In a 24-month carcinogenicity study of granisetron hydrochloride, rats were treated orally with 1, 5 or 50 mg/kg/day. The 50 mg/kg/day dose was reduced to 25 mg/kg/day during week 59 due to toxicity. For a 60 kg person, the 1, 5, and 25 mg/kg/day doses represent approximately 7, 34 and 169 times, respectively, the maximum recommended human dose (MRHD) (10 mg granisetron/week, approximately 6.2 mg/m2/week) of SUSTOL 10 mg/week, based on body surface area. There was a statistically significant increase in the incidence of hepatocellular carcinomas and adenomas in male rats treated with 5 mg/kg/day (approximately 34 times the MRHD of SUSTOL 10 mg/week, based on body surface area) and above, and in female rats treated with 25 mg/kg/day (approximately 169 times the MRHD of SUSTOL 10 mg/week, based on body surface area). No increase in liver tumors was observed at a dose of 1 mg/kg/day (approximately 7 times the MRHD of SUSTOL 10 mg/week, based on body surface area) in male rats and 5 mg/kg/day (approximately 34 times the MRHD of SUSTOL 10 mg/week, based on body surface area) in female rats.

A 24-month subcutaneous carcinogenicity study in rats evaluated the carcinogenic potenial of the polymer vehicle in SUSTOL. There were no drug-related neoplasms up to 0.295 g/week (approximately 9 to 30 times the amounnt of polymer vehicle present in the MRHD of SUSTOL 10 mg/week, based on body surface area).

In a 12-month oral toxicity study with granisetron hydrochloride, rats were treated at 100 mg/kg/day (approximately 677 times the MRHD of SUSTOL 10 mg/week, based on body surface area). This dose produced hepatocellular adenomas in male and female rats while no such tumors were found in the control rats. A 24-month mouse carcinogenicity study of granisetron did not show a statistically significant increase in tumor incidence, but the study was not conclusive. Because of the tumor findings in rat studies, SUSTOL should be prescribed only at the dose and for the indication recommended [see Indications and Usage (1), Dosage and Administration (2.2)].

Granisetron hydrochloride was not mutagenic in an in vitro Ames test and mouse lymphoma cell forward mutation assay, and in vivo mouse micronucleus test and in vitro and ex vivo rat hepatocyte unscheduled DNA synthesis (UDS) assays. However, granisetron hydrochloride was positive in a mouse lymphoma assay with metabolic activation and produced a significant increase in UDS in HeLa cells in vitro and a significant increased incidence of cells with polyploidy in an in vitro human lymphocyte chromosomal aberration test.

Neither SUSTOL nor the polymer vehicle for SUSTOL was mutagenic in the Ames test, mouse lymphoma assay, and the in vivo rat bone marrow micronucleus test.

Granisetron hydrochloride at subcutaneous doses up to 6 mg/kg/day (approximately 40 times the MRHD of SUSTOL 10 mg/week, based on body surface area), and oral doses up to 100 mg/kg/day (approximately 677 times the MRHD of SUSTOL 10 mg/week, based on body surface area) was found to have no effect on fertility and reproductive performance of male and female rats.

The polymer vehicle for SUSTOL at subcutaneous doses up to 0.295 g per day (approximately 137 times the amount of polymer vehicle present in the maximum recommended /weekly single human dose of SUSTOL, based on body surface area) was found to have no adverse effect on fertility and reproductive performance of male and female rats.