taken for up to 43 days indicates that there is no evidence to support the development of tolerance to the hypnotic effects of Halcion; that is, the difference in the effects between drag versus placebo was consistent over time (0.5 mg for 43 days, 0.25 mg for 28 days, 0.125 mg for 8 days, and 0.25 mg for 16 weeks). In addition, polysomnographic data from clinical trials do not provide evidence of tolerance, but the polysomnographic literature suggests that tolerance may develop.
Available data suggest, however, that tens of thousands of prescriptions for much longer periods of time are being obtained by patients for much longer periods of time (e.g., the Evaluation of Medications for Insomnia in Canada study reports a mean duration of 1.7 years of use in Canada [Mariano and Gardner, 1988]; see Chapter 3). No data indicating the efficacy (or safety) of long-term use of Halcion for chronic insomnia exist.
Recommendation 4: Determine Tolerance. Controlled clinical trials of a duration of Halcion use beyond that recommended in the current labeling would be needed to determine whether tolerance to Halcion develops with long-term use.