Ambrisentan
Generic Details
Generic Name
Ambrisentan
Other Names
- Letairis
Drug Class
- Endothelin Receptor Antagonist
Chemical Formula
C22H22N2O4S
Molecular Weight
378.49 g/mol
Mechanism of Action
- Selective antagonist of endothelin-1 receptors, leading to vasodilation
Indications
- Pulmonary arterial hypertension (PAH)
Common Dosage Forms
- Tablet
Typical Dosage
- Initial: 5 mg once daily, may increase to 10 mg once daily
Pediatric Dosage
- Not established
Geriatric Dosage
- Use with caution, as age-related changes in renal function may impact dosing
Side Effects
- Headache
- Nasopharyngitis
- Flushing
- Edema
- Anemia
Contraindications
- Hypersensitivity to ambrisentan
- Pregnancy (due to teratogenic effects)
Pregnancy Category
- X - Contraindicated in pregnancy
Lactation Safety
- Not recommended during breastfeeding
Drug Interactions
- Cyclosporine (increased ambrisentan levels)
- Ketoconazole (increased ambrisentan levels)
Overdose Symptoms
- Hypotension
- Headache
- Flushing
- Dizziness
Antidote for Overdose
- Supportive care and symptomatic treatment
Storage Conditions
- Store at room temperature (20-25°C)
Pharmacokinetics
- Absorption: Rapidly absorbed, bioavailability ~70%
- Distribution: Highly bound to plasma proteins
- Metabolism: Primarily hepatic (via glucuronidation and oxidation)
- Excretion: Renal (majority as metabolites)
Precautions
- Monitor liver function tests periodically
- Avoid abrupt withdrawal
Warnings
- Risk of embryo-fetal toxicity
- Risk of hepatic injury
Others
- Regular monitoring of hemoglobin levels is recommended due to the risk of anemia.