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Indications/Uses
Bosentan is an endothelin receptor antagonist indicated for the treatment of pulmonary arterial hypertension (PAH) to improve exercise ability and to decrease clinical worsening.
Dosage/Direction for Use
In pulmonary hypertension, patients over 12 years of age may be given bosentan orally in an initial dose of 62.5 mg twice daily, increased after 4 weeks to a maintenance dose of 125 mg twice daily. In those with low body weight (below 40 kg) both the initial and maintenance doses are 62.5 mg twice daily. In systemic sclerosis with ongoing digital ulcer disease, bosentan is given in the same doses as for pulmonary hypertension; there are no data on safety or efficacy in patients under 18 years of age. Or as prescribed by the physician.
Administration
May be taken with or without food.
Contraindications
Moderate to severe hepatic impairment (Child-Pugh class B or C).
Special Precautions
Bosentan is contra-indicated in patients with moderate to severe hepatic impairment (Child-Pugh Class B or C). Liver-aminotransferase concentrations should be measured before starting therapy, at monthly intervals during therapy, and 2 weeks after any increase in dose.
Bosentan therapy should not be started in patients with concentrations more than 3 times the upper limit of normal.
If concentrations increase to between 3 and 5 times the upper limit of normal during treatment, Bosentan should be stopped or the dose reduced and concentrations should be monitored every 2 weeks until they are below the pretreatment value; therapy may then be continued or reintro-duced, but aminotransferase concentrations should be checked after 3 days, after a further of 2 weeks, and then monthly.
If concentrations rise to more than 5 times the upper limit of normal, Bosentan should be stopped; reintroduction may be reconsidered when concentrations return to below the pretreat-ment value.
Bosentan therapy should not be started in patients with concentrations more than 3 times the upper limit of normal.
If concentrations increase to between 3 and 5 times the upper limit of normal during treatment, Bosentan should be stopped or the dose reduced and concentrations should be monitored every 2 weeks until they are below the pretreatment value; therapy may then be continued or reintro-duced, but aminotransferase concentrations should be checked after 3 days, after a further of 2 weeks, and then monthly.
If concentrations rise to more than 5 times the upper limit of normal, Bosentan should be stopped; reintroduction may be reconsidered when concentrations return to below the pretreat-ment value.
Drug Interactions
Bosentan is metabolised by the cytochrome P450 isoenzymes CYP2C9 and CYP3A4 and is also an inducer of the same isoenzymes. It may also possibly induce CYP2C19.
Interactions may therefore occur with the other drugs that are either metabolised by, or inhibit, these isoenzymes. Use with ciclosporin is contraindicated since plasma concentrations of Bosentan are significantly increased. There is an increased risk of hepatotoxicity if Bosentan is given with glibenclamide and such use should be avoided; the hypoglycemic effect of glibenclamide may also be reduced. Bosentan has reduced the plasma concentrations of some hormonal contraceptives and additional; contraceptive measures are advised.
Interactions may therefore occur with the other drugs that are either metabolised by, or inhibit, these isoenzymes. Use with ciclosporin is contraindicated since plasma concentrations of Bosentan are significantly increased. There is an increased risk of hepatotoxicity if Bosentan is given with glibenclamide and such use should be avoided; the hypoglycemic effect of glibenclamide may also be reduced. Bosentan has reduced the plasma concentrations of some hormonal contraceptives and additional; contraceptive measures are advised.
Storage
Store at temperatures not exceeding 30°C.
Action
Pharmacology: Pharmacokinetics: Bosentan is absorbed from the gastrointestinal tract with an absolute bioavailability of about 50%. Peak plasma concentrations occur about 3 to 5 hours after an oral dose. It is more than 98% bound to plasma proteins, mainly to albumin. Bosentan is metabolised in the liver by the cytochrome P450 isoenzymes CYP2C9 and CYP3A4 and is an inducer of these enzymes and possibly also of CYP2C19; after multiple dosing, plasma concentrations of bosentan decrease gradually to 50% to 65% of those seen after a single dose. Bosentan has three metabolites, one of which is active. Bosentan is excreted almost entirely as metabolites in the bile; less than 3% of an oral dose is excreted in the urine. The terminal elimination half-life is about 5 hours.
MedsGo Class
Other Antihypertensives
Features
Dosage
125mg
Ingredients
- Bosentan
Packaging
Film-Coated Tablet 1's
Generic Name
Bosentan
Registration Number
DR-XY45267
Classification
Prescription Drug (RX)
Product Questions
Questions
