Sildenafil (Viagra) May Help Improve Control of Pulmonary Hypertension

Summaries for Patients are a service provided by Annals to help patients better understand the complicated and often mystifying language of modern medicine.

Summaries for Patients are presented for informational purposes only. These summaries are not a substitute for advice from your own medical provider. If you have questions about this material, or need medical advice about your own health or situation, please contact your physician. The summaries may be reproduced for not-for-profit educational purposes only. Any other uses must be approved by the American College of Physicians-American Society of Internal Medicine.

The summary below is from the full report titled "Combination Therapy with Oral Sildenafil and Inhaled Iloprost for Severe Pulmonary Hypertension." It is in the 2 April 2002 issue of Annals of Internal Medicine (volume 136, pages 515-522). The authors are HA Ghofrani, R Wiedemann, F Rose, H Olschewski, RT Schermuly, N Weissmann, W Seeger, and F Grimminger. The summaries may be reproduced for not-for-profit educational purposes only. Any other uses must be approved by the American College of Physicians-American Society of Internal Medicine.

What is the problem and what is known about it so far?

Some diseases can narrow the blood vessels in the lungs, which leads to high blood pressure in the lungs (pulmonary hypertension) even when blood pressure in the rest of the body is normal. Pulmonary hypertension is a highly fatal disorder since the strain of pumping blood through narrowed vessels often leads to failure of the heart muscle. When the heart muscle fails, the lungs cannot supply enough oxygen to meet the body's needs. Treatments for this disorder widen the damaged blood vessels in the lung and make it easier for the heart to pump blood through the lungs. One such drug (epoprostenol) is effective only if given intravenously through a small plastic tube that must remain in the vein permanently. Another treatment involves continuous inhalation of a gas (nitric oxide) that also widens blood vessels in the lungs. A newer approach has been an inhaled mist form of epoprostenol called iloprost. Because each mist treatment lasts only about 60 minutes, up to 12 treatments each day are required. Each of these treatments has its drawbacks. Recently, researchers learned that a drug used for erectile dysfunction, sildenafil (Viagra), can enhance and prolong the actions of both iloprost and nitric oxide.

Why did the researchers do this particular study?

To see whether sildenafil alone and combined with other treatments was an effective treatment for pulmonary hypertension.

Who was studied?

30 patients with severe pulmonary hypertension; 11 of these patients had previously received iloprost.

How was the study done?

All patients received nitric oxide inhalation alone and were then randomly assigned to one of four treatment groups: 1) low-dose sildenafil, 2) low-dose sildenafil followed by inhaled iloprost, 3) high-dose sildenafil, or 4) high-dose sildenafil followed by inhaled iloprost. The researchers measured blood flow and blood pressure in the lung vessels at intervals for up to 3 hours.

What did the researchers find?

High-dose sildenafil followed by inhaled iloprost was the most effective treatment for pulmonary hypertension. The next most effective treatment was low-dose sildenafil plus inhaled iloprost, followed by either iloprost alone or high-dose sildenafil alone (both were about equally effective). Least effective was either low-dose sildenafil alone or nitric oxide inhalation alone. No patients experienced serious side effects.

What were the limitations of the study?

The authors could not measure the effect of the treatment on some causes of pulmonary hypertension because they excluded patients with these diseases from the study. In addition, the study included a relatively small number of patients and had a short observation period.

What are the implications of the study?

When combined with standard treatments for pulmonary hypertension, sildenafil may significantly improve control of this fatal disease. Because experience with this treatment is limited, it is too early to make firm recommendations for treatment.