8506
document
The interaction between propofol and clonidine for loss of consciousness . UNLABELLED Clonidine premedication reduces the intraoperative requirement for opioids and volatile anesthetics . Clonidine also reduces the induction dose of IV anesthetics . There is no information , however , regarding the effect of oral clonidine premedication on the propofol blood concentrations required for loss of consciousness , and the interaction between propofol and clonidine . We randomly administered target effect-site concentrations of propofol ranging from 0.5 to 5 . 0 microg/mL by using computer-assisted target-controlled infusion to 3 groups of healthy male patients : Control ( n = 35 ) , 2.5 microg/kg Clonidine ( n = 36 ) , and 5.0 microg/kg Clonidine ( n = 36 ) groups . Nothing was administered to the Control group . Clonidine ( 2.5 or 5.0 microg/kg ) was administered orally 90 min before the induction of anesthesia in the Clonidine groups . After equilibration between the blood and effect-site for 15 min , a verbal command to open their eyes was given two times to the patients . Arterial blood samples for analysis of the serum propofol and clonidine concentrations were taken immediately before verbal commands were given . Measured serum propofol concentrations in equilibrium with the effect-site at which 50 % of the patients did not respond to verbal commands ( EC50 for loss of consciousness ) were determined by logistic regression . The EC50 +/- SE values in the Control , 2.5 microg/kg Clonidine , and 5.0 microg/kg Clonidine groups were 2.67 +/- 0.18 , 1.31 +/- 0.12 , and 0.91 +/- 0.13 microg/mL , respectively . The EC50 in the 2.5 and 5.0 microg/kg clonidine groups was significantly smaller than that in the Control group ( P < 0.001 ) . The use of a response surface modeling analysis indicated that there was an additive interaction between measured arterial propofol and clonidine concentrations in relation to loss of consciousness . These results indicate that propofol and clonidine act additively for loss of consciousness . IMPLICATIONS Oral clonidine 2.5 and 5.0 microg/kg premedication decreases the propofol concentration required for loss of consciousness .
8507
Intervention_Pharmacological
propofol and clonidine
8508
Intervention_Pharmacological
Clonidine
8509
Intervention_Pharmacological
Clonidine
8510
Intervention_Pharmacological
clonidine
8511
Intervention_Pharmacological
propofol
8512
Intervention_Pharmacological
propofol and clonidine .
8513
Intervention_Pharmacological
propofol
8514
Intervention_Control
Control
8515
Intervention_Pharmacological
Clonidine
8516
Intervention_Pharmacological
Clonidine
8517
Intervention_Control
Nothing was administered to the Control group .
8518
Intervention_Pharmacological
Clonidine
8519
Intervention_Pharmacological
Clonidine
8520
Intervention_Pharmacological
propofol and clonidine
8521
Intervention_Pharmacological
propofol
8522
Intervention_Pharmacological
Clonidine
8523
Intervention_Pharmacological
Clonidine
8524
Intervention_Pharmacological
propofol and clonidine
8525
Intervention_Pharmacological
clonidine
8526
Intervention_Pharmacological
propofol
8527
Outcome_Physical
Arterial blood samples
8528
Outcome_Physical
serum propofol concentrations in equilibrium
8529
Outcome_Physical
EC50
8530
Outcome_Physical
EC50
8531
Outcome_Physical
additive interaction
8532
Outcome_Physical
loss of consciousness
8533
Outcome_Physical
loss of consciousness
8534
Participant_Condition
healthy
8535
Participant_Sex
male
8536
Participant_Sample-size
35
8537
Participant_Sample-size
36
8538
Participant_Sample-size
36