Pharmacological Classification of Xanax (Alprazolam)
Xanax (alprazolam) is a triazolobenzodiazepine, which is a subclass of the benzodiazepine family of central nervous system depressants. 1
Chemical Structure and Classification
- Alprazolam is specifically classified as a triazolo analog of the 1,4 benzodiazepine class of central nervous system-active compounds 1
- The chemical name is 8-Chloro-1-methyl-6-phenyl-4H-s-triazolo[4,3-α]1, 4 benzodiazepine, which distinguishes it from classical benzodiazepines by the incorporation of a triazolo ring 1, 2
- This structural modification (the triazolo ring) may confer additional modes of action beyond typical benzodiazepines, including potent inhibition of platelet-activating factor 2
Mechanism of Action
- Like all benzodiazepines, alprazolam activates GABA-A receptors in the brain, enhancing the activity of the inhibitory neurotransmitter GABA and thereby reducing central nervous system excitability 3
- Alprazolam has a non-selective affinity for GABA-A receptors and acts as a full agonist 3
- Benzodiazepines with high affinity for the α1 subunit (such as alprazolam) may cause more sedation and cognitive impairment 3
Pharmacokinetic Profile
- Alprazolam has an intermediate half-life of 9-16 hours (some sources cite 10-15 hours), which is shorter than diazepam but longer than ultrashort-acting agents 4, 5, 6
- Peak serum levels are achieved in 0.7 to 2.1 hours after oral administration 4, 5
- Absolute bioavailability of oral alprazolam averages 80-100% 5
- Benzodiazepines with shorter half-lives like alprazolam may lead to withdrawal symptoms between doses, unlike longer-acting agents such as clonazepam 3
Controlled Substance Status
- Alprazolam is a Schedule IV controlled substance under the Controlled Substances Act by the Drug Enforcement Administration 1
- Physical and psychological dependence is a risk with all benzodiazepines, including alprazolam, with increased risk at doses greater than 4 mg/day and with longer-term use 1
Clinical Context
- Alprazolam is primarily used to treat anxiety disorders, particularly panic disorder 3, 4, 6
- The drug is metabolized primarily by hepatic microsomal oxidation via the CYP3A enzyme system 7, 5
- Drugs metabolized by CYP3A (including triazolo-benzodiazepines like alprazolam) can have elevated concentrations when co-administered with CYP3A inhibitors like erythromycin 7