A simple and efficient approach to overcome the purification bottleneck of polar unstable prodrugs & New Chemical Entities (NCEs)

Abstract

High-Performance Liquid Chromatography (HPLC), a sophisticated form of column chromatography, remains a workhorse technique that is commonly used in the pharmaceutical industry and academia for the purification of organic substances from complicated mixtures. The HPLC technique uses a high-pressure pump through a chromatographic column packed with small particles with a mobile phase buffer system which could be acidic, basic, or neutral and is chosen based on the compatibility requirements of the compound to be purified. However, purification of prodrugs that have highly sensitive cleavable linkers remains challenging via HPLC conditions. The sensitivity of the linkers is due to their instability to either basic or acidic conditions. Even though a neutral buffer method is developed for such compounds, the majority of compounds often degrade due to their longer contact time with the aqueous mobile phase during prep. HPLC and lyophilization. Towards this, we propose a simple method of purification of such compounds which is efficient and cost-effective. This method utilizes hydrophobic, reverse-phase, silica-bound C18 cartridges on a bench-top setup. We compared the effectiveness of purification of some sensitive compounds using these cartridges with the conventional prep-HPLC purification. Our method reduces cost, minimizes solvent consumption, and reduces purification time drastically. The compounds were obtained with a good recovery and purity using cartridges as shown in Fig. 1. This method was suitable for purifying compounds that had stability issues during prep-HPLC purification.

In addition, we hope this method being versatile and simple would promote routine purification and catalyze innovation in colleges and institutes around the globe that cannot afford preparative HPLC for routine purification. Even in industry, our learning is that this method when used in tandem with preparative HPLC as it reduces TAT (turnaround time), is cost-effective, and prolongs prep HPLC column life. Also, we demonstrated that this cartridge method can be used in tandem with prep. HPLC in industry. This reduces net purification machine time, reduces cost, and prolongs HPLC column life.