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Clay-based formulations for metformin controlled release

AuthorsRebitski, Ediana P.; Aranda, Pilar ; Darder, Margarita ; Carraro, Rafaelle; Ruiz-Hitzky, Eduardo
Issue Date2017
CitationXVI International Clay Conference (2017)
AbstractCurrently, metformin hydrochloride is the reference drug used for the treatment of type 2 diabetes [1,2], which as it is well known, is a widespread chronic metabolic disease, characterized by elevated blood glucose (hyperglycemia) [3,4]. Metformin is able to decrease blood glucose concentration by mechanisms other than insulin or sulphonylureas [2,3]. It also decreases plasma insulin concentrations, contributing to increase peripheral glucose uptake and decreasing hepatic glucose production [5]. In this way, the glycemic index is improved without gaining weight by the patient. For optimal therapeutic effect, a metformin dosage of 250-500 mg 3-4 times daily, is required to reach a maximum of 2.5 g/day. The absolute bioavailability of metformin hydrochloride is 50-60% in which it has a biological half-life of 6.2 hours. However, the use of therapy with metformin results in a high incidence of gastrointestinal side effects [6], and therefore, it is of great relevance to produce formulations that allow a controlled release of the drug. In this context, clay minerals have proved to be efficient substrates to produce systems for controlled drug delivery [7]. Thus, here is evaluated the possibility of using montmorillonite to stabilize metformin, allowing its further incorporation in a formulation that may increase its biological half-life, decreasing the daily dosage and presumably, other side effects associated with the regular use of metformin. The selected clay mineral is a commercial sodium montmorillonite (MMT) known as Cloisite®-Nathat presents a cation exchange capacity ca. 93 mEq/100 g, and acceptable characteristics for uses in pharmacology [7]. As a first step, metformin has been intercalated in that clay by a cation-exchange reaction carried out in water under agitation during 24 h at room temperature. The resulting hybrid material has been characterized by diverse physicochemical techniques showing a drug content of 190 mEq/100g entrapped in the intracrystalline space of the silicate. The intercalation compound was also combined with pectin and chitosan to produce bionanocomposite materials, in which the presence of chitosan may have additional advantages related to its mucoadhesive properties in view to increase its permanence in the intestinal tract[8,9]. The prepared materials montmorillonite-metformin (MMT-MET) pectin-chitosan/metformin (PEC-CHT/MET) and pectin-chitosan/montmorillonite-metformin (PEC-CHT/MMT-MET) were in vitro tested in release experiments in which their passage through the gastro-intestinal tractis simulated by switching the pH conditions and the elapsed time in the different media. Based on obtained preliminary results, the PEC-CHT/MMTMET system considerably provides a good controlled release compared to the other two systems (MMT-MET and PEC-CHT/MET). Thus, pectin-chitosan/MMT-metformin formulation seems a promising candidate for the oral administration of metformin for the control of type 2 diabetes.
DescriptionOral presentation given at the XVI International Clay Conference, held in Granada (Spain) on July 17-21, 2017.
Appears in Collections:(ICMM) Comunicaciones congresos
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