ANZEMET can cause ECG interval changes (PR, QTc, JT prolongation and QRS widening). These changes are related in magnitude and frequency to blood levels of the active metabolite. These changes are self-limiting with declining blood levels. Some patients have interval prolongations for 24 hours or longer. Interval prolongation could lead to cardiovascular consequences, including heart block or cardiac arrhythmias. These have rarely been reported.
A cardiac conduction abnormality observed on an intra-operative cardiac rhythm monitor (interpreted as complete heart block) was reported in a 61-year-old woman who received 200 mg ANZEMET for the prevention of postoperative nausea and vomiting. This patient was also taking verapamil. A similar event also interpreted as complete heart block was reported in one patient receiving placebo.
A 66-year-old man with Stage IV non-Hodgkins lymphoma died suddenly 6 hours after receiving 1.8 mg/kg (119 mg) intravenous ANZEMET Injection. This patient had other potential risk factors including substantial exposure to doxorubicin and concomitant cyclophosphamide.
Dolasetron should be administered with caution in pediatric patients who have or may develop prolongation of cardiac conduction intervals, particularly QTc. Rare cases of sustained supraventricular and ventricular arrhythmias, cardiac arrest leading to death, and myocardial infarction have been reported in children and adolescents (See Precautions, General, and Adverse Reactions – Postmarketing Experience).
Dolasetron should be administered with caution in patients who have or may develop prolongation of cardiac conduction intervals, particularly QTc. These include patients with hypokalemia or hypomagnesemia, patients taking diuretics with potential for inducing electrolyte abnormalities, patients with congenital QT syndrome, patients taking anti-arrhythmic drugs or other drugs which lead to QT prolongation, and cumulative high dose anthracycline therapy.
Cross hypersensitivity reactions have been reported in patients who received other selective 5-HT3 receptor antagonists. These reactions have not been seen with dolasetron mesylate.
The potential for clinically significant drug-drug interactions posed by dolasetron and hydrodolasetron appears to be low for drugs commonly used in chemotherapy or surgery, because hydrodolasetron is eliminated by multiple routes. See PRECAUTIONS, General for information about potential interaction with other drugs that prolong the QTc interval. Blood levels of hydrodolasetron increased 24% when dolasetron was coadministered with cimetidine (nonselective inhibitor of cytochrome P-450) for 7 days, and decreased 28% with coadministration of rifampin (potent inducer of cytochrome P-450) for 7 days. Maximum plasma concentration increased 15% when dolasetron was coadministered with cimetidine and decreased 17% when coadministered with rifampin, but the changes were not associated with any clinical adverse event. ANZEMET does not induce cytochrome P-450 enzymes.
ANZEMET has been safely coadministered with drugs used in chemotherapy and surgery. As with other agents which prolong ECG intervals, caution should be exercised in patients taking drugs which prolong ECG intervals, particularly QTc.
In patients taking furosemide, nifedipine, diltiazem, ACE inhibitors, verapamil, glyburide, propranolol, and various chemotherapy agents, no effect was shown on the clearance of hydrodolasetron. Clearance of hydrodolasetron decreased by about 27% when dolasetron mesylate was administered intravenously concomitantly with atenolol. ANZEMET did not influence anesthesia recovery time in patients. Dolasetron mesylate did not inhibit the antitumor activity of four chemotherapeutic agents (cisplatin, 5-fluorouracil, doxorubicin, cyclophosphamide) in four murine models.
Carcinogenesis, Mutagenesis, Impairment of Fertility
In a 24-month carcinogenicity study, there was a statistically significant (P<0.001) increase in the incidence of combined hepatocellular adenomas and carcinomas in male mice treated with 150 mg/kg/day and above. In this study, mice (CD-1) were treated orally with dolasetron mesylate 75, 150, or 300 mg/kg/day (225, 450 or 900 mg/m2/day). For a 50 kg person of average height (1.46 m2body surface area), these doses represent 3, 6, and 12 times the recommended clinical dose (74 mg/m2) on a body surface area basis. No increase in liver tumors was observed at a dose of 75 mg/kg/day in male mice and at doses up to 300 mg/kg/day in female mice.
In a 24-month rat (Sprague-Dawley) carcinogenicity study, oral dolasetron mesylate was not tumorigenic at doses up to 150 mg/kg/day (900 mg/m2/day, 12 times the recommended human dose based on body surface area) in male rats and 300 mg/kg/day (1800 mg/m2/day, 24 times the recommended human dose based on body surface area) in female rats.
Dolasetron mesylate was not genotoxic in the Ames test, the rat lymphocyte chromosomal aberration test, the Chinese hamster ovary (CHO) cell (HGPRT) forward mutation test, the rat hepatocyte unscheduled DNA synthesis (UDS) test or the mouse micronucleus test.
Dolasetron mesylate was found to have no effect on fertility and reproductive performance at oral doses up to 100 mg/kg/day (600 mg/m2/day, 8 times the recommended human dose based on body surface area) in female rats and up to 400 mg/kg/day (2400 mg/m2/day, 32 times the recommended human dose based on body surface area) in male rats.
Pregnancy Category B
Teratology studies have not revealed evidence of impaired fertility or harm to the fetus due to dolasetron mesylate. These studies have been performed in pregnant rats at oral doses up to 100 mg/kg/day (8 times the recommended human dose based on body surface area) and pregnant rabbits at oral doses up to 100 mg/kg/day (16 times the recommended human dose based on body surface area). There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.
It is not known whether dolasetron mesylate is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when ANZEMET Tablets are administered to a nursing woman.
Dolasetron should be administered with caution in pediatric patients who have or may develop prolongation of cardiac conduction intervals, particularly QTc. Rare cases of sustained supraventricular and ventricular arrhythmias, cardiac arrest leading to death, and myocardial infarction have been reported in children and adolescents (See Warnings and Adverse Reactions – Postmarketing Experience).
ANZEMET Tablets are expected to be as safe and effective as when ANZEMET Injection is given orally to pediatric patients. ANZEMET Tablets are recommended for children old enough to swallow tablets (see CLINICAL PHARMACOLOGY, Pharmacokinetics in Humans).
Prevention of cancer chemotherapy-induced nausea and vomiting (CINV)
In controlled clinical trials in the prevention of chemotherapy-induced nausea and vomiting, 301 (29%) of 1026 patients were 65 years of age or older. Of the 301 geriatric patients in the trial, 282 received oral ANZEMET Tablets. No overall differences in safety or effectiveness were observed between geriatric and younger patients, and other reported clinical experience has not identified differences in responses between geriatric and younger patients, but greater sensitivity of some older individuals cannot be ruled out.
Prevention and treatment of post-operative nausea and vomiting (PONV)
Controlled clinical studies in the prevention and treatment of post-operative nausea and vomiting did not include sufficient numbers of patients aged 65 years or older – only 5 (0.4%) geriatric patients (all 5 received intravenous ANZEMET Injection) out of 1167 total patients participated in the controlled PONV trials – to determine whether they respond differently from the younger patients. Other reported clinical experiences have not identified differences in responses between geriatric and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
The pharmacokinetics, including clearance of oral ANZEMET Tablets, in elderly and younger patients are similar (see CLINICAL PHARMACOLOGY, Pharmacokinetics in Humans). Dosage adjustment is not needed in patients over the age of 65.