title: Methanesulfonic acid salt forms of carbamazepine and 10,11-dihydrocarbamazepine.
abstract: New methanesulfonic acid salt forms of the anticonvulsant and analgesic active pharmaceutical ingredient carbamazepine and its closely related structural analogue 10,11-dihydrocarbamazepine have been prepared and characterized by single-crystal X-ray diffraction at 120 and 100 K, respectively {namely [(5H-dibenzo[b,f]azepin-5-yl)(hydroxy)methylidene]azanium methanesulfonate, C15H13N2O(+)·CH3SO3(-), and [(10,11-dihydro-5H-dibenzo[b,f]azepin-5-yl)(hydroxy)methylidene]azanium methanesulfonate, C15H15N2O(+)·CH3SO3(-)}. In light of the structural information obtained, the crystal structure of the carbamazepine trifluoroacetic acid monosolvate [dibenzo[b,f]azepine-5-carboxamide-trifluoroacetic acid (1/1), C15H12N2O·CF3COOH] was redetermined at 100 and 270 K, and from this data it was concluded that the protonation state for this solvate species is best described as in an `intermediate state' with the acidic proton located almost at the mid-point between the acid and base.
authors.affiliation: Pharmorphix Limited, 250 Cambridge Science Park Milton Road, Cambridge CB4 0WE, England.
authors.forename: Alex R
authors.initials: AR
authors.lastname: Eberlin
authors.forename: Mark D
authors.initials: MD
authors.lastname: Eddleston
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Frampton
mesh_terms: D002220:Carbamazepine / Q000031:analogs & derivatives* / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008698:Mesylates / Q000737:chemistry*; D012492:Salts / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D008698:Mesylates; D012492:Salts; C045880:methanesulfonic acid; D002220:Carbamazepine; C054135:10,11-dihydrocarbamazepine
keywords: 10,11-dihydrocarbamazepine; carbamazepine; intermediate protonation; methanesulfonic acid; salt forms; trifluoroacetic acid