As for other 5-HT3 antagonists, cases of ECG modifications including QT prolongation have been reported with granisetron. In patients concurrently treated with medicinal products known to prolong QT interval and/or which are arrhythmogenic, this may lead to clinical consequences (see Precautions).
In studies in healthy subjects, no evidence of any interaction has been indicated between granisetron and benzodiazepines (lorazepam), neuroleptics (haloperidol) or anti-ulcer medicinal products (cimetidine). Additionally, granisetron has not shown any apparent medicinal product interaction with emetogenic cancer chemotherapies.
No specific interaction studies have been conducted in anaesthetised patients.
Serotonergic medicinal products (e.g. SSRIs and SNRIs): There have been reports of serotonin syndrome following concomitant use of 5-HT3 antagonists and other serotonergic medicinal products (including SSRIs and SNRIs) (see Precautions).