Kytril Drug Interactions

Kytril did not induce or inhibit the cytochrome P₄₅₀ drug metabolizing enzyme system in rodent studies or inhibit the activity of any well characterized P₄₅₀ sub-families studied in in vitro investigations.
In humans, hepatic enzyme induction with phenobarbital resulted in an increase in total plasma clearance of intravenous Kytril of approximately one-quarter. In in vitro human microsomal studies, ketoconazole inhibited ring oxidation of Kytril. However, given the absence of pK/pD relationship with granisetron, these changes are believed to have no clinical consequences.
Kytril has been safely administered in humans with benzodiazepines, neuroleptics and anti-ulcer medications, commonly prescribed with antiemetic treatments. Additionally, Kytril has shown no apparent drug interaction with emetogenic cancer chemotherapies.
No specific interaction studies have been conducted in anesthetized patients, but Kytril has been safely administered with commonly used anesthetic and analgesic agents. In addition, the activity of the cytochrome P₄₅₀ subfamily 3A4 (involved in the metabolism of some of the main narcotic analgesic agents) is not modified by Kytril.
As for other 5-HT₃ antagonists, cases of ECG modifications including QT prolongation have been reported with KYTRIL. These ECG changes with KYTRIL were minor and generally not of clinical significance, specifically with no evidence of proarrhythmia. However, in patients concurrently treated with drugs known to prolong QT interval and/or are arrhythmogenic, this may lead to clinical consequences.
As with other 5-HT₃ antagonists, cases of serotonin syndrome have been reported following the concomitant use of Kytril and other serotonergic drugs. If concomitant treatment with granisetron and other serotonergic drugs is clinically warranted, appropriate observation of this patient is advised (see Precautions).