1 What is Letairis?

Brand: Letairis

Generic: Ambrisentan

Letairis is an endothelin receptor antagonist which is used to treat pulmonary arterial hypertension (PAH) in which there is raised blood pressure in the main artery that supplies blood to the lungs from the right ventricle. 

Here, small blood vessels of lungs show more resistance against blood flow and that’s why the right ventricle has to work harder to pump adequate blood. Ambrisentan causes inhibition of vasoconstriction leading to relaxation of those blood vessels. 

As a result, blood supply to the lungs is increased with subsequent reduction in the workload of the heart. 5mg and 10 mg tablet of ambrisentan are available in the market but you can get it only when it is recommended by a doctor.

2 What to Know Before Using

Before using Letairis, you must know all about the risks and complications associated with it.

If you are about to start a drug therapy, the risk and benefit ratio of taking the medicine should be considered. This is a decision that your doctor will make with your active participation.

For this medicine, certain factors that may alter the drug action should be considered. Present and past illness, drug interactions, hypersensitivity reactions, pregnancy, lactation and metabolic impairments should be considered cautiously.

Certain drugs should not be used concurrently with such medications. It is always recommended to consult with your doctor if you are in need of some drugs for another health problem. 

Sometimes it is must to avoid the particular medicines during a drug therapy in order to remain out of danger of serious drug reactions. Tell your doctor if you are receiving cyclosporine or rifampicin.

Ambrisentan may cause fetal harm when administered to a pregnant woman. Ambrisentan is contraindicated in women who are or may become pregnant. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus. 

Studies in animals or humans have demonstrated fetal abnormalities and/or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits. 

That’s why pregnancy must be excluded before the initiation of treatment with ambrisentan and prevented during treatment and for one month after stopping treatment. 

Ambrisentan is contraindicated in lactation (as it passes through breast milk) and patients with idiopathic pulmonary fibrosis (IPF) including IPF patients with pulmonary hypertension (WHO Group 3).

3 Proper Usage

To use Letairis properly, you must follow all instructions given by your doctor.

Medicines should be used following the directions given by a doctor. The dose of this medicine will vary according to patient’s condition or requirements. You should follow the doctor's directions and advices. 

The amount of medicine that you take should not exceed the maximum therapeutic dose. Also, the frequency of your daily drug administration and the duration of drug therapy depend on the particular medical problem for which you are taking the medicine. 

In order to treat pulmonary arterial hypertension 5mg ambrisentan is given once daily as the initial dose of treatment. You may consider increasing the dose to 10 mg once daily if 5 mg is tolerated.

Dose adjustment of ambrisentan in patients with mild or moderate renal impairment is therefore not required. 

There is no information on the exposure to ambrisenatan in patients with severe renal impairment. But this drug is not recommended in patients with moderate or severe hepatic impairment.

Always try to take your medicine in time. If you miss any dose of this medicine, you should take it as soon as possible. But when it is time for your next dose, then skip the missed dose and go back to your regular dosing schedule. 

You should store the medicine in a closed container at room temperature away from heat, moisture, and direct light. All kinds of medicines should be kept out of the reach of children. Outdated medicine must be disposed by an appropriate way.

4 Precautions to Take

Before using Letairis, there are some precautions you must take.

Some important measures should be taken if you feel any discomfort following any drug therapy. In case of such drug therapy, you may not need to discontinue the therapy as there is least chance of drug toxicity. But you should not delay to consult with your physician if you feel any of the following side-effects:

  • Fluid retention: peripheral edema is a known side-effect of endothelin receptor antagonists, and is also a clinical consequence of PAH and worsening PAH. 
  • Pulmonary veno-occlusive disease: if patients develop acute pulmonary edema during initiation of therapy with vasodilating agents such as ambrisentan, the possibility of pulmonary veno-occlusive disease should be considered, and if confirmed. Ambrisentan should be discontinued.
  • Hematological changes: decreases in hemoglobin concentration and hematocrit have followed.
  • Hepatic impairment: ambrisentan is not recommended in patients with moderate or severe hepatic impairment.

5 Potential Side Effects

As with many medications, there are several potential side effects associated with Letairis.

There are some unwanted side-effects associated with each drug that usually do not need medical attention. These side-effects usually go away during the treatment episode as your body adjusts to the medicine. 

Additionally, your health care professional may advise you about the ways how to prevent or reduce those unwanted side-effects. 

Sometimes you may need to consult with the doctor if you feel any of these symptoms during ambrisentan therapy: 

  • nausea
  • vomiting
  • fever
  • loss of appetite
  • pain in the abdominal area
  • yellowing of your skin
  • dark urine
  • itching etc. 

Some serious adverse reactions such as peripheral edema, nasal congestion, sinusitis, decreased sperm count and flushing may occur frequently. 

Decreased hemoglobin concentration and hematocrit have followed administration of other endothelin receptor antagonists and were observed in clinical studies with ambrisentan.

6 Related Clinical Trials