16.3 : 抗不安薬: ベンゾジアゼピンとブスピロン

Benzodiazepines are anxiolytic drugs known for their safety due to a substantial therapeutic-to-lethal dose ratio.

After oral administration, these lipophilic drugs are readily absorbed, reaching the CNS. They bind to the allosteric site of the GABA_A receptor, enhancing the neurotransmitter GABA's inhibitory effects to prevent neurotransmission.

Benzodiazepines are categorized into three types. Short-acting benzodiazepines have a half-life of 3-8 hours, while intermediate-acting have a half-life of 10-20 hours. Long-acting benzodiazepines have a half-life of 1-3 days.

The common side effects include drowsiness, confusion, cognitive dysfunction, and impaired body coordination.

In contrast, buspirone, a partial agonist, binds to 5-HT_1A receptors, promoting serotonin -associated neuronal activity to alleviate anxiety. Its anxiolytic effects manifest gradually and primarily treat generalized anxiety disorder.

Unlike benzodiazepines, buspirone lacks sedative, anti-seizure properties, or psychomotor impairment.

Side effects may include chest pain, tachycardia, palpitations, dizziness, and gastrointestinal distress.