LIPID SOLUBILITY OF PANCURONIUM AND VECURONIUM DETERMINED BY N-OCTANOL WATER PARTITIONING

We have measured the n-octanol/water distribution coefficients at 37-d egrees-C of two steroidal myoneural blockers (pancuronium and vecuroni um) and of their 3-hydroxy metabolites over a pH range from 1.5 to 11. Pancuronium was found not to be lipid soluble. The mean distribution coefficient of 3-hydroxy vecuronium at pH = 7.4 was 0 and that of vecu ronium 0.12 (SD 0.1). Distribution coefficients of the parent drug sho wed a slightly greater lipid solubility than the metabolite (11.37 (2. 91) and 9.53 (3.44), respectively (mean t0.05 x SE)). Because of its l ipid solubility, vecuronium may penetrate into lipid structures.