Comparison of the effectiveness of different opioid peptides in suppressing heroin withdrawal.

The effectiveness of beta-endorphin, dynorphin-(1-13), dynorphin-(1-10) amide, alpha-neoendorphin and [D-Ala2,D-Leu5]enkephalin in suppressing withdrawal in heroin addicts was compared in this study. Groups of six patients were stabilized overnight in the hospital and were treated with either saline or peptide when withdrawal symptoms began to appear the following morning. Withdrawal was scored before and after treatment by the patient himself and an independent observer. Peptides were administered in a bolus dose of 60 micrograms/kg body weight. The patient, the observer and the physician who administered the injection were all blind to the nature of the compound given. All treatments, including those with saline, produced an overall reduction of withdrawal score. However, by statistical analysis, only treatments with beta-endorphin, [D-Ala2,D-Leu5]enkephalin and dynorphin-(1-13) were effective in producing a significant decrease of withdrawal symptoms. The length of relief brought about by the different peptides varied from less than an hour to a maximum of 5 h in one case. The average period of relief brought about by beta-endorphin, dynorphin-(1-13) and [D-Ala2,D-Leu5]enkephalin was 44, 46 and 60 min, respectively. Of the five peptides administered [D-Ala2,D-Leu5]enkephalin produced the largest number of side-effects.