title: Oil-in-water microemulsions stabilized by 3-(N,N- dimethylalkylammonio)propanesulfonate surfactants of varying alkyl chain length: Solubilisation of testos-terone propionate.
abstract: Solubilisation of the poorly-water soluble drug, testosterone propionate, in co-surfactant-free, dilutable, oil-in-water microemulsions stabilized by zwitterionic surfactants of varying alkyl chain length, namely 3-(N,N-dimethyloctylammonio)propanesulfonate and 3-(N,N-dimethyldodecylammonio)propanesulfonate and containing one of four ethyl ester oils, has been investigated. Both 3-(N,N-dimethyloctylammonio)propanesulfonate and 3-(N,N-dimethyldodecylammonio)propanesulfonate-stabilized microemulsions containing two short chain length oils, ethyl butyrate and ethyl caprylate, while only 3-(N,N-dimethyldodecylammonio)propanesulfonate formed microemulsions incorporating the longer chain length oils, ethyl palmitate and ethyl oleate, albeit to a very much reduced extent. Significantly the microemulsions containing the short chain length oils, ethyl butyrate and ethyl caprylate solubilised more testosterone propionate than the corresponding micelles. However, an inverse correlation existed between testosterone propionate solubility in the bulk oil and solubilisation in the microemulsions, in that ethyl caprylate containing microemulsions solubilised more testosterone propionate than those containing an equivalent amount of ethyl butyrate, despite the drug being more soluble in ethyl butyrate. These results suggest that drug solubility in bulk oil is a poor indicator of drug solubility in microemulsions containing that oil, and whether or not the addition of oil improves drug solubility is dependent upon on how it is incorporated within the microemulsion. The longer the chain length of the oil, the more likely the oil is to form a core in the microemulsion droplet, resulting in an additional locus of drug solubilisation and the possibility of an enhanced solubilisation capacity.
authors.affiliation: Department of Pharmacy, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NN, United Kingdom.
authors.forename: Chien-Ming
authors.initials: CM
authors.lastname: Hsieh
authors.affiliation: Department of Food and Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand.
authors.forename: Warangkana
authors.initials: W
authors.lastname: Warisnoicharoen
authors.affiliation: Department of Pharmacy, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NN, United Kingdom.
authors.forename: Raju K
authors.initials: RK
authors.lastname: Patel
authors.affiliation: Department of Pharmacy, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NN, United Kingdom.
authors.forename: Farnoosh
authors.initials: F
authors.lastname: Kianfar
authors.affiliation: Department of Pharmacy, King's College London, Franklin Wilkins Building, 150 Stamford Street, London SE1 9NN, United Kingdom. Electronic address: jayne.lawrence@kcl.ac.uk.
authors.forename: M Jayne
authors.initials: MJ
authors.lastname: Lawrence
mesh_terms: D017738:Alkanesulfonic Acids / Q000737:chemistry*; D004339:Drug Compounding; D004655:Emulsions / Q000737:chemistry*; D009821:Oils; D011092:Polyethylene Glycols; D011422:Propionates; D012995:Solubility; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D017738:Alkanesulfonic Acids; D004655:Emulsions; D009821:Oils; D011422:Propionates; D013501:Surface-Active Agents; C068559:propylsulfonic acid; D011092:Polyethylene Glycols
keywords: 3-(N,N-dimethylalkylammonio)propanesulfonate; Ethyl ester oils; Oil-in-water microemulsions; TP