Frézard F, Martins PS, Bahia APCO, Le Moyec L, de Melo AL, Pimenta AMC, Salerno M, da Silva JBB, Demicheli C. Enhanced oral delivery of antimony from meglumine antimoniate/beta-cyclodextrin nanoassemblies.
Int J Pharm 2007;
347:102-8. [PMID:
17656054 DOI:
10.1016/j.ijpharm.2007.06.029]
[Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Revised: 06/16/2007] [Accepted: 06/18/2007] [Indexed: 11/24/2022]
Abstract
The composition comprising the highly water-soluble drug meglumine antimoniate (MA) and beta-cyclodextrin (beta-CD) was shown previously to enhance the absorption of Sb by oral route and render MA orally active in a murine model of cutaneous leishmaniasis. This unexpected behaviour was attributed, in part, to the fact that the heating of equimolar mixture of MA and beta-CD (first step of preparation of MA/beta-CD composition) induced the depolymerization of MA from high-molecular weight Sb complexes into 1:1 Sb-meglumine complex, resulting in an enhanced oral bioavailability of Sb. In the present work, we demonstrate that the heated MA+beta-CD mixture still produced significantly lower serum Sb levels when compared to the MA/beta-CD composition, indicating that the freeze-drying process (second step of preparation of MA/beta-CD composition) is required for achieving a high absorption of Sb by oral route. To get insight into the physicochemical alterations induced by the freeze-drying step, the MA/beta-CD composition was further characterized by circular dichroism, (1)H NMR and ESI(-)-MS and photon correlation spectroscopy. The freeze-drying process was found to promote the formation of supramolecular nanoassemblies with a mean hydrodynamic diameter of 190 nm, comprising 1:2:1, 2:2:1 and 2:2:2 NMG-Sb-beta-CD complexes. Another important observation was the ability of the MA/beta-CD composition to act as a sustained release system of the antimonial drug MA, suggesting that this property may result in the change of the drug absorption site in the gastrointestinal tract. A model is proposed for the mechanisms involved in the enhanced absorption of Sb from the MA/beta-CD composition.
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