Preparation and evaluation of the doxazosin-bentonite composite as a pH-dependent controlled-release oral formulation

Combined Orobol-Bentonite Composite Formulation for Effective Topical Skin Targeted Therapy in Mouse Model

“…The mechanism of drug loading into the bentonite composite includes pH-dependent cation exchange and physical adsorption. 10 During the preparation of bentonite-drug complex, pH of the medium plays a very important role since acidic solution keeps cationic molecules in their protonated form, which in turn enhances the exchange with intercalated cations and electrostatic surface interaction with negatively charged interlayer space of clay sheets. 8 , 10 Thus, orobol-loaded bentonite composites were prepared in acidic aqueous HCl solution to enhance the adsorption efficiency.…”

“…The adsorption of orobol and PC onto bentonite was conducted by a previous method with minor modification ( Figure 1 ). 9 , 10 , 19 Various compositions of orobol-loaded bentonite (Bt@Orobol) and orobol-loaded PC-bentonite (Bt-PC@Orobol) composite formulations prepared in this study are summarized in Table 1 . Briefly, to prepare the Bt@Orobol composite formulations, 30 mg of bentonite (Ca 0.15 Na 0.13 K 0.02 )(Ti 0.02 Al 1.28 Fe 0.18 Mg 0.56 )Si 4 O 10 (OH) 2 (Korea Institute of Geoscience and Mineral Resources, Daejeon, Korea), was dispersed into 24.9 mL of 1 N HCl solution.…”

“…The cumulative amount of orobol released (F; %) against time (t) profile was fitted to the following mathematical models ( Equations 4 – 7 ) using the DDSolver program: 10 , 24–26 …”

“… 8 It has been formulated as an inactive pharmaceutical excipient for sustaining the release and/or reducing the initial burst release in oral drug delivery systems. 9 , 10 Although there have been many studies on bentonite as a pharmaceutical excipient for oral delivery, the application of bentonite as a carrier for the topical delivery of active pharmaceutical ingredients (APIs) has rarely been reported. Topical application of bentonite was limited only as an adsorbing excipient for dust, pollen and skin wounds.…”

“…However, the “strong interaction” between API and bentonite has resulted in slow and/or incomplete release of API from the bentonite-API composite. 7 , 10 , 14 Thus, it would be necessary to optimize the formulation for enhancing and completing the release of orobol from the complex. Phosphatidylcholine (PC) is amphiphilic in nature and is composed of an esterified glycerol backbone with fatty acids and a choline head.…”