In vitro-in vivo availability of metformin hydrochloride-PLGA nanoparticles in diabetic rats in a periodontal disease experimental model.

CONTEXT: Metformin is an important oral anti-hyperglycemic used in diabetes. Polylactic-co-glycolic acid (PLGA) has been widely used due to its reliability in controlling the release of drugs. OBJECTIVE: This study evaluates the in vitro-in vivo availability of metformin hydrochloride-loaded polylactic-co-glycolic acid. MATERIAL AND METHODS: In vitro metformin release (Met-free or PLGA + Met-12.5 mg/mL per 360 min) was evaluated using static Franz vertical diffusion cells. The in vivo study was performed with two control groups (validation bioanalytical method) and two experimental groups of diabetic male Wistar rats treated with PLGA + Met 10 mg/kg or Met 100 mg/kg by oral gavage. Diabetes was induced by streptozotocin (40 mg/kg) through the penile vein. Blood samples were collected 0.5, 1, 4, 7, 10, 12, 18, 24, 36, 48 and 72 h and analysed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). RESULTS: PLGA + Met 10 mg/kg was released in the in vitro assay suggesting a parabolic diffusion kinetic model (K -0.0619-0.5h) with a 100% release profile in 10 h by controlled diffusion. The in vivo assay showed the apparent volume of distribution Vz/F (PLGA + Met 10 mg/kg, 40971.8 mL/kg vs. Met 100 mg/kg, 2174.58 mL/kg) and mean residence time MRTinf (PLGA + Met 10 mg/kg, 37.66 h vs. Met 100 mg/kg, 3.34 h). DISCUSSION AND CONCLUSIONS: The formulation modifies pharmacokinetics parameters such as apparent distribution volume and mean residence time. The PLGA + Met 10 mg/kg had a slower elimination rate compared to Met 100 mg/kg in diabetic rats in a periodontal disease experimental model.

Sequential pore wall functionalization in covalent organic frameworks and application to stable camptothecin delivery systems.

Post-synthetic modification of covalent organic frameworks (COFs) is strongly demanded in order to provide additional functionalities to their structures. However, the introduction of functional groups during the synthesis of two dimensional COFs (2D COFs) is highly discouraged, as they can interfere with the π-π stacking forces, compromising framework integrity. Here, we show that direct incorporation of nucleophyllic groups (e.g., primary amines) on pore wall during the synthesis of a 2D-COF (COF-5) is possible by sequential substitution of original monomers. Subsequent bonding of the antitumor drug camptothecin results in a stable hydrophobic drug delivery system. Water adsorption isotherms modelling indicates that the insertion of CPT ligand in the framework promotes a hydrophobic effect that protects a region of COF chain from boronate ester hydrolysis and resulting degradation, which is also proven by stability testing in physiological conditions. Furthermore, this hydrophobic nature favors cell internalization kinetics by promoting interactions with the lipophilic cell membrane. To the best of our knowledge, this is the first case of a stable drug delivery system based on covalently conjugated COFs.