INDIAN DRUGS 60 (10) OCTOBER 2023 7 REVIEW ARTICLE DRUG-CYCLODEXTRIN COMPLEXES: CURRENT STATUS AND RECENT ADVANCEMENTS Vikas S. Panwar a , Lokesh Adhikari a , Mona Semalty a and Ajay Semalty a * (Received 05 April 2021) (Accepted 08 December 2021) ABSTRACT Cyclodextrins are water-soluble oligosaccharides formed by the action of cyclodextrin glucosyl transferase enzyme (CGTase) on the medium containing starch. Cyclodextrins are proven to be a cost-effective breakthrough in the pharmaceutical industry by formulating them with polymers and drugs to improve the safety, bioavailability, and solubility of APIs. This review describes the current status and advancement of cyclodextrin research in drug delivery. The use of cyclodextrins to improve the solubility and dissolution properties of poor water-soluble products has been reviewed exhaustively with a specific focus on their physicochemical property, practical methods, toxicity, the drug-cyclodextrin compatibility and its applications. a Department of Pharmaceutical Sciences, H.N.B. Garhwal University (A Central University) Srinagar (Garhwal) - 246 174, Uttarakhand, India *For Correspondence: E-mail: semaltyajay@gmail.com https://doi.org/10.53879/id.60.10.12952 Keywords: Cyclodextrin, cyclodextrin complex, drug delivery, inclusion complex INTRODUCTION Cyclodextrin (CD) is an oligosaccharide produced through enzymatic starch conversion 1 . On starch-containing media, the enzyme cyclodextrin glucosyltransferase (CGTase) produces cyclodextrin. Polysaccharide with sixD-(+)-glucopyranose units bonded to α (1 - 4) linkages. The outer shell of cyclodextrin is hydrophilic, while the core is relatively hydrophobic. Cyclodextrin is a fine white crystalline powder with a pleasant, sweet taste and no odour. In both solid and liquid states, inclusion complexes are formed by the diffusion of guest molecules into cyclodextrin cavities 2,3 . A wide range of industries use CDs, including pharmaceuticals, medical devices, cosmetics, food and chemicals. These are typically found in tablets, eye drops and ointments. The drug’s solubility is critical to it's bioavailability. The drug discovery process and a clinical trial process both require this method. The chemical structure of many newly developed medications contribute to their limited solubility in water. A wide variety of methods is used to enhance solubility, including solid dispersion, salt generation, co-solvency, micellar solubilization, as well as CD complexation, nanosizing and particle engineering 4 . Recently, lipid drug delivery methods or nano- emulsions have been studied 5,6 . Each of these traditional solubilization techniques has disadvantages in solubilizing ability, patient acceptance and safety 7,8 . In this article, it is shown that cyclodextrins are utilized widely to increase the aqueous solubility of drugs with low water-solubility. Historical background This type of CD is made up of 6 or more glucopyranose units that are linked by a bond of α- (1→4). The enzyme CD glucosyltransferase 9 initiates intramolecular transglycosylation events from starch breakdown (Fig. 1). Villiers made the initial discoveries in 1891, while studying the action of butyric ferment Bacillus amylobacter on potato starch 10 . Villiers observed a crystalline material he termed “cellulosine.” “Crystallized dextrin α” and “Crystallized dextrin β” were isolated by Schardinger in 1903, and afterwards were termed as Schardinger dextrins 1 . From 1930 to 1970, enzymatic CD processing