Letairis (Ambrisentan) Dosages: Your GoodRx Guide

Letairis (ambrisentan) is an oral medication used to treat pulmonary arterial hypertension (PAH). It belongs to a class of medications called endothelin receptor antagonists (ERAs) that can help improve blood flow through your lungs. Depending on your symptoms, you may be prescribed an ERA such as Letairis on its own or with other PAH medications.

Below, we’ll discuss the typical Letairis dosage for PAH and answer some commonly asked questions. But if other questions arise, or if you’re still unsure about how to take Letairis, contact your prescriber or pharmacist. 

What to expect when starting Letairis

If you’re able to get pregnant, you’ll be told about a required special safety program before starting Letairis, known as a Risk Evaluation and Mitigation Strategies (REMS) program. This is because Letairis can be harmful to a growing fetus if you’re pregnant while taking it.

Your prescriber will enroll you in the REMS program before you start taking Letairis. The pharmacy that dispenses Letairis to you will also be enrolled in the program. The purpose of this program is to ensure that all parties involved are aware of the risks of Letairis.

You shouldn’t take Letairis if you’re pregnant or become pregnant during treatment. So, you’ll have to take a pregnancy test before starting Letairis, once monthly during treatment, and one month after stopping Letairis. You’ll also need to use an effective method of contraception, such as an intrauterine device (IUD) or birth control pills used with condoms.

What’s the typical Letairis dosage?

Letairis is available as an oral tablet in 5 mg and 10 mg doses. The tablets should be swallowed whole — don’t crush, cut, or chew them. You can take Letairis with or without food.

The typical starting Letairis dosage for PAH is 5 mg by mouth once daily. After 4 weeks, your dose may be increased to 10 mg daily. The maximum dose of Letairis is 10 mg by mouth once daily.

Depending on your symptoms, your prescriber may start you on another medication called tadalafil (Adcirca, Alyq, Tadliq) at the same time as Letairis.

Are there any dosage adjustments for health conditions or drug interactions?

There aren’t recommended dosage adjustments for people with kidney or liver problems. However, Letairis hasn’t been studied in people with severe kidney disease. And Letairis is not recommended if you have moderate-to-severe liver disease. Depending on your health history, your prescriber can determine if Letairis is safe for you to take.

However, there are certain Letairis interactions that require a dosage adjustment. If you take cyclosporine (Neoral, Gengraf), it’s recommended that your maximum Letairis dosage is 5 mg once daily. 

What happens if you miss a dose of Letairis?

If you miss a dose of Letairis, take the dose as soon as you think of it that same day. But if it’s close to or already the next day, then skip the dose you missed and continue with the next dose at your normal time. Do not take two doses at one time. Contact your healthcare team if you have questions about steps you should take after missing a dose.

What should you do if you take too much Letairis?

There isn’t much evidence about what happens if you take too much Letairis, but overdose is unlikely. So if you accidentally take two doses of Letairis at the same time, don’t fret.

But if you take large amounts of Letairis, you may feel side effects such as severe headaches, nausea, facial redness, or dizziness. In more severe cases, your blood pressure could drop too low. If you think that you have taken too much, contact your prescriber or Poison Control at 1-800-222-1222 for guidance. If your symptoms feel severe, seek medical care as soon as possible.

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Written by:

Lauren Freels, PharmD Candidate

During her schooling, Lauren has gained experience in a multitude of fields within pharmacy, such as community, hospital, and nontraditional pathways. All of her experiences have driven her passion for public health and being able to have a positive impact in the healthcare field.

Edited by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

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