eight male surgical patients , 52-80 yr old , were randomly divided into eight groups of ten to receive fentanyl , 5 , 7 , 10 , or 13 micrograms/kg , or sufentanil , 0.5 , 0.7 , 1.0 , or 1.3 micrograms/kg .
C0015846
fentanyl
C0143993
sufentanil