FDA drug approvals
Granisetron is a selective 5-HT3 serotonin receptor antagonist that has little or no affinity for other serotonin receptors. Through binding to 5-HT3 receptors, granisetron blocks serotonin stimulation, which consequently inhibits vomiting after the administration of emetogenic agents. The granisetron transdermal system was approved on September 12, 2008, for the prevention of nausea and vomiting in patients receiving moderately and/or highly emetogenic chemotherapy regimens of ≤5 consecutive days duration.
Efficacy. The efficacy of the granisetron transdermal system was evaluated in a phase 3, randomized, parallel-group, double-blind, double-dummy trial. In this study, patients (N=641) undergoing chemotherapy for >1 day were randomized to treatment with either the granisetron patch or oral granisetron 2 mg/d. The patch was applied 24 to 48 hours before the first dose of chemotherapy and was left in place for 7 days; oral granisetron was administered 1 hour before each chemotherapy dose. The primary end point was the proportion of patients who experienced no vomiting and/or retching and no more than mild nausea and who did not require rescue medication from the first administration until 24 hours after initiation of the last day of chemotherapy administration. A total of 60.2% of patients treated with transdermal granisetron achieved this end point versus 64.8% of patients treated with oral granisetron (difference, 4.89%; 95% CI, 12.91% to 3.13%). An assessment of patch adhesion demonstrated that <1% of patches became detached over the 7-day treatment period.
Safety. Use of granisetron may mask progressive ileus or gastric distention related to a patients underlying condition. In clinical trials, application-site reactions were reported in patients treated with the granisetron patch; these reactions were generally mild and did not result in discontinuation. The most common adverse event reported in association with the granisetron transdermal system is constipation.