Proton NMR: A New Tool for Understanding Dissolution

We present the use of H-1 NMR as a new measurement approach for improving understanding of the dissolution of pharmaceutical tablets. NMR has benefits over the conventional UV measurement approach in respect to much greater analyte selectivity and the ability to detect non-UV-absorbing species such as sugars. We used an in-line flow cell and water suppression experiments to determine the release profiles of three drug substances and lactose from the same tablet. Dissolution was performed in a pharmacopieal dissolution system with a standard protic buffer. NMR was shown to give high selectivity with each analyte having a well-resolved signal and sufficient sensitivity to determine the full release profile of even a compound present at only 5 mg in the tablet. The in-line flow cell gives excellent quality NMR spectra having little impact on peak shape. Dissolution of all the drug substances and lactose were determined to proceed at the same relative rates.