"Naltrexone is a long acting opioid receptor antagonist used in drug rehabilitation programmes to maintain opioid abstinence. However, when consumed in conjunction with an opioid substance, prolonged opioid withdrawal will be precipitated resulting in unpredictable and life threatening medical consequences."
Boyce SH, Armstrong PAR, Stevenson J. Effect of innappropriate naltrexone use in a heroin misuser. Emergency Medicine Journal 2003;20:381-382.