Prescription Drugs for Pulmonary Hypertension
PULMONARY ARTERIAL HYPERTENSION
Pulmonary hypertension, also known as Pulmonary Arterial Hypertension (PAH), is a condition characterised by a hardening and narrowing of the arteries that carry blood from the heart to the lungs. Over time the increase in pressure creates more stress on the heart muscle and may lead to heart disease. PAH is a very serious condition for which this is no known cure.
I approach an article of this sort very seriously. I recognize that some who read this may themselves be diagnosed with this condition and already understand the prognosis. For others, it may be a loved one or close friend who has developed pulmonary hypertension. Whatever the case may be, I hope that the information provided in this HUB will help provide you with some answers that you are looking for. Nothing written is intended to take the place of the advice you have received, or may receive, from your own physician.
Facts: There are about 30-50 cases of Pulmonary hypertension seen in every million people, according to a 2003 study in the British Medical Journal. It is twice as common in women than men, and the average age for diagnosis is 36. Approximately 40% of PAH cases are from unknown causes, also referred to as "Idiopathic Pulmonary Hypertension" or "Primary Pulmonary Hypertension (an older term)."
Symptoms: The symptoms of PAH are also frequently seen in other conditions and diseases, making it sometimes difficult to initially diagnose. These symptoms include:
- Shortness of breath (SOB)
- Fatigue and becoming easily tired after little or no activity
- Vertigo (dizziness)
- Feelings of Chest pain or chest pressure
- Palpitations (Rapid heartbeat)
- Fluid retention resulting in swelling of the ankles, legs and abdomen
PRESCRIPTION DRUGS FOR PULMONARY HYPERTENSION
A variety of prescription medications can be used to treat the symptoms associated with pulmonary hypertension. These medications include:
- Blood thinners (to help improve blood flow, e.g. warfarin)
- Calcium Channel blockers (to lower blood pressure, e.g. diltiazem)
- Diuretics (to help reduce fluid retention, e.g. furosemide)
- Digoxin (to improve the force of the heart's ability to contract)
- Endothelin Receptor antagonists (Tracleer, Letairis)
- PDE-5 Inhibitors (e.g. Adcirca, Revatio)
- Prostacyclins (Remodulin, Tyvaso, Ventavis, Flolan)
For the sake of this article, I will be focusin primarly on the last 3 categories as these are the categories of medications which are used exclusively for pulmonary hypertension.
Tracleer for Pulmonary Hypertension
ENDOTHELIN RECEPTOR ANTAGONISTS
Think of "endothelins" as the "squeeze" proteins in our body. We all have them. They are an essential part of normal blood pressure control. Endothelins are involved in the constricting process. However, in patients with pulmonary hypertension, endothelin levels are elevated, causing too much constriction in the blood vessels of the lungs. This is where "endothelin receptor blockers" come in. They BLOCK the effect of endothelin and thus the arteries are not constricted quite so much. Make sense?
The drugs in this family include:
1. Tracleer (generic name bosentan) is an oral tablet manufactured by Actelion Pharmaceuticals in San Francisco, California. The possibility of Tracleer was initially discovered by a scientist, but the company he worked for was not willing to continue the research. This researcher, along with several other colleagues, went off on their own to pursue the devlopment of this drug. Shortly thereafter Tracleer was introduced to the market and has since helped "over 75,000 patients around the world" according to their website. Tracleer is sometimes referred to as a "dual" receptor blocker because it blocks both Endothelin types A and B.
Strengths: 62.5mg, 125mg tablets
Dosing: Generally begun at 62.5mg twice daily, and then increased to 125mg twice daily after 4 weeks. Tracleer may be taken with or without food.
Warnings: Tracleer may cause liver damage or birth defects. For this reason all patients taking Tracleer must be enrolled in the manufacturers Tracleer Access Program (T.A.P.).
2. Letairis (generic name ambrisentan) is an oral tablet manufactured by the pharmaceutical company Gilead, located in Foster City, California. Like Tracleer, patients must enroll in a special program to help ensure the safe use of their product given the risks of liver damage and birth defects. Gilead's program is known as the Letairis Education and Access Program (L.E.A.P.).
Strengths: 5mg, 10mg tablets
Dosing: 5mg once daily is the usual starting dose. The dose is increased to 10mg once daily if tolerated.
Side Effects for Tracleer and Letairis include fluid retention, nasal congestion, sinus infection, flushing, palpitations, stomach pain and constipation.
Adcirca for Pulmonary Hypertension
The next category of prescription drugs specifically for the treatment of pulmonary hypertension are the "PDE-5 Inhibitors." Don't be intimidated by the name. PDE is an abbreviation for a substance called "phosphodiesterase." "5" just identifies the type of phosphodiesterase it is (I know, it isn't very creative). Allow me to VERY briefly describe how these agents work.
Blood vessels can expand and they can contract (squeeze). This is perfectly normal and necessary. As explained above, "endothelin" can be thought of as a "squeeze" protein. Your body also has substances to make blood vessels EXPAND. One of these is known as "cyclic GMP" (cGMP). PDE-5 Inhibitors ENHANCE the effectiveness of cGMP and thereby improve the ability of blood vessels to EXPAND AND RELAX. By the way, as a side note, this is exactly the same mechanism by which the popular drugs Viagra, Levitra and Cialis work to treat erectile dysfunction in men.
THERE ARE 2 PDE-5 INHIBITORS APPROVED FOR THE TREATMENT OF PAH:
1. Adcirca (tadalafil) is manufactured by United Therapeutics which has headquarters in Silver Spring, MD. This company has dedicated a lot of time, money and research into pulmonary hypertension. They are also the manufacturers of 2 other PAH drugs: Remodulin and Tyvaso (see discussion below in the next category).
Strengths: 20mg tablet
Dosing: Taken once daily with our without food
2. Revatio (sildenafil) is manufactured by Pfizer pharmaceuticals which has Research and Development sites around the U.S. and in England.
Dosage forms and strengths: Revatio is available as an oral tablet AND an IV injectable formulation that would normally be used for hospitalized patients.
- Tablets: 20mg
- Injection: 10mg/vial (12.5ml)
Dosing: Both forms must be dosed 3 times daily (at least 4-6 hours apart). This, of course, is not extremely convenient and may make Adcirca a better choice for many patients.
Inhalation System for Ventavis
PROSTACYCLINS FOR PULMONARY HYPERTENSION
The final category of prescription drugs for pulmonary hypertension are known as "prostacyclins" (or sometimes referred to as 'prostanoids').
There are currently 4 prescription drugs in the U.S. that fall into this category.
Each of the following drugs has a "link" for the name which will bring you directly to the manufacturers website for this product.
Flolan (epoprostenol) is an injectable product developed by GlaxoSmithKline (GSK) but marketed in the U.S. by Gilead Pharmaceuticals and is administered by continuous IV infusion.
Remodulin (treprostinil) is an injectable product from United Therapeutics and is delivered by continuous subcutaneous infusion or, if not tolerated, by IV infusion.
Tyvaso (treprostinil) is an orally inhaled prostacyclin product from United Therapeutics for use with the Tyvaso Inhalation System provided by the manufacturer. It is generally used 4 times daily (4 hours between each dose, during waking hours). This system is designed to deliver 6mcg per breath, and starting doses are usually 3 breaths per treatment, but may be lowered if necessary.
Ventavis (iloprost) is an orally inhaled prostacyclin product from Actelion Pharmaceuticals. As with Tyvaso, it requires the use of a specialized inhalation nebulizer unit, and is typically prescribed for dosing 2.5mcg to 5mcg taken 6-9 times per day.
All of these prostacyclin products work essentially the same way. Prostacyclins are an important part of a somewhat complicated biological process that results in the dilation (expansion) of arteries in our lungs and in our body. They also inhibit blood clotting to some degree, although whether or not this is related to their effectiviness for treating PAH is unknown presently.
For more information on Pulmonary Hypertension, the following organizations are excellent resources:
Pulmonary Hypertension Association
801 Roeder Road.
Silver Spring, MD 20910
1309 12th Ave.
San Francisco, CA 94122-2213
American Lung Association
61 Broadway, 6th Floor
New York, NY 10006