Psychotropics are no longer easy to be sorted in single-functioning slots. Most antidepressants, some anticonvulsants, and even antipsychotics, have been used for the treatment of anxiety. This chapter focuses chiefly on the large family of benzodiazepines, which serves as the most frequently used anxielytics and hypnotics. Nonbenzodiazepine gamma-aminobutyric acid (GABA) receptor binding agents are also reviewed here, along with a few other relevant anxielytics and hypnotics.

Benzodiazepines were first developed by Roche Laboratories in 1950s. The first benzodiazepine introduced was chlordiazepoxide (Librium), followed by diazepam (Valium) in a few years. Continued laboratory study developed a large group of agents, which share the same core structure (Figure 30–1) and broad spectrum of clinical effects as hypnotics, muscle relaxants, sedatives, anxielytics, and anticonvulsants. All the benzodiazepines have the same mechanism of action, and all bear risk of addiction. The difference between one benzodiazepine and another lays mainly on the half-life. The rate of absorption and lipophilicity also play important roles in these agents' individual personality. Benzodiazepines have their naturally occurring receptors in human brain. Some fungi may be able to synthesize benzodiazepine. However, at this point, no endogenous ligands for benzodiazepine receptors have been found. Commonly used benzodiazepines include

1. ▶ Alprazolam (Xanax, Xanax XR, Niravam)

2. ▶ Midazolam (Versed)

3. ▶ Oxazepam (Serax)

4. ▶ Triazolam (Halcion)

5. ▶ Lorazepam (Ativan)

6. ▶ Estazolam (ProSom)

7. ▶ Temazepam (Restoril)

8. ▶ Chlordiazepoxide (Librium)

9. ▶ Clonazepam (Klonopin, Klonopin Wafers)

10. ▶ Clorazepate (Tranxene SD, Tranxene T-Tab)

11. ▶ Diazepam (Valium)

12. ▶ Flurazepam (Dalmane)

A new group of nonbenzodiazepine, selective GABA-binding hypnotics has been gaining popularity with relative safety and probable less tendency of abuse.