Dependence on opioids

Naltrexone is used to treat persons dependent on opioids. Fhtients receiving naltrexone have been detoxified and are enrolled in a program for treatment of narcotic addiction. Naltrexone, along with other methods of treatment (counseling, psychotherapy), is used to maintain an opioid-free state Fhtients taking naltrexone on a... 

The expected outcomes of the person formerly dependent on opioids may include an optimal response to therapy, which includes compliance with the treatment program, remaining drug free, and an understanding of the drug rehabilitation program. 

Patients tolerant to or physically dependent on op/o/c/s. Nalmefene may cause acute withdrawal symptoms in individuals who have some degree of tolerance to and dependence on opioids. Closely observe these patients for symptoms of withdrawal. Administer subsequent doses with intervals of at least 2 to 5 minutes between doses to allow the full effect of each incremental dose of nalmefene to be reached. Reversal of postoperative opioid depression Use 100 mcg/mL dosage strength (blue label) refer to the following table for initial doses. The goal of treatment with nalmefene in the postoperative setting is to achieve reversal of excessive opioid effects without inducing a complete reversal and acute pain. This is best accomplished with an initial dose of 0.25 mcg/kg followed by 0.25 mcg/kg... 

Risk of precipitated withdrawal Nalmefene is known to produce acute withdrawal symptoms and, therefore, should be used with extreme caution in patients with known physical dependence on opioids or following surgery involving high uses of opioids. 

Drug dependence Administer cautiously to people who are known or suspected to be physically dependent on opioids, including newborns of mothers with narcotic dependence. Reversal of narcotic effect will precipitate acute abstinence syndrome. Repeat administration The patient who has satisfactorily responded should be kept under continued surveillance. Administer repeated doses as necessary, because the duration of action of some narcotics may exceed that of the narcotic antagonist. Respiratory depression Not effective against respiratory depression due to nonopioid drugs. 

Naltrexone is generally taken once a day in an oral dose of 50 mg for treatment of alcoholism. An extended-release formulation administered as an IM injection once every 4 weeks is also effective. The drug can cause dose-dependent hepatotoxicity and should be used with caution in patients with evidence of mild abnormalities in serum aminotransferase activity. The combination of naltrexone plus disulfiram should be avoided, since both drugs are potential hepatotoxins. Administration of naltrexone to patients who are physically dependent on opioids precipitates an acute withdrawal syndrome, so patients must be opioid-free before initiating naltrexone therapy. Naltrexone also blocks the therapeutic effects of usual doses of opioids. 

Naltrexone Nonselective competitive antagonist of opioid receptors Reduced risk of relapse in individuals with alcoholism Available as an oral or long-action parenteral formulation Toxicity Gastrointestinal effects and liver toxicity will precipitate a withdrawal reaction in individuals physically dependent on opioids and will prevent the analgesic effect of opioids... 

Use of opioid drugs in acute situations may be contrasted with their use in chronic pain management, in which a multitude of other factors must be considered, including the development of tolerance to and physical dependence on opioid analgesics. 

A limiting factor in the clinical utilization of opioids for pain relief is that repeated administration leads to the development of tolerance to and physical dependence on opioids. At the cellular level, tolerance can be viewed as a form of persistent receptor desensitization associated with repeated drug administration. Phosphorylation of opioid receptors by protein kinases, especially PKC, is hypothesized to play a major role in this desensitization hence, opioid receptors in tolerant and dependent states are thought to be highly phosphorylated [135-140]. 

Codeine and morphine should also be used with caution in convulsive disorders and if a patient is dependent on opioids, they should not be withdrawn abruptly. (See BNF for further cautions and contraindications.)... 

Babies born to mothers dependent on opioids may show a physical withdrawal syndrome. 

A dose of analgesic should be left accessible to the patient, especially at night, when unnecessary suffering may result from reluctance to call a nurse or disturb a relative. In terminal illness, the question of whether or not the patient will become dependent on opioids ceases to be of importance (but see below) and the ordinary precautions against dependence — low, widely-spaced doses — need not be rigorously applied. 

Physical dependence on opioids appears to occur in patients who use opioids for long-term pain relief, and cases of addiction have been reported. However, rates of addiction are low and occur mainly in individuals who have a history of substance misuse. The role of longterm opioid medication in non-cancer-related chronic pain remains controversial. Opiophobia, a fear of the legitimate use of opioid analgesics because of the potential for addiction, remains a significant issue for physicians, patients, and relatives alike. The review is illustrated with a report of a 52-year-old man with multiple myeloma who displayed tolerance to oral morphine over 2 years. 

Tablets for oral use now contain pentazocine hydrochloride (equivalent to 50 mg of the base) and naloxone hydrochloride (equivalent to 0.5 mg of the base Talwin NX), which reduces the potential use of tablets as a source of injectable pentazocine. After oral ingestion, naloxone is destroyed rapidly by the liver however, if the material is dissolved and injected, the naloxone produces aversive effects in subjects dependent on opioids. An oral dose of about 50 mg pentazocine results in analgesia equivalent to that produced by 60 mg codeine oraUy.

Opioid antagonists have established uses in the treatment of opioid-induced toxicity, especially respiratory depression in the diagnosis of physical dependence on opioids and as therapeutic agents in the treatment of compulsive users of opioids (Chapter 23). Naltrexone is also FDA-approved for the treatment of alcohol abuse. 

Both physical and psychological dependence on opioid analgcsic-s gradually develops and sudden iciminaiion of drag administration precipitates a withdrawal syndrome (Chapter 31). 

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