By Toni Clarke
WASHINGTON (Reuters) - The U.S. Food and Drug Administration said on Tuesday it has approved Bayer AG's drug to treat two types of pulmonary hypertension.
The drug, Adempas, also known as riociguat, is designed to treat thromboembolic pulmonary hypertension, a rare disease typically caused by blood clots that restrict the flow of blood from the heart to the lungs.
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.
The drug will carry a boxed warning, the most serious possible, against use in pregnant women due to the risk of harming the fetus. All female patients must be enrolled in a risk mitigation program, comply with pregnancy testing and be counseled on the need for contraception.
Prescribers will be required to be certified by enrolling in the program, and pharmacies will only be able to dispense Adempas to patients eligible to receive it under the risk mitigation program.
Adempas belongs to a class of drugs known as soluble guanylate cyclase stimulators that help arteries relax to increase blood flow and decrease blood pressure. It is designed to improve the ability of patients to exercise.
The FDA had initially suggested the drug be approved at doses lower than the maximum 2.5 milligram dose proposed by Bayer, arguing that a starting dose of 0.5 milligram 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 low blood pressure.
But a panel of outside advisors to the FDA disagreed and 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 physicians. In approving the drug, the FDA did not restrict the maximum dose to 1.5 milligrams.
(Editing by Bob Burgdorfer)