Introduction
1The 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.
2The 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.
1Despite 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.
Results and Discussion
The complexation was carried out without difficulties, because the drug is hydrophilic and this characteristic facilitates the complexing process.
The techniques chosen for verification of the IC in the solid state were the thermal analysis, thermogravimetry and differential scanning calorimetry and for confirmation of the IC were carried out NMR and two dimensional NMR. All techniques provide fast and accurate results.
Conclusions
A new range of possibilities opens to the pharmaceutical industry for the complexation of photosensitive drugs.
Even when the complexation not cause increase in the potency of the drug is important to evaluate the costs to complex and to coat the photosensitive drug. Moreover, the industrial dynamic processes should be well evaluated because time is a critical point for pharmaceutical industries in all areas. After all, the sectors of Manufacturing, Quality Control and Sales go together.
Acknowledgements
CAPES, CNPq, FAPESP, UNESP, União Química Indústria Farmacêutica, Consejo Nacional de Investigaciones Científicas y Tecnológicas de la Nación (CONICET).
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1Lyra, M. A. M.; Alves, L .D. S.; Fontes, D. A. F.; Soares-Sobrinho, J. L.; Rolin-Neto, P. J. Ferramentas analíticas aplicadas à caracterização de complexos de inclusão fármaco-ciclodextrina, Revista de Ciências Farmacêuticas Básica e Aplicada, v. 31(2), p.117-124, 2010.
2Cunha-Filho, M. S. S.; Sá-Barreto, L. C. L. Utilização de ciclodextrinas na formação de complexos de inclusão de interesse farmacêutico, Revista de Ciências Farmacêuticas Básica e Aplicada, v. 28, p.1-9, 2007.
