ABSTRACT
Phosphate esters of arachidonylethanolamide (AEA) and R-methanandamide were synthesized and evaluated as water-soluble prodrugs. Various physicochemical properties (pK(a), partition coefficient, aqueous solubility) were determined for the synthesized phosphate esters. The chemical stability of phosphate esters was determined at pH 7.4. In vitro enzymatic hydrolysis rates were determined in 10% liver homogenate, and in a pure enzyme-containing (alkaline phosphatase) solution at pH 7.4. The intraocular pressure (IOP) lowering properties of R-methanandamide phosphate ester were tested on normotensive rabbits. The phosphate promoiety increased the aqueous solubility of the parent compounds by more than 16500-fold at pH 7.4. Phosphate esters were stable in buffer solutions, but rapidly hydrolyzed to their parent compounds in alkaline phosphatase solution (t(1/2)<<15 s) and liver homogenate (t(1/2)=8-9 min). The phosphate ester of R-methanandamide reduced IOP in rabbits. These results indicate that the phosphate esters of AEA and R-methanandamide are useful water-soluble prodrugs.
Subject(s)
Arachidonic Acids/chemical synthesis , Organophosphorus Compounds/chemical synthesis , Prodrugs/chemical synthesis , Animals , Arachidonic Acids/chemistry , Arachidonic Acids/pharmacology , Drug Stability , Endocannabinoids , Enzymes/chemistry , Esters , Female , Hydrolysis , Intraocular Pressure/drug effects , Male , Ophthalmic Solutions , Organophosphorus Compounds/chemistry , Organophosphorus Compounds/pharmacology , Polyunsaturated Alkamides , Prodrugs/chemistry , Prodrugs/pharmacology , Rabbits , Solubility , Stereoisomerism , Water/chemistryABSTRACT
A novel codrug, in which L-Dopa and entacapone are linked via a biodegradable carbamate spacer to form a single chemical entity, was synthesized and studied kinetically. This carbamate codrug provides adequate stability [t(1/2) = 12.1 h (pH 1.2); 1.4 h (pH 5.0); 1.1 h (pH 7.4)] against chemical hydrolysis but rapidly hydrolyzes to L-Dopa and entacapone in liver homogenate (t(1/2) = 7 min; pH 7.4) at 37 degrees C. The therapeutical potential of this novel codrug is discussed.
