Tracleer Bosentan Tablets

1. Indications and Usage
Pulmonary Arterial Hypertension (PAH): Indicated for the treatment of adult patients with PAH (WHO Group 1) to improve exercise ability and decrease the risk of clinical worsening.
It is used to treat adult patients with pulmonary arterial hypertension (PAH, WHO Group 1) to improve exercise endurance and reduce the risk of clinical deterioration.
2. Dosage and Administration
Administration: Oral administration, with or without food (can be taken in the morning and evening).
Starting Dose: 62.5 mg twice daily for 4 weeks.
Maintenance Dose: Increase to 125 mg twice daily based on tolerability. Doses higher than 125 mg twice daily do not provide sufficient benefit to offset the risk of liver toxicity.
Monitoring: Liver transaminases (ALT/AST) must be measured prior to initiation and monthlythereafter.
Discontinuation: Do not abruptly stop treatment; taper the dose over 3-7 days to avoid clinical worsening.
3. Mechanism of Action
Endothelin Receptor Antagonist (ERA): Bosentan is a non-peptide, competitive antagonist of endothelin receptors ETA and ETB.
Pathway: It blocks the vasoconstrictive and proliferative effects of endothelin-1 (ET-1) on vascular smooth muscle cells, leading to pulmonary and systemic vasodilation and reduced vascular resistance。
4. Safety and Warnings
Hepatotoxicity: Associated with dose-dependent elevations in liver aminotransferases. Contraindicated in patients with moderate to severe hepatic impairment or baseline transaminases >3x ULN.
Embryo-Fetal Toxicity: Contraindicated in pregnancy (Pregnancy Category X). It may cause major birth defects. Pregnancy tests must be performed monthly.
Edema: Can cause fluid retention; monitor for signs of heart failure.
Hemoglobin Reduction: Dose-dependent decrease in hemoglobin; monitor levels at baseline and periodically.
5. Adverse Reactions
Most Common: Abnormal liver function tests, headache, flushing, respiratory tract infection, low hemoglobin, and edema.
6. Drug Interactions
Contraindicated:
Cyclosporine A: Significantly increases bosentan exposure; co-administration is contraindicated.
Glibenclamide: Increases risk of liver injury; contraindicated.
Hormonal Contraceptives: May reduce the efficacy of oral contraceptives (alternative contraception is recommended).
Inducers: Bosentan induces CYP2C9 and CYP3A4, potentially decreasing concentrations of co-administered drugs (e.g., warfarin, statins).
7. Pharmaceutical Information
Chemical Name: 4-tert-Butyl-N-[6-(2-hydroxyethoxy)-5-(2-methoxyphenoxy)-2-(2-pyrimidinyl)pyrimidin-4-yl]benzenesulfonamide monohydrate.
Molecular Formula: C27H29N5O6S · H2O.
Storage: Store at 20°C to 25°C (68°F to 77°F). Keep container tightly closed to protect from moisture。