Gefapixant Citrate
Indications
Gefapixant is indicated in the treatment of-
- Refractory chronic cough or
- Unexplained chronic cough in adults.
Pharmacology
Gefapixant is a selective antagonist of the P2X3 receptor. P2X3-containing receptors belong to the family of purinergic receptors and are ATP-dependent ion channels, which are also located on sensory C-fibers of the vagus nerve in the airways. C-fibers are activated in response to inflammation or chemical irritants. Under inflammatory conditions, ATP is released by mucosal cells of the respiratory tract. The binding of extracellular ATP to P2X3 receptors is recognized by C-fibers as a damage signal and is perceived as a coughing stimulus, which in turn triggers a cough reflex. Gefapixant blocks ATP-mediated activation of P2X3 receptors, which are thought to be responsible for chronic cough.
Dosage & Administration
Treatment with Gefapixant should be initiated and monitored by physicians experienced in managing patients with chronic cough disorders.
Adult patients: One 45 mg tablet orally twice daily with or without food. Patients should be advised that if a missed dose is missed, they should skip it and take the next dose at the regular time.
Use in elderly patients: No dose adjustment of Gefapixant due to age is required and no age-specific differences in the efficacy or safety of Gefapixant has been established. This medicine is essentially excreted by the kidneys. Since older patients are more likely to have impaired renal function, the risk of adverse effects may be higher in these patients. Caution should be exercised at the initial dosing frequency.
Use in the pediatric population: The safety and efficacy of Gefapixant have not been established in patients below 18 years of age.
Obstructive sleep apnea: Gefapixant should not be used in patients with refractory chronic cough or unexplained chronic cough and comorbid obstructive sleep apnoea.
Patients with liver disease: Gefapixant has not been studied in patients with hepatic impairment.
Patients with renal impairment: The recommended dose of Gefapixant in patients with severe impairment (eGFR<30 ml/minute/1.73 m2) renal function on non-dialysis is one 45 mg tablet once daily with or without food. No dose adjustment is required in patients with mild or moderate renal impairment (eGFR >30 ml/minute/1.73 m2). In patients with severe renal impairment (eGFR <30 ml/minute/1.73 m2) renal function not requiring dialysis, the dose of Gefapixant should be adjusted.
Effect on driving ability and on the use of machines: Patient may experience dizziness after using Gefapixant, which may affect the ability to drive and use machines.
Adult patients: One 45 mg tablet orally twice daily with or without food. Patients should be advised that if a missed dose is missed, they should skip it and take the next dose at the regular time.
Use in elderly patients: No dose adjustment of Gefapixant due to age is required and no age-specific differences in the efficacy or safety of Gefapixant has been established. This medicine is essentially excreted by the kidneys. Since older patients are more likely to have impaired renal function, the risk of adverse effects may be higher in these patients. Caution should be exercised at the initial dosing frequency.
Use in the pediatric population: The safety and efficacy of Gefapixant have not been established in patients below 18 years of age.
Obstructive sleep apnea: Gefapixant should not be used in patients with refractory chronic cough or unexplained chronic cough and comorbid obstructive sleep apnoea.
Patients with liver disease: Gefapixant has not been studied in patients with hepatic impairment.
Patients with renal impairment: The recommended dose of Gefapixant in patients with severe impairment (eGFR<30 ml/minute/1.73 m2) renal function on non-dialysis is one 45 mg tablet once daily with or without food. No dose adjustment is required in patients with mild or moderate renal impairment (eGFR >30 ml/minute/1.73 m2). In patients with severe renal impairment (eGFR <30 ml/minute/1.73 m2) renal function not requiring dialysis, the dose of Gefapixant should be adjusted.
Effect on driving ability and on the use of machines: Patient may experience dizziness after using Gefapixant, which may affect the ability to drive and use machines.
Interaction
Effect of proton pump inhibitor: Concomitant use of the proton pump inhibitor omeprazole had no clinically meaningful effect on the pharmacokinetics of gefapixant.
Potential influence of Gefapixant on other medicines: Based on in vitro studies, the potential of Gefapixant for CYP inhibition or induction is low.
Effect of Gefapixant on other medicines: No clinically dependent drug interactions have been identified.
Effect of other medicines on Gefapixant: No clinically meaningful drug interactions have been identified.
Potential influence of Gefapixant on other medicines: Based on in vitro studies, the potential of Gefapixant for CYP inhibition or induction is low.
Effect of Gefapixant on other medicines: No clinically dependent drug interactions have been identified.
Effect of other medicines on Gefapixant: No clinically meaningful drug interactions have been identified.
Contraindications
Severe hypersensitivity reaction to Gefapixant or any of the ingredients.
Side Effects
Very Common side effects are dysgeusia, ageusia, hypogeusia. Frequent side effects are upper respiratory tract infections, decreased appetite, taste disturbance, dizziness, nausea, diarrhea, dry mouth, hypersalivation, epigastric pain, dyspepsia, oral hypoesthesia, oral paresthesia etc. Occasionally: Urinary stones, bladder stones, nephrolithiasis are seen.
Pregnancy & Lactation
The use of Gefapixant in women during pregnancy has not been studied. As a precautionary measure, the use of Gefapixant during pregnancy and in women of childbearing potential who do not use contraception is not recommended. It is not known whether gefapixant is present in human breast milk, affects milk formation, or has an effect on breastfed infants. Gefapixant has been detected in milk in animal studies.
Fertility: There are no clinical data on the effects of Gefapixant on fertility in humans. Animal studies showed no impairment of fertility.
Fertility: There are no clinical data on the effects of Gefapixant on fertility in humans. Animal studies showed no impairment of fertility.
Precautions & Warnings
Gefan should be used with caution in patients with known hypersensitivity to sulphonamides.
Overdose Effects
Patient should be observed for adverse reactions and appropriate symptomatic treatment initiated. Gefapixant is partially removed by hemodialysis.
Storage Conditions
Store below 30°C in a cool and dry place. Keep away from light. Keep out of the reach of children.
