In a brief cross-over trial of naltrexone versus placebo in a group of 30 non-treatment-seeking heavy drinkers, no difference in treatment response was observed for those with the Asp40 allele (Mitchell et al. 2007). Similarly, Tidey et al. (2008) found no moderating effect of the Asn40Asp SNP on drinking outcomes in a brief placebo-controlled trial of naltrexone in 173 non-treatment-seeking heavy drinkers.
