Background & Aims : Quality control of medicinal products- especially the amount of active ingredients of toxic side effects and complications- is important. The present study was performed to measure oxytocin (OT) in commercially available drug products in the drug market of Iran.

  Materials & Methods : In this study pharmaceutical dosage form of OT with different brands at a concentration of 5 and 10 IU/ml was prepared from a local pharmacy. A previously published method was optimized for the conditions in our laboratory. High Performance Liquid Chromatography (HPLC) was used as the preferred analytical tool. The method used a C₁₈ column. The mobile phase consist of acetonitrile/ phosphate buffer with (pH= 5, 0.08 M) (20:80) and UV detection at 220 nm.

  Results : The results of these experiments showed a linear standard curve for OT over the range of 0.5-12 IU/ml. The corresponding regression equation was A=133.1C-2.193 with an r² value of 0.99. The Inter-day coefficient of variation for the method ranged between 1.97 IU/ml and 9.93 IU/ml% and the Intra-day value ranged between 1.10 IU/ml and 1.76 IU/ml. The accuracy of method range was between 96.40% and 107.5% for Inter-day analysis and 93% and 99.6 % for Intra-days analysis. The lower limit of quantification was 0.25 IU/ml. The percentage content, taking one of the bulk samples as 100% references, was 107-120% and 114.2-216.6% recovery of the label claim for OT of 10IU/ml and OT of 5 IU/ml, respectively.

  Conclusion : These findings confirm that the amount of oxytocin in some of dosage forms is higher than the declared amounts. This study emphasizes on the necessity of quality and accurate control s over the industrial pharmaceutical.  

  SOURCE: URMIA MED J 2014: 24(12): 965 ISSN: 1027-3727