrations of amiodarone, the drugs associated in the therapeutic plan belonged to: diuretics (furosemide), beta-blockers, statins, antiplatelets (clopidogrel), fluoroquinolones (ciprofloxacine) and non-steroidal anti-inflammatory drugs. It was observed that there was a statistically significant difference between the plasmatic concentrations of amiodarone in patients treated with furosemide vs patients treated concomitantly with other drugs. The interactions between other mentioned drugs and amiodarone were not registered. It was observed that an increase in transaminases or creatinine is correlated with an increase in amiodarone’s plasmatic concentration.

Conclusion 48.2% of the patients with AF under chronic treatment with amiodarone had the plasmatic concentration of amiodarone out of the therapeutic range. We can report an underuse of amiodarone for these patients. It was found that there was a significant interaction between furosemide and amiodarone. In order to confirm this interaction, we need to continue the research on a larger sample.

References and/or Acknowledgements Thanks to all the collaborators.

No conflict of interest