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Issue 7, 2018
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Cocrystals of zileuton with enhanced physical stability

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Zileuton (ZIL) is an active oral inhibitor of the enzyme 5-lipoxygenase used for the maintenance treatment of asthma. Though ZIL was first approved by the United States FDA 20 years ago, structural knowledge of this active pharmaceutical ingredient (API) has been omitted. Here, we report the crystal structure of the commercially available anhydrous ZIL (form A) for the first time. It's also found that a monohydrate of ZIL (form H) can be formed when the compound is exposed to high relative humidity (RH) conditions. Such a phase change is not desired during manufacturing and storage, for the physicochemical and pharmacokinetic behaviours of ZIL may also be modified along with the solid state hydration. Cocrystallization experiments involving ZIL with nicotinamide (NIC) and isonicotinamide (ISO) were successfully performed and the obtained cocrystal forms, ZIL–NIC and ZIL–ISO, demonstrated superior phase stability against moisture. Additionally, all these ZIL forms were characterized by a variety of analytical methods, which provide plentiful information for the solid-state landscape of this important drug substance.

Graphical abstract: Cocrystals of zileuton with enhanced physical stability

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Publication details

The article was received on 13 Dec 2017, accepted on 10 Jan 2018 and first published on 11 Jan 2018

Article type: Paper
DOI: 10.1039/C7CE02150J
Citation: CrystEngComm, 2018,20, 990-1000
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    Cocrystals of zileuton with enhanced physical stability

    X. Chen, D. Li, C. Luo, J. Wang, Z. Deng and H. Zhang, CrystEngComm, 2018, 20, 990
    DOI: 10.1039/C7CE02150J

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