When can Suboxone (buprenorphine) be started after discontinuing Naltrexone (naltrexone)?

Starting Suboxone After Naltrexone Discontinuation

You can safely start Suboxone (buprenorphine) 2-3 days after discontinuing oral naltrexone, or 24-30 days after the last extended-release naltrexone injection. 1, 2

Timing Based on Naltrexone Formulation

Oral Naltrexone

• Wait 2-3 days after the last oral naltrexone dose before initiating buprenorphine 1, 2
• This washout period accounts for naltrexone's 4-hour plasma half-life and its active metabolite (6-β-naltrexol) with a 13-hour half-life 1, 2
• The metabolite accumulates during therapy and antagonist effects persist for 2-3 days after discontinuation 1

Extended-Release Naltrexone (Vivitrol)

• Wait 24-30 days after the last injection before starting buprenorphine 1, 2
• The extended-release formulation requires a much longer washout period due to sustained drug release from the depot injection 1, 2

Clinical Rationale

The waiting period is necessary because:

• Naltrexone is a competitive opioid receptor antagonist that blocks mu, kappa, and delta opioid receptors 2
• If buprenorphine is started too early while naltrexone still occupies opioid receptors, the buprenorphine will be ineffective and may precipitate withdrawal 2
• The full therapeutic effect of naltrexone persists for 2-3 days as the active metabolite clears 1

Important Caveats

• Patients discontinuing naltrexone are at increased risk of opioid overdose due to decreased tolerance 2
• Close monitoring during the transition period is essential to prevent relapse 2
• The reverse transition (methadone/buprenorphine to naltrexone) can be accomplished more rapidly using naltrexone-precipitated withdrawal protocols, but this is not applicable to your question 3, 4