Palonosetron Hydrochloride (Page 2 of 5)

6.2 Postmarketing Experience

The following adverse reactions have been identified during post approval use of another intravenous formulation of palonosetron HCl. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Very rare cases (<1/10,000) of hypersensitivity reactions including anaphylaxis and anaphylactic shock and injection site reactions (burning, induration, discomfort and pain) were reported from postmarketing experience of palonosetron HCl 0.25 mg in the prevention of chemotherapy-induced nausea and vomiting.

7 DRUG INTERACTIONS

7.1 Serotonergic Drugs

Serotonin syndrome (including altered mental status, autonomic instability, and neuromuscular symptoms) has been described following the concomitant use of 5-HT3 receptor antagonists and other serotonergic drugs, including selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs). Monitor for the emergence of serotonin syndrome. If symptoms occur, discontinue Palonosetron HCl Injection and initiate supportive treatment [see Warnings and Precautions (5.2)].

8 USE IN SPECIFIC POPULATIONS

8.1 Pregnancy

R i sk Summary

There are no available data on palonosetron HCl use in pregnant women to inform a drug-associated risk. In animal reproduction studies, no effects on embryo-fetal development were observed with the administration of oral palonosetron HCl to rats and rabbits during organogenesis at doses up to 1894 and 3789 times the recommended human intravenous dose, respectively [see Data].

The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.

D ata

Animal Data

In animal reproduction studies, no effects on embryo-fetal development were observed in pregnant rats given oral palonosetron HCl at doses up to 60 mg/kg/day (1894 times the recommended human intravenous dose based on body surface area) or pregnant rabbits given oral doses up to 60 mg/kg/day (3789 times the recommended human intravenous dose based on body surface area) during the period of organogenesis.

8.2 Lactation

R i sk Summary

There are no data on the presence of palonosetron in human milk, the effects of palonosetron on the breastfed infant, or the effects of palonosetron on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for Palonosetron HCl Injection and any potential adverse effects on the breastfed infant from palonosetron or from the underlying maternal condition.

8.4 Pediatric Use

This product has not been approved for use in pediatric patients for prevention of chemotherapy-induced nausea and vomiting.

8.5 Geriatric Use

Of the 1374 adult cancer patients in clinical studies of intravenously administered palonosetron HCl for CINV, 316 (23%) were aged 65 years and over, while 71 (5%) were aged 75 years and over. No overall differences in safety or effectiveness were observed between these subjects and the younger subjects, but greater sensitivity in some older individuals cannot be ruled out. Population pharmacokinetics analysis did not reveal any differences in palonosetron pharmacokinetics between cancer patients aged 65 years and older and younger patients (18 to 64 years). No dose adjustment or special monitoring are required for geriatric patients.

10 OVERDOSAGE

There is no known antidote to palonosetron HCl. Overdose should be managed with supportive care.

Dialysis studies have not been performed; however, due to the large volume of distribution, dialysis is unlikely to be an effective treatment for palonosetron HCl overdose. A single intravenous dose of palonosetron HCl at 30 mg/kg (947 and 474 times the human dose for rats and mice, respectively, based on body surface area) was lethal to rats and mice. The major signs of toxicity were convulsions, gasping, pallor, cyanosis and collapse.

11 DESCRIPTION

Palonosetron Hydrochloride Injection contains palonosetron as palonosetron HCl, an antiemetic and antinauseant agent. It is a serotonin-3 (5-HT3 ) receptor antagonist with a strong binding affinity for this receptor. Chemically, palonosetron HCl is: (3aS)-2-[(S)-1-Azabicyclo [2.2.2]oct-3-yl]-2,3,3a,4,5,6­ hexahydro-1-oxo-1H benz[de ]isoquinoline hydrochloride. The empirical formula is C19 H24 N2 O•HCl, with a molecular weight of 332.87. Palonosetron HCl exists as a single isomer and has the following structural formula:

structure
(click image for full-size original)

Palonosetron HCl is a white to off-white crystalline powder. It is freely soluble in water, soluble in propylene glycol, and slightly soluble in ethanol and 2-propanol.

Palonosetron HCl Injection is a sterile, clear, colorless, non-pyrogenic, non-buffered, hypotonic solution for intravenous administration. Palonosetron HCl Injection contains no preservative or chelating agent. Palonosetron HCl Injection is available as 2 mL single-dose vial.

Each 2 mL vial contains 0.25 mg palonosetron base equivalent to 0.28 mg palonosetron HCl, and water for intravenous administration.

The pH of the solution in the 2 mL vial is 6.5 to 8.5.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Palonosetron is a 5-HT3 receptor antagonist with a strong binding affinity for this receptor and little or no affinity for other receptors.

Cancer chemotherapy may be associated with a high incidence of nausea and vomiting, particularly when certain agents, such as cisplatin, are used. 5-HT3 receptors are located on the nerve terminals of the vagus in the periphery and centrally in the chemoreceptor trigger zone of the area postrema. It is thought that chemotherapeutic agents produce nausea and vomiting by releasing serotonin from the enterochromaffin cells of the small intestine and that the released serotonin then activates 5-HT3 receptors located on vagal afferents to initiate the vomiting reflex.

12.2 Pharmacodynamics

C ardiac Electrophysiology

The effect of intravenous palonosetron HCl on blood pressure, heart rate, and ECG parameters including QTc were comparable to intravenous ondansetron and dolasetron in CINV clinical trials. In non-clinical studies palonosetron possesses the ability to block ion channels involved in ventricular de- and re-polarization and to prolong action potential duration.

The effect of palonosetron on QTc interval was evaluated in a double blind, randomized, parallel, placebo and positive (moxifloxacin) controlled trial in adult men and women. The objective was to evaluate the ECG effects of intravenously administered palonosetron HCl at single doses of 0.25, 0.75 or 2.25 mg in 221 healthy subjects. At a dose 9 times the maximum recommended dose, palonosetron did not prolong the QT interval to any clinically relevant extent.

12.3 Pharmacokinetics

After intravenous dosing of palonosetron HCl in healthy subjects and cancer patients, an initial decline in plasma concentrations is followed by a slow elimination from the body. Mean maximum plasma concentration (Cmax ) and area under the concentration-time curve (AUC0-∞ ) are generally dose-proportional over the dose range of 0.3 to 90 mcg/kg in healthy subjects and in cancer patients. Following a single intravenous dose of palonosetron HCl at 3 mcg/kg (or 0.21 mg/70 kg) to six cancer patients, the mean (±SD) maximum plasma concentration was estimated to be 5630 ± 5480 ng/L and the mean AUC was 35.8 ± 20.9 h•mcg/L.

Following intravenous administration of palonosetron HCl 0.25 mg once every other day for 3 doses in 11 cancer patients, the mean increase in plasma palonosetron concentration from Day 1 to Day 5 was 42 ± 34%. Following intravenous administration of palonosetron HCl 0.25 mg once daily for 3 days in 12 healthy subjects, the mean (±SD) increase in plasma palonosetron concentration from Day 1 to Day 3 was 110 ± 45%.

Distribution
Palonosetron has a volume of distribution of approximately 8.3 ± 2.5 L/kg. Approximately 62% of palonosetron is bound to plasma proteins.

Elimination
After a single intravenous dose of 10 mcg/kg [14 C]-palonosetron HCl, approximately 80% of the dose was recovered within 144 hours in the urine with palonosetron representing approximately 40% of the administered dose. In healthy subjects, the total body clearance of palonosetron was 0.160 ± 0.035 L/h/kg and renal clearance was 0.067 ± 0.018 L/h/kg. The mean terminal elimination half-life is approximately 40 hours.

M etabolism
Palonosetron is eliminated by multiple routes with approximately 50% metabolized to form two primary metabolites: N-oxide-palonosetron and 6-S-hydroxy-palonosetron. These metabolites each have less than 1% of the 5-HT3 receptor antagonist activity of palonosetron. In vitro metabolism studies have suggested that CYP2D6 and to a lesser extent, CYP3A4 and CYP1A2 are involved in the metabolism of palonosetron. However, clinical pharmacokinetic parameters are not significantly different between poor and extensive metabolizers of CYP2D6 substrates.

Excretion
Palonosetron is partially eliminated from the body through renal excretion.

Specific Populations
Renal Impairment
Mild to moderate renal impairment does not significantly affect palonosetron pharmacokinetic parameters. Total systemic exposure increased by approximately 28% in patients with severe renal impairment relative to healthy subjects. This increase is not considered clinically meaningful.

H epatic Impairment
Hepatic impairment does not significantly affect total body clearance of palonosetron compared to the healthy subjects.

Race/Ethnicity
The pharmacokinetics of palonosetron were characterized in twenty-four healthy Japanese subjects over the dose range of 3 to 90 mcg/kg. Total body clearance was 25% higher in Japanese subjects compared to Whites; however, no dose adjustment is required. The pharmacokinetics of palonosetron in Blacks has not been adequately characterized.

Drug Interaction Studies
I n vitro studies indicated that palonosetron is not an inhibitor of CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6, CYP2E1 and CYP3A4/5 (CYP2C19 was not investigated) nor does it induce the activity of CYP1A2, CYP2D6, or CYP3A4/5. Therefore, the potential for clinically significant drug interactions with palonsetron appears to be low.

D examethasone
Coadministration of 0.25 mg palonosetron HCl and 20 mg dexamethasone administered intravenously in healthy subjects revealed no pharmacokinetic drug-interactions between palonosetron and dexamethasone.

O ral Aprepitant
In an interaction study in healthy subjects where a single 0.25 mg intravenous dose of palonosetron HCl was administered on day 1 and oral aprepitant for 3 days (125 mg/80 mg/80 mg), the pharmacokinetics of palonosetron were not significantly altered (AUC: no change, Cmax : 15% increase).

M etoclopramide
A study in healthy subjects involving a single 0.75 mg intravenous dose of palonosetron HCl and steady state oral metoclopramide (10 mg four times daily) demonstrated no significant pharmacokinetic interaction.

C orticosteroids, Analgesics, Antiemetics/Antinauseants, Antispasmodics and Anticholinergic Agents In controlled clinical trials, palonosetron HCl has been safely administered with corticosteroids, analgesics, antiemetics/antinauseants, antispasmodics and anticholinergic agents.

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