Crystalline vs. ionic liquid salt forms of active pharmaceutical ingredients: A position paper

Jelena Stoimenovski, Douglas Robert Macfarlane, Katharina Bica, Robin D Rogers

Research output: Contribution to journalArticleResearchpeer-review

279 Citations (Scopus)


Why not consider liquid salt forms of active pharmaceutical ingredients (APIs) as an alternative versatile tool in the pharmaceutical industry? Recent developments have shown that known APIs can be readily converted into ionic liquids and that these novel phases often possess different properties (e.g., improved solubilities and dissolution rates), which may have a direct impact on the pharmacokinetics and pharmacodynamics of the drug. They may also offer the potential of novel and more efficient delivery modes, as well as patent protection for each of the new forms of the drug. Since these pharmaceutically active ionic liquids represent a thermodynamically stable phase, they avoid the troublesome issues surrounding polymorphism and polymorphic transformation. In some cases, an active cation and an active anion can be combined to produce a liquid possessing dual functionality. Here we examine and challenge the current industry reliance on crystalline APIs by discussing the breadth and potential impact of liquid salts as a possible approach to phase control.
Original languageEnglish
Pages (from-to)521 - 526
Number of pages6
JournalPharmaceutical Research
Issue number4
Publication statusPublished - 2010

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