Abstract:In clinical practice, side effects of anti-arrhythmic medicines such as propafenone are commonly registered. Therapeutic drug monitoring is a solution to the problem regarding to side effects of drugs and aiming to control substance concentration in biological fluids. The objective of the research is the development of a methodology for isolation and determination of propafenone in whole blood. Liquid-liquid extraction method was used for the isolation propafenone, which was done at pH 4, via acetate buffer and with chloroform used as an extraction agent. HPLC (high performance liquid chromatography), TLC (thin layer chromatography) and UV (ultra violet) spectrophotometric methodology for identification and quantitative determination of propafenone was established. The developed method of isolation and determination of the propafenone was tested by studying the blood of volunteers who received therapeutic concentrations (150 mg) of these drugs in the form of tablets. TLC methodology allows to determine and to purify an extract. Chromatographic system including chloroform, ethyl acetate and ethanol (10:3:1) were determined at Rf 0.42 for propafenone. UV-spectroscopy analysis illustrated maximum absorption at 248 and 304 nm. HPLC is considered as the most precise and accurate method allowing qualitatively and quantitatively determine propafenone in therapeutic concentrations of blood (0.46-0.88 µg/L in a single dose 150 mg).