Field Cycling NMR Relaxometry as a Tool for Detecting the Quality of Biotechnological Drugs

Abstract

Biotechnological drugs mostly contain proteins or peptides; therefore, any change in ambient conditions during their storage and administration to patients may cause structural modifications, which, in turn, lower the drug quality/effectiveness. Among different drug quality issues hampering drug stability and pharmacokinetics, the commonly observed ones are aggregation and glycation. Both processes include changes at a molecular level that can indeed be probed by field cycling NMR relaxometry as an alternative to traditional techniques used in the detection of drug quality issues. In this study, as a forthcoming problem in diabetes pharmaceuticals, aggregation effects on a commercially available insulin drug (Humulin-R) and glucose-mediated glycation of bovine serum albumin (BSA, as a model serum protein for in vitro tests) were investigated by means of FFC NMR relaxometry experiments. 1H spin–lattice relaxation rate dispersion (NMRD) profiles obtained on insulin samples treated under three different stress conditions showed that, for a sample agitated at a high temperature (T = 50 °C), one observes a significant low-frequency dispersion that can be associated with rotational/reorientational motion of aggregates formed under this condition. Regarding the glycation experiments on the BSA solution, the low-frequency proton relaxation rate, R1, increases with glycation temperature and glycation time, which is related to the aggregation induced by advanced glycation end-product (AGEs) formation on the surface of BSA. Overall, for the detection of drug quality issues, FFC NMR relaxometry is promising as a noninvasive and relatively low-cost technique that does not involve any additional sample preparation procedures or use of chemicals.