FDA Approves Ambrisentan Generics for PAH

The US Food and Drug Administration (FDA) has approved the first generics for pulmonary arterial hypertension (PAH) drug ambrisentan (Letairis).

The oral tablet generics, approved at 5 mg and 10 mg strengths, also come with 2 approved shared system risk evaluation and mitigation strategy (REMS) programs for ambrisentan. The first, Ambrisentan REMS, is the former Letairis REMS and comprised the reference listed drug (RLD) or brand sponsor, plus 3 abbreviated new drug applications (ANDAs).

The second REMS program, PS-Ambrisentan REMS, is comprised of just 1 ANDA sponsor and denotes the parallel system that differentiates the programs within the market.

The FDA advises that physicians who prescribe ambrisentan enroll in the latter program, to ensure they are enrolled in both programs on the market, as those enrolled in Letairis REMS will automatically transfer to Ambrisentan REMS. They advise prescribing physicians also enroll their current ambrisentan-treated patient into PS-Ambrisentant REMS as well, to ensure they could access both branded and generic forms of the therapy.

Both REMS programs come with procedural requirements specific to their own program.

The endothelin receptor antagonist (ERA) drug class in which ambrisentan resides is a relatively new addition to the PAH therapy market. In an interview with MD Magazine® while at the 2018 American College of Chest Physicians (CHEST) Annual Meeting, Victor Tapson, MD, director of the Venous Thromboembolism & Pulmonary Vascular Disease Research Program at the Cedars-Sinai Medical Center, highlighted ERA’s proven benefits in patients with PAH.

“People worried about the endothelin receptor antagonists and liver problems for a long time. We had to check liver functions every month. Now, with our newer ERAs…we don't need to do that,” Tapson said. “Furthermore, they're safe and effective, and proven safe and effective in patients with liver disease.”

Last month, CHEST announced updates to its evidence-based guidelines for treating PAH. In the new recommendations, they advise that treatment-naïve patients with PAH who are considered functional class 2 and 3 as per the World Health Organization (WHO) received initial combination ambrisentan and tadalfil therapy, in order to improve six-minute walking distance (6MWD) metrics.

They also advised that stale or symptomatic patients with PAH on background ambrisentan therapy receive the combination therapy to improve 6MWD.