Benzodiazepine Conversion Calculator

Diazepam is preferred for structured benzodiazepine tapering because of its long half-life (20–100 h) and active metabolite desmethyldiazepam (half-life 36–200 h). This produces stable plasma levels with gradual self-tapering between doses, minimising peaks and troughs that cause inter-dose withdrawal symptoms.¹

Practical advantages of diazepam for tapering:

• Available in 2 mg and 5 mg tablets, allowing fine-grained dose reduction
• Liquid preparation (2 mg/mL) available on special order for very small dose steps
• Smooth blood level decline reduces rebound anxiety and withdrawal severity
• Funded in NZ; less abuse liability than short-acting agents at equivalent doses

How to switch: Calculate the diazepam equivalent of the current daily dose using this tool. Switch to the equivalent diazepam dose (usually in 2–4 divided doses daily to maintain stable levels). Stabilise on diazepam for 1–2 weeks before beginning the taper. Some patients may need a brief period at a slightly lower equivalent dose if they are distressed by the switch.

Note: Patients on short-acting, high-potency benzos (especially alprazolam and lorazepam) may experience more difficulty switching and may need specialist input for complex cases.

Ashton Protocol (most widely referenced): Reduce dose by approximately 10% of the current dose every 1–4 weeks. This percentage-based approach means reductions become progressively smaller in absolute terms as the dose decreases - which is appropriate, as withdrawal is often most intense in the final stages.¹

Rate of taper: Most patients tolerate a taper lasting 3–12 months. Patients on high doses or who have been taking benzodiazepines for many years may require longer (up to 2–3 years in some cases). There is no single correct speed - the patient's comfort and functioning should guide the pace.

Practical reduction steps using diazepam:

• Starting dose >30 mg/day: Reduce by 2–5 mg every 1–2 weeks
• 20–30 mg/day: Reduce by 2 mg every 1–2 weeks
• 10–20 mg/day: Reduce by 1–2 mg every 2 weeks
• 5–10 mg/day: Reduce by 1 mg every 2–4 weeks
• Below 5 mg/day: Use 0.5 mg steps or liquid diazepam; reduce every 4 weeks or slower as needed

Pausing the taper: If withdrawal symptoms are severe, hold the current dose for 2–4 weeks before continuing. Do not increase the dose unless there is a compelling reason (e.g., risk of seizures). Remind patients that temporary worsening does not mean the taper cannot succeed.

Monitoring: Review monthly during the taper. Assess for withdrawal symptoms, mood, sleep, and anxiety. Watch for relapse of the underlying condition that benzodiazepines were originally prescribed for.

BPAC NZ guidance recommends a collaborative approach, shared decision-making, and written tapering schedules provided to patients. Brief psychological interventions (CBT, motivational interviewing) significantly improve taper success rates.³

Physical dependence (neuroadaptation to GABA-A receptor downregulation) develops within 2–4 weeks of regular use at therapeutic doses. This is distinct from addiction (compulsive drug-seeking behaviour), though the two can co-exist.

Risk factors for dependence: Higher dose, longer duration, short-acting agents (more pronounced peaks and troughs), concurrent alcohol use, anxiety disorders, and previous substance use history.

Withdrawal syndrome - symptoms:

• Common: Anxiety, insomnia, irritability, tremor, sweating, palpitations, muscle tension, headache
• Perceptual: Paraesthesias, hypersensitivity to light, sound and touch, depersonalisation
• Severe (less common): Seizures, delirium, psychosis - particularly with abrupt cessation or rapid taper

Timing of withdrawal by half-life:

• Short-acting (oxazepam, temazepam): Withdrawal begins within 12–24 h, peaks at 1–3 days
• Intermediate-acting (lorazepam, alprazolam): Onset 24–48 h, peaks 3–5 days
• Long-acting (diazepam): Onset 3–7 days, peaks 1–2 weeks; more protracted but generally milder

Post-acute withdrawal syndrome (PAWS): Prolonged anxiety, insomnia, cognitive difficulties, and mood disturbance can persist for weeks to months after cessation, particularly with long-term use. Reassure patients this is time-limited and will resolve. PAWS is a major driver of relapse.

Seizure risk: Most significant with abrupt withdrawal from high doses or long-term use. If seizure risk is high (prior withdrawal seizures, epilepsy, high-dose use, concomitant alcohol withdrawal), admit for supervised withdrawal.

Elderly patients: Use the lowest effective dose. Benzodiazepines significantly increase fall and fracture risk, cognitive impairment, and motor vehicle accident risk in older adults.⁴ The LOT drugs - Lorazepam, Oxazepam, Temazepam - are preferred because they lack active metabolites and do not require hepatic oxidation. Avoid long-acting agents (diazepam, nitrazepam, chlordiazepoxide) as sedation accumulates. Reduce doses by 50% as a starting point. Include in STOPP/START review (see Geriatric Assessment tool).

Hepatic impairment: Avoid agents requiring oxidative hepatic metabolism (diazepam, chlordiazepoxide, clonazepam, nitrazepam). LOT drugs undergo glucuronidation, which is preserved in hepatic disease, and are therefore preferred. Use with caution in severe hepatic failure regardless of agent.

Renal impairment: Benzodiazepines are generally safe in mild-to-moderate renal impairment. Reduce doses in severe renal impairment (eGFR <30). Active metabolites may accumulate.

Pregnancy: Benzodiazepines cross the placenta. Use should be minimised, particularly in the first trimester (teratogenicity risk remains debated but is a precautionary concern) and near term (neonatal withdrawal syndrome, floppy infant syndrome, respiratory depression). If benzodiazepine use is unavoidable, use the lowest effective dose and taper before delivery if possible. Discuss with obstetric team. Benzodiazepines are not recommended during breastfeeding.²

Concurrent alcohol use disorder: Cross-tolerance means higher than usual doses may be required for alcohol withdrawal. Benzodiazepine use in patients who drink heavily requires careful monitoring for combined CNS depression. See alcohol withdrawal section below.

Diazepam is the first-line agent for alcohol withdrawal in NZ. Both symptom-triggered (CIWA-Ar guided) and fixed-schedule approaches are used depending on the clinical context.^5,6

Indications for admission: Seizure history, prior severe withdrawal (delirium tremens), multiple previous detoxifications, high alcohol intake (>30 standard drinks/day), significant medical comorbidity, CIWA-Ar score >15, or unable to manage safely in community.

Community withdrawal (mild AWS, CIWA-Ar <10):

• Diazepam 5–10 mg every 4–6 h as needed for withdrawal symptoms
• Daily review; reducing doses over 5–7 days
• Thiamine 100 mg oral daily (minimum) - use IM if absorption uncertain
• Check HealthPathways Canterbury for current community detox protocol

Inpatient withdrawal (moderate AWS, CIWA-Ar 10–15):

• Diazepam 10–20 mg every 4–6 h symptom-triggered (CIWA-Ar guided)
• Or front-loading: diazepam 20 mg every 1–2 h until CIWA-Ar <8, then PRN
• Thiamine 100 mg IV/IM TDS for at least 3 days (Pabrinex if available) - give before glucose
• Monitor for delirium tremens and respiratory depression

Severe AWS / Delirium Tremens: ICU or high-dependency setting. High-dose diazepam (up to 60–120 mg/day or more in refractory DT). Phenobarbitone as add-on if benzodiazepine-refractory. Specialist management required.

Note: Diazepam accumulation can occur with front-loading doses in patients with hepatic impairment. Monitor closely. Some services use lorazepam (shorter acting, no active metabolites) in significant hepatic disease.

Zopiclone (7.5 mg) is the most widely prescribed hypnotic in NZ and acts on GABA-A receptors via a binding site overlapping with benzodiazepines. Despite initial marketing as non-habit-forming, it produces physical dependence, tolerance, and a withdrawal syndrome similar to short-acting benzodiazepines.⁷

Deprescribing zopiclone:

• Reduce dose gradually over 4–8 weeks minimum
• Zopiclone 7.5 mg can be halved to 3.75 mg as a first step
• For patients unable to reduce directly, switching to a low-dose diazepam equivalent (approximately 5 mg) may be used, then taper diazepam - though this conversion is less well-established than benzo-to-benzo switches
• Address sleep hygiene and CBT-I (Cognitive Behavioural Therapy for Insomnia) concurrently

CBT-I is the most effective long-term treatment for chronic insomnia and should be offered to all patients being weaned off hypnotics. BPAC NZ has patient resources available.³

Melatonin (Circadin 2 mg MR) is funded in NZ for short-term use in patients aged ≥55 years as a hypnotic - may assist transition off zopiclone in appropriate patients.