1 3 DOI 10.1007/s10337-014-2712-y Chromatographia (2014) 77:1067–1080 ORIGINAL UHPLC Study on the Degradation Profiles of Olopatadine Hydrochloride in Eye Drops Subjected to Heat and Filtration Methods of Sterilisation L. Munjas Jurkic · M. Buratovic · I. Valentic · D. Stanfel Received: 29 November 2013 / Revised: 23 May 2014 / Accepted: 3 June 2014 / Published online: 16 July 2014 © Springer-Verlag Berlin Heidelberg 2014 Keywords UHPLC · Sterilisation method · Sterilisation by filtration · Terminal sterilisation · Olopatadine hydrochloride · Degradation products Introduction Olopatadine hydrochloride (Fig. 1) is chemically desig- nated as {(11Z)-11-[3-(dimethylamino)propylidene]-6,11- dihydrodibenzo[b,e]oxepin-2-yl}acetic acid. It has an empirical formula C 21 H 23 NO 3 and a molecular weight of 337.412 g mol -1 [1]. It is the second-generation antihis- tamine used for allergic disorders such as ocular itching associated with allergic conjunctivitis [2]. Literature survey reveals that a number of different methods have been devel- oped for the determination of olopatadine, including HPLC [3–8], HPTLC [9], LC–MS [10, 11] and spectrophotometry (UV–VIS) [12–14]. High-performance liquid chromatogra- phy (HPLC) has been used for the determination of olopata- dine content and related compounds in biological fluids [11], in bulk drug form and pharmaceutical formulations, mainly in ophthalmic solutions [3–8, 15]. RP-HPLC is a fast, accu- rate and reliable method (retention time under 3 min), so it is especially applicable to drug products [3, 5, 6]. Different mobile phases such as methanol: 0.1 % formic acid (65:35) [3], 0.1 % orthophosphoric acid (pH 4.5) with triethylamine: acetonitrile (75:25) [15], methanol: phosphate buffer 60:40 [5], methanol: water (70:30) [6], phosphate buffer: methanol: triethylamine (55:45:0.1, pH 3.0) [7] or methanol: ammo- nium acetate buffer (80:20, pH 5.5) [8] were used in HPLC method. Detection wavelengths ranged from 244–246 nm [5, 6, 8] to 299–300 nm [3, 7] in HPLC and 206 [13]–220 nm [12] in UV spectrophotometry. HPLC is considered a method of choice for the deter- mination of olopatadine hydrochloride and its impurities Abstract A validated ultra-high performance liquid chro- matography (UHPLC) method has been proposed, vali- dated and used for the determination of olopatadine hydro- chloride degradation products in olopatadine 1 mg mL -1 eye drops solution under the influence of two different steri- lisation methods, heating and filtration, with good precision and accuracy. We found that the heat sterilization method yields a higher content of olopatadine hydrochloride degra- dation products in eye drops compared to unsterilized drug product or drug product sterilized by filtration, except for α-hydroxy olopatadine impurity, which remains stable with time and applied sterilization method. Contents of olopat- adine related compound B shows a higher increase (from <0.005 to 0.044 %) when sterilised by heating than when subjected to aging and sterilization by filtration (increase up to 0.011 %). Similarly, total amount of all impurities is also increased from 0.13 to 0.49 % when the drug product is sterilised by heating instead of filtration (up to 0.39 %). Content of olopatadine related compound B and of all impurities is increased by aging, probably through thermal and oxidative degradation. Forced degradation studies were correlated with the sterilisation study and possible degra- dation pathways were identified. Olopatadine shows strong degradation under oxidative and moderate degradation under photolytic environment, with the olopatadine related compound B as the main degradation product. Sterilization of eye drops solution by filtration is recommended. Published in the special paper collection 19th International Symposium on Separation Sciences with guest editors Tomislav Bolanc ˇa and Boguslaw Buszewski. L. Munjas Jurkic (*) · M. Buratovic · I. Valentic · D. Stanfel Chromatographic Laboratory, Research and Development Department, JGL d.d. Rijeka, Svilno 20, 51000 Rijeka, Croatia e-mail: lela.munjas@jgl.hr