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The first examples of possible metformin prodrugs have been synthesized and characterized by spectroscopic methods. These five different types of chemically stable prodrugs were prepared from metformin and the corresponding halogenated promoieties. The products from unstable derivatives were also identified and reasons for the rearrangements are discussed. [ABSTRACT FROM AUTHOR]

AbstractPurpose??A cyclic phosphate prodrug of a descriptive molecule containing an alcohol functionality was designed, synthesized and characterizedin vitroas a cytochrome P450 (CYP) -selective prodrug.Materials and Methods??To achieve efficient CYP-oxidation and prodrug bioconversion, 1,3-cyclic propyl ester of phosphate was designed to have a C4-aryl substituent and synthesized using phosphorus(III) chemistry. The two-step bioconversion of the cyclic phosphate prodrug was evaluatedin vitrousing human liver microsomes and recombinant CYP enzymes.Results??This cyclic phosphate prodrug underwent initial CYP-catalyzed oxidation and was mainly catalyzed by the CYP3A4 form. The hydroxylated product was slowly converted to a ring-opened intermediate, which subsequently transformed by ?-elimination reaction to a free phosphate. The free phosphate was further dephosphorylated by microsomal phosphatases, releasing the parent molecule with a free hydroxyl group. The cyclic phosphate was reasonably stable in buffer solutions at the pH range 1.0?9.0.Conclusions??Since CYP enzymes reside predominantly in the liver and secondarily in the small intestine, the results indicate that cyclic phosphate prodrugs represent a very feasible liver- or intestinal-targeted drug delivery strategy for drug molecules containing an alcohol functionality. This may potentially improve the efficacy and the safety profile of the alcoholic parent drugs. [ABSTRACT FROM AUTHOR]