THE threat posed by bird flu may just have receded a little.
The Indian company Cipla says it will begin marketing a generic version of the antiviral drug oseltamivir, better known as Tamiflu, by December and will be able to make a million 10-capsule courses of treatment per month by next July. The drug is one of the few that can block replication of the H5N1 virus, potentially preventing the illness from becoming fatal.
The move had been opposed by Swiss pharmaceutical giant Roche, which holds the patent on Tamiflu. But this week, in a dramatic turnaround, Roche said it would not oppose companies that want to strike a licensing deal.
Advertisement
If a pandemic of H5N1 flu arrives soon, antivirals are the best hope of saving lives. A potential vaccine against H5N1 has been available since early 2004, but trials in humans are only now beginning (New Scientist, 15 October, p 6).
So governments are looking to stockpile antiviral drugs. One class of these drugs, adamantanes, works against the H5N1 virus strain found last week in Europe. But they have no effect on the strain that has killed at least 60 people in east Asia, and even susceptible strains quickly become resistant. This has led to heavy demand for the second class of drugs, neuraminidase inhibitors, of which Tamiflu is the most widely available.
While some strains of H5N1 are resistant even to Tamiflu, they are thought to be too weak to pose a serious threat. But H5N1 is so virulent that the drug may not save the patient. In experiments published in July, the equivalent of the 10-capsule course of treatment used in humans saved only half of infected mice, and even 16 capsules saved only 80 per cent.
The main problem, however, is supply (see 鈥淲hy so little Tamiflu?鈥�). Roche, the only company now making Tamiflu, says it doubled production in 2004, doubled it again this year and will double it again by 2007. Though Roche will not say how much drug that amounts to, its annual report suggests it could be of the order of 40 million courses a year.
Even at that rate, it will take Roche more than two years to fulfil the orders it now has. And the drug is expensive. Roche says it 鈥渉aggled鈥� a favourable price for governments, thought to be around $30 per course. Apart from 3 million courses Roche donated to the World 午夜福利1000集合 Organization, there is almost no Tamiflu in developing countries.
Now Cipla, the Indian firm that makes 75 per cent of the AIDS drugs used in Africa, says it can make generic Tamiflu. Thailand is planning to do the same, while Taiwan said last week that only patent restrictions are stopping it.
Roche鈥檚 about-face is the first major success for generic drug makers under an agreement on access to drugs reached at a World Trade Organization meeting in Doha, Qatar, in 2001 (New Scientist, 24 November 2001, p 4). Under this agreement, Cipla could have legally sold Tamiflu in less developed countries, including most of Africa, without Roche鈥檚 permission. These countries needn鈥檛 recognise patents until 2016.
Now it is clear the company will be able to sell the drug in India too. That鈥檚 just as well, Cipla managing director Amar Lulla told New Scientist. 鈥淚f a pandemic comes to India, people will die like flies,鈥� he says. 鈥淲e have nothing.鈥�
Why so little tamiflu?
Until now, there has not been a large market for Tamiflu. It cuts the duration of ordinary flu by a few days, and then only if taken very soon after symptoms appear. In 2001 Roche sold only about 2 million courses of treatment. This was well within its manufacturing capacity, so it was in little hurry to build more.
Moreover, the starting chemical came from a wild variety of the spice star anise, harvested in China only from March to May, and turning it into the drug required a difficult 10-step process. Now Roche has spliced the gene that makes the starting chemical into bacteria, and plans to use them to boost production from next year. When Indian drug manufacturer Cipla makes Tamiflu it will use star anise.
Drugs in the same family as Tamiflu might be useful if Tamiflu resistance becomes a problem. But they remain neglected: one sells in small quantities, and another has never been brought to market.
