Flashcards in Ambrisentan (Letairis) Deck (16)
What is the initial dose of ambrisentan for PAH?
5 mg once daily
What is the maximum dose of ambrisentan?
10 mg once daily
What is the maximum dose of ambrisentan when a patient is also getting cyclosporine?
Ambrisentan dose should not exceed 5 mg/day
When should ambrisentan dose be reduced?
1. No renal recommendations for mild to moderate impairment
2. Use not recommended in severe hepatic impairment
What are the labeled indications for ambrisentan?
1. PAH WHO 1, predominantly patients with functional class II/III
Per the guidelines from the Fifth World Symposium on Pulmonary Hypertension (WSPH) how should ambrisentan be utilized in functional class IV patients?
Very few functional class IV patients were included in ambrisentan trials, most experts consider ambrisentan as second line therapy
What specific warnings are listed in Lexi that are associated with adverse effects with ambrisentan / macitentan?
1. Fluid retention
2. Hematologic reduction in first weeks
3. Hepatic effects - increases in liver aminotransferases
4. Spermatogenesis - Sperm count may be reduced
Are there any concerns for using ambrisentan / macitentan in patients with pulmonary veno-occlusive disease?
Discontinue ambrisentan in any patient with pulmonary edema suggestive of pulmonary veno-occlusive disease
What are the black box warnings for ambrisentan?
1. Pregnancy. "Ambrisentan is very likely to produce serious birth defects...pregnancy must be excluded before initiation of treatment...contraception during treatment and 1 month after... monthly pregnancy tests"
2. Females can only receive through REMS because of embryo-fetal toxicity
What qualifies as reliable contraception with ambrisentan / macitentan for REMS?
1. Two reliable methods must be used
2. Hormone method + barrier or two barrier methods
3. Tubal ligation or the insertion of a contraceptive implant or intrauterine device do not require additional contraception
What is the pregnancy risk factor category for ambrisentan / macitentan?
Are females with PAH able to be pregnant?
Females with PAH are encouraged to avoid pregnancy (McLaughlin 2009, Taichman 2014)
What breast feeding considerations should be made with ambrisentan?
1. Not known if excreted in breast milk
2. Should discontinue drug or discontinue nursing due to black box
What is the mechanism of action for ambrisentan?
1. Block endothelin receptors
2. Has great affinity for ETa receptor (>4,000 fold)
What are the differences in the endothelin receptor subtypes?
1. ETa stimulation = vasoconstriction and cellular proliferation
1. ETb stimulation = vasodilation, antiproliferative effects, and endothelin clearance