Ultra-Low-Dose Naltrexone Administration Guidelines

Pharmacokinetics and Administration Timing

The pharmacokinetics of naltrexone include a half-life of 4 hours, while its active metabolite 6-β-naltrexol has a longer half-life of 13 hours, according to the Mayo Clinic Proceedings 1, 2
Naltrexone's pharmacological effects are most pronounced within the first several hours after dosing, making morning administration optimal for daytime coverage, as reported by the Mayo Clinic Proceedings 2
Morning dosing aligns with the pharmacokinetic profile of naltrexone, allowing its effects to diminish by bedtime, and is the established standard practice for standard naltrexone formulations, as stated by the American Academy of Family Physicians 3

For patients undergoing surgical procedures while on ULDN therapy, the American Academy of Family Physicians recommends communicating with the perioperative team about the dosing schedule 1
If the patient is planning for surgery, the Mayo Clinic Proceedings suggests that standard naltrexone should be held for 2-3 days prior to elective procedures if opioids are expected to be used perioperatively 1, 2
Extended-release naltrexone formulations should be held for 24-30 days before elective surgical procedures, according to the Mayo Clinic Proceedings 2
Liver function tests should be monitored at baseline and periodically during treatment, even with ultra-low doses, as recommended by the American Academy of Family Physicians 3