Encysive Pharmaceuticals announced that the Australian Therapeutic Goods Administration (TGA) has granted marketing approval for Thelin (sitaxentan sodium 100 mg tablets as a once daily oral treatment for patients with pulmonary arterial hypertension (PAH).

Thelin is indicated for the treatment of PAH in patients with New York Heart Association (NYHA)/World Health Organization (WHO) functional class III symptoms to improve exercise ability. Efficacy has been shown in primary pulmonary hypertension and in pulmonary hypertension associated with connective tissue disease. Thelin is the first selective endothelin A receptor antagonist and first once daily oral treatment available for patients with PAH.

PAH is characterized by high blood pressure and structural changes in the walls of the pulmonary arteries, the blood vessels that connect the right side of the heart to the lungs. As these arteries become increasingly constricted, blood flow and oxygenation may be inadequate to meet the body's demands. Since the heart must then pump harder to overcome the resistance, patients are susceptible to heart failure.

"As an oral medication administered just once per day, Thelin may be more convenient for PAH patients who often take additional medications daily," said Anne Keogh, MD, joint head, victor chang cardiac research institute transplant Programme and Professor of Medicine, St Vincent's Hospital, University of New South Wales. "PAH has different causes, so treatments such as Thelin that are shown to be useful in a variety of patients, including those with PAH resulting from a connective tissue disease, are a welcome addition to the therapeutic landscape."

"Approval in Australia marks another proud achievement for Encysive's global Thelin development programme," commented Bruce D Given, MD, president and CEO of Encysive Pharmaceuticals. "We will continue our focus of rolling out Thelin abroad while we await the FDA's decision in the United States."

Thelin (sitaxentan sodium) is an endothelin A receptor antagonist, a small molecule that blocks the action of endothelin, a potent mediator of blood vessel constriction and growth of smooth muscle in vascular walls.