Crystal Structures and Physicochemical Properties of Four New Lamotrigine Multicomponent Forms

Chadha, Renu and Saini, Anupam and Khullar, Sadhika and Jain, Dharamvir Singh and Mandal, Sanjay K and Row, Guru TN (2013) Crystal Structures and Physicochemical Properties of Four New Lamotrigine Multicomponent Forms. In: CRYSTAL GROWTH & DESIGN, 13 (2). pp. 858-870.

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Abstract

In the present study, four new multicomponent forms of lamotrigine (LTG) with selected carboxylic acids, viz. acetic acid, propionic acid, sorbic acid, and glutaric acid, have been identified. Preliminary solid-state characterization was done by differential scanning calorimetry/thermogravimetric, infrared, and powder X-ray diffraction techniques. X-ray single-crystal structure analysis confirmed the proton transfer, stoichiometry, and the molecular composition, revealing all of these to be a new salt/salt-cocrystal/salt monosolvate monohydrate of LTG. All four compounds exhibited both the aminopyridine dimer of LTG (motif 4) and cation-anion dimers between protonated LTG and the carboxylate anion in their crystal structures. Further, these new crystal forms were subjected to solubility studies in water, powder dissolution studies in 0.1 N HCl, and stability studies under humid conditions in comparison with pure LTG base. The solubility of these compounds in water is significantly enhanced compared with that of pure base, which is attributed to the type of packing motifs present in their crystal structures as well as to the lowering of the pH by the acidic coformers. Solid residues of all forms remaining after solubility and dissolution experiments were also assessed for any transformation in water and acidic medium.

Item Type:	Journal Article
Publication:	CRYSTAL GROWTH & DESIGN
Publisher:	AMER CHEMICAL SOC
Additional Information:	Copyright for this article belongs to AMER CHEMICAL SOC, WASHINGTON
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	18 Mar 2013 05:26
Last Modified:	18 Mar 2013 05:26
URI:	http://eprints.iisc.ac.in/id/eprint/46073

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