Fentanyl Challenges

This report describes effective prolonged opiate blockade by subcutaneous depotnaltrexone (d-NTX) preparation. The d-NTX is a 1000 mg pellet inserted at opiate detoxification. The assay of effective opiate blockade was direct opiate challenge. Fifteen challenges were performed. Opiate challenges occurred from 21 to 70 days after d-NTX implantation (mean 40.9 days). All patients were refractory to the opiate. The data suggest that this d-NTX preparation is effective for at least 4 weeks after implantation. While not a “cure” for opiate dependence, d-NTX may allow a prolonged interval after detoxification during which addicts will have time to benefit from social/psychological interventions. Naltrexone (NTX) is a potent and effective narcotic antagonist.(1) People with drug levels ≥ 1 ng/ml are refractory to the effects of intravenous opiates,(2) and it has potential efficacy as an adjunct to help maintain abstinence in opiate addicts after detoxification. Naltrexone was discovered in the late 1960s and evaluated at some length in the 1970s.(1,3) After it aroused clinical excitement in the early 1970s, however, its potential efficacy met two major barriers. First, patients had to be completely detoxified before NTX can be started, as dosing an active opiate user will lead to full-blown and accelerated withdrawal.(4) Second, although it is orally available and has a longer duration of effect than the other available narcotic antagonists, oral NTX still needs to be given a minimum of three times a week, making compliance an issue.(5) We feel that the first issue has a solution in the use of accelerated opiate detoxification under sedation or anesthesia.(6) The second issue may have a solution in the use of slow-release subcutaneous depot-