Stockpile zanamivir in case of pandemic, say experts
The report recommends stockpiling zanamivir as a second line of
defence |
Influenza experts are calling on the Government to stockpile a second antiviral drug — zanamivir (Relenza) — as part of its preparations for a flu pandemic in the light of emerging evidence that the avian influenza virus H5N1 can develop resistance to oseltamivir (Tamiflu).
The Royal Society and the Academy of Medical Sciences this week published
a report “Pandemic influenza: science to policy” (PDF 1MB),
which urges the Government to revisit its decision to stockpile only
one antiviral
drug. Sir John Skehel, vice-president of the Academy of Medical Sciences
and chairman of the report’s working group, said: “The Government
was right to order Tamiflu in early 2005. However, we are concerned that
it is not updating its plans as the landscape of what we know about influenza
changes.”
The report also recommends the appointment of a leading influenza specialist
as a high-level independent adviser to the Government.
The need for further research into methods of increasing the effectiveness
of pandemic flu vaccines is also highlighted in the report. It recommends
that the Department of Health should take the lead in assembling a work
programme with industry and academia for the development of new adjuvants
for vaccines.
The working group hopes that its recommendations will inform the Government’s
revision of its pandemic influenza contingency plan, to be disseminated
early next year.
In response to the report, Lindsey Davies, director of pandemic influenza
preparedness at the DoH, said: “We are already addressing many
of the report’s recommendations in our ongoing pandemic preparedness
planning.” She added that the DoH’s antiviral strategy is
informed by international consensus and expert advice, and the current
stockpile should be adequate to treat all those who fall ill in a pandemic
of similar proportions to those in the 20th century.
Resistance to oseltamivir
Limited observations on the use of oseltamivir in humans infected
with H5N1 highlight the possibility that extensive use could
generate large numbers of resistant viruses, the report says. It
adds that
observations that oseltamivir resistance occurs in H5N1 viruses
that retain sensitivity to zanamivir suggest that both drugs
should be in the UK stockpile. There are also indications that
higher
doses of oseltamivir will be necessary for the successful treatment
of H5N1, and therefore a larger stockpile may be required of
both drugs, it says. The stockpile needs to be large enough for
multiple
waves of a pandemic since the interval between waves may not
be long enough to manufacture and purchase more antivirals. The
DoH
currently has a stockpile of 14.6 million courses of oseltamivir,
enough to treat 25 per cent of the population.
In a statement, Roche (the manufacturer of Tamiflu) said that
only three cases of avian influenza in humans have shown reduced
susceptibility
to oseltamivir; two patients were treated outside the recommended
48 hours and one was treated with a sub-optimal dose. In addition,
it says, resistant mutations of the H5N1 virus have been detected
in two patients after treatment with oseltamivir but the mutation
led to reduced transmissibility. |
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The
Pharmaceutical Journal
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