Zyban warnings are strengthened in UK

GlaxoSmithKline's smoking cessation drug Zyban (bupropion) has had itsprescribing regimen changed and label warnings strengthened to reduce the number of people who experience adverse reactions to the product. The move follows concerns about the drug's safety which hit the headlines in the UK last month (Marketletter May 7).

The UK Committee on Safety of Medicines has advised the company that the prescribing regimen for Zyban should be amended to delay the increase in dose from day four to day seven of treatment in order to give more time for drug levels to stabilize. The new titration regimen is 150mg once-daily for six days (previously three days), increasing to 150mg twice-daily on day seven (previously day four).

In addition, to tighten up warnings relating to the risk of seizure with Zyban, the most medically significant adverse event associated with the drug, known central nervous system tumors and abrupt withdrawal from benzodiazepines or alcohol have been added to the list of contraindications. The labeling has also been rewritten to emphasize that the drug should not be used in patients experiencing seizures or those with any history of seizures. Finally, additional drugs have been added to the list of those that should not be prescribed concomitantly with Zyban - antimalarials, tramadol, quinolones and sedating antihistamines - which lower seizure threshold.