Tamea Sisco
mid-nineties, the same drug was approved for the treatment of alcoholism under the name Rivera®.
Clinical Trials for Alcoholism
Thus, in this brief review, we focus on the few double-blind trials available. Voipicelli (1992) and colleagues reported on a 12-week trial of 50 milligrams of naltrexone per day in 34 alcohol-dependent outpatient men, comparing results with 36 men treated with placebo. All individuals received the usual treatment for alcohol rehabilitation, and everyone was evaluated weekly. By the end of the twelve weeks, 23 percent of naltrexone treated patients had relapsed into heavy regular drinking, compared to 54 percent of the patients on placebo. These data indicate naltrexone may have been especially helpful for patients who had “slipped” and begun to drink; almost half of them were likely to return to abstinence if they were on naltrexone, while the same is true for only five percent of those treated with placebo. The authors suggested it is possible the naltrexone blocked part of the high or reinforcing effect of alcohol, making it easier for people who had initially returned to drinking do not go on to escalating doses of alcohol. At the same time, the study also reported a possible decrease in craving for alcohol with this narcotic antagonist (Volpicelli et al., 1992).
Also, O’Malley and colleagues (1992) reported on 97 alcoholic men and women, 46 of who received 50mg per day of naltrexone and the remainder placebo over 12 weeks. While the project was complex and other questions were being tested, those on naltrexone demonstrated improved rates of abstinence and lower rates of alcohol intake and problems if they had returned to drinking.
Other more recent studies include both positive and negative reports but the consensus favors the limited use of narcotic antagonism in the treatment of alcoholism (consensus report, 1996) The following list is representative of over 5,000 papers on the subject since the first work of associates in the early 70s showing the anti-alcohol effect of naloxone in mice and rats (reduction of sleep-time, delay in withdrawal reactions, reduced ethanol intake, and reduction of ethanol-induced dependence).
Positive reports in humans include (Kranzler et al., 1998; King et al., 1997; Mason et al., 1994,Oslin et al., 1997; O’Malley et al., 1996; Volpicelli et al., 1995; O’Malley et al., 1996; Volpicelli et al., 1995; King et al., 1997; and, O’Malley et al., 1992). The most up to date and complete review of the subject is by Herz from the Department of Neuropharmacology at the Max- Planck Institute for Psychiatry in Germany (1997).
In terms of negative reports, we believe a reason for non-compliance resides in the very nature of the pharmacological and physiological basis of the use of narcotic antagonism in treating either opiates or alcohol. Craving behavior is distinct from euphoria and different set of mechanism are involved. Blocking of euphoria represents the occupancy of a narcotic antagonist, naloxone, on mu opiate receptors and reducing craving is due to dopamine occupancy on dopamine-D, receptors.
Opiates
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The use of heroin continues to increase and is estimated that eight million people in the world (0.14%) abuse opiates. The region with the highest annual prevalence (2%) are South East and South West Asia and based on the National Household Survey, the annual prevalence of heroin use in the United States is 0.3% with a rising trend of heroin use in the last 2 years (Van der Burgh (1999).
New pharmacological treatments for heroin addiction include drugs that reduce withdrawal symptoms and agents that are given during the maintenance phase of treatment. A variety of different types of pharmacological agents (opioid agonists, opioid antagonists and alpha 2- adrenoreceptor agonists ) have been extensively studied.
Clinical Trials for Opiates
In a review and meta-analysis of randomized controlled studies evaluating the use of naltrexone as a maintenance agent, Kurchmayer et al ( 2001).found a tendency in favor if naltrexone but concluded that there is not sufficient evidence to evaluate the efficacy of naltrexone treatment for opioid dependence. Shufman et al. (1994) in a double-blind, controlled design evaluated the efficacy of naltrexone in reducing opioid positive mine tests during a 12-week trial and found naltrexone to be superior to placebo. Similarly, on a multi-center, randomized controlled trial, Hollister (1978), examined 170 opiate-dependent patients at a 9 month follow-up, and found that the group treated with Naltrexone had