28 September 1998: Experts have released new scientific information at a medical conference in the US which shows that an inhaled influenza drug, zanamivir, is effective for both treatment and prevention of the influenza infection.
"Zanamivir is a new antiviral that stops influenza dead in its tracks," said Professor Chris Silagy, Flinders Medical Centre, South Australia. "It is given by the inhaled route so the medicine goes straight to where the influenza virus infects the body -- in the breathing passages. By inhaling zanamivir, the drug gets to the site of infection faster than taking it by mouth."
New information from two phase III clinical trials was presented at the meeting*. The findings from the treatment trial, conducted in Australia, New Zealand and South Africa were:
- Patients treated with the inhaled drug zanamivir experienced a significant
reduction in the severity of their symptoms (such as feverishness, cough,
weakness, aches and pains), so much so that they recovered from the illness on
average as much as 2.5 days earlier than those who did not receive the drug.
- Patients at risk of developing complications (which can include pneumonia,
bronchitis and pleurisy) as a result of having influenza, experienced a 70 per
cent reduction in complications if given zanamivir.
- Patients on zanamivir experienced no more side-effects than those on placebo (a dummy version of the medicine).
Overall, patients taking zanamivir felt:
- Their health improved more quickly.
- They could get back to normal activities more quickly.
In a second trial conducted in the US, where patients took zanamivir once a day for 28 days to prevent flu, it was found that:
Two thirds of patients who had not been vaccinated against influenza and were given zanamivir were protected from being ill with flu. Those patients who did get ill were less likely to develop illness with fever when receiving zanamivir.
In addition, a phase II treatment trial was presented at the medical conference. Scientists in the Netherlands noted that although the flu virus can become readily resistant to the effects of some other drugs, resistance to zanamivir did not develop in this study. This ensures that the medicine remains effective during treatment.
True influenza (type A and type B) is a serious infection of the breathing passages and is different from the common cold. It can have some serious effects. For example, in the elderly or those who have an existing condition, such as asthma, diabetes or a heart complaint, it can be fatal. Even when those who are otherwise healthy get true flu, it can 'knock us off our feet'.
There are also economic considerations. True flu costs businesses and governments millions every year in lost productivity, days off work and healthcare costs, such as hospital treatment for complications caused by the virus.
Zanamivir is not yet available to the patient or doctor, however, the results of the clinical trials presented at this medical meeting could mean that once it becomes available the future treatment and prevention of influenza will change.
* The results of these clinical trials were presented at ICAAC - the 38th Interscience Conference on Antimicrobial Agents and Chemotherapy, 24-27 September, San Diego, California, USA.
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