LC-MS-Compatible Chromatographic Method for Quantification of Potential Organic Impurities of Elagolix Sodium in Tablet Dosage Form with Identification of Major Degradation Products

BACKGROUND: Elagolix is a gonadotropin-releasing hormone (GnRH) modulator and used for pain relief from endometriosis. OBJECTIVE: The present research was performed to develop and validate a simple, novel, fast, sensitive, and cost-effective LC-MS-compatible chromatographic method for quantification of all prominent organic impurities of elagolix sodium in tablet formulation with identification of major degradation products. METHODS: The optimum separation of the organic impurities of elagolix sodium was achieved on an ACE C18-PFP (250 mm × 4.6 mm, 5 µm) column by employing pH 5.6 acetate buffer-acetonitrile (95 + 5, by volume) as mobile phase A, and acetonitrile-methanol (90 + 10, by volume) as mobile phase B. UV detection of the drug and impurities was carried out at 210 nm. A forced degradation study was carried out by employing acid, alkali, oxidative, thermal, and photolytic stress conditions on elagolix sodium drug substance and its drug product. The major degradation products observed during the stress study were identified by using mass spectrometry. RESULTS: Elagolix sodium and its prominent organic impurities were resolved in the developed method through a gradient elution program of 46 min at a flow rate of 1.3 mL/min. Significant degradation was observed during alkali hydrolysis and oxidative stress conditions with a mass balance of more than 97.0%. The method was validated in line with present International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q2(R1) guidelines. CONCLUSION: The forced degradation study suggested that the developed method is specific and stability-indicating and can be used for related substance analysis of elagolix drug substance and its dosage forms. HIGHLIGHTS: This is the first research paper which describes a simple and sensitive (LOD 0.08 µg/mL) HPLC method for quantification of all probable impurities of elagolix in tablet dosage forms. The noticeable feature of the developed method is resolution of impurities of similar structures in a short time using routine solvents which are easily available in the QC laboratory.