Flolan (epoprostenol GM) is a treatment developed and marketed by GlaxoSmithKline to treat pulmonary arterial hypertension (PAH). It is injected into the patient’s bloodstream to improve exercise capacity, circulation, and PAH symptoms. It has been approved in the U.S. since 1995.

How Flolan works

Flolan is a synthetic variant of prostacyclin, a member of a group of molecules called prostaglandins, which naturally exist in the body and are involved in many biological functions, including dilating and relaxing blood vessels.

In pulmonary hypertension, the smaller blood vessels in the lungs become resistant to blood flow and force the heart to work harder to pump enough blood through the lungs.

Flolan works by relaxing blood vessels and therefore facilitating blood supply from the heart to the lungs and reducing the workload of the heart.

Besides this action, Flolan also inhibits platelet clumping, inflammation, and the production of smooth muscles around the blood vessels, which may lead to plaque buildup inside blood vessels.

Flolan in clinical trials

Several randomized clinical trials, as well as observational studies and registries, have investigated Flolan as a potential treatment for PAH. Flolan’s approval for the treatment of pulmonary hypertension was based on the results of two clinical trials.

The first was a randomized trial that evaluated Flolan in 24 patients with pulmonary hypertension. Patients received either a Flolan injection or conventional therapies such as anticoagulants (therapies that thin the blood), oral vasodilators (therapies taken orally that dilate the blood vessels), and diuretics (therapies that increase the amount of water and salt being expelled from the body as urine). The results of this trial showed that Flolan was associated with a significant and sustained decrease in total pulmonary resistance (PR) and a reduction in pulmonary artery pressure (PAP) compared to patients on conventional therapies. Furthermore, patients who received Flolan for up to 18 months showed persistent effects in key blood circulation parameters.

In the second randomized trial, 41 patients with pulmonary hypertension were treated with Flolan plus conventional therapies, and 40 patients were treated with conventional therapies alone for 12 weeks. The results of this trial showed that Flolan significantly improved exercise capacity (measured by the six-minute walk distance test) and key cardiopulmonary parameters including PAP and pulmonary vascular resistance (PVR), compared to conventional therapies alone. This study also showed that treatment with Flolan reduced mortality in patients with severe primary pulmonary hypertension.

Other randomized controlled clinical trials published in the scientific journals Annals of Internal Medicine and The Journal of Rheumatology as well as non-controlled trials have confirmed the results observed in these studies.

Flolan also has been shown to be effective and well-tolerated when used in combination with other treatments for PAH. The 16-week BREATHE-2 study investigated treatment with Flolan alone or in combination with Tracleer (bosentan) in 33 patients with PAH and showed a trend toward blood circulation or clinical improvements with the combination compared with Flolan alone. Then, an observational study confirmed this trend.

Flolan also has been studied in combination with Revatio (sildenafil) in a 16-week, placebo-controlled trial of 267 patients with PAH. Results showed an improvement in exercise capacity, and a longer time to clinical worsening with the combination compared with Flolan alone.

A triple combination therapy of Flolan, Tracleer, and Revatio in patients with severe PAH has also been evaluated in a retrospective registry, with results showing major improvements in the six-minute walk distance and PVR at four months from the study’s start, which were sustained over the long-term.

Other information

To overcome some of the handling limitations of Flolan, Actelion Pharmaceuticals developed a new formulation of epoprostenol called Veletri. Veletri requires less frequent mixing than Flolan and does not need to be stored in cold temperatures.

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