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Double Dose of Tamiflu Offers No Added Benefit in Severe Influenza

High-dose recommendation not grounded in evidence, researchers say (May 31)

Administering double doses of the antiviral drug oseltamivir (Tamiflu, Roche) offers no clinical or virological advantages over a standard dose for patients admitted to hospitals with severe influenza infection, according to a randomized trial published online in the British Medical Journal.

The new study is the first to look at the effectiveness of higher doses of oseltamivir in cases of severe flu infection and has implications for global guidelines on clinical management and stockpiling drugs for pandemic preparedness, including the current outbreak of the deadly H7N9 “bird flu” virus in China.

Most people who are infected with flu will recover within 2 weeks, but some people will develop complications, such as difficulty breathing, that can result in hospital admission and that can be life-threatening. Studies have shown that early treatment with oseltamivir is beneficial for patients with uncomplicated flu infection and improves survival in hospitalized patients with severe infection. This has led some authorities to recommend double doses of oseltamivir for the treatment of patients with severe flu infections.

The new study, conducted by the South East Asia Infectious Disease Clinical Research Network (SEAIDCRN), involved 326 patients with severe flu infection at hospitals in Indonesia, Singapore, Thailand, and Vietnam. Most of the patients were children under the age of 15.

Patients were given either a standard dose or a double dose of oseltamivir for 5 days. Their virus levels were monitored for the duration of the treatment, along with other outcomes, such as admission to intensive care, the need for mechanical ventilation to assist with breathing, and death.

The findings showed no difference in virus levels at day 5 between the two groups. There were also no clinical differences in patient outcomes, including the need for ventilation, the time in hospital, the rate of death, or the rates of adverse events, between the different doses.

Professor Jeremy Farrar, director of SEAIDCRN, said: “The recommendation to give higher doses of oseltamivir to severe cases of flu infection has major implications for clinical management, public health, and planning for antiviral stockpiles but has not been grounded in evidence. Our findings do not support routine use of double doses to treat severe flu infections, which could help to conserve drug stocks in the event of a pandemic.”

Sources: Wellcome Trust; May 31, 2013; and BMJ; May 31, 2013.

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