Naltrexone

The euphoric effect of alcohol is mediated through the endogenous opioid system, with activation of the prefrontal cortex (Tuhonen et al., 1994). Naltrexone, an opioid antagonist, has documented beneficial effect in reducing relapse and craving in alcoholic patients (O'Malley et al., 1992; Swift et al., 1994; Volpicelli et al., 1992). Alcoholics taking nal-trexone report a less pleasurable effect or high from alcohol consumption and do not escalate their drinking as rapidly as control groups (Volpicelli et al., 1995). A decreased craving for alcohol has not been universally reported. Naltrexone is given as a daily 50-mg tablet or a monthly 300-mg injection. This dosage provides a surmountable opioid blockage that will render other opioids ineffective unless given in greatly increased doses. Naltrexone is not an aversive agent. Many alcoholic patients report a less-than-expected pleasurable experience with alcohol consumption, whereas others report some mild aversive symptoms.

Naltrexone undergoes first-pass hepatic metabolism and is hepatotoxic in excessive doses. It should not be given to patients currently addicted to opiates because it will precipitate acute opiate withdrawal (Croop et al., 1997). The most common side effects at the usual dosage include nausea, headache, dizziness, anxiety, and somnolence. Good candidates for naltrexone are those likely to be compliant with therapy, those concomitantly addicted to opiates who have been detoxified and have not received opiate replacement therapy, and those with heavy alcohol cravings at entry to therapy (Volpicelli et al., 1997). Naltrexone should not be used as a single treatment agent but rather in conjunction with other behavioral or motivational treatment modalities. Questions remain about the duration of treatment with naltrexone in alcohol use disorders. Generally, prolonged abstinence rates improve after 12 months of continuous abstinence.

Poor compliance with oral naltrexone reduces its potential benefits (Volpicelli et al., 1997). In a pilot study, alcohol-dependent patients treated with subcutaneous depot formulation of naltrexone had detectable plasma concentrations of the medication for more than 3 days after injection and had reduced frequency of heavy drinking compared with the placebo group (Kanzler et al., 1998). A randomized clinical trial with depot naltrexone did not demonstrate reduced incidence of heavy drinking, although it did demonstrate significantly delayed onset of drinking, increased number of abstinent days, and increased abstinence (Kanzler et al.,

2004). The FDA approved long-acting naltrexone (Vivitrol), 380 mg each month intramuscularly (IM) in the buttock, for alcohol dependency in 2006. Patients should be abstinent when they are started on naltrexone.

An alternative opioid antagonist with some success in patients with alcohol dependency, but not as well studied, is nalmefene (Kanzler et al., 2009).

According to the Agency for Health Care Policy and Research, there is good (level B) evidence to support the use of naltrexone to reduce craving and relapse (AHCPR, 1999).

Alcohol No More

Alcohol No More

Do you love a drink from time to time? A lot of us do, often when socializing with acquaintances and loved ones. Drinking may be beneficial or harmful, depending upon your age and health status, and, naturally, how much you drink.

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