[Naltrexone. An opioid antagonist to support the drug-free state in previous opioid addicts having stopped the habit].

Naltrexon (Nemexin) is an opioid antagonist for oral use and with a relatively long duration time. The preparation is valuable as supplementary therapy for maintenance of the drug-free state in previous opioid addicts who have broken the habit. Clinical use requires thus that the patient is completely detoxified from opioids. Prior to commencement of the first dose of naltrexon, a drug-free period of seven to ten days is recommended. The drug-free state may be verified by screening of the urine or a trial injection of naloxon. The detoxification/drug-free phase may be abbreviated by combined treatment with clonidine and naltrexon. Following the detoxification and drug-free phase, naltrexon therapy is initiated with the half dose (25 mg) on the first day and continued with 50 mg daily. The preparation should not be given to pregnant women or women who are breast-feeding, to children under the age of 18 years or to patients with renal failure. Liver enzyme control tests should be carried out before and during treatment. The number of side-effects reported are few. In clinical investigations, naltrexon has proved to be valuable in a significant minority of opioid dependent patients investigated. Utility is increased with the patients' motivation for this form of treatment. The success rate for naltrexon supportive treatment measured by retention in the therapeutic programme is higher than for traditional drug-free treatment but lower than for methadone supported treatment. Effects on the risk of relapse in the long run have not been documented.