New Delhi: As swine flu spread to as many as 30 countries, killing some 53 people and infecting 4,694 others, India has asked a group of scientists to do a detailed study on trees to source shikimic acid, a key ingredient used for making Tamiflu, the most popular drug to treat what has been renamed A/H1N1 influenza.
Indian scientists have already identified some trees in the Western Ghats. A considerable quantity of shikimic acid can be drawn from the leaves of these trees.
Swine flu was first reported by the World Health Organization on 24 April. So far, no case of infection or death has been reported from India.
Cautious: The staff at a hospital in Pune wearing masks as two patients in an isolation ward await medical tests for swine flu. So far, no case of infection or death has been reported in India. AFP
The country’s department of biotechnology has asked a team from the University of Agricultural Sciences, Bangalore, to do the study in the eastern Himalayas.
“We’ve got funding from the department of biotechnology to explore trees in the eastern Himalayas that may be rich sources of shikimic acid,” said Priti Vaidyanathan, a researcher at the university who is involved in the project. The details of investment in the project weren’t disclosed.
Vaidyanathan declined to name the trees in the Western Ghats that are rich sources of shikimic acid, which is used in making oseltamivir phosphate—the chemical name for Tamiflu.
Shikimic acid is produced by most trees but in very small quantities, making them unviable for extraction. Currently, most shikimic acid is sourced from China, where fruits of a herb called star anise yield the vital chemical. This fruit yields 3-7% of its weight as the acid, which is further synthesized into crystals to be useful as a tablet.
Shikimic acid is extracted in a 10-stage manufacturing process—13g of star anise produces 1.3g of shikimic acid, which can be made into 10 oseltamivir phosphate 75mg capsules, according to Hoffman-La Roche Inc., the drug maker that owns the global marketing rights for Tamiflu.
Vaidyanathan said the trees in the Western Ghats were special because their leaves exuded shikimic acid. The Chinese herb bears fruit only for a few months, whereas the leaves are far more abundant; so, using the trees will be far more viable, she said.
A shortage of shikimic acid immediately impacts Tamiflu production.
In early 2005, Hoffman-La Roche had announced a shortage in production of the drug. According to the company, the major bottleneck in oseltamivir production was the availability of shikimic acid, which is only effectively isolated from star anise.
With the outbreak of A/H1N1 influenza, some manufacturers say there could be a shortage of shikimic acid. “We have been interacting with our Chinese suppliers and we are told that their supply position (of shikimic acid) is very tight,” said Srinivas Reddy, director, marketing, Hetero Drugs Ltd, the only Indian generic firm licensed by Roche to make Tamiflu. Hyderabad-based Hetero will supply nine of the 10 million doses of the drug that the Indian government is procuring.
“The supply of shikimic acid is very limited. We are negotiating with our suppliers. The situation is very uncertain and things are very fluid at this stage regarding supply of the ingredient,” said Amar Lulla, managing director of Cipla Ltd, which also sells Tamiflu in India. The company will supply 1 million Tamiflu doses to the government.
Meanwhile, the Chinese government has told Guilin Layn Natural Ingredients Corp., which claims to be the only listed company in China that supplies this extract, not to release any information about shikimic acid without prior approval.
“We are a public company and also the only one in the plant extract industry,” chief executive Alan Liao said. “The (Chinese) government has informed us that we need to report all the shikimic acid relevant information to them and release to the public under their approval.”