Granisetron Drug Information

Granisetron hydrochloride tablets are indicated for the prevention of: Nausea and vomiting associated with initial and repeat courses of emetogenic cancer therapy, including high-dose cisplatin. Nausea and vomiting associated with radiation, including total body irradiation and fractionated abdominal radiation.

​ DOSAGE AND ADMINISTRATION Emetogenic Chemotherapy The recommended adult dosage of oral granisetron hydrochloride is 2 mg once daily or 1 mg twice daily. In the 2 mg once-daily regimen, two 1 mg tablets are given up to 1 hour before chemotherapy. In the 1 mg twice-daily regimen, the first 1 mg tablet is given up to 1 hour before chemotherapy, and the second tablet, 12 hours after the first.

Either regimen is administered only on the day(s) chemotherapy is given. Continued treatment, while not on chemotherapy, has not been found to be useful. Use in the Elderly, Renal Failure Patients or Hepatically Impaired Patients No dosage adjustment is recommended (see CLINICAL PHARMACOLOGY: Pharmacokinetics ). Pediatric Use Safety and effectiveness in pediatric patients have not been established.

Radiation (Either Total Body Irradiation or Fractionated Abdominal Radiation) The recommended adult dosage of oral granisetron hydrochloride is 2 mg once daily. Two 1 mg tablets are taken within 1 hour of radiation. Pediatric Use Safety and effectiveness in pediatric patients have not been established.

Use in the Elderly No dosage adjustment is recommended.

prolongation has been reported with granisetron hydrochloride (see PRECAUTIONS and Drug Interactions ). Chemotherapy-Induced Nausea and Vomiting Over 3700 patients have received granisetron hydrochloride tablets in clinical trials with emetogenic cancer therapies consisting primarily of cyclophosphamide or cisplatin regimens. In patients receiving granisetron hydrochloride tablets 1 mg twice a day for 1, 7 or 14 days, or 2 mg daily for 1 day, adverse experiences reported in more than 5% of the patients with comparator and placebo incidences are listed inTable 4. Table 4 Principal Adverse Events in Clinical Trials Percent of Patients With Event Granisetron Hydrochloride 1 Tablets 1 mg twice a day (n=978) Granisetron Hydrochloride 1 Tablets 2 mg once a day (n=1450) Comparator 2 (n=599) Placebo (n=185) Headache 21% 20% 13% 12% Constipation 18% 14% 16% 8% Asthenia 14% 18% 10% 4% Diarrhea 8% 9% 10% 4% Abdominal pain 6% 4% 6% 3% Dyspepsia 4% 6% 5% 4% 1 Adverse events were recorded for 7 days when granisetron hydrochloride tablets were given on a single day and for up to 28 days when granisetron hydrochloride tablets were administered for 7 or 14 days. 2 Metoclopramide/dexamethasone; phenothiazines/dexamethasone; dexamethasone alone; prochlorperazine. Other adverse events reported in clinical trials were: Gastrointestinal: In single-day dosing studies in which adverse events were collected for 7 days, nausea (20%) and vomiting (12%) were recorded as adverse events after the 24 hour efficacy assessment period.

Hepatic: In comparative trials, elevation of AST and ALT (>2 times the upper limit of normal) following the administration of granisetron hydrochloride tablets occurred in 5% and 6% of patients, respectively. These frequencies were not significantly different from those seen with comparators (AST: 2%; ALT: 9%). Cardiovascular: Hypertension (1%); hypotension, angina pectoris, atrial fibrillation, and syncope have been observed rarely. Central Nervous System: Dizziness (5%), insomnia (5%), anxiety (2%), somnolence (1%). One case compatible with, but not diagnostic of, extrapyramidal symptoms has been reported in a patient treated with granisetron hydrochloride tablets.

Hypersensitivity: Rare cases of hypersensitivity reactions, sometimes severe (e.g., anaphylaxis, shortness of breath, hypotension, urticaria) have been reported. Other: Fever (5%). Events often associated with chemotherapy also have been reported: leukopenia (9%), decreased appetite (6%), anemia (4%), alopecia (3%), thrombocytopenia (2%). Over 5000 patients have received injectable granisetron hydrochloride in clinical trials. Table 5 gives the comparative frequencies of the five commonly reported adverse events (≥3%) in patients receiving granisetron hydrochloride injection, 40 mcg/kg, in single-day chemotherapy trials.

These patients received chemotherapy, primarily cisplatin, and intravenous fluids during the 24 hour period following granisetron hydrochloride injection administration. Table 5 Principal Adverse Events in Clinical Trials - Single-Day Chemotherapy Percent of Patients with Event Granisetron Hydrochloride Injection 1 40 mcg/kg (n=1268) Comparator 2 (n=422) Headache 14% 6% Asthenia 5% 6% Somnolence 4% 15% Diarrhea 4% 6% Constipation 3% 3% 1 Adverse events were generally recorded over 7 days post-granisetron hydrochloride injection administration. 2 Metoclopramide/dexamethasone and phenothiazines/dexamethasone. In the absence of a placebo group, there is uncertainty as to how many of these events should be attributed to granisetron hydrochloride, except for headache, which was clearly more frequent than in comparison groups.

Radiation-Induced Nausea and Vomiting In controlled clinical trials, the adverse events reported by patients receiving granisetron hydrochloride tablets and concurrent radiation were similar to those reported by patients receiving granisetron hydrochloride tablets prior to chemotherapy. The most frequently reported adverse events were diarrhea, asthenia, and constipation. Headache, however, was less prevalent in this patient population.

Postmarketing Experience QT prolongation has been reported with granisetron hydrochloride (see PRECAUTIONS and Drug Interactions ).

Drug Interactions Granisetron does not induce or inhibit the cytochrome P-450 drug-metabolizing enzyme system in vitro. There have been no definitive drug-drug interaction studies to examine pharmacokinetic or pharmacodynamic interaction with other drugs; however, in humans, granisetron hydrochloride injection has been safely administered with drugs representing benzodiazepines, neuroleptics, and anti-ulcer medications commonly prescribed with antiemetic treatments. Granisetron hydrochloride injection also does not appear to interact with emetogenic cancer chemotherapies.

Because granisetron is metabolized by hepatic cytochrome P-450 drug-metabolizing enzymes, inducers or inhibitors of these enzymes may change the clearance and, hence, the half-life of granisetron. No specific interaction studies have been conducted in anesthetized patients. In addition, the activity of the cytochrome P-450 subfamily 3A4 (involved in the metabolism of some of the main narcotic analgesic agents) is not modified by granisetron hydrochloride in vitro.

In in vitro human microsomal studies, ketoconazole inhibited ring oxidation of granisetron hydrochloride. However, the clinical significance of in vivo pharmacokinetic interactions with ketoconazole is not known. In a human pharmacokinetic study, hepatic enzyme induction with phenobarbital resulted in a 25% increase in total plasma clearance of intravenous granisetron hydrochloride.

The clinical significance of this change is not known. QT prolongation has been reported with granisetron hydrochloride. Use of granisetron hydrochloride in patients concurrently treated with drugs known to prolong the QT interval and/or are arrhythmogenic, this may result in clinical consequences.

Serotonin syndrome (including altered mental status, autonomic instability, and neuromuscular symptoms) has been described following the concomitant use of 5-HT 3 receptor antagonists and other serotonergic drugs, including selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs) ( see WARNINGS ).

Pregnancy Teratogenic Effects Pregnancy Category B. Reproduction studies have been performed in pregnant rats at oral doses up to 125 mg/kg/day (750 mg/m 2 /day, 507 times the recommended human dose based on body surface area) and pregnant rabbits at oral doses up to 32 mg/kg/day (378 mg/m 2 /day, 255 times the recommended human dose based on body surface area) and have revealed no evidence of impaired fertility or harm to the fetus due to granisetron. 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.

Pediatric Use Safety and effectiveness in pediatric patients have not been established.

Granisetron hydrochloride is contraindicated in patients with known hypersensitivity to the drug or any of its components.

There is no specific treatment for granisetron hydrochloride overdosage. In case of overdosage, symptomatic treatment should be given. Overdosage of up to 38.5 mg of granisetron hydrochloride injection has been reported without symptoms or only the occurrence of a slight headache.