Granodex

Granodex Mechanism of Action

granisetron

Manufacturer:

Dexa Medica

Distributor:

Averroes Pharma
Full Prescribing Info
Action
Pharmacology: Pharmacodynamics: Serotonin receptors of the 5-HT3 type are located peripherally in vagal nerve terminals and centrally in the chemoreceptor trigger zone of the area postrema. During chemotherapy-induced vomiting, mucosal enterochromaffin cells release serotonin, which stimulates 5-HT3 receptors. This invokes vagal afferent discharge, inducing vomiting.
Granisetron is a potent antiemetic and highly selective antagonist of 5-hydroxytryptamine (5-HT3) receptors. Granisetron has negligible affinity for other receptor types including 5-HT and dopamine D2 binding site.
Pharmacokinetics: Absorption: Absorption of granisetron is rapid and complete, though oral bioavailability is reduced to about 60% as a result of first pass metabolism.
Distribution: Granisetron is extensively distributed, with a mean volume of distribution of approximately 3l/kg. Plasma protein binding is approximately 65%.
Metabolism: Biotransformation pathways involve N-demethylation and aromatic ring oxidation followed by conjugation. Granisetron's major route of metabolism is inhibited by ketoconazole, suggestive of metabolism mediated by the cytochrome P450 3A subfamily.
Elimination: Clearance is predominantly by hepatic metabolism. Urinary excretion of unchanged granisetron averages 12% of dose while that of metabolites amounts to about 47% of dose. The remainder is excreted in feces as metabolites. Mean plasma half-life in patients by the oral and intravenous route is approximately 9 hours.
Special Populations: Renal failure: In patients with severe renal failure, data indicate that pharmacokinetic parameters after a single intravenous dose are generally similar to those in normal subjects.
Hepatic impairment: In patients with hepatic impairment due to neoplastic liver involvement, total plasma clearance of an intravenous dose was approximately halved compared to patients without hepatic involvement. Despite these changes, no dosage adjustment is necessary.
Elderly: In elderly subjects after single intravenous doses, pharmacokinetics parameters were within the range found for non-elderly subjects.
Paediatrics: In children, after single intravenous doses, pharmacokinetics are similar to those in adults when appropriate parameters (volume of distribution, total plasma clearance) are normalized for body weight.
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