Gliquidone Research Articles

Cinnamon oil-based self-emulsifying system for augmented dissolution and hypoglycemic efficacy of gliquidone

The aim was to formulate self-emulsifying drug delivery systems (SEDDS) to hasten dissolution and oral bioavailability of gliquidone (GLQ) as lipophilic oral hypoglycemic. In the developed formulations, cinnamon oil served as the oily phase, while Tween 20 and Transcutol® HP constituted the surfactant/cosurfactant system. A phase diagram was employed to select formulations showing transparent/translucent system after dispersion. These formulations were loaded with GLQ and subjected to in vitro dissolution studies relative to unprocessed GLQ. Optimum systems providing the fastest release were characterized for globule size and morphology. In addition, the in vivo hypoglycemic effect GLQ-loaded SEDDSs was assessed after oral administration to diabetic rats relative to GLQ aqueous dispersion (control). Optimized GLQ-loaded SEDDSs (3 formulations) displayed a significant improvement of dissolution rate as indicated from the amount dissolved after 5 min which recorded 72.83 %, 83.34 % and 92.38 %. Fast dissolution was parallel correlated with globule size values which were 335.4, 211.8 and 175.8 nm for the same formulations, respectively. Ultrafast dispersion and dissolution were revealed further in the in vivo hypoglycemic effect which was shown increasing the area under blood glucose reduction curve by 1.58, 1.61 and 2.11-fold after administration of the same formulation, compared with the control, respectively. Overall, the developed SEDDSs successfully enhanced both the dissolution rate and the bioavailability of GLQ.

Gliquidone improves retinal injury to relieve diabetic retinopathy via regulation of SIRT1/Notch1 pathway

BackgroundDiabetic retinopathy (DR) is a common and potentially devastating microvascular complication of diabetes mellitus (DM). The main features of DR are inflammation and oxidative damage. Gliquidone (GLI) is confirmed to be a hypoglycemic drug by oral administration. The current study is aimed to investigate the role and mechanism of GLI on the pathogenesis of DR.MethodsHigh glucose (HG)-induced human retinal endothelial cells (HRECs) were used to explore the anti-inflammatory and anti-oxidant effects of GLI on DR in vitro. Streptozotocin (STZ)-induced DM rats were used to investigate the effects of GLI on retinal structures, inflammation, and oxidative stress. The levels of SIRT1/Notch1 pathway-related proteins were determined by western blotting.ResultsGLI treatment promoted the viability and inhibited the apoptosis of HG-induced HRECs. Meanwhile, the levels of interleukin (IL)-6, IL-1β, tumour necrosis factor alpha and reactive oxygen species were suppressed, while both catalase and superoxide dismutase were elevated after GLI treatment in HG-induced HRECs. Furthermore, we found that Silencing information regulator 2 related enzyme 1 (SIRT1) silencing reversed the inhibiting effects of GLI on the levels of protein Notch1 and effector genes Hes1 and Hey2. Similar anti-inflammatory and anti-oxidant effects of GLI in STZ-induced DM rats were observed. Additionally, GLI administration also repressed vascular hyperpermeability in vivo.ConclusionGLI may be an effective agent to improve DR through repression of inflammation and oxidative stress via SIRT1/Notch1 pathway.

Rosmarinic acid, the active component of Salvia miltiorrhizae, improves gliquidone transport by regulating the expression and function of P-gp and BCRP in Caco-2 cells.

Salvia miltiorrhiza (Danshen) is typically used in the treatment of diabetic complications and is often co-prescribed with gliquidone in China. However, whether danshen affects the absorption of gliquidone has not been elucidated. In this study, the effects of an aqueous extract of danshen (danshen injection, DSI) and its primary compounds (danshensu, protocatechuic aldehyde, rosmarinic acid and salvianolic acid B) on gliquidone transport across Caco-2 monolayer cells was investigated. DSI enhanced the transport of gliquidone in Caco-2 cell monolayers from the apical (AP) to basolateral (BL) sides and from the BL to AP sides. Rosmarinic acid (RA) also significantly increased the Papp (AP-BL) value for gliquidone transport. Verapamil (a P-gp inhibitor) and Ko143 (a BCRP inhibitor) inhibited the BL-AP transport of gliquidone and promoted the AP-BL transport of gliquidone, whereas MK571 (an MRP1 inhibitor), probenecid (an MRP2 inhibitor), and benzbromarone (an MRP3 inhibitor) had no effect on gliquidone transport. RA also enhanced the intracellular accumulation of Rho123 and Hoechst 33342. The expression of P-gp and BCRP was significantly downregulated, and P-gp ATPase activity was promoted by RA in a dose-dependent manner. These results indicate that an aqueous extract of danshen can increase the transport of gliquidone in Caco-2 cell monolayers and that RA may be the primary compound associated with this activity, which is in agreement with RA simultaneously suppressing the function and expression of P-gp and BCRP.

Screening and quantification of fourteen synthetic antidiabetic adulterants in herbal pharmaceuticals and health foods by HPLC and confirmation by LC-Q-TOF-MS/MS

ABSTRACTA procedure was established and fully validated for the screening and quantification of fourteen synthetic antidiabetic adulterants in herbal pharmaceuticals and health foods, including metformin (MF), buformin (BF), phenformin (PHF), rosiglitazone (RGZ), pioglitazone (PGZ), chlorpropamide (CPM), glipizide (GPZ), tolbutamide (TBM), gliclazide (GCZ), glibenclamide (GBM), glimepiride (GMR), repaglinide (RGN), gliquidone (GQD) and nateglinide (NGN). The samples were extracted by methanol and separated by HPLC. Retention times and ultraviolet spectra were used for the preliminary screening, and the suspected adulterants were then confirmed by liquid chromatography-quadrupole-time of flight mass spectrometry (LC-Q-TOF-MS/MS) and quantified by HPLC. The developed procedure was successfully applied to assess twenty-four herbal samples, and PHF, GCZ, GBM, MF, GPZ and BF were found in many. To the best of our knowledge, this is the first report of simultaneous screening and quantification of these fourteen synthetic antidiabetic adulterants from any matrix.

Study of gliquidone degradation behavior by high-performance thin-layer chromatography and ultra-performance liquid chromatography methods.

Gliquidone (GQ) is an oral hypoglycemic agent, belonging to second-generation sulfonylurea derivatives. New high-performance thin-layer chromatography (HPTLC) and ultra-performance liquid chromatography (UPLC) methods have been developed and validated and used for complete stability study of GQ following International Conference on Harmonization guidelines. GQ was subjected to stress and forced degradation under hydrolytic, oxidative and photolytic conditions. The drug was found to be unstable under acidic, alkaline and oxidative conditions with the formation of gliquidone sulfonamide (GQS), while a marked stability was confirmed under thermal and photolytic stress conditions. GQS is the British pharmacopeial impurity A of GQ and also considered as its synthesis intermediate. The developed chromatographic methods have been utilized for anticipating the degradation behavior of GQ under the studied conditions and then used for quantitation of GQ and GQS either in their pure forms or in laboratory prepared mixtures. The methods were successfully applied to GQ in pharmaceutical formulation. The methods have the advantages of being sensitive and less time consuming compared with the reported methods. The obtained results were statistically compared with a reported HPLC method showing no significant difference regarding both accuracy and precision.

LC-MS–MS in MRM Mode for Detection and Structural Identification of Synthetic Hypoglycemic Drugs Added Illegally to ‘Natural’ Anti-Diabetic Herbal Products

Several products marketed as natural drugs for enhancement of anti-diabetic function have been analyzed and found to contain synthetic hypoglycemic drugs. In the work discussed in this paper, LC-MS analysis ten such drugs [gliquidone (GLQ), glipizide (GLZ), gliclazide (GLC), glibenclamide (GLB), glimepiride (GLM), rosiglitazone (RGL), repaglinide (RPG), metformin (DMBG), phenformin (DBI), and tolbutamide (TOL)] has been improved. Quantification was by use of multiple reaction monitoring mode. The intra-day and inter-day precision of the method ranged from 2.13 to 5.55% and from 3.78 to 8.14%, respectively. LOQ was 1, 1, 1.2, 2, 3, 3, 5, 5, 2, and 1 μg L−1 for GLQ, GLZ, GLC, GLB, GLM, RGL, RPG, DMBG, DBI, and TOL, respectively. The structures of the compounds were identified by collision-induced dissociation mass spectral analysis. The results showed that a variety of synthetic drugs had been illegally added to anti-diabetic herbal products. A surprising result was that some of the adulterants were added into the capsule shell instead of capsule contents. LC-MS–MS is a powerful tool, and the method has wide applicability.

Improvement of gliquidone hypoglycaemic effect in rats by cyclodextrin formulations.

This study was carried out with the aim to optimize the pharmacological profile of gliquidone (GLI)--a poorly bioavailable hypoglycaemic agent sparingly soluble in water--through complexation with cyclodextrins. In order to increase the apparent solubility of GLI, two cyclodextrins, namely beta-cyclodextrin (betaCD) and hydroxypropyl-beta-cyclodextrin (HPbetaCD), were tested. The effect of cyclodextrin addition on the aqueous solubility of GLI was evaluated by the phase solubility method at different pH values. The amount of GLI in solution increased upon CD addition according to A type plots. The aqueous solubility of GLI was enhanced more at higher pH values and using HPbetaCD. On the basis of its performance, HPbetaCD was selected as host to prepare GLI oral formulations. GLI/HPbetaCD solid systems were prepared at 1:2 molar ratio by co-grinding, spray-drying and freeze-drying and characterized by DSC, FTIR and X-ray powder diffractometry. Powders were amorphous and showed an improved dissolution rate in comparison with GLI. GLI/HPbetaCD co-ground and freeze-dried products were the most interesting systems, since they dissolved 62 and 94% of total drug after 15 min, respectively. The hypoglycaemic effect of the most rapidly dissolving binary systems was evaluated after oral administration in fasted rats by measuring plasma glucose level in the time interval 0.5-36 h and compared to free GLI. Our findings indicate that cyclodextrin-containing formulations not only provide an onset of hypoglycaemic effect faster than GLI, but also enhance significantly the pharmacological effect due to improved biopharmaceutics. The association GLI/HPbetaCD allows a reduction of the oral dose and is expected to provide a better control over drug side effects, contributing to improve safety and efficacy of GLI.

Methylamine and benzylamine induced hypophagia in mice: modulation by semicarbazide-sensitive benzylamine oxidase inhibitors and aODN towards Kv1.1 channels.

1. In starved mice, the anorectic activity of methylamine (MET) and benzylamine (BZ), both substrates of semicarbazide-sensitive benzylamine oxidases (Bz-SSAO), was compared with that of the potassium channel blocking agents charybdotoxin (ChTX), tetraethylammonium (TEA), gliquidone (GLI), ammonium chloride (NH(4)(+)) and of the anoressants amphetamine (AMPH) and nicotine (NIC). After i.c.v. administration, an approximate ranking order of potency was: ChTX> or =AMPH>NIC=TEA> or =GLI> or =MET>BZ>NH(4)(+). 2. Clorgyline (2.5 mg kg(-1) i.p.) or deprenyl (10 mg kg(-1) i.p.) potentiated the anorectic effect of i.c.v.-administered BZ, NIC and AMPH. The effect of TEA was increased only by deprenyl, while MET, NH(4)(+), ChTX and GLI were not affected by either of the inhibitors. 3. The Bz-SSAO inhibitors alpha-aminoguanidine (50 mg kg(-1) i.p.), B24 (100 mg kg(-1) i.p.) and MDL 72274 (2.5 mg kg(-1) i.p.) potentiated the effect of i.p., but not of i.c.v.-administered MET. 4. Antisense oligodeoxyribonucleotides (aODN) to Kv1.1 potassium channels abolished the effect of BZ and TEA, but was ineffective in reducing the activity of MET and other compounds. 5. These results suggest that MET is endowed with peculiar hypophagic effects at dosage levels that are not able to affect gross behaviour in mice. The effect of MET, differently from BZ, seems unrelated to an increase in the central release of monoaminergic mediators, as well as to a Kv1.1 blocking activity. Through a reduction of the endogenous breakdown of MET, Bz-SSAO inhibitors enhance the central pharmacological activity of this amine.

Sulphonylureas reduce the slowly inactivating D-type outward current in rat hippocampal neurons.

1. Using intracellular recording in hippocampal slices, we have examined, in CA3 pyramidal neurons, the effects of sulphonylureas (blockers of ATP-sensitive K+ channels) on the slowly inactivating D-type K+ current (ID). 2. In the presence of TTX (1 microM) to block Na+ currents, ID had the following characteristics: activation by large depolarizing pulses from membrane potentials negative to -75 mV, slow inactivation kinetics, high sensitivity to 4-aminopyridine (4-AP, 3-40 microM), insensitivity to tetraethylammonium (TEA, 10 mM), Cs+ (3 mM) and carbachol (50 microM). 3. Applications of glibenclamide (10 microM) did not modify the input conductance of the cell, but reduced the amplitude of ID by 31.2 +/- 5.6% (n = 16), without altering its voltage dependence and inactivation kinetics. The effects were usually reversible. 4. Glibenclamide also reduced ID in the presence of TEA (10 mM), Cs+ (3 mM) and carbachol (50 microM), to block several K+ currents (IK, IC, IQ, IM), as well as kynurenate (1 mM) and bicuculline (10 microM) to block on-going synaptic currents mediated by activation of non-NMDA (N-methyl-D-aspartate) and GABA (gamma-aminobutyrate)-A receptors, respectively. 5. Comparable depressions of ID were produced by two other sulphonylureas: gliquidone (10 microM), 42.6 +/- 7.9% (n = 13) and tolbutamide (500 microM), 39.1 +/- 12.8 (n = 8). 6. It is concluded that, in the central nervous system, sulphonylureas can modulate K+ currents which are not generated by ATP-sensitive K+ channels.