[Synergism of midazolam and propofol in the induction of anesthesia].
BACKGROUND
The purpose of this study was to determine the possible interaction of midazolam and propofol in the induction of anesthesia.


METHODS
A double-blind study of 90 ASA I-II women undergoing elective general surgery and gynecology was performed. The patients were divided into three groups of 30 patients receiving midazolam, propofol and a combination of both as the anesthesia induction agent. As a test of anesthetic induction the response to the verbal order of opening their eyes was evaluated. The dose-response curves for each group were determined by a logistic regression procedure while isobolographic analysis compared the actions of both agents separately and together.


RESULTS
The ED50 in the propofol group was 1.56 mg.kg-1 and that of the midazolam group was 0.24 mg.kg-1. In the midazolam-propofol group the ED50 of midazolam was reduced approximately a quarter (0.068 mg.kg-1) when associated to the half of the ED50 of propofol anteriorly obtained. Isobolographic analysis revealed that the conjunctive action of both drugs was synergic (p = 0.04).


CONCLUSIONS
Propofol potentiates the action of midazolam in anesthetic induction. Although this synergism also reduces with the association of thiopental-midazolam, the mechanism of action is not demonstrated as the same. Thiopental increases the affinity of the benzodiazepines for the GABA complex receptors which has not been described for propofol.
Caba
F
F
Servicio de Anestesiología-Reanimación, Hospital Universitario de Valme, Sevilla.
Echevarría
M
M
Morales
R
R
Guerrero
J A
JA
Rodríguez
R
R
D000328:Adult; D000758:Anesthesia; D000773:Anesthesia, Obstetrical; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004357:Drug Synergism; D005260:Female; D006801:Humans; D008874:Midazolam; D008875:Middle Aged; D015742:Propofol
D008874:Midazolam; D015742:Propofol