Determination of hydrochlorothiazide (Esidrex®) in tablets

Hydrochlorothiazide is a benzothiadiazine-diuretic, often used for treatment of hypertonicity, heart insuffiency and oedemas. Abuse of diuretics of this kind for doping purposes occurs in sports. They are therefore on the IOC list of banned drugs. For analysing a large number of samples at the same time a cost effective screening method is demanded.
Extracts of tablets are chromatographed on silica with ethyl acetate – cyclohexane 9:1 and evaluated densitometrically at 270 nm
Urine extracts are chromatographed on silica with ethyl acetate – methanol – ammonia 85:10:5. post chromatographic derivatization converts Esidrex® and similar drugs as well as their metabolites into azo dyes. The therapeutic range for hypertonicity patients is 0.2-1.6 mg/L urine. In sports every positively identified quantity is regarded as doping. Determination limit of the method is 0.2 mg/L, detection limit <0.1 mg/L: