Vasudev Prema G, Aravinda Subrayashastry, Ananda Kuppanna, Veena Shettykere Dayananda, Nagarajan Kuppuswamy, Shamala Narayanaswamy, Balaram Padmanabhan
Department of Physics, Indian Institute of Science, Bangalore 560012, India.
Chem Biol Drug Des. 2009 Jan;73(1):83-96. doi: 10.1111/j.1747-0285.2008.00726.x. Epub 2008 Nov 5.
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 P2(1)/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 Pca2(1), while the Z isomer crystallized in the space group P2(1)/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.
加巴喷丁是一种广泛使用的抗癫痫药物，它能以多种多晶型形式结晶。本文报道了加巴喷丁一水合物在空间群Pbca中的一种新晶型，并将其堆积排列与先前报道的空间群为P2(1)/c的多晶型进行了比较[伊伯斯，J.A.（2001年）《晶体学报》；C57:641]。加巴喷丁多晶型也可由1,1-二取代环己烷两种不同椅式构象中的一种选择产生。4-叔丁基加巴喷丁的E型和Z型异构体的晶体结构为分析加巴喷丁构象异构体中预期的堆积模式提供了模型。E型异构体在空间群Pca2(1)中结晶，而Z型异构体在空间群P2(1)/c中结晶。E-4-叔丁基加巴喷丁的晶体结构是在非中心对称空间群中结构的唯一实例。本文报道了4-叔丁基衍生物的盐酸盐和氢溴酸盐的晶体结构。结果表明，鉴于该分子可获得多种构象状态，对于加巴喷丁而言，可能存在一个较大的“多晶型空间”。
