Relationship between Polysorbate 80 solubilization descriptors and octanol-water partition coefficients of drugs

The molar solubilization capacities (kappa) and the molal micelle-water partition coefficients (k(M)(N)) in Polysorbate 80 of several drugs (including barbituates, steroids, and benzoic acid derivatives) are related to their log octanol-water partition coefficients (log P). Both kappa and K-M(N) values were calculated from solubility versus Polysorbate 80 concentration profiles, which were either experimentally determined or obtained from the literature. There is a linear relationship between log P of the tested compounds and the logarithm of the molar micelle-water partition coefficient (log K-M(N)). On the other hand molar solubilization capacities are nearly independent of log P. It is shown that the ability of Polysorbate 80 to solubilize a drug can be predicted from its log P value. (C) 2000 Elsevier Science B.V. All rights reserved.