Antiviral combo cuts flu virus shedding but not symptoms

A new study published in The Lancet Infectious Diseases suggests that a triple combination of antivirals reduced the number of days the influenza virus was shed from participants compared with treatment of oseltamivir (Tamiflu) alone but did not did not provide a clinical benefit to patients.

The study was the largest study ever conducted on antivirals, and the first to assess mono and combination therapies.

To conduct the randomized, double-blind study, the researchers gave 239 participants in an ambulatory setting a triple combination of antivirals (oseltamivir 75 milligram [mg], ribavirin 600 mg, and amantadine 100 mg twice a day) and 394 patients oseltamivir (75 mg twice a day). All participants had lab-confirmed influenza and virology samples conduced on day 3.

Only 40% of the participants in the combination treatment group had detectable virus on day 3, as opposed to 50% in the oseltamivir-only group. But there was no statistically significant effect seen on the duration of symptoms, which were 4.5 days for the combination group and 4 days for the oseltamivir-only group.

Despite the 10-percentage-point reduction in shedding, the authors of the study said the effect was limited. "By day 7, however, a similarly high proportion of participants in both groups had stopped shedding influenza virus, and the difference between treatment groups was no longer significant," they wrote.

Combo could help fight resistance

Though combining antivirals may not help a patient feel better faster, a commentary that accompanied the study suggested the approach could help curb growing antiviral resistance.

"Combinations of two or more drugs with different mechanisms of action hold greater promise in enhancing the outcomes of influenza compared with monotherapy and should continue to be studied," Michael Ison, MD, of Northwestern University's Feinberg School of Medicine.

"Combination therapies should be studied in populations that have prolonged shedding and enhanced risk of emergence of resistance, including patients admitted to hospital and immunocompromised patients," Ison adds.

See also:

Sep 22 Lancet Infect Dis study

Sep 22 Lancet Infect Dis commentary

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