FDA approves Chimerix's oral suspension smallpox antiviral, giving treatment option to dysphagic patients  

Chimerix has received FDA approval for tablet and oral suspension formulations of its smallpox drug Tembexa. The approval makes Tembexa the first smallpox antiviral authorized for use in infants and people who have difficulty swallowing. 

Recognition of the potential for smallpox to damage the throat, making it hard or impossible for patients to swallow tablets, has spurred interest in formulations suitable for use in patients with dysphagia. Siga Technologies filed for FDA approval of an intravenous formulation of its oral Tpoxx product last month, but Chimerix has beaten it to market with its oral suspension.

The FDA approval covers a 100-mg tablet and a 10-mg/mL oral suspension formulation, both of which are given weekly for two weeks. Formulating the antiviral into an oral suspension enabled Chimerix to get an FDA label that covers all age groups and patients who have difficulty swallowing. Siga’s label for Tpoxx limits use to adults and children weighing 13 kg or more.

Chimerix’s tablet formulation of Tembexa could serve the same smallpox patient population as Tpoxx, although its active ingredient, brincidofovir, has a different mechanism of action than the Siga drug. The Biomedical Advanced Research and Development Authority (BARDA) is currently seeking to source a smallpox antiviral countermeasure with a distinct mechanism of action from Tpoxx. 

The BARDA notice called for submissions from companies developing products under NDA review. Chimerix thinks Tembexa was the only drug that fits the BARDA qualifying parameters, leading it to respond to the request.

“With this approval in hand, we now look forward to advancing our discussions with the Biomedical Advanced Research and Development Authority toward a procurement contract to support national preparedness,” Chimerix CEO Mike Sherman said in a statement.

Chimerix brought Tembexa to market on the strength of data from two lethal orthopoxvirus animal models of human smallpox disease. The studies linked the antiviral to a significant survival benefit over placebo in rabbits and mice infected with lethal viral doses.