eight dogs received fentanyl 100 micrograms x kg-1 followed by an infusion of 1 microgram x kg-1 x min-1 while ventilated with o2 : n2 ( 1:2 ) , and eight dogs received sufentanil 30 micrograms x kg-1 with an infusion of 0.3 micrograms x kg-1 x min-1 .
C0015846
fentanyl
C0143993
sufentanil