US regulators warn on Glaxo asthma drug

US drugs industry regulators yesterday said they would slap warning labels on one of GlaxoSmithKline's most established asthma treatments after about 45 African-American patients suffered severe attacks, some causing death, during a 28-week routine test.

London-listed GSK said it had agreed with the US food and drug administration to issue a warning to patients taking Serevent, a drug designed to open airways in the chest, which has been on the market since 1990.

Serevent patients will be warned of the potential risk and advised to take the drug in combination with an inhaled anti-inflammatory steroid.

Sales of Serevent have been in decline for some time as patients have been encouraged to switch to GSK's newer product Seretide, which combines Serevent and an inhaled steroid in a single product.

A GSK spokesman noted that an unusually high number of African-American patients involved in the recent test were taking the older drug without combining it with a steroid treatment. He also pointed out that a number of severe asthma attacks and deaths had been expected across all ethnic backgrounds. However, he admitted that data from African-American patients raised concerns.

Yesterday shares in GSK slipped 43p to £10.87, though some analysts suggested the test data would only hasten patient uptake of GSK's Seretide product, which is branded Advair in the US.

In the three months to October GSK's Serevent sales were down 21% to £116m, while sales of Seretide were up 70% to £392m over the same period.

Aside from the success of ulcer treatment Zantac, anti-asthma drugs have been the bedrock of GSK's revenue generation since Glaxo first developed Ventolin inhalers.