Halcion: an independent assessment of safety and efficacy data

Regulatory agencies in the United States and the United Kingdom, among several other countries, have reviewed extensively the safety and efficacy of Halcion (triazolam) - a once commonly-used hypnotic drug.

Concerns about the drug's safety began to emerge when a Dutch physician reported a possible link between Halcion users and a syndrome that included such effects as depression, amnesia, hallucinations and increased anxiety.

In addition, in 1991 Halcion's manufacturer, Upjohn, noted that "errors had been identified in a report of one of the clinical studies included in the original" application for approval.

Since then, the drug has been removed from the market in several countries.

In the United States and Canada, the drug's labelling has been modified to reduce the recommended dose and duration of treatment and to heighten awareness of possible side effects.

Yet different data and analyses have resulted in conflicting messages that are difficult to reconcile and interpret.;In respose to a request from the US Food and Drugs Administration to resolve the controversy concerning Halcion, this text assesses the adequacy of the drug's clinical trials; the quality and quantity of data on adverse reactions; overall confidence in the data on effectiveness, adverse events, and side effects at different dose, and whether additional studies are needed.