electrical pain stimulation (Oertel et al., 2006); of interest, this dose did not increase respiratory depression, suggesting it may be safe to give a higher dose of opioid analgesics to patients that carry the G118 allele. Other studies, however, have reported divergent results, showing that G118 was associated with reduced pain responses. For instance, in healthy volunteers receiving different experimental pain procedures, the G118 allele was associated with reduced pain responses to pressure (Fillingim et al., 2005). Additionally, males carrying the G118 allele rated thermal pain lower than those carrying the A118 allele. However, the G118 allele-carrying females reported higher pain scores following this thermal pain administration, consistent with previous literature demonstrating elevated pain responses (Fillingim et al., 2005).
