Adamas Pharmaceuticals has expanded its Phase II clinical study of a new proprietary investigational triple-combination antiviral drug therapy for influenza to include centers in the United States, Canada and Europe.

The study, which began in August 2009 in the Southern Hemisphere, is designed to investigate the company’s triple combination antiviral drug (TCAD) therapy as a treatment for influenza strains, including the H1N1 pandemic strain.

The TCAD therapy includes Adamas’s proprietary combination of amantadine and ribavirin, administered adjunctively with a neuraminidase inhibitor such as oseltamivir.

The study is designed to assess the ability of TCAD therapy to suppress replication of the influenza A virus, alleviate symptoms and stop the development of resistance.

Adamas CEO and chairman Gregory Went said that immune-compromised patients are at increased risk from influenza infection, therefore the development of a broad-spectrum anti-influenza treatment is critical.

“We have accelerated our development efforts to generate clinical data that demonstrate how TCAD therapy can address the needs of influenza patients,” he said.

The Adamas antiviral influenza drug study is a Phase II, open-label, randomised study that will enroll up to 250 immune-compromised adults and children with influenza A in up to 45 study sites.