Enzymatic kinetic method for determination of propranolol hydrochloride in pharmaceuticals based on its inhibitory effect on cholinesterase

Propranolol, a widely used beta-blocker, inhibits the reaction of enzyme cholinesterase hydrolysis. Measurements of the hydrolysis rate differences between and inhibited reactions, allows the development of a kinetic method for its determination. Both systems, enzyme-substrate-chromogen and enzyme-substrate-chromogen-inhibitor, were characterized through biochemical kinetic parameters (KM = 0.326-0.330 mmol/L; Vmax = 40-42.99 μmol/Lmin), inhibition type was recognized as competitive, and inhibition constant, Ki, was determined to be 22.60 μmol/L. The detection and quantification limits were calculated as 0.004 and 0.0136 μmol/L, respectively. Accuracy and precision of proposed methods were tested. Proposed method is characterized with good sensitivity, selectivity, simplicity and rapidity, thus it is convenient for clinical applications.