title: Stability-indicating proton nuclear magnetic resonance spectroscopic method for determination of S-adenosyl-L-methionine in tablets.
abstract: We present a simple, accurate, stability-indicating nuclear magnetic resonance (NMR) method for determining active (S,S) and inactive (R,S) epimers of S-adenosyl-L-methionine (SAM) in tablets. The SCH3 resonances of SAM epimers were well resolved at 300 MHz. Individual assays of 5 SAM tablets gave SAM values of 101.3 +/- 1.7% of declared amounts. Tablet solutions were assayed at a level of 8.0 mg/mL, but the method was linear for SAM concentrations ranging from 64 to 1 mg/mL (correlation coefficient, 0.9996). Reproducibility was indicated by a relative standard deviation of 0.33% for 6 replicate assays for total SAM at a concentration of 8 mg/mL. In contrast to the propietary liquid chromatographic (LC) method, which requires SAM as an external standard, the NMR method uses sodium trimethylsilylpropionate-d4 (TSP) both as an internal standard and as a chemical shift reference. The method was used to test the stability of SAM analytes under various pH levels and temperatures. We found 8% inactivation of SAM due to epimerization over a 24 h period at room temperature and pH 5. SAM solutions showed no detectable inactivation after 14 days when stored below 0 degrees C.
authors.affiliation: U.S. Food and Drug Administration, Division of Drug Analysis, St. Louis, MO 63101, USA.
authors.forename: L K
authors.initials: LK
authors.lastname: Revelle
authors.forename: D A
authors.initials: DA
authors.lastname: d'Avignon
authors.forename: J C
authors.initials: JC
authors.lastname: Reepmeyer
authors.forename: R C
authors.initials: RC
authors.lastname: Zerfing
mesh_terms: D002853:Chromatography, Liquid; D004355:Drug Stability; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D012015:Reference Standards; D015203:Reproducibility of Results; D012436:S-Adenosylmethionine / Q000032:analysis*; D013607:Tablets / Q000737:chemistry; D014297:Trimethylsilyl Compounds
chemical_list: D013607:Tablets; D014297:Trimethylsilyl Compounds; D012436:S-Adenosylmethionine