Solubilization of certain Analgesics by cetomacrogol 1000

Solubilization of certain nonsteroidal anti-inflammatory drugs, viz., phenacetin, ibuprofen and indomethacin by Cetomacrogol 1000 [Cetomacrogol] has been investigated. The values of the ratio of mole drug solubilized per mole micellar Cetomacrogol revealed that the solubilizing power of Cetomacrogol towards ibuprofen is higher than that for phenacetin or indomethacin. One Cetomacrogol micelle solubilizes 38, 17 and 6 molecules of ibuprofen, phenacetin and indomethacin, respectively. Spectrophotometry as well as solubility measurements in different solvents have been used to provide evidence on the environment of the solubilizate molecule in the micelle. On the basis of the results obtained, it was concluded that these drugs are solubilized as follows: Phenacetin and ibuprofen are solubilized in the hydrocarbon core and in the polyoxyethylene region adjacent to the hydrocarbon core. Indomethacin is wholly solubilized in the polyoxyethylene layer adjacent to the hydrocarbon core. The ability of the surfactants to accelerate the dissolution rate of the drug was also investigated. The dissolution profiles of these drugs in Cetomacrogol revealed marked enhancement of dissolution and there is a good correlation between the dissolution efficiency of the three drugs and their solubility in Cetomacrogol at the same temperature