Recent case of a 22-year-old woman suffering from swine flu virus resistant to Tamiflu has indicated that intravenous dose of the antiviral Relenza can help such patients. However, doctors say that more study should be done in this regard.

The 22-year-old had chemotherapy for Hodgkin's disease. She was later diagnosed with H1N1 infection, increasing shortness of breath, build-up of fluid in both lungs. Her condition kept on deteriorating as she was not responding to Tamiflu.

She was not able to breathe herself hence she needed a ventilator to breathe. As she remained critically ill with severe respiratory failure without any effect of any medicines, doctors decided to use unlicensed intravenous relenza provided by GlaxoSmithKline.

Special permission was taken from the family and a hospital committee as Relenza, or zanamivir, is usually inhaled and is not licensed to be given intravenously. After she was given the medicine her condition started to improve.

Michael Kidd, of University College London and colleagues said: "Although this is a single case report and direct cause and effect cannot be confirmed, the improvement in clinical status following intravenous relenza encourages prompt further investigation, both alone and in combination with high-dose methylprednisolone."