October 29 (HealthDay News) -- Cialis (tadalafil), a drug used to treat erectile dysfunction, appears effective in treating pulmonary hypertension, researchers report.

Pulmonary hypertension is caused by high blood pressure in the arteries that supply the lungs with blood. People who suffer from the condition can become tired, dizzy and short of breath, because the arteries feeding the lungs constrict and reduce the supply of oxygenated blood being circulating throughout the body.

But Cialis "was found to improve exercise capacity, health-related quality of life, delay time to clinical worsening, and improve hemodynamic [blood-linked] parameters of disease severity," said lead researcher Dr. Robyn J. Barst, a professor of pediatrics at Columbia University College of Physicians & Surgeons in New York City. The drug was also well-tolerated, she added.

The report was to be presented Tuesday at the American College of Chest Physicians annual meeting, in Philadelphia.

For the study, Barst's team randomly assigned 405 pulmonary hypertension patients to Cialis or placebo once a day, or to Cialis and bosentan (Tracleer) a common treatment for pulmonary hypertension.

The researchers found that over 16 weeks, Cialis increased patients' six-minute walk distance and delayed their time to clinical worsening, which included death, hospitalizations, worsening functional class and the need for adding new pulmonary arterial hypertension therapy.

In addition, Cialis increased heart output and reduced pulmonary artery pressures compared with those measures at the start of the trial, Barst's group found.

"We would anticipate that tadalafil will be reviewed and approved by the regulatory agencies as an additional therapy available for the treatment of pulmonary hypertension," Barst said. "It is useful for the treatment for pulmonary hypertension, as for many other diseases, to have more than one drug per class approved, due to individual patient responses and side effects," she added.

Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles, noted that pulmonary hypertension is a progressive disease which results in substantial morbidity and mortality.

"Prior studies have shown that the oral phosphodiesterase type 5 inhibitor, sildenafil (Viagra, Revatio) improves exercise capacity in patients with pulmonary arterial hypertension," Fonarow said. "This medication is currently FDA-approved for this indication, but must be taken three times daily."

This new study of Cialis, taken once daily, demonstrates that the drug substantially improves functional capacity, improves quality of life, and also results in less clinical worsening in patients with pulmonary arterial hypertension, Fonarow said.

"These are impressive findings," Fonarow said. "Tadalafil represents a very promising new therapy for patients with pulmonary arterial hypertension, that may be used alone or in combination with other treatments such as bosentan."

SOURCES: Robyn J. Barst, M.D., professor, pediatrics, Columbia University College of Physicians & Surgeons, New York City; Gregg C. Fonarow, M.D., professor, cardiology, University of California, Los Angeles; Oct. 28, 2008, presentations, American College of Chest Physicians annual meeting, Philadelphia