Bayer gains two orphan drug designations for riociguat

German drug major Bayer’s (BAYN: DE) investigational drug riociguat has been granted two orphan drug designations by the US Food and Drug Administration, one for treatment of pulmonary arterial hypertension and the other for chronic thromboembolic pulmonary hypertension.

The Orphan Drug Designation program provides orphan status to drugs and biologics that are defined as those intended for the safe and effective treatment, diagnosis or prevention of rare diseases and disorders.

Bayer submitted a New Drug Application for riociguat in February 2013 for two indications: (i) the treatment of PAH (WHO Group 1) to improve exercise capacity, improve WHO functional class and delay clinical worsening; and (ii) the treatment of persistent/recurrent CTEPH (WHO Group 4) after surgical treatment or inoperable CTEPH to improve exercise capacity and WHO functional class.

If approved by the FDA, it would create a new class of drugs available in the USA. Pulmonary hypertension is associated with endothelial dysfunction, impaired synthesis of nitric oxide (NO) and insufficient stimulation of soluble guanylate cyclase (sGC). Riociguat stimulates sGC independent of NO and increases the sensitivity of sGC to NO.