Diazepam vs Alprazolam
## Overview
Diazepam is a long-acting benzodiazepine; alprazolam is a short-to-intermediate acting triazolobenzodiazepine with FDA approval for panic disorder. Alprazolam is more potent per milligram and has a more pronounced withdrawal syndrome due to its shorter half-life.
## Mechanism of Action
Both enhance GABA-A receptor-mediated Cl- influx. Alprazolam's triazolo ring fusion alters receptor binding kinetics and may contribute to its pronounced anxiolytic and antipanic effects.
## Pharmacokinetics
Alprazolam: half-life 6–27 h, CYP3A4 (major substrate), no significant active metabolites at clinical doses, oral bioavailability ~80%. Diazepam: half-life 20–100 h, active metabolites persisting for days.
## Withdrawal and Dependence
Due to its shorter half-life and higher potency (alprazolam 0.5 mg ≈ diazepam 10 mg), alprazolam has a more severe, abrupt withdrawal syndrome. Seizures can occur with abrupt discontinuation. Tapering alprazolam often involves switching to an equivalent diazepam dose and gradual reduction.
## Indications
Alprazolam: FDA-approved for GAD and panic disorder (XR formulation). Its rapid onset and higher potency may contribute to dependence potential. Diazepam: anxiety, alcohol withdrawal, muscle spasm, status epilepticus, procedural sedation.
## Key Takeaways
- Alprazolam: high potency, FDA-approved for panic, severe withdrawal syndrome
- Diazepam: lower potency per mg, self-tapering via active metabolites, used for withdrawal protocols
- Alprazolam XR reduces peak-trough fluctuation
Verdict
Alprazolam is preferred for panic disorder (FDA-approved). Diazepam is preferred for alcohol withdrawal, muscle spasm, and situations where its self-tapering pharmacokinetics are beneficial. Long-term use of either carries dependence risk; alprazolam's shorter half-life makes abrupt discontinuation more dangerous.