Buprenorphine — NZ Medication Guide

What is Buprenorphine?

Buprenorphine (generic name: buprenorphine (with or without naloxone)) is a medication used primarily for opioid use disorder treatment and severe pain management. Suboxone (buprenorphine/naloxone) and Subutex (buprenorphine) are funded by Pharmac for OST. Norspan patches are funded for chronic pain. OST prescribing requires addiction medicine specialist authorisation.

What is Buprenorphine Used For?

Buprenorphine is prescribed by healthcare professionals in New Zealand for the following indications:

• Opioid use disorder — maintenance treatment (Suboxone, Subutex)
• Moderate to severe chronic pain (transdermal patches — Norspan)
• Postoperative pain management
• Palliative care pain management

How Does Buprenorphine Work?

Buprenorphine is a partial agonist at mu-opioid receptors and an antagonist at kappa-opioid receptors. As a partial agonist, it activates opioid receptors but produces a submaximal effect with a ceiling on respiratory depression — making it significantly safer in overdose than full opioid agonists. The combination product Suboxone adds naloxone to deter injection misuse (naloxone is poorly absorbed sublingually but precipitates withdrawal if injected).

How to Take Buprenorphine

For opioid substitution (Suboxone sublingual film or tablet): place under the tongue and allow to dissolve completely — do not swallow, chew, or smoke. Doses are typically once daily under an authorised prescriber. For chronic pain (Norspan transdermal patch): apply once weekly to clean, dry, non-hairy skin on the upper arm, chest, or back. Rotate application sites. Do not cut patches.

Common Side Effects

• Constipation
• Nausea and vomiting (particularly during initiation)
• Headache
• Insomnia
• Sweating
• Oral numbness or ulceration (sublingual formulations)

Serious Side Effects — Seek Medical Attention

• Respiratory depression (lower risk than full agonists but significant with CNS depressants)
• Precipitated withdrawal if started too soon after last opioid use
• Liver toxicity — elevated liver enzymes, jaundice (monitoring required)
• Severe allergic reaction
• Opioid withdrawal if patch falls off or dose is missed

Drug Interactions

• Benzodiazepines and other CNS depressants — respiratory depression and death risk
• Other opioids — buprenorphine may displace them and precipitate withdrawal
• CYP3A4 inhibitors (azole antifungals, HIV protease inhibitors) — increase buprenorphine levels
• CYP3A4 inducers (rifampicin, carbamazepine) — decrease buprenorphine efficacy
• Alcohol — enhanced CNS and respiratory depression

New Zealand Prescribing Information

In New Zealand, buprenorphine-naloxone (Suboxone) is increasingly preferred over methadone for OST due to its superior safety profile. Ministry of Health NZ guidelines recommend Suboxone as first-line for many patients. Extended-release injectable buprenorphine (Buvidal) is also available for patients who prefer monthly injections over daily oral dosing.

Frequently Asked Questions

Why does Suboxone contain naloxone?

Naloxone is added to deter injection misuse. When Suboxone is used correctly under the tongue, naloxone is minimally absorbed and has no effect — only buprenorphine acts. However, if someone injects it, naloxone becomes active and triggers acute withdrawal, making injection misuse unpleasant and unattractive.

When is the right time to start buprenorphine?

Starting too soon after your last opioid use can trigger acute withdrawal. Your prescriber will ask you to wait until you are in mild-moderate withdrawal (typically 12–24 hours for short-acting opioids, 24–72 hours for methadone). The COWS (Clinical Opioid Withdrawal Scale) is used to assess readiness.

References & Further Information

The following New Zealand and international resources were used to inform this page:

• New Zealand Formulary — Buprenorphine
• NZ Drug Foundation — Opioid Substitution Treatment
• Ministry of Health NZ — OST Clinical Guidelines
• Pharmac — Funded Medicines Schedule

Reviewed by a Registered Pharmacist — KiwiMeds New Zealand