Quantitative 13C Solid-State NMR Spectra by Multiple-Contact Cross-polarization for Drug Delivery: From Active Principles to Excipients and Drug Carriers

In this contribution, we present an analysis of the main parameters influencing the efficiency of the 1H → 13C multiple-contact cross-polarization nuclear magnetic resonance (NMR) experiment in the context of solid pharmaceutical materials. Using the optimum experimental conditions, quantitative 13C NMR spectra are then obtained for porous metal-organic frameworks (potential drug carriers) and for components present in drug formulations (active principle ingredient and excipients, amorphous or crystalline). Finally, we show that mixtures of components can also be quantified with this method and, hence, that it represents an ideal tool for quantification of pharmaceutical formulations by 13C cross-polarization under magic-angle spinning NMR in the industry as it is robust and easy to set up, much faster than direct 13C polarization and is efficient for samples at natural abundance.