It is believed to be the first time a pharmaceutical company has taken such action on a licensing matter. The outright ban on the drug, once the biggest selling sleeping tablet in the world, followed conflicting evidence on its safety.
Ley S Smith, president and chief operating officer of the US company, said Upjohn regretted taking such 'drastic' action, but 'the public deserves to know why the licensing authority rejected expert scientific advice given to it under British law'.
Halcion, also known as triazolam, has been linked with cases of amnesia, paranoia, suicide and murder and was withdrawn at 24 hours' notice in October 1991 by the Committee on Safety of Medicines (CSM), the body that advises ministers on drug licensing. An appeal to the CSM was later upheld, but the Medicines Commission, said that the drug should be available at lower doses.
An expert committee found in April this year that the drug was not a 'significant hazard' and its benefits outweighed the risks.
However, earlier this month Brian Mawhinney, the health minister, said the licence would be revoked and that 'it was right to be cautious.'
Mr Smith said that Halcion was safe when used appropriately. 'We believe that there are insufficient grounds for the licensing authority's actions.'