Possible Interaction: Fentanyl and Quinidine

“ Quinidine … oral fentanyl (3.4 ± 1.3 vs. 2.3 ± 1.3 mm, p < 0.05), commensurate with increases in plasma concentrations, but concentration‐effect relationships … the transfer between plasma and effect compartment (ke0) (1.9 ± 1.0 vs. 3.6 ± 2.6 h−1) were not significantly different.”

“ Quinidine , however, inhibited the binding of fentanyl to plasma proteins and red cells equally, to maintain a partition coefficient of unity.”