title: Application of 13C CPMAS NMR for qualitative and quantitative characterization of carvedilol and its commercial formulations.
abstract: (13) C cross-polarization magic-angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy was applied to the identification and characterization of carvedilol (1-(9H-carbazol-4-yloxy)-3-[2-(2-methoxyphenoxy)-ethylamino]-propan-2-ol) in pharmaceutical preparations. Solid-state spectra (standard linewidth and lack of signal multiplicity) of carvedilol indicate that its physical form is the same (freebase form II); no other polymorphic forms were detected. The spectra of excipients, recorded under the same conditions, were helpful in their identification. The differences in chemical shifts for tablets I-VI are insignificant and suggest that there are no strong intermolecular drug-excipient interactions. The drugs from six manufacturers contained the same amount (25 mg) of the active substance per tablet; however, tablets differ in size and thus in the concentration of carvedilol. An attempt at quantitation of carvedilol in the dosage forms was made. The cross-polarization kinetics and other measurement parameters affecting the intensity and reproducibility of the spectra were determined. The results revealed a satisfying relationship between the composition of the tablets and the intensity of selected NMR signals. The (13) C CPMAS NMR technique was found to provide accurate quantification of drugs without any chemical preparation, as shown by the particular case of carvedilol's solid formulations.
authors.affiliation: Department of Physical Chemistry, Faculty of Pharmacy, Medical University of Warsaw, Warsaw 02-097, Poland. monika.zielinska-pisklak@wum.edu.pl
authors.forename: Monika
authors.initials: M
authors.lastname: Zielińska-Pisklak
authors.forename: Dariusz Maciej
authors.initials: DM
authors.lastname: Pisklak
authors.forename: Iwona
authors.initials: I
authors.lastname: Wawer
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000032:analysis*; D002227:Carbazoles / Q000032:analysis*; D002247:Carbon Isotopes; D000077261:Carvedilol; D002626:Chemistry, Pharmaceutical; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011412:Propanolamines / Q000032:analysis*
chemical_list: D000319:Adrenergic beta-Antagonists; D002227:Carbazoles; D002247:Carbon Isotopes; D011412:Propanolamines; D000077261:Carvedilol