TRIPLE ANESTHETIC COMBINATION - PROPOFOL-MIDAZOLAM-ALFENTANIL

The hypnotic effects of propofol, midazolam, alfentanil, and their bin ary and triple combinations, were studied in 130 unpremedicated patien ts in a randomized, double-blind fashion. The ability to open eyes on verbal command was used as an end-point. Dose-response curves for the three drugs given separately and in combination were determined with a probit procedure and the ED(50) values were compared with an isobolog raphic analysis. The ratios of a single-drug fractional dose (ED(50) = 1.0) to a combined fractional dose (in fractions of single-drug ED(50 ) values) indicating the degree of superadditivity (synergism) were: 1 .4 (P < 0.05) for propofol-alfentanil, 1.8 (P < 0.0005) for midazolam- propofol, 2.8 (P < 0.0001) for midazolam-alfentanil, and 2.6 (P < 0.00 01) for propofol-midazolam-alfentanil. The results indicate that the p ropofol-midazolam-alfentanil interaction produces a profound hypnotic synergism which is not significantly different from that of the binary midazolam-alfentanil combination.