(Updates with comments from panelists, background)
By Toni Clarke
Aug 6 Bayer AG's experimental drug to
treat two types of pulmonary hypertension should be approved at
doses proposed by the company, an advisory panel to the U.S.
Food and Drug Administration ruled on Tuesday.
The panel voted 11-0 that the FDA should approve the drug,
riociguat, which in clinical trials extended the distance
patients could walk during a six-minute test.
The FDA is not obliged to follow the recommendation of its
advisory panel, but typically does so. If approved, the drug
would be sold under the brand name Adempas.
The drug is designed to treat chronic thromboembolic
pulmonary hypertension, a rare disease typically caused by blood
clots that restrict the flow of blood from the heart to the
lungs. The drug would be used for patients who are not
candidates for surgery to remove the clots.
It is also designed to treat pulmonary arterial
hypertension, in which arteries of the lungs constrict, forcing
the heart to work harder. Symptoms of both conditions are
similar and include shortness of breath, fatigue, weakness and
potential heart failure.
If approved, the drug is expected to generate sales of $610
million, according to the average estimate of six analysts
polled by Thomson Reuters.
Reviewers for the FDA recommended the drug be approved at
doses lower than the maximum 2.5 milligram dose proposed by
Bayer. They argued that a starting dose of 0.5 milligrams and
maximum dose of 1.5 milligrams three times a day would confer
the same benefit as the higher dose with a reduced risk of side
effects, particularly hypotension, or low blood pressure.
Low blood pressure can cause dizziness, fainting, nausea and
potentially loss of consciousness.
Dr. Preston Dunnmon of the FDA said the agency was concerned
that most people with coronary artery disease were excluded from
Bayer's clinical trials and that in an unscreened population the
negative impact from hypotension could be more prevalent than
Dr. John Newman, professor of pulmonary medicine at
Vanderbilt School of Medicine, agreed, saying that once the drug
has been approved "we don't really know what the increased risk
will be in a general population."
Overall, however, panelists recommended approving the drug
with a 2.5 milligram limit, saying they wanted as many options
as possible and that decisions on dosing should be left to
Dr. Stuart Rich, a panel member and professor of medicine at
the University of Chicago Pritzker School of Medicine, said he
was not concerned about low blood pressure unless it caused
symptoms, and those numbers were relatively low in the trial.
Rich said he was impressed with the apparent ability of the
higher dose of the drug to increase cardiac output, or the
volume of blood pumped by the heart per minute.
(Reporting by Toni Clarke in Washington; Editing by John
Wallace, Gerald E. McCormick and Andrew Hay)