Cyclodextrins were isolated for the first time in 1891 by De Villiers. In 1903, Schardinger identified them as oligosaccharides and named them "dextrins". Around 1948, Freudenberg and Cramer showed that they could form inclusion complexes.
The cyclodextrins are obtained during the enzymatic degradation of starch and consist of a series of cyclic oligosaccharides formed by 6 (α), 7 (β) or 8 (γ) units of α-D- [1,4 ] glucose, which form a rigid toroidal molecular structure with a cavity inside of an specific volume.
Various applications have been patented throughout history as the cyclodextrins have a hydrophilic exterior and an interior hydrophobic cavity where they can host non-polar organic molecules. There are several applications of these within the food industry, in agriculture and in the pharmaceutical industry. For example, the addition of α- or β-cyclodextrin increases the water solubility of several lipophilic substances, such as prostaglandins.
In this way, the cyclodextrins may form crystalline compounds based on organic molecules in solid, liquid and even gaseous state. Consequently, molecules insoluble in water can become completely soluble by being treated with an aqueous solution of cyclodextrin, without any chemical modification in the molecule.
The cyclodextrins increase the solubility and improve absorption and stability; they also reduce the local irritation, and are useful excipients in various ophthalmic formulations. The use of cyclodextrins in Latanoprost is a clear example, which is commercially available, and its effectiveness and benefits against other products without cyclodextrins has been highly proved.
Although cyclodextrins have been known for more than a century, their use in Ophthalmology is very recent. Cyclodextrins are useful excipients for eye drops in a variety of lipophilic drugs that otherwise would not be available for topical use; at the same time they are improving the bioavailability and stability of the encapsulated molecule.
Einar Stefánsson and Thorsteinn Loftsson. Faculty of Pharmacy, University of Iceland. Cyclodextrins in Eye Drop Formulations. Journal of Inclusion Phenomena and Macrocyclic Chemistry, December 2002; 44(1-4):23-27.
Gerardo Martínez, Marina A. Gómez. Ciclodextrinas: Complejos de inclusión con Polímeros. Rev Iberoam Polim. 2007; 8(4): 300-312.
Miguel Alcalde Galeote. Modificación Química y Estabilización de Glicosiltransferazas: Cilodextrin Glicosiltransferaza y dextransacarasa. Departamento de Bioquímica y Biología molecular. Universidad Complutense de Madrid y araza. 1999.