Force degradation behavior of glucocorticoid deflazacort by UPLC: isolation, identification and characterization of degradant by FTIR, NMR and mass analysis

Abstract

In this investigation, sensitive and reproducible methods are described for quantitative determination of deflazacort in the presence of its degradation product. The method was based on high performance liquid chromatography of the drug from its degradation product on reverse phase using Acquity UPLC BEH C18 columns (1.7 µm, 2.1 mm × 150 mm) using acetonitrile and water (40:60 V/V) at a flow rate of 0.2 mL/minute in UPLC. UV detection was performed at 240.1 nm. Deflazacort was subjected to oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The drug was found to be stable in water and thermal stress, as well as under neutral stress conditions. However, forced-degradation study performed on deflazacort showed that the drug degraded under alkaline, acid and photolytic stress. The degradation products were well resolved from the main peak, which proved the stability-indicating power of the method. The developed method was validated as per ICH guidelines with respect to accuracy, linearity, limit of detection, limit of quantification, accuracy, precision and robustness, selectivity and specificity. Apart from the aforementioned, the results of the present study also emphasize the importance of isolation characterization and identification of degradant. Hence, an attempt was made to identify the degradants in deflazacort. One of the degradation products of deflazacort was isolated and identified by the FTIR, NMR and LC-MS study.

Keywords: Deflazacort; characterization; degradant; forced degradation.

Fig. 1. Structure of deflazacort and its forced degradation product (A), chromatogram plot of standard deflazacort (B), contour plot of deflazacort (C).

Deflazacort was found to be a stable drug under stress condition such as thermal, neutral and oxidative condition. However, the forced-degradation study on deflazacort showed that the drug degraded under alkaline, acid and photolytic conditions.The name of the identified degradation product is 21 hydroxy deflazocort (11, 21- dihydroxy, 2'-methyl-5'H – pregna-1,4-dione [17,16-d] oxazole- 3, 20-dione.

Fig. 2. UPLC chromatograph of deflazacort and its degradants upon exposure to (A) to water after 24 days, R_T 5.324; thermal degradation in hot air oven at 50°C(B), and photodegradation study after two days exposure of drug to sunlight(C).

Fig. 3. UPLC chromatograph of deflazacort and its degradants upon exposure to 30% H₂O₂ for 24 hours, R_T 5.224(A); 0.1N HCl, R_T 5.32(B); 0.1N NaOH(C) after 24 hours of exposure.

Fig. 4. Method optimization: UPLC chromatogram showing separation of deflazacort and its degradation products in a mixture of stressed samples.

Fig. 5. Mass fragmentation pathway for degradant product of deflazacort.