What is Benzodiazepine Conversion?
Benzodiazepine conversion (or equivalency dosing) is the process of calculating the equivalent dose of one benzodiazepine relative to another. This is essential when switching a patient from one benzodiazepine to another, cross-tapering during discontinuation, or comparing potency between agents.
All benzodiazepines work by enhancing the effect of the neurotransmitter GABA at the GABAA receptor, but they differ significantly in potency, onset of action, duration of effect, and half-life. The standard reference is diazepam 10 mg, to which all other benzodiazepines are compared.
Equivalency Dose Table
The following table shows approximate oral equivalent doses compared to diazepam 10 mg. These values are derived from published clinical references including the Ashton Manual and standard pharmacology textbooks:
| Benzodiazepine | Brand Name | Equivalent Dose (mg) | Half-Life (hours) | Onset |
|---|---|---|---|---|
| Diazepam | Valium | 10 | 20–100 | Fast |
| Alprazolam | Xanax | 0.5 | 6–12 | Fast |
| Lorazepam | Ativan | 1 | 10–20 | Medium |
| Clonazepam | Klonopin | 0.5 | 18–50 | Medium |
| Chlordiazepoxide | Librium | 25 | 5–30 | Medium |
| Clorazepate | Tranxene | 15 | 36–200 | Fast |
| Flurazepam | Dalmane | 30 | 40–250 | Fast |
| Midazolam | Versed | 7.5 | 1.5–2.5 | Fast |
| Nitrazepam | Mogadon | 10 | 15–38 | Medium |
| Oxazepam | Serax | 20 | 4–15 | Slow |
| Temazepam | Restoril | 20 | 8–22 | Medium |
| Triazolam | Halcion | 0.5 | 2–5 | Fast |
| Clobazam | Onfi | 20 | 36–42 | Medium |
Pharmacokinetic Comparison
How to Use This Calculator
- Select the source benzodiazepine – the medication the patient is currently taking.
- Enter the current dose in milligrams.
- Select the target benzodiazepine – the medication you want to convert to.
- Click Convert to see the equivalent dose and detailed comparison.
The calculator also generates a full equivalency table showing what the entered dose would be for every benzodiazepine in the database.
Half-Lives & Duration of Action
Understanding half-lives is critical when converting between benzodiazepines:
- Ultra-short acting (<6h): Midazolam, triazolam. Used for procedural sedation and short-term insomnia. Higher risk of rebound and dependence.
- Short-acting (6–12h): Alprazolam, oxazepam. Commonly prescribed for panic disorder. May require multiple daily doses.
- Intermediate (12–24h): Lorazepam, temazepam, nitrazepam. Good balance of duration and clearance.
- Long-acting (>24h): Diazepam, clonazepam, clorazepate, flurazepam. Smoother plasma levels, preferred for tapering protocols.
Active metabolites can significantly extend the effective half-life. Diazepam's active metabolite (desmethyldiazepam) has a half-life of 36–200 hours, meaning the drug's clinical effects persist long after the parent compound is eliminated.
Cross-Tapering Protocol
When switching between benzodiazepines, a cross-taper approach is recommended to avoid withdrawal:
- Calculate the equivalent dose of the target benzodiazepine
- Week 1–2: Reduce source by 25%, introduce target at 25% of equivalent dose
- Week 3–4: Reduce source to 50%, increase target to 50%
- Week 5–6: Reduce source to 25%, increase target to 75%
- Week 7+: Discontinue source, target at full equivalent dose
The Ashton Manual recommends converting to diazepam before tapering, as its long half-life provides smoother withdrawal. Typical taper reductions are 1–2 mg diazepam equivalent every 1–2 weeks.
Clinical Considerations
Hepatic Metabolism
- Phase I (oxidation): Diazepam, alprazolam, midazolam, triazolam – affected by CYP3A4 inhibitors and liver disease
- Phase II only (glucuronidation): Lorazepam, oxazepam, temazepam – preferred in elderly and liver disease (LOT mnemonic)
Special Populations
- Elderly: Use lower doses; prefer lorazepam, oxazepam, or temazepam (no active metabolites, Phase II metabolism only)
- Hepatic impairment: Avoid long-acting agents with active metabolites; prefer LOT agents
- Renal impairment: Most benzodiazepines are hepatically metabolized; dose adjustments rarely needed
- Pregnancy: Category D – associated with cleft palate risk in first trimester and neonatal withdrawal syndrome
Frequently Asked Questions
Are benzodiazepine equivalency doses exact?
No. Equivalency tables provide approximate guidelines based on clinical studies and expert consensus. Individual variation is significant due to differences in metabolism, tolerance, receptor sensitivity, and comorbidities. Always use clinical judgment.
Why is diazepam the reference standard?
Diazepam was one of the first benzodiazepines widely studied, has well-characterized pharmacokinetics, is available in multiple formulations, and its long half-life makes it ideal for tapering protocols. The 10 mg dose was historically chosen as the reference point.
Can I switch benzodiazepines abruptly?
Abrupt switching is generally not recommended due to risk of withdrawal seizures, rebound anxiety, and other withdrawal symptoms. A gradual cross-taper over several weeks is safer. The exception is equivalent-dose substitution in acute settings under medical supervision.
What about Z-drugs (zolpidem, zopiclone)?
Z-drugs act on the same GABAA receptors but are structurally different from benzodiazepines. Approximate equivalencies exist (e.g., zolpidem 20 mg ≈ diazepam 10 mg) but cross-tolerance is incomplete, and direct conversion is not recommended without clinical oversight.