et al., 2003; Anton et al., 2008) where naltrexone appears to exert a stronger effect on those individuals with the asp40 OPRM1 SNP. However, this finding is not universal as several reports suggest that it may not be as salient (Gelernter et al., 2007; Ooteman et al., 2009). While there is accumulating evidence that this OPRM1 genetic difference has functional importance in humans, before it can be used clinically, more information is needed especially from prospective and controlled clinical study investigation (O’Brien, 2008).
