DRUG FORMULATIONS AND CLINICAL METHODS Resolution and Quantitation of Triamcinolone Acetonide and Its Coformulated Drug in the Presence of Its Impurities and Degradation Products by HPTLC and HPLC SAMAH S. ABBAS and MAHA A. HEGAZY Cairo University, Faculty of Pharmacy, Analytical Chemistry Department, 11562 Kasr El-Aini St, Cairo, Egypt HASSAN A.M. HENDAWY National Organization for Drug Control and Research, 6 Abu Hazem St, El-Haram St, Giza, Egypt SOHEIR A. WESHAHY Cairo University, Faculty of Pharmacy, Analytical Chemistry Department, 11562 Kasr El-Aini St, Cairo, Egypt MAY H. ABDELWAHAB 1 National Organization for Drug Control and Research, 6 Abu-Hazem St, El-Haram St, Giza, Egypt Two specific, sensitive, and precise stability- indicating chromatographic methods have been developed for the determination of triamcinolone acetonide (TMC) and its coformulated drug, econazole nitrate (ECZ), in the presence of TMC impurities and degradation products. The first method was based on HPTLC-spectrodensitometry in which resolution and quantitation was achieved by using silica gel 60 F 254 HPTLC plates and an ethyl acetate–tetrahydrofuran–ammonia mobile phase (10.0 + 7.0 + 0.1, v/v/v). The second method was a reversed-phase HPLC method in which separation was achieved using an acetonitrile–methanol–0.05 M potassium dihydrogen phosphate mobile phase, pH 3.0 (25.0 + 15.0 + 60.0, v/v/v). In both methods, the separated components were detected at 225 nm. Validation of both methods was conducted in compliance with International Conference on Harmonization (ICH) guidelines, and system suitability was confirmed. The linearity ranges were 0.20–28.00 and 0.50–55.00 μg/band for TMC and ECZ by HPTLC, whereas for HPLC, the range was 0.05–30.00 and 1.00–40.00 μg/mL for both drugs, respectively. The methods were successfully applied for the analysis of a pharmaceutical formulation and were compared with the reported method with no significant difference. T riamcinolone acetonide (TMC) is chemically designated as pregna-1,4-diene-3,20-dione,9-fluoro-11,21-dihydroxy- 16,17-[(1-methylethylidene) bis(oxy)]-, (11b,16a) (1; Figure 1). It is a topical corticosteroid belongs to the synthetic steroid class of drugs and is used as an anti-inflammatory and antipruritic agent either alone or in combination with other drugs (2). Econazole nitrate (ECZ) is 1H-imidazole,1-[2-[(4-chlorophenyl) methoxy-]2-(2,4-dichlorophenyl)[ethyl]-, mononitrate,(±) (1) and is used as an antifungal agent (2; Figure 1). A combination of TMC and ECZ is topically administered for the treatment of inflammatory dermatoses, superficial pyodermia, paronychia, diaper dermatitis, dry subchronic dermatoses, and other inflammatory diseases accompanied by fungal infection (3). Two impurities were stated in the United States Pharmacopeia (USP), British Pharmacopoeia (BP), and European Pharmacopoeia (EP; 1, 4, 5): triamcinolone (TMC Imp I) and TMC 21-acetate (TMC Imp II). TMC shows marked instability and undergoes degradation under oxidative, alkali, acid, and photostress conditions, whereas ECZ is considerably stable (6). TMC monographs describe HPLC assays (1, 4, 5). Other methods were reported for its determination by micellar electrokinetic chromatography (7) and spectrofluorimetry (8). TMC was also determined with coformulated drugs by HPLC (9–13) and GC (14). TMC along with salicylic acid were determined by HPLC (15, 16) and by capillary electrophoresis (17). On the other hand, several HPLC methods were reported for ECZ determination, either officially (1, 5) or nonofficially (18, 19). It was also determined among other azole antifungal drugs by UV-spectrophotometry (20). ECZ and estradiol were determined in human plasma by near-IR spectrometry (21). Two HPLC methods were found for the determination of TMC and ECZ in binary mixtures (22) and in the presence of their degradation products (23) without any isolation or identification of the degradation products. However, no method was found for the determination of the studied compounds in the presence of TMC impurities. A literature survey revealed that there is no stability-indicating TLC method for TMC and ECZ. So, our work aimed primarily to prepare, isolate, and identify oxidative, alkali, acid, and photoinduced degradation products of TMC and, secondarily, to develop and validate stability-indicating methods for the determination of TMC and ECZ in the presence of TMC impurities and degradation products. Experimental Apparatus (a) Densitometer.—Camag dual-wavelength lamp flying TLC scanner 3 densitometer (Muttenz, Switzerland) controlled by winCATS software (Version 3.15; Camag) and run in Received December 23, 2016. Accepted by JB July 11, 2017. 1 Corresponding author’s e-mail: mai.hassan2012@yahoo.com DOI: https://doi.org/10.5740/jaoacint.16-0422 ABBAS ET AL.:JOURNAL OF AOAC INTERNATIONAL VOL. 101, NO. 4, 2018 XXX