Abstract

Background: Ubrogepant is a regulated peptide receptor antagonist associated with the calcitonin gene, granted approval in the United States for the specific treatment of migraine headaches.

Objective: An impurity found in the alkali hydrolysis of drug dosage forms has a structure very similar to that of ubrogepant. This research aims to characterize this analogous impurity utilizing NMR and LC-MS spectroscopy tools. Moreover, it is critical to develop an extremely sensitive and superior resolution analytical procedure for identifying and determining the amount of analogous impurity in pharmaceutical products.

Method: The ubrogepant impurity was identified using an optimized chromatographic method that relies on reversed-phase HPLC with UV detection. This technique utilized a charged surface hybrid (CSH) technology column operating in gradient elution mode. A mixture of A-channel (0.1% trifluoroacetic acid) and B-channel (acetonitrile and water, 80:20% v/v) constituted the eluent. The analogous impurity was isolated through fraction collection, purified using flash chromatography, and characterized using NMR (1D and 2D) and LC-MS.

Results: The analogous impurity was successfully separated from the ubrogepant peak with a resolution above 2.0. The concentration of the impurity was approximately 10% compared to the ubrogepant peak after alkaline stressing at room temperature for 30 minutes. NMR (1D 13C NMR and 1H, 2D HMBC, HSQC, NOESY, and COSY) and LC-MS analysis characterized the ubrogepant impurity, revealing it to be an epimer of ubrogepant. The developed approach was highly sensitive, allowing for the quantification of the ubrogepant impurity even at a concentration of 0.2 μg/mL.

Conclusion: The approach demonstrated a remarkable degree of precision, linearity, specificity, and accuracy. This new impurity deserves special attention because of its striking similarity to the active ingredient, ubrogepant.

Keywords: Ubrogepant, epimer, LC-MS, NMR, NOESY, HPLC, flash chromatography