Background Riociguat is a relatively new drug that has been on the market for a short time. Most of the information available on the drug comes from clinical trials that led to its commercialisation.

Purpose Results based on clinical practice often differ from results obtained in clinical trials. The purpose of this study was to evaluate the safety profile of riociguat in clinical practice as well as to analyse possible interactions riociguat may have when administered with other medicines used by HAP patients.

Material and methods A retrospective observational study was conducted in all patients treated with riociguat from September 2015 to 2016. Interactions were identified and classified according to their clinical relevance. The reason for suspension–interruption of treatment and clinical variability associated with adverse effects were also analysed

Results 43 patients were included, mean age 66±16.09 years, 65.12% women. 140 potential interactions with riociguat were recorded, belonging to 26 different drugs. 97.67% of patients had at least one interaction and the median number of interactions per patient was 3 (range 0–7). The most frequently involved drugs in these interactions were: furosemide (24.29%), omeprazole (20%) and spironolactone (18.57%). Depending on their relevance, potential interaction distribution was: 24 moderate (92.31%) and 2 severe (7.69%). In the registered interactions, the primary mechanism involved was based on the risk of hypotension (61.54%). The two most serious potential interactions were with phenytoin, which can decrease levels of riociguat, and calcium+cholecalciferol carbonate, which can modify the solubility of riociguat

Regarding the safety profile, 39.53% of patients suffered any adverse reaction associated with riociguat: nervous system (30.95%), digestive (26.19%) and vascular (19.05%). 2 patients had dose reduction, 1 due to congestive heart failure, associated with the drug. A case of syncope forced suspension of the treatment.

Conclusion Most of the patients included in the study had at least one potential interaction between their own medication and riociguat. Only 3 patients had dose reduction or suspension due to adverse effects related to riociguat. According to the results, it can be assumed that riociguat may be a safe drug despite the high number of potential interactions found in patients with polypharmacy.

References and/or acknowledgements CLINICAL TRIALS:

PATENT-1,CHEST-1,PATENT-2 and CHEST-2.

No conflict of interest