November 3rd, 2004

"Bosentan side effect risks may soon be replaced with erectile dysfunction drugs"

Pulmonary arterial hypertension (PAH) is a rare disorder that strikes mostly women in the prime of their lives. The disorder elevates the blood pressure in the artery between the heart and lungs and usually proves to be fatally within three years of the onset of symptoms. Since many symptoms of PAH can be confused with other conditions, it can take years before an appropriate diagnosis is made.

The Swiss biotech company Actelion has a drug for PAH on the market called bosentan, or Tracleer by its brand name. While there is no cure for PAH, the use of bosentan is supposed to help with symptom management, but the drug can cause serious side effects like liver damage and birth defects.

For a number of patients with health problems because of bosentan, the use of already available drugs on the market might soon be able to help provide beneficial symptom relief for PAH patients. According to medical experts and analysts, the use of Viagra or Cialis, erectile dysfunction drugs for men, used in combination with a drug now in late stage development at Encysive Pharmaceuticals, might allow symptom relief without the negative drug side effects associated to bosentan.

Viagra and Cialis work by increasing blood flow throughout the body. When taken with Thelin, a one-a-day pill in development that is short for “endothelin,” the hormone believed to constrict blood vessels and is found at high levels in PAH patients, evidence of safer and more effective results than bosentan are being discovered.

Encysive CEO Bruce Given says the company has also tested Thelin with Viagra on two-dozen patients to make sure no dangerous interactions occur. Dr. Robyn Barst of Columbia University Medical Center believes Thelin could be a better alternative, especially for the bosentan patients with liver toxicity that have not been shown to occur among Thelin patients as of yet.

Encysive is expected to release the first data on its two-pronged pivotal phase three clinical trial of Thelin by the end of this year and hopes to file for FDA approval next spring.