Serotonin-1A Anxiolytics: An Overview

The selective serotonin-1A receptor partial agonist anxiolytics represent a new class of pharmacologic agents that have demonstrated efficacy in the treatment of generalized anxiety disorder (GAD). These compounds offer a completely different pharmacologic approach to this disorder from previous medications. The selective 5-hydroxytryptamine-1A (5-HT1A) anxiolytics buspirone, gepirone, ipsapirone, and SM-3997 have several important new and unique features that will be reviewed in this paper. These features include no cross-tolerance with alcohol or benzodiazepines, no evidence of abuse or misuse potential, and no withdrawal symptoms or rebound anxiety on cessation of therapy. The 5-HT1A anxiolytics have no muscle relaxant, sedative, or anticonvulsant properties and do not impair psychomotor functioning. They do have a slower onset of effect than standard benzodiazepines – clinical response is usually noted in 1–3 weeks. The side effect profile is quite different from that of the benzodiazepines. It includes gastrointestinal symptoms such as nausea and diarrhea, headache, dizziness, and restlessness. Some patients with GAD who have received chronic ( > 1 month) benzodiazepine therapy may not respond as well to these compounds initially as will patients with no prior benzodiazepine treatment, especially if the benzodiazepine has been discontinued only recently. These compounds, buspirone in particular, have been shown to have excellent maintenance and prophylactic properties and to be well tolerated with long-term therapy ( > 3 months). Because of their unique mechanism of action and side effect profile, and no evidence of misuse or abuse potential or interference with mental acuity, these compounds represent a definite advance in the pharmacologic management of GAD.