the ed50s of subcutaneously injected morphine , meperidine , fentanyl , and sufentanil in depressing the minute volume response to 8 % co2 in air were 2300 micrograms/kg , 8800 micrograms/kg , 20 micrograms/kg , and 2.3 micrograms/kg , respectively .
C0015846
fentanyl
C0143993
sufentanil