Zyban Linked to Spike in UK Adverse Drug Reactions

By Richard Woodman

LONDON (Reuters Health) - The number of suspected adverse drug events being reported in the UK has shot up by over one third, mainly because of GlaxoSmithKline's smoking cessation drug Zyban, the Medicines Control Agency (MCA) said on Wednesday.

The MCA's latest statistics show that 37% more so-called ''yellow cards'' recording adverse reactions were received from January to April 2001 compared with the same period in 2000. The number of serious reports also rose 16%.

``The main factor in the 37% increase is the large number of reports associated with the smoking cessation aid, Zyban,'' an MCA spokeswoman explained in a statement to Reuters Health.

She pointed out that reporting for this drug only began in July 2000 and was therefore not a factor at this time last year. However from January to April 2001 Zyban ``accounted for 32% of all yellow cards.''

On May 31, the UK Committee on Safety of Medicines issued a statement to doctors ordering changes to the starting dosages of Zyban and warning that patients at risk of a seizure should take the drug only if there were compelling reasons to do so.

It said there had been over 5,000 adverse reports relating to Zyban, including 40 deaths.

Today's statement makes clear that the number of reports of adverse reactions that are received in association with a drug depends on many factors, including the extent of use of the drug and the publicity surrounding the drug.

``In addition, reporting tends to be high for newly introduced medicines. Therefore, the number of reports received in association with Zyban is expected to be high, as thisdrug has been widely prescribed--at least 419,000 individuals have received Zyban (in the UK)--and has been the subject of considerable public interest.''

The spokeswoman said another reason for the high number of reports was that doctors had been asked to report suspected adverse events as well as events they felt were definitely linked to Zyban.

A GSK spokesman told Reuters Health that it was well known that Zyban is a prescription-only medicine that must be taken appropriately and not by patients with a history of seizures.

He said over five million people had taken the medication worldwide and there had been huge usage in the UK. The rate of seizures seen was consistent with the clinical trials' experience, he said, and the product remained a very valuable medicine for quitting smoking.

The yellow card scheme was introduced in the UK after the Thalidomide tragedy-a jump in the rate of severe birth defects in Europe in the 1950s and 1960s that occurred when the sedative drug was taken by pregnant women. The system is intended to pick up side effects of drugs that may not have been seen during clinical trials. The cards are filled in by doctors and other healthcare professionals and sent to regulators.

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