Drug giant Glaxo is to more than triple its production of flu treatment Relenza to cope with the outbreak of the H1N1 virus or swine flu.It expects to have an annual production capacity of 190m treatment courses of the drug, up from 60m recently.Glaxo also said it last month started production of an H1N1 adjuvanted vaccine and is on track to meet the orders placed by many governments and the World Health Organisation.The firm also posted a fall in revenue in the second quarter as generic competition in the US hit sales.Turnover fell by 2% from the same period the previous year to £6.7bn as the US pharmaceuticals business saw sales slide by 15% to £2.3bn.Product sales impacted by competition from other companies which gained the right to sell the drugs included the epilepsy treatment Lamictal (down 73% to £103m), migraine treatment Imigran (down 65% to £68m) and allergy drug Flonase down 46% to £39m.European sales grew 1% to £1.7bn, sales in emerging markets grew 14% to £720m and sales in Asia-Pacific/Japan rose 6% to £609m.Glaxo said its strategy to diversify from western markets and conventional drugs was proving successful, with the 'white pill/western market' accounting for 31% of sales compared with 38% over the same quarter the previous year.