A greater-than-expected rate of serious allergic reactions has led to GlaxoSmithKline putting on hold one batch, consisting of over 170,000 doses, of its swine flu vaccine in Canada.

The firm said that following discussions with Health Canada, it has advised the country’s health authorities, as a precautionary measure, to not use one lot of Arepanrix until investigations have been completed. GSK has taken this action as a result of a higher-than-expected rate of anaphylaxis which has not been reported with vaccines from any other lots.

The company added that the “vast majority of suspected adverse reactions” correspond to side-effects listed in the product information, such as tiredness, headache, fever, joint/muscle pain, redness or a hard lump at the injection site. No other lots are impacted by this voluntary hold.

To date, some 15 million doses of Arepanrix have been distributed in Canada and the frequency of severe allergic reactions following immunisation is less than one event per 100,000 doses. GSK added that this does not exceed the rates typically reported for other vaccines.

Meantime GSK has signed a deal with Gilead Sciences covering the latter’s Viread (tenofovir disoproxil) for chronic hepatitis B. Gilead will retain exclusive rights for commercialisation of the drug for HBV in Hong Kong, Singapore,South Korea and Taiwan, while in China, GSK will have those exclusive rights and registration responsibilities for the drug for HBV – Viread is also used in combination with other antiretrovirals for the treatment of HIV.

The companies noted that they are working to expand this agreement to include Japan and other countries. The prevalence of HBV in most countries in Asia is greater than 8%, or about 280 million people.
Abbas Hussain, president of emerging markets at GSK, said that developing and launching Viread in China provides an important addition to the firm’s current portfolio “in one of our key markets”. The drug is currently approved for HBV in the USA, the European Union, Turkey, Australia, New Zealand and Canada.

The pact builds on a deal signed in April 2002, whereby GSK received exclusive rights to sell Gilead’s other HBV treatment Hepsera (adefovir dipivoxil) in various territories, including China, Japan, South Korea and Taiwan.