Eczacılık Fakültesi / Faculty of Pharmacy

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Subject: search.filters.subject.Exendin-4

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    Oral self-nanoemulsifying formulation of GLP-1 agonist peptide exendin-4: development, characterization and permeability assesment on Caco-2 cell monolayer
    (2021) Celebi, Nevin; Tekeli, Merve Celik; Aktas, Yesim; https://orcid.org/0000-0002-6402-5042; https://orcid.org/0000-0002-5234-8434; 33398527; AAL-6931-2021
    The objective of this study was to prepare a stable self-nanoemulsifying formulation of exendin-4, which is an antidiabetic peptide. As exendin-4 is commercially available only in subcutaneous form, several attempts have been made to discover an effective oral formulation. Self-nanoemulsifying drug delivery systems are known to be suitable carriers for the oral administration of peptide drugs. Various ratios of oil, surfactant, and co-surfactant mixtures were used to determine the area in the pseudoternary phase diagram for clear nanoemulsion. The Design of Experiment approach was used for the optimization of the formulation. Blank self-nanoemulsifying formulations containing ethyl oleate as oil phase, Cremophor EL(R), and Labrasol(R) as surfactant, absolute ethanol, and propylene glycol as co-solvent in various proportions were approximately 18-50 nm, 0.08-0.204 and - 3 to - 23 mV in droplet size, polydispersity index, and zeta potential, respectively. When all formulations were compared by statistical analysis, five of them with smaller droplet sizes were selected for further studies. The physical stability test was performed for 1 month at 5 degrees C +/- 3 degrees C and 25 degrees C +/- 2 degrees C/60% RH +/- 5% RH storage conditions. As a result of the characterization and physical stability test results, ethyl oleate: Cremophor EL(R):absolute ethanol (30:52.5:17.5) formulation and four formulations containing ethyl oleate: Cremophor EL(R):Labrasol(R):propylene glycol:absolute ethanol at varying concentrations were considered for peptide encapsulation efficiency. Formulation having the highest encapsulation efficiency of exendin-4 containing ethyl oleate: Cremophor EL(R):Labrasol(R):propylene glycole:absolute ethanol (15:42.5:21.25:15.94:5.31) was selected for in vitro Caco-2 intestinal permeability study. The permeabiliy coefficient was increased by 1.5-folds by exendin-4-loaded self-nanoemulsifying formulation as compared to the exendin-4 solution. It can be concluded that intestinal permeability has been improved by self-nanoemulsifying formulation.
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    Evaluation of the hypoglycemic effect of exendin-4's new oral self-nanoemulsifying system in rats
    (2021) Celik Tekeli, Merve; Celebi, Nevin; Tekeli, M. Yasin; Aktas, Yesim; 33197556
    The objective of this study is to develop a new self-nanoemulsifying system containing exendin-4 with or without enzyme inhibitor chymostatin and to evaluate the effects of oral administration of exendin-4 and exendin-4/chymostatin loaded self nanoemulsifying system on plasma exendin-4, plasma insulin, blood glucose levels and to compare with the oral and subcutaneous administration of exendin-4 in non-diabetic and streptozotocin-induced type 2 diabetic rats. Exendin-4 and exendin-4/chymostatin loaded self-nanoemulsifying system containing ethyl oleate as the oil phase, Cremophor EL (R)/Labrasol (R) as the surfactants and propylene glycol as the co-solvent were prepared. The mean droplet size, polydispersity index, zeta potential and viscosity of exendin-4 loaded self-nanoemulsifying system were found as 24.28 +/- 0.43 nm, 0.17 +/- 0.01, -1.28 +/- 3.61 mV, 79.60 +/- 3.30 m.Pas, respectively. The mean droplet size, polydispersity index, zeta potential and viscosity of exendin-4/chymostatin loaded self-nanoemulsifying system were found as 20.25 +/- 0.35 nm, 0.11 +/- 0.02, -1.85 +/- 2.49 mV, 100.02 +/- 7.65 m.Pas, respectively according to our previous study. In the present study, we focused on long-term physical stability studies, pharmacokinetic studies and pharmacodynamic studies of prepared self-nanoemulsifying systems. According to the long-term physical stability data, exendin-4 and exendin-4/chymostatin loaded self-nanoemulsifying systems were found stable both at 5 degrees C +/- 3 degrees C and at 25 degrees C +/- 60% RH for 12 months. Exendin-4 and exendin-4/chymostatin loaded self-nanoemulsifying systems increased AUC and C-max values in non-diabetic rats compared to the oral exendin-4 solution. In diabetic rats, exendin-4/chymostatin loaded self nanoemulsifying systems increased C-max values compared to the exendin-4 solution. Exendin-4/chymostatin loaded self-nanoemulsifying system decreased inter-subject variability compared to commercial Byetta (R). At 30th minute after administration of exendin-4 loaded self-nanoemulsifying system, exendin-4/chymostatin loaded self nanoemulsifying system and Byetta (R), blood glucose levels decreased to 23%, 25%, 29%, respectively. It has been shown that pharmacodynamic response is close to Byetta (R) with exendin-4/chymostatin self-nanoemulsifying system oral administration. In conclusion, a self nanoemulsifying system was found to be a suitable carrier system, and the combination with enzyme inhibitor chymostatin is thought to be promising for oral delivery of exendin-4.