Crude bile, when applied to keratinstripped human skin in a cream vehicle at acid pH, under occlusion, produced noticeable pruritus after a period of 15 to 17 hours. At neutral or alkaline pH, no pruritus resulted. Purified, unconjugated sodium deoxycholate and chenodeoxycholate in a cream vehicle at acid pH also produced pruritus. Purified cholate sodium and sodium lithocholate, as well as synthetic straight chain anionic and neutral detergents failed to induce pruritus under the same experimental conditions. In complete biliary obstruction, chenodeoxycholate seems to be mainly responsible for the pruritus.
David P. Varadi. Pruritus Induced by Crude Bile and Purified Bile AcidsExperimental Production of Pruritus in Human Skin. Arch Dermatol. 1974;109(5):678–681. doi:10.1001/archderm.1974.01630050024005