Crystal Structures of a New Polymorphic Form of Gabapentin Monohydrate and the E and Z Isomers of 4-Tertiarybutylgabapentin

Vasudev, Prema G and Aravinda, Subrayashastry and Ananda, Kuppanna and Veena, Shettykere Dayananda and Nagarajan, Kuppuswamy and Shamala, Narayanaswamy and Balaram, Padmanabhan (2008) Crystal Structures of a New Polymorphic Form of Gabapentin Monohydrate and the E and Z Isomers of 4-Tertiarybutylgabapentin. In: Chemical Biology & Drug Design, 73 (1). pp. 83-96.

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Abstract

Gabapentin, a widely used antiepileptic drug, crystallizes in multiple polymorphic forms. A new crystal form of gabapentin monohydrate in the space group Pbca is reported and the packing arrangement compared with that of a previously reported polymorph in the space group P21/c [Ibers, J.A. (2001) Acta Crystallogr; C57:641]. Gabapentin polymorphs can also occur from a selection of one of the two distinct chair forms of the 1,1-disubstituted cyclohexane. Crystal structures of the E and Z isomers of 4-tert-butylgabapentin provide models for analyzing anticipated packing modes in the conformational isomers of gabapentin. The E isomer crystallized in the space group Pca21, while the Z isomer crystallized in the space group P21/c. The crystal structure of E-4-tert-butylgabapentin provides the only example of a structure in a non-centrosymmetric space group. Crystal structures of the hydrochloride and hydrobromide salts of 4-tert-butyl derivatives are reported. The results suggest that for gabapentin, a large 'polymorph-space' may be anticipated, in view of the multiple conformational states that are accessible to the molecule.

Item Type:	Journal Article
Publication:	Chemical Biology & Drug Design
Publisher:	Blackwell Publishing
Additional Information:	Copyright of this article belongs to Blackwell Publishing.
Keywords:	1;1-disubstituted cyclohexane;crystal structures; gabapentin;polymorphs;tert-butylgabapentin.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit Division of Physical & Mathematical Sciences > Physics
Date Deposited:	17 Aug 2009 09:39
Last Modified:	19 Sep 2010 05:00
URI:	http://eprints.iisc.ac.in/id/eprint/18141

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