Managing Missed Doses of Naltrexone
If you miss a dose of naltrexone, you should take the missed dose as soon as you remember, but skip it if it's almost time for your next scheduled dose. Do not take double doses.
Understanding Naltrexone's Pharmacology
Naltrexone is an opioid receptor antagonist with the following key characteristics:
- Plasma half-life of approximately 4 hours
- Active metabolite (6-β-naltrexol) with a longer half-life of about 13 hours
- Antagonist effects may persist for 2-3 days due to metabolite accumulation during long-term therapy 1
Proper Approach to Missed Doses
When to Take the Missed Dose
- If you remember within a few hours: Take the missed dose as soon as possible
- If it's close to your next scheduled dose: Skip the missed dose and resume your regular dosing schedule
- Never take double doses to make up for a missed dose
Rationale for This Approach
The recommendation against taking double doses is based on several factors:
- Naltrexone's antagonist effects persist beyond its plasma half-life due to its active metabolite
- Taking double doses could potentially increase the risk of side effects without providing additional therapeutic benefit
- The medication's effects on opioid receptors are already substantial at standard doses
Important Considerations
Side Effects to Monitor
Naltrexone can cause several adverse effects that might be exacerbated by irregular dosing:
Special Circumstances
- For patients on naltrexone for alcohol dependence: Maintaining regular dosing is important for effectiveness, but a single missed dose is unlikely to significantly impact treatment outcomes
- For patients on naltrexone for opioid dependence: Consistent dosing is crucial to maintain opioid receptor blockade
Clinical Implications
Maintaining Therapeutic Effect
- The primary goal is to maintain consistent blood levels of naltrexone
- A single missed dose is unlikely to significantly compromise treatment effectiveness due to the presence of the active metabolite
- Regular, consistent dosing provides the best therapeutic outcomes 4
Avoiding Withdrawal
Unlike opioid agonists, missing a dose of naltrexone (an antagonist) will not cause withdrawal symptoms in patients who are not opioid-dependent
Key Takeaway
The most important aspect of naltrexone therapy is maintaining consistent dosing over time. If a dose is missed, take it when remembered unless it's almost time for the next dose, in which case simply resume the regular schedule. This approach balances maintaining therapeutic effect while avoiding potential adverse effects from double dosing.