Mu-opioid receptor (A118G) single-nucleotide polymorphism affects alfentanil requirements for extracorporeal shock wave lithotripsy: a pharmacokinetic-pharmacodynamic study

We demonstrated increased opioid requirement for alfentanil in patients with the G118 SNP, who self-administered a higher dose, achieved higher plasma concentration, and yet complained of more severe pain. This observation suggests that G118 SNP impairs the analgesic response to opioids.