Switching from Naltrexone to Suboxone
Stop naltrexone immediately and wait a minimum of 72 hours (3 days) before initiating Suboxone to allow complete clearance of the opioid antagonist and prevent precipitated withdrawal when buprenorphine is introduced. 1
Critical Timing Considerations
The washout period is essential because:
- Naltrexone has a half-life of 4 hours, but its active metabolite 6-β-naltrexol has a half-life of 13 hours 1
- After 5 half-lives of the active metabolite (approximately 65 hours or ~3 days), the antagonist effects will be sufficiently cleared 1
- Extended-release naltrexone formulations require 24-30 days washout before opioid initiation, but your client is on daily oral naltrexone, which clears much faster 1
Step-by-Step Transition Protocol
Days 1-3: Naltrexone Washout Phase
- Discontinue the 50mg daily naltrexone dose immediately 1
- Monitor for any emerging opioid cravings during this period 2
- Ensure the patient has no active opioid use during washout, as they will have no opioid blockade protection 2
- Wait minimum 72 hours (preferably 4-5 days for complete safety margin) before Suboxone initiation 1
Day 4-5: Suboxone Induction
- Confirm the patient is in mild-to-moderate opioid withdrawal before administering the first Suboxone dose to prevent precipitated withdrawal from buprenorphine's partial agonist properties 3
- If the patient has no baseline opioid dependence (naltrexone was used for other indications), buprenorphine can be started without waiting for withdrawal symptoms 3
- Begin with low-dose buprenorphine induction (typically 2-4mg sublingual) and titrate based on response 3, 4
Stabilization Phase
- Gradually increase buprenorphine dose over several days to achieve stabilization, typically reaching 8-16mg daily for opioid use disorder 3, 4
- The stabilization period ensures tolerability and identifies appropriate maintenance dosing 3
- Monitor for adequacy of symptom control and adverse effects during titration 3
Critical Pitfalls to Avoid
Do NOT attempt to use naltrexone to precipitate withdrawal for buprenorphine induction in this scenario - this approach is only used for rapid transition FROM methadone or other full agonist opioids TO buprenorphine, not from naltrexone 5. Your client is already opioid-free on naltrexone maintenance.
Do NOT start Suboxone while naltrexone is still in the system - the naloxone component in Suboxone is irrelevant here; the issue is that residual naltrexone will block buprenorphine's therapeutic effects and waste the medication 1.
Ensure liver function tests are checked before initiating Suboxone, as both naltrexone and buprenorphine require hepatic monitoring 1.