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.

Liquid Chromatographic Method Development for Quantification of Inorganic Nitrite and Nitrate Impurities from Nitroglycerin Drug Substance by Using Ion-Pair Reagents with Liquid-Liquid Extraction Technique.

A large number of laboratory studies have reported Nitrite (NO2-) and Nitrate (NO3-) to be among the most common degradation products of the high-explosive Nitroglycerin drug substance. A novel, simple, robust and rapid reversed-phase high-performance liquid chromatography method has been developed for quantification of inorganic Nitrite and Nitrate impurities from Nitroglycerin drug substance. Successful separation was achieved in isocratic elution, using Inertsil C8-3, (250 × 4.6 mm, 5.0 µm) column, with mobile phase consisting of pH 7.0 tetrabutyl ammonium hydrogen sulfate buffer, methanol and acetonitrile (96:02:02, v/v/v). Flow rate was monitored at 2.0 mL min-1 and ultraviolet detection at 220 nm. The present work describes the role of an ion-pair reagent in the separation of polar compounds and liquid-liquid extraction technique for separation of polar and non-polar compounds. Nitroglycerin was subjected to various stress conditions to demonstrate the stability-indicating power of the method. The performance of the method was validated as per present International Council for Harmonisation (ICH) guidelines for specificity, linearity, accuracy, precision, ruggedness and robustness. The developed method can be a valuable alternative to the current ion-exchange chromatographic method mentioned in the literature. To the best of our knowledge, a rapid Liquid Chromatography (LC) method, which separates inorganic Nitrite and Nitrate impurities of Nitroglycerin, disclosed in this investigation was not published elsewhere.

Rational Discovery of Novel Squalene Synthase Inhibitors through Pharmacophore Modelling.

INTRODUCTION: In the present research work, a pharmacophore based virtual screening was performed using Discovery Studio 2.1 for the discovery of some novel molecules as inhibitors of Squalene Synthase Enzyme, a key enzyme in cholesterol biosynthetic pathway. METHODS: A quantitative pharmacophore HypoGen was generated and the best HypoGen had two ring aromatic and one hydrogen bond acceptor lipid features. The best HypoGen showed a very good correlation coefficient (r = 0.901) with satisfactory cost analysis. Furthermore, the HypoGen was validated externally by predicting the activity of test set. The developed model was found to be predictive as it showed low error of prediction for test set molecules. The developed model was used as a search query for virtually screening two chemical databases: sample database from catalyst and minimaybridge. RESULTS AND DISCUSSION: The best hit with good fit value and low predicted activity was further modified to design novel drug-like molecules, which were able to bind to Squalene synthase enzyme active site. CONCLUSION: The best scoring molecule, compound 67 showed 53% inhibition of the human Squalene synthase enzyme, isolated from the cell lysates of Human Hepatoma Cell Line, at a dose of 10 mcg with an IC50 value of 9.43 µm.