Letairis is an endothelin receptor antagonist. Endothelins are proteins that have a variety of actions in the body, including effects on the heart, blood vessels, lungs, and kidneys. One of the things endothelins do is to cause blood vessels to constrict (narrow). People with PAH have higher-than-normal levels of endothelins in the body.
Endothelin can bind to two receptors. Letairis works by blocking one of those receptors (endothelin A, or ETA receptor), preventing the endothelin from binding to the receptor. This helps block the actions of the extra endothelin in people with PAH.
This drug is not approved for use in children (usually defined as individuals younger than 18 years old), as it has not been adequately studied in children. Talk to your child's healthcare provider about the risks and benefits of using Letairis in a child.
Older adults can use this medication. However, they may need to be monitored more closely. In Letairis clinical trials, individuals aged 65 and older were more likely to develop swelling in the arms, legs, or feet (peripheral edema). They also had less improvement in exercise ability.
On occasion, your healthcare provider may recommend this medicine for something other than the uses discussed in this article. This would be known as an "off-label" use. At this time, there are no widely accepted off-label uses for Letairis.