Complexation of drugs: a new view about the subject

KOGAWA, A.C.; ZOPPI, A.; QUEVEDO, M.A.; LONGHI, M.R.; NUNES SALGADO, H.R.

Araraquara

Congreso; II International symposium on drug discovery; 2011

Comité Organizador del II International symposium on drug discovery

The cyclodextrins (CDs) are cyclic oligosaccharides composed of glucose units linked by a -1.4 connections originating from the degradation of starch by the enzyme glucosyltransferase, synthesized by some microorganisms. The CDs obtained with higher yields are commonly known natural and CDs containing six, seven or eight glucose units, are known a-cyclodextrins (CD-a), b-cyclodextrin (b-CD) and cyclodextrin-g (g-CD), respectively. The b-CD is the most widely used in commercial formulations currently available. The cyclodextrins are currently classified as excipients and they have been used in the development of pharmaceuticals, particularly because of complexing properties, which provide increased solubility and consequent increase in the rate of dissolution of poorly soluble drugs, stability, reduction of irritation and reduction or elimination of odors or flavors in liquid formulations. Variations in the physicochemical properties of host-molecules can be identified by analytical methods, which can detect the formation of complexes. To characterize the formation of inclusion complexes (IC) in the solid state can be used thermal methods, infrared spectroscopy, scanning electron microscopy and analysis of dissolution properties. Already in the liquid state, nuclear magnetic resonance spectroscopy (NMR) spectroscopy, ultraviolet visible and solubility phase diagram. The incorporation of the CDs in pharmaceutical systems is a consolidated reality. The b-CD is quoted at about $ 5US/kg. It is expected that the number of formulations containing this adjuvant to expand considerably in the next years. Despite the growing number of studies using CDs in the formation of IC, for photosensitive drugs is not known what are the advantages of isolating the drug from the external environment. Therefore, the complexation of doxycycline and b-CD was performed.