MEASUREMENT OF OXYTOCIN IN HUMAN SERUM AND PHARMACEUTICAL PRODUCTS AVAILABLE IN THE IRANIAN MARKET BY MICROEXTRACTION METHOD

Background & Aims: Given the clinical importance and frequent use of oxytocin in serum and pharmaceutical products, along with the significant impact of improper dosage on both the therapeutic efficacy and adverse effects, this study aimed to develop and validate a dispersive liquid-liquid microextraction (DLLME) method for the rapid and precise measurement of oxytocin concentrations in these matrices. Materials & Methods:In this study, a DLLME method was optimized using carbon tetrachloride as the extraction solvent and acetonitrile as the dispersing solvent.Various parameters, including temperature and stirring speed, were systematically investigated and optimized.Analyses were conducted using gas chromatography with flame ionization detection (GC-FID).The materials utilized included oxytocin, ethanol, methanol, acetone, dichloromethane, carbon tetrachloride, acetonitrile, and calcitonin (as the internal standard).Results: Analysis of oxytocin concentrations in serum and commercial vials (5 and 10 IU/mL doses) from two domestic manufacturers (Company A and B) revealed that Company A's products more closely matched their labeled concentrations compared to those of Company B. Method validation using a German reference standard (Rotexmedica) demonstrated comparable results for domestic samples, with no statistically significant differences observed.The analytical method showed excellent performance characteristics, with a linear detection range of 0.02-60 IU/mL, a calibration equation of A = 190731C -21483, and a correlation coefficient (R) of 0.999. Conclusion:The developed DLLME method proved to be a simple, cost-effective, and reliable technique for quality control of oxytocin pharmaceutical preparations and the measurement of serum oxytocin levels.The findings revealed significant variations in oxytocin concentrations between different commercial products available in the Iranian market and demonstrated the method's capability for accurate quantification in biological samples.