In 1996, a U.S. Food and Drug Administration (FDA) task force looking into the medical, procedural, and legal aspects of the drug's approval process concluded that Halcion was "safe when prescribed according to current labeling" and "effective in the treatment of insomnia at doses and durations currently recommended in the labeling." The task force also recommended that a separate reassessment of the safety and efficacy of Halcion be conducted by a panel of experts. To that end FDA requested that the Institute of Medicine (IOM) assess the following:

• the adequacy of the study designs and quantitative endpoints used in the major clinical trials of Halcion;

• the quality and quantity of postmarketing data with respect to adverse drug reactions;

• the overall confidence in the data on the effectiveness, adverse events, and side effects of Halcion at different doses and for different durations, including those specified in the current product labeling; and

• the need for additional studies to clarify and characterize the risk and efficacy profiles of Halcion.

The committee evaluated numerous sources of data to provide a broad perspective on the efficacy and safety of Halcion. These sources are listed in detail in Appendix. E. An abbreviated list appears in Box 1.

The primary purpose of a hypnotic agent is to improve the quality of sleep. The efficacies of hypnotic agents are assessed through subjective evaluations that involve the use of questionnaires or interviews and also through objective (polysomnographic) measurement of endpoints that include time to onset of sleep, duration of sleep, and number of awakenings.