Determination of the stability of morphine tablets by ion-pair reversed-phase liquid chromatography

Abstract

The main objective of this study was to develop and test the applicability of a sensitive and rapid ion-pair reversed-phase liquid chromatographic method for evaluating a new dosage form for the oral administration of morphine, based on ion pairing with heptane-1-sulphonic acid. Pseudomorphine was identified by gas chromatography-mass spectrometry as the major degradation product of liquid samples of morphine hydrochloride (used as control) that had been subjected to accelerated decomposition. No degradation product was found in the analyses of tablets. Validation of the method yielded a linear regression r=0.9988; the relative standard deviation was 1.10% at 0.24 mg ml −1 (more than 200 samples). The limits of detection were 0.006 mg ml −1 for morphine and 0.012 mg ml −1 for pseudomorphine. The results of stability studies performed during 12 months confirmed the marked stability of tablets prepared in the laboratory.