A review of the synthesis and applications of renewable, biocompatible, and biodegradable hydrogels made from cellulose, chitin, and some of their derivatives indicates increased attention due to their excellent processability, high absorbency, porosity, bioactivity, and abundant active groups.

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A new realm of potential drugs is hiding in plain sight. Pharmaceutical research, manufacture and regulation focuses on solid active ingredients, delivered as powders or tablets. Liquid forms are neglected and viewed as an intermediate step, rather than an endpoint.Yet many promising solid drug candidates are too insoluble for the body to absorb. Of Develop ionic liquid drugsUpdate regulation to spur research into drugs that the body absorbs more easily and that could reach market more quickly, urge Julia L. Shamshina and colleagues. . Ionic liquids can also be configured to deliver two or more active ingredients at once.For example, combining active ions from the pain reliever procaine and the non-steroidal anti-inflammatory drug (NSAID) salicylic acid generates a liquid salt, procainium salicylate. It could deliver the medical benefits of both compounds more efficiently and cheaply while opening up new treatment options.With the drug-discovery pipeline clogged, it is time to try alternatives. We call on chemists and the pharmaceutical industry to develop liquid salt forms of drugs. Chemists will need to learn more about the spectrum of interactions in ionic liquids, how to engineer ionic bonds, and how the choice of ions changes the chemical, physical and biological properties of ionic compounds. Regulations must be updated to consider active ingredients in liquid as well as solid states. OLD HABITSWhy are ionic liquids being ignored? First, most academic and industrial chemists lack understanding and experience of working with them. Chemistry courses and textbooks teach that new molecules are made by manipulating covalent bonds (where electrons are shared between atoms) rather than ionic ones.Second, pharmaceutical companies are conservative. Ionic liquids are unfamiliar, unregulated and felt to be too risky to develop commercially.And there is a perception problem. Over the past 20 years many researchers (including us) have demonstrated the value of ionic liquids as solvents, electrolytes and compressor fluids that are reusable, non-volatile and safe. Yet many researchers and journalists still associate the term with the first such chemicals widely studied: for example, dialkylimidazolium, quaternary ammonium and phosphonium salts, which were explored in the 1990s as potential 'green' solvents and electrolytes. With each new study, the class as a whole became pigeonholed -as expensive, cheap, green, toxic, biodegradable, nonbiodegradable, non-flammable, flammable, volatile or non-volatile. In reality, ionic liquids have an infinite range of characteristics.The effect of an ionic liquid on a living organism (such as toxicity) should be exploited rather than being seen as a problem, especially given that liquid salts can be more soluble in the body than are solids. The rate at which a drug is taken up depends on many factors, including its solubility, permeability, dissolution rate and the metabolic pathways involved.Ionic liquid pharmaceuticals face similar problems to nanotechnology.

We present evidence of hydrogen bond formation, not salt formation, as the driving force in the liquefaction of a solid pharmaceutical in the form of a neutral acid-base complex, as exemplified by the liquid formed from a mixture of the local anesthetic lidocaine with fatty acids; these complexes exist at the boundary between simple eutectics and partially ionised ionic liquids.

The authors believe that API-IL approaches may save failed lead candidates, extend the patent life of current APIs, lead to new delivery options or even new pharmaceutical action. They encourage the pharmaceutical industry to invest more research into the API-IL platform as it could lead to fast-tracked approval based on similarities to the APIs already approved.