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This research aimed to study the inhibitory effect of Glurenorm (gliquidone) on epithelial-to-mesenchymal-transition (EMT) of renal tubular epithelial cells based on the diabetic nephropathy (DN) model. In this study, 30 specific pathogen-free (SPF) mice were selected to construct DN model and randomly rolled into groups A, B, and C, with 10 mice in each group. Low-dose, mediumdose, and high-dose Glurenorm were administered intragastrically. The results showed that the serum urea nitrogen content (7.23±0.39 mmol/L, 6.18±0.46 mmol/L) of control and C group was considerably inferior to A group (8.01±0.48 mmol/L), and the content of C group was greatly lower than controls (P < 0.05). The creatinine clearance rate (2.97±0.44 mL/min, 4.02±0.31 mL/min) of mice in control and C group was notably superior to A group (2.18±0.38 mL/min), and that of C group was obviously higher versus controls (P < 0.05). After 5 weeks of intragastric intervention by Glurenorm, the body mass of the mice in control and C group was evidently lower relative to A group, and that of C group was obviously higher versus controls (P < 0.05). Mice in control and C group were remarkably lower in body mass at the 7th week after Glurenorm intervention versus A group, and C group was relatively lower versus controls (P < 0.05). In short, EMT played an important role in promoting the occurrence and progression of renal fibrosis. Glurenorm can reduce the progression of renal fibrosis, inhibit EMT of renal tubular epithelial cells, and effectively protect kidney function.

The main objective of this study is to increase the dissolution rate of gliquidone using its solid dispersions with pluronic F-68 by solvent evaporation method. The solid dispersion of the ...

Background:Sulphonylureas are the oldest and commonly used to treat diabetic patients, but its efficacy declines by time. It was reported that quinazoline nucleus exhibits a potent hypoglycemic effect in diabetic animal models.Objective:The current study aimed to synthesize new quinazoline-sulfonylurea conjugates and evaluate their hypoglycemic effects in alloxan-induced diabetic rats.Methods:The conjugates were synthesized by bioisosteric replacement of 5-chloro-2-methoxybenzamide moiety in glibenclamide or 1,3-dioxo-3,4-dihydroisoquinoline moiety in gliquidone with 6,7-dimethoxy-4-oxoquinazoline moiety (compounds 4a-4d, 9b-9c and 10b-10d). Diabetes was induced in rats by a single i.p. administration of alloxan, followed by treatment with the synthesized conjugates (5mg/kg Body weight).Results:All conjugates showed hypoglycemic effects with different efficacy indicated by the reduction in blood glucose and elevation of insulin levels. Moreover, these conjugates up-regulated the expression of pancreatic glucose transporter 2, muscle glucose transporter 4, and insulin receptor substrate-1 genes, compared to the diabetic group. A normal pancreatic tissue pattern was noticed in diabetic rats treated with compounds 9b, 9c, and 10c.Conclusion:Conjugation of sulfonylurea with quinazoline (especially 9b, 9c, 10c) possessed a significant hypoglycemic effect through improving blood insulin level and insulin action and consequently increased the glucose uptake by the skeletal muscles.

Background: Sulphonylureas (SU) are known to cause weight gain. Some investigators have reported increased insulin sensitivity with some sulphonylurea agents. Objective: To review available evidence of SU agents having PPARγ agonist activity. Methods: We searched online databases of PubMed®, Embase®, Google Scholar® and Web of Science® as per current guidance, published in English, between 1st January 1970 and 31st December 2017. The search found 6 articles. Results: None of the 1st generation SU drugs have any demonstrable PPARγ agonist activity. Most of the 2nd generation SU agents had a positive correlation between their concentration and PPARγ agonist activity except Gliclazide. The demonstrated PPARγ agonist activity was maximum in experiments with Glimepiride and Gliquidone and was seen in these in-vitro experiments at concentrations which were pharmacologically achievable in-vivo. The PPARγ agonist activity may be responsible for some sideeffect of the SU agents as weight gain. On the contrary, the clinical efficacy of the thiazolidinediones could theoretically be reduced when used in combination with the SUs with significant PPARγ agonist activity. Conclusion: The PPARγ agonist activity demonstrated in vitro experiments may have clinical connotations.

Background Coronavirus disease 2019 (COVID‐19), caused by severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2), is currently posing significant threats to public health worldwide. It is notable that a substantial proportion of patients with sever COVID‐19 have coexisting diabetic conditions, indicating the progression and outcome of COVID‐19 may relate to diabetes. However, it is still unclear whether diabetic treatment principles can be used for the treatment of COVID‐19. Methods We conducted a computational approach to screen all commonly used clinical oral hypoglycemic drugs to identify the potential inhibitors for the main protease (Mpro) of SARS‐CoV‐2, which is one of the key drug targets for anti‐COVID‐19 drug discovery. Results Six antidiabetic drugs with docking scores higher than 8.0 (cutoff value), including repaglinide, canagliflozin, glipizide, gliquidone, glimepiride, and linagliptin, were predicted as the promising inhibitors of Mpro. Interestingly, repaglinide, one of the six antidiabetic drugs with the highest docking score for Mpro, was similar to a previously predicted active molecule nelfinavir, which is a potential anti‐HIV and anti‐COVID‐19 drug. Moreover, we found repaglinide shared similar docking pose and pharmacophores with a reported ligand (N3 inhibitor) and nelfinavir, demonstrating that repaglinide would interact with Mpro in a similar way. Conclusion These results indicated that these six antidiabetic drugs may have an extra effect on the treatment of COVID‐19, although further studies are necessary to confirm these findings., Highlights The progression and outcome of coronavirus disease 2019 (COVID‐19) may relate to diabetes; however, whether the diabetic treatment principles can be used for COVID‐19 is unclear.Here, we screened all commonly used clinical oral hypoglycemic drugs to identify the potential inhibitors of Mpro and found six candidate drugs, including repaglinide, canagliflozin, glipizide, gliquidone, glimepiride, and linagliptin.The results indicated that these six antidiabetic drugs may have an extra effect on the treatment of COVID‐19, although further preclinical experiment and clinical research are necessary to confirm these findings.

In this research, the crystal structure of antidiabetic drug gliquidone (GQD) is analysed and multicomponent crystals such as piperazine (PPZ) salt and eutectics are designed and synthesized based on its structural features. Three polymorphs of the salt are obtained together with five solvates. Fortunately, four single crystals of the salts are determined for the first time. The results reveal that the high hydrogen bond-forming ability of PPZ plays a vital role in breaking the original packing of GQD and resulting in salts instead of eutectics. Finally, comprehensive characterization of the salt polymorphs is performed and the result shows that the powder properties and powder dissolution are enhanced by the salt formation compared with the parent form.

Stability testing on gliquidone was conducted under different conditions followed by adoption of two smart and selective spectrophotometric methods namely; mean centering of ratio spectra and derivative ratio for the determination of gliquidone in presence of alkaline degradation products. Degradation products have been elucidated by LC/MS and IR spectroscopy. The spectrum of alkaline degradation products (10 μg/ml) was chosen as a divisor to resolve the overlapped spectra of gliquidone and its degradation products. Mean centering of ratio spectra method depends on using Matlab software and measuring the mean centered values at 260 nm. Derivative ratio method is based on the measurements of analytical signal at 253 nm. Instrumental parameters and divisor concentration were carefully studied. The adopted methods have been validated as per International Conference on Harmonization guidelines. Linearity was obeyed in the range 1-18 μg/ml and detection limit was found to be 0.180, 0.324 μg/ml for mean...

Sulfonylureas (SUs) such as glibenclamide, gliclazide, glimepiride, glipizide and gliquidone are one of the first oral medicines available for the treatment of type 2 diabetes and are widely used for the treatment of hyperglycaemia. The hepatic transporters, organic anion transporting polypeptide 1B1 (OATP1B1) and organic anion transporting polypeptide 1B3 (OATP1B3), play an important role in the disposition of a variety of drugs by mediating their uptake from blood into hepatocytes. Drug-drug interactions mediated by OATP1B1/1B3 may result in the hepatic transporting change for drug substrates. The inhibitory effects of glibenclamide and glimepiride on sulfobromophthalein (BSP) uptake have been previously studied, and glibenclamide has been reported as the substrate of OATP1B3, but it remains unclear whether other SUs such as gliclazide, glipizide and gliquidone are substrates of OATP1B1 and OATP1B3. Here, we investigated the relationship between the five most commonly applied SUs (glibenclamide, gliclazide, glimepiride, glipizide, gliquidone) and OATP1B1 and OATP1B3. We performed uptake and inhibition assays in HEK293T cells stably expressing OATP1B1 or OATP1B3, respectively, and established a liquid chromatography-mass spectrometry (LC-MS) method for the simultaneous measurement of five SUs. We demonstrated that gliclazide and glimepiride are substrates of OATP1B1 and glibenclamide and glipizide are substrates of OATP1B3. We also confirmed the interaction between these SUs and rosuvastatin. No transporting was observed for gliquidone, suggesting that it is not a substrate of either transporter.

A sensitive, rapid, simple and economical ultra-performance liquid chromatographyâtandem mass spectrometric method (UPLCâMS/MS) was developed and validated for simultaneous determination of imatinib, dasatinib and nilotinib in human plasma using gliquidone as internal standard (IS). Liquid-liquid extraction method with ethyl acetate was used for sample pre-treatment. The separation was performed on an Xtimate Phenyl column using isocratic mobile phase consisting of A (aqueous phase: 0.15% formic acid and 0.05% ammonium acetate) and B (organic phase: acetonitrile) (A:B=40:60, v/v). The flow rate was 0.25Â mL/min and the total run time was 6Â min. The multiple reaction monitoring (MRM) transitions, m/z 494.5â394.5 for imatinib, 488.7â401.5 for dasatinib, 530.7â289.5 for nilotinib and 528.5â403.4 for IS, were chosen to achieve high selectivity in the simultaneous analyses. The method exhibited great improvement in sensitivity and good linearity over the concentration range of 2.6â5250.0Â ng/mL for imatinib, 2.0â490.0Â ng/mL for dasatinib, and 2.4â4700.0Â ng/mL for nilotinib. The method showed acceptable results on sensitivity, specificity, recovery, precision, accuracy and stability tests. This UPLCâMS/MS assay was successfully used for human plasma samples analysis and no significant differences were found in imatinib steady-state trough concentrations among the SLC22A5 â1889T>C or SLCO1B3 699G>A genotypes (P>0.05). This validated method can provide support for clinical therapeutic drug monitoring and pharmacokinetic investigations of these three tyrosine kinase inhibitors (TKIs). Keywords: UPLCâMS/MS, Imatinib, Dasatinib, Nilotinib, Polymorphism

The present work embarks upon increasing the dissolution rate and the bioavailability of model anti-diabetic drug, gliquidone, a sulfonylurea class drug used for treating diabetes mellitus type 2. The gliquidone nanoparticles were prepared by using anti-solvent precipitation technique in which, gliquidone solution in acetone was added at a controlled rate to an aqueous solution containing polyvinylpyrrolidone K25 (PVP K25) as stabilizer. The effect of drug concentration (X1), polymer concentration (X2) and solvent to anti-solvent ratio (X3) on particle size and dissolution was studied using Box-Behnken design. The results revealed that by decreasing the drug concentration and by increasing the stabilizer concentration and solvent/anti-solvent ratio, reduction in the size of the particles was observed. The mentioned parameters were optimised and particle of size about 175 nm was achieved. The relative dissolution rate of prepared gliquidone nanoparticles in phosphate buffer pH 7.4 was ~ 4.7 times faster than original drug at t = 45 min. Further, the gliquidone nanoparticles were characterized by scanning electron microscope (SEM), Fourier transform-infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD). The particles revealed to be oval in shape with stabilizer molecules on surface and exhibited decreased crystalline nature when compared to free gliquidone. Finally, the in vivo studies using gliquidone nanoparticles revealed ~ 2.5-fold increase in Cmax when taken orally in the form of hard gelatin capsules in comparison to free gliquidone. Thus, overall investigation suggests that the developed strategy of gliquidone nanoparticles possess a keen potential for exhibiting anti-diabetic effect.

Repurposing of currently approved medications is an attractive option for the development of novel treatment strategies against physiological and infectious diseases. The antidiabetic sulfonylurea glyburide has demonstrated off-target capacity to inhibit activation of the NLRP3 inflammasome in a variety of disease models, including vaginal candidiasis, caused primarily by the fungal pathogen Candida albicans. Therefore, we sought to determine which of the currently approved sulfonylurea drugs prevent the release of interleukin 1β (IL-1β), a major inflammasome effector, during C. albicans challenge of the human macrophage-like THP1 cell line. Findings revealed that the second-generation antidiabetics (glyburide, glisoxepide, gliquidone, and glimepiride), which exhibit greater antidiabetic efficacy than prior iterations, demonstrated anti-inflammatory effects with various degrees of potency as determined by calculation of 50% inhibitory concentrations (IC(50)s). These same compounds were also effective in reducing IL-1β release during noninfectious inflammasome activation (e.g., induced by lipopolysaccharide [LPS] plus ATP), suggesting that their anti-inflammatory activity is not specific to C. albicans challenge. Moreover, treatment with sulfonylurea drugs did not impact C. albicans growth and filamentation or THP1 viability. Finally, the use of ECE1 and Candidalysin deletion mutants, along with isogenic NLRP3(−/−) cells, demonstrated that both Candidalysin and NLRP3 are required for IL-1β secretion, further confirming that sulfonylureas suppress inflammasome signaling. Moreover, challenge of THP1 cells with synthetic Candidalysin peptide demonstrated that this toxin is sufficient to activate the inflammasome. Treatment with the experimental inflammasome inhibitor MCC950 led to similar blockade of IL-1β release, suggesting that Candidalysin-mediated inflammasome activation can be inhibited independently of potassium efflux. Together, these results demonstrate that the second-generation antidiabetic sulfonylureas retain anti-inflammatory activity and may be considered for repurposing against immunopathological diseases, including vaginal candidiasis.

In the in vivo study on rabbits investigated the effect of the vildagliptin and gliqui-done combination on the background of norm and experimental alloxan-induced diabetes mellitus (DM) type 2 on the P-glycoprotein (P-gp, ABCB1 protein) functional activity and its expression in the tissues of the jejunum, liver, kidney and the blood-brain barrier. Introduction of combination of vildagliptin at a dose of 5 mg/kg and gliquidone 10 mg/kg body weight on the background of norm for 14 days did not result in P-glycoprotein changes. On the 5-day of the cancellation of this combination observed inhibition of transporter protein functional activity without altering its expression. In the combination therapy of vildagliptin and gliquidone alloxan-induced diabetes type 2 showed complete recovery of P-glycoprotein functional activity and expression reduced on the pathology background. On the 5-day of treatment withdrawal again occurred inhibition of functional activity of the transporter protein and a decrease in its expression.

The study was carried out to investigate using rabbits in vivo effect of Gliquidone on functional activity of protein-carrier of glycoprotein-P (P-gp, ABCB1-protein). The activity of P-gp was evaluated according pharmacokinetics of its marker substrate - Fexofenadine after single endogastric introduction. The application of Gliquidone in dosage of 10 mg per 1 kg of body mass during 14 days resulted in no alteration of concentration of Fexofenadine, period of its partial ejection, area under pharmacokinetic curve “concentration-time” from zero to last point of blood sampling, area under pharmacokinetic curve “concentration-time” from zero to infinity and also time of holding of marker substrate, total clearance and absorption coefficient. All this testifies absence of effect of Gliquidone on functional activity of protein-carrier at the level of integral organism. No alterations of pharmacokinetic parameters of Fexofenadine at the 5th day of cessation of Gliquidone were observed.

A 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.

In this work, novel ionic liquid (IL) functionalized polyacrylonitrile nanofibers mat (IL/PAN–NFsM) was firstly prepared through thiol–ene “click” reaction and evaluated for the establishment of a sensitive and high-throughput screening method. Because of its excellent pre-separation efficiency, IL/PAN–NFsM can adsorb trace-level targets from complex sample matrix within tens of seconds by performing a solid-phase extraction (SPE) process, and then served as sampling modules of direct analysis real time mass spectrometry (DART–MS) without any additional processing. This means the target analytes concentrated on IL/PAN–NFsM were directly desorbed, ionized, and detected by DART–MS. To verify the feasibility of the proposed method, three illegal added synthetic drugs (gliclazide, glimepiride, and gliquidone) were screened in six types of antidiabetic health-care tea samples. The results indicated that the sensitivity is in the level of ng g −1 , while total analysis time does not exceed 1.0 min per sample. Moreover, the stability expressed as relative standard deviation (RSD) varies from 1.7% to 17.3%. We proposed a new screening mode based on the direct combination of functionalized NFsM and DART–MS, which is expected to become a universal method in food safety analysis.

Forced degradation studies of gliquidone were conducted under different stress conditions. Three degradates were observed upon using HPLC and TLC and elucidated by LC-MS and IR. HPLC method was performed on C18 column using methanol-water (85:15 v/v) pH 3.5 as a mobile phase with isocratic mode at 1 mL.min-1 and detection at 225 nm. HPLC analysis was applied in range of 0.5-20 µg.mL-1 (r =1) with limit of detection (LOD) 0.177 µg.mL-1. TLC method was based on the separation of gliquidone from degradation products on silica gel TLC F254 plates using chloroform-cyclohexane-glacial acetic acid (6:3:1v/v) as a developing system with relative retardation 1.15±0.01. Densitometric measurements were achieved in range of 2 -20 µg /band at 254 nm (r = 0.9999) with LOD of 0.26 µg /band. Least squares regression analysis was applied to provide mathematical estimates of the degree of linearity. The analysis revealed a linear calibration for HPLC where a binomial relationship for TLC. Stability testing and methods validation have been evaluated according to International Conference on Harmonization guidelines. Moreover, the proposed methods were applied for the analysis of tablets and the results obtained were statistically compared with those of pharmacopeial method revealing no significant difference about accuracy and precision.

Background/Aims: Diabetic nephropathy is a common complication of diabetes. This study explored the renal protective effect and possible mechanism of gliquidone in mice with diabetic nephropathy. Methods: Animal model of diabetic nephropathy was established in KKAy mice. The renal protective effect of gliquidone was studied by evaluating the kidney function through measures of urinary protein, blood urea nitrogen (BUN), serum creatinine (Scr) and serum triglyceride (TG) that were performed using an automatic biochemical analyzer. The levels of oxidative stress indicators, such as nitric oxide (NO), superoxide dismutase (SOD) and malondialdehyde (MDA), were evaluated in renal tissue homogenates using the automatic biochemical analyzer. The inhibitory effect of gliquidone on renal interstitial fibrosis and its association with Notch / Snail1 signaling pathway in diabetic nephropathy was investigated using molecular biological techniques. Results: It was found that low-, medium- and high-dose gliquidone improved the mice’s general health condition, such as mental status, fur condition, eating, and drinking. Gliquidone reduced the body weight and the kidney weight /body weight ratio of mice. Gliquidone improved the kidney function, indicated by reductions in urinary protein, blood urea nitrogen, and serum creatinine and triglyceride. Gliquidone treatment increased levels of nitric oxide and superoxide dismutase, but decreased level of malondialdehyde. The expression of Jagged1/Notch1/hes1/Snail1/α-SMA decreased, while the expression of E-cadherin increased in gliquidone-treated kidneys. High dose gliquidone showed the best effect, one that was similar to that of the positive control drug irbesartan. Conclusion: Taken together, our results suggested that gliquidone can ameliorate the diabetic symptoms of diabetic nephropathy through inhibiting Notch / Snail1 signaling pathway, improving anti -oxidative response and delaying renal interstitial fibrosis. The efficacy of gliquidone is dose-dependent.

In the in vivo study in rabbits the effect of gliquidone at 10 mg / kg body weight of the functional activity of the protein transporter P-glycoprotein (P-gp, ABCB1 protein) was studied. P-gp activity was evaluated by pharmacokinetics of its marker substrate - fexofenadine after a single intragastric administration. Applying gliquidone for 14 days led to an increase in the maximum concentration of fexofenadine, its halflife, area under the concentration-time curve from zero to the last point of drawing blood, area under the concentration-time curve from zero to infinity, and the retention time of marker substrate and reduce the overall clearance and rate of absorption, indicating that the inhibition of the functional activity of the protein transporter at the level of the whole organism.

A sensitive LC method has been developed for the simultaneous determination of co-administered drugs amlodipine, gliquidone and pioglitazone in bulk drug, pharmaceutical formulations, and human serums. The assay involved an isocratic elution of analytes on a Purospher® STAR RP-18 end capped (5 μm, 25 x 0.46 cm) column at ambient temperature with a mobile phase consisting of methanol: water: acetonitrile (80:10:10 v/v/v) at a flow rate of 0.7 mLmin-1 at 230 nm. The pH was adjusted to 3.50 with phosphoric acid and glibenclamide was used as an internal standard. The linearity of the method was found to be 5-50 μgmL–1 for all the drugs with correlation coefficients were 0.9991, 0.9992 and 0.9963; the limit of detection was found to be 0.34, 0.06 and 0.33 μgmL–1 for amlodipine, gliquidone and pioglitazone, respectively. All the validated parameters were in the acceptable range. The recovery rates of drugs were 98.2-101.53 %, 100.40-101.60 % and 98.25-101.20 % in human serum for amlodipine, gliquidone a...

The efficacy of gliquidone for the treatment of diabetic nephropathy was investigated by implanting micro-osmotic pumps containing gliquidone into the abdominal cavities of Goto-Kakizaki (GK) rats with diabetic nephropathy. Blood glucose, 24 h urinary protein, and 24 h urinary albumin levels were measured weekly. After 4 weeks of gliquidone therapy, pathological changes in the glomerular basement membrane (GBM) were examined using an electron microscope. Real-time PCR, western blotting, and immunohistochemistry were employed to detect glomerular expression of receptors for advanced glycation end products (RAGE) (AGER), protein kinase C β (PKCβ), and protein kinase A (PKA) as well as tubular expression of the albumin reabsorption-associated proteins: megalin and cubilin. Human proximal tubular epithelial cells (HK-2 cells) were used to analyze the effects of gliquidone and advanced glycation end products (AGEs) on the expression of megalin and cubilin and on the absorption of albumin. Gliquidone lowered blood glucose, 24 h urinary protein, and 24 h urinary albumin levels in GK rats with diabetic nephropathy. The level of plasma C-peptide increased markedly and GBM and podocyte lesions improved dramatically after gliquidone treatment. Glomerular expression of RAGE and PKCβ decreased after gliquidone treatment, while PKA expression increased. AGEs markedly suppressed the expression of megalin and cubulin and the absorption of albumin in HK-2 cells in vitro, whereas the expression of megalin and cubilin and the absorption of albumin were all increased in these cells after gliquidone treatment. In conclusion, gliquidone treatment effectively reduced urinary protein in GK rats with diabetic nephropathy by improving glomerular lesions and promoting tubular reabsorption.

Simple, smart and sensitive normal fluorescence and stability-indicating derivative synchronous spectrofluorimetric methods have been developed and validated for the determination of gliquidone in the drug substance and drug product. Normal spectrofluorimetric method of gliquidone was established in methanol at λ excitation 225 nm and λ emission 400 nm in concentration range 0.2–3 μg/ml with LOD equal 0.028. The fluorescence quantum yield of gliquidone was calculated using quinine sulfate as a reference and found to be 0.542. Stability-indicating first and third derivative synchronous fluorescence spectroscopy were successfully utilized to overcome the overlapped spectra in normal fluorescence of gliquidone and its alkaline degradation product. Derivative synchronous methods are based on using the synchronous fluorescence of gliquidone and its degradation product in methanol at Δ λ50 nm. Peak amplitude in the first derivative of synchronous fluorescence spectra was measured at 309 nm where degradation product showed zero-crossing without interference. The peak amplitudes in the third derivative of synchronous fluorescence spectra, peak to trough were measured at 316,329 nm where degradation product showed zero-crossing. The different experimental parameters affecting the normal and synchronous fluorescence intensity of gliquidone were studied and optimized. Moreover, the cited methods have been validated as per ICH guidelines. The peak amplitude-concentration plots of the derivative synchronous fluorescence were linear over the concentration range 0.05–2 μg/ml for gliquidone. Limits of detection were 0.020 and 0.022 in first and third derivative synchronous spectra, respectively. The adopted methods were successfully applied to commercial tablets and the results demonstrated that the derivative synchronous fluorescence spectroscopy is a powerful stability-indicating method, suitable for routine use with a short analysis time. Statistical comparison between the results obtained by normal fluorescence and derivative synchronous methods and the official one using student's t-test and F-ratio showed no significant difference regarding accuracy and precision.

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.

The present work is aimed to study the interactions between cefpirome and hypoglycemic agents (gliquidone, metformin, and pioglitazone) by chromatographic and spectroscopic techniques. In the first case, reversed-phase high-performance liquid chromatographic methods have been developed, validated for the simultaneous determination of cefpirome with hypoglycemic agents, and was applied for interaction studies. These interactions were carried out in simulated gastric juice (pH1), buffers of pH 4, 7.4, and 9 at 37 °C for 3 h. In the second case, cefpirome–hypoglycemic agents complexes were synthesized and elucidated on the basis of FT-IR, 1H-NMR, and 13C-NMR studies.

A sensitive and accurate LC-MS/MS method for the identification and quantification of 5 oral anti-diabetics (glipizide, glibenclamide, gliclazide, gliquidone and metformin) in serum and hair was developed using glibornuride as the internal standard. We have developed a rapid and robust extraction procedure by using acetonitrile for serum protein precipitation and methanol for the extraction of anti-diabetics from hair. Anti-diabetics (ADs) were separated by UPLC over a C18 column and detection was performed on a Waters Xevo TQ MS mass spectrometer in positive ionization mode using electrospray ionization. Each AD was identified by three specific ion transitions in multiple reaction monitoring (MRM) mode. The method was validated according to international guidelines. For all compounds the variation coefficient (CV) was

In present paper, we describe in vitro drug interactions of antidiabetic agents; gliquidone and pioglitazone hydrochloride with an antihypertensive, losartan potassium. Co-administration of antihypertensive and antidiabetic drugs is most common, as both of these ailments are synergistic to each other and often occur together. These studies were carried out in different pH environments simulating human body compartments and using UV spectrophotometer and HPLC. Antidiabetic agents and losartan were found to inhibit or enhance each other’s availability, which may affect their therapeutic efficacy. These results were further verified by IR and NMR spectroscopic studies and computational molecular modeling.

Co-administration of HMG-CoA reductase with antidiabetic drugs is most common since antidiabetic drugs are mostly prescribed for long term therapy. In the present paper, we describe the simultaneous determination of antidiabetic (pioglitazone hydrochloride and gliquidone) in presence of statins (rosvastatin and simvastatin) in formulations and in human serum using RP-HPLC technique. The serum samples were subjected to protein precipitation with acetonitrile prior to an HPLC analysis. At a flow rate of 1 mL·min−1 isocratic elution was employed, using mobile phase consisting of methanol/water (90:10, V:V), pH 3.50 with phosphoric acid and absorbance was recorded at 235 nm. The assay was reproducible, linear (concentration range of 5–50 μg·mL−1) and accurate. The LOD and LOQ values were 1.32, 0.28, 0.05 and 0.57 μg·mL−1 and 4.39, 0.93, 0.16 and 1.90 μg·mL−1 for pioglitazone hydrochloride, gliquidone, rosvastatin and simvastatin, respectively. There were no interfering peaks due to the excipients present in the pharmaceutical tablet and serum. Thus, the proposed method is simple and suitable for the analysis of active ingredient in tablet form and human serum.

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.

Controlling blood sugar levels is crucial for diabetic patients and is managed through administration of drugs such as gliquidone. Coadministration of antidiabetic drugs with H1-receptor antagonists is common but is also a source of concern due to potential coadministered drug interaction, especially in patients prone to allergic disorders. In this work, we describe in vitro drug interactions of gliquidone with commonly coadministered H1-receptor antagonists (fexofenadine hydrochloride, cetirizine dihydrochloride, and levocetirizine dihydrochloride). These studies were performed at 37°C in different pH environments simulating human body compartments using UV spectrophotometry and high performance liquid chromatography (HPLC). It was observed that the percentage availability values of gliquidone and H1-receptor antagonists were not affected in the presence of each other. No significant difference between gliquidone and H1-receptor antagonists and no remarkable changes in availability values were observed when these interactions were studied using UV–visible and HPLC techniques. This study thus supports the safe coadministration of gliquidone and H1-receptor blockers as an effective diabetic health management regimen.

Complexes of gliquidone with Mg(II), Ca(II), Cr(II), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) were obtained in methanolic solution to study the interaction of the drug with essential and trace elements present in human body or co administered during multivitamin therapy. These complexes were then characterized by spectroscopic techniques involving IR, 1 H NMR, CHN elemental analysis, atomic absorption analysis and conductometric titrations. In most of the complexes, it is observed that the N–H stretch of sulfonamide and amide has disappeared.

Separation of metformin and glibenclamide was achieved within a single chromatographic run on a Zorbax CN column, under isocratic conditions, using acetonitrile and aqueous component (0.01 moles/L ammonium acetate adjusted at pH 3.5 with acetic acid) in volumetric ratio 1/1. Plasma sample preparation is based on protein precipitation by means of organic solvent addition. 1,3,5-Triazine-2,4,6-triamine (IS1) was used as internal standard for metformin, while gliquidone (IS2) played the same role for glibenclamide. Detection was performed with an ion trap mass analyzer, using atmospheric pressure chemical ionization (APCI). A single MS stage was used for detection of metformin and IS1, by extracting ion chromatograms corresponding to molecular ions. MS/MS detection in the SRM mode was used for glibenclamide (m/z transition from 494 to 369 Da) and IS2 (m/z transition from 528 to 403 Da). The method produces linear responses up to 2000 ng/mL for metformin and 400 ng/mL for glibenclamide, respectively. Low limits of quantification were found in the 40 ng/mL range for metformin and at the 4 ng/mL level for glibenclamide. Precision was characterized by relative standard deviations (RSD%) below 9%. The analytical method was successfully applied to a single dose, open-label, randomized, two-period, two-sequence, crossover bioequivalence study of two commercially available anti-diabetic combinations containing 400 mg metformin and 2.5 mg of glibenclamide per coated tablet.

Pharmaceutical counterfeiting is becoming a serious problem in the world, especially in developing countries including China. Herein an isocratic reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for screening counterfeit medicines and adulterated dietary supplement products. The developed method could be employed to separate and determine simultaneously six anti-diabetic drugs (glipizide, gliclazide, glibenclamide, glimepiride, gliquidone, repaglinide) on an isocratic solvent system using an Alltima C18 column (5 μm, 150 mm × 4.6 mm) with an isocratic mobile phase of methanol–phosphate buffer (pH 3.0; 0.01 mol/L) (70:30, v/v), at a flow rate of 1.0 mL/min and at a wavelength of 230 nm. The proposed method was successfully applied to the analysis of medicinal and dietary supplement samples purchased from the local market in China.

A simple and fast method intended for large-scale bioequivalence studies for the determination of glibenclamide in plasma samples is presented. The chromatographic separation was achieved on a monolithic octadecyl chemically modified silicagel column and a mobile phase containing 42% aqueous 0.1% HCOOH solution (v/v) and 58% acetonitrile, at a flow rate of 1 mL/min, in isocratic conditions. Preparation of plasma samples was based on protein precipitation with acetonitrile. Gliquidone was used as internal standard. The target analytes were transferred into an ion trap mass analyzer via an atmospheric pressure chemical ionization interface. The precursor ions with mass 494 a.m.u. for glibenclamide and 528 a.m.u. for gliquidone were isolated, while in the second MS stage product ions 369 a.m.u. and 403 a.m.u., respectively, were monitored. The analytical process was characterized by a low limit of quantitation of 1.5 ng/mL. The mean recovery for glibenclamide was 98.1+/-2.8% over a concentration interval ranging from 1 to 500 ng/mL. Intra-day and inter-day precision calculated over 2-400 ng/mL concentration interval ranged from 15.4% to 3.4%. Inter-sequence accuracy expressed as % bias from theoretical concentration values over the concentration interval of 10-400 ng/mL fall within -13.9% and +14.6%. The method was applied for evaluation of the bioequivalence between two formulations containing 3.5mg glibenclamide per dose.

A new model of pancreatic β-cell membrane chromatography has been established by using a β-cell membrane stationary phase (β-CMSP) prepared by immobi-lizing the β-cell membrane onto the surface of silica carrier. The protein level and K+, Na+-ATP enzymatic activity of the β-CMSP were detected respectively. The surface characteris-tics of the β-CMSP were tested by using the scanning elec-tron microscope and surface energy spectrometer. In this model, the column (10 mm × 2 mm, I.D.) packed with β-CMSP, 25 mmo1/L ammonium sulfate buffer solution (pH 7.4) as mobile phase with the flow rate of 0.2 mL/min at 37 ± 0.5℃ were used in the following studies. The retention char-acteristics of the sulfonylureas (gliquidone, glibenclamide, gliclazide and glipizide) were investigated under the chro-matographic conditions above. The affinities of the sulfony-lureas on β-cell membrane and receptor will be expressed by using the logk′ values (the logarithm of capacity factor of a solute) in the model. The correlation of the affinity with the pharmacological effect of the sulfonylureas was analyzed also.

Oxidative stress plays an important role in chronic complications of diabetes mellitus, and hence the regulation of free radicals is essential in the treatment of diabetes. The aim of the current study is to investigate the effect of glurenorm (10 mg/kg) on liver tissue in experimental diabetes. Diabetes was induced by intraperitoneal injection of 65 mg/kg streptozotocin. Glurenorm was administered to one diabetic and one control group separately, from days 14 to 42. On day 42, cardiac blood samples and liver tissue were taken from each rat. In diabetic rats, blood glucose, serum alkaline phosphatase and serum amino transferase activities, serum uric acid, serum sodium and potassium levels, liver nonenzymatic glycosylation, and lipid peroxidation increased, whereas body weight and liver glutathione levels decreased. The diabetic group given glurenorm blood glucose, serum alkaline phosphatase and aminotransferase activities, serum uric acid, sodium and potassium, liver nonenzymatic glycosylation, and lipid peroxidation levels decreased, and liver glutathione levels increased. As a result of all the biochemical findings obtained, it was concluded that glurenorm has a protective effect on damage of liver of streptozotocin-induced diabetes in rats.

We are seeking to discover potent CNS-active sulfonylureas with structural features that allow for the formation of several types of prodrugs. We report herein the syntheses of compounds comprising an initial series of hydroxyl-substituted analogues of the potent ATP-sensitive potassium channel blockers glyburide (glibenclamide) and gliquidone. Somewhat unexpectedly, several of the compounds were found to be comparably potent to glyburide as inhibitors of specific [ 3 H]glyburide binding in rat brain preparations.

Background and objective Reduction of renal function in patients with type 1 or type 2 diabetes is associated with a clearly increased risk of hypoglycemia. Main causes are an altered pharmacokinetics of insulin and oral antidiabetics and/or impaired renal glucose production. A knowledge of renal function is, therefore, essential for preventing hypoglycemia caused by antidiabetic treatment. But serum creatinine, most commonly used in general practice, is an imprecise indication of renal function. This investigation assessed the significance of a false estimation of renal function as a partial cause of severe hypoglycemia. Patients and methods The study group consisted of 35 diabetics (21 females, 14 males; average age 61 years) who had been hospitalized because of an episode of severe hypoglycemia accompanied by loss of consciousness. Renal function was measured by serum creatinine and by creatinine clearance as calculated by the formula of Cockcroft and Gault. Also taken into account were HBA1c the antidiabetic treatment before and after discharge, and any additional medication. Results Impaired renal function was established by the serum creatinine level in 9 patients and by calculated creatine clearance in 24. Compared with patients with normal renal function, those with renal failure were older (74.3 vs. 32.8 years), had more rarely undergone intensive insulin treatment (5 of 24 vs. 9 of 11) and had more commonly received ACE inhibitors (10/24 vs. 1/11). The insulin dosage at discharge had been reduced in 16 off 22 insulin-dependent patients in renal failure, and long-acting sulfonylurea preparation were discontinued or changed to gliquidone in the others. Conclusion This investigation indicates that false estimation of renal function from the level of serum creatinine is an important partial cause of hypoglycemia requiring treatment, especially in elderly persons with reduced muscle mass in whom renal function should be determined by calculating or measuring creatinine clearance.

Objecive: To study the effects of Huoxue Jiedu Jiangtang formulation (HJJF) on endoplasmic reticulum stress (ERS) coupled inflammatory response From the molecular mechanism in diabetic vascular disease. Methods: Type 2 diabetes were established in male SD rats by feeding high lipid diet and injection of streptozotocin. after T2DM models established successfully, the rats were divided into model group, low-dose HJJF group (HJJF1), high-dose HJJF group (HJJF2), and Western medicine group (Gliquidone+Benazepril), and accepted corresponding drugs for 8 weeks respectively. Another normal group were used as control group, fed with normal diet, no drug intervention. The levels of fasting blood glucose (FBG), serum superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), IL-6 and TNF-α were tested. The ERS signaling molecules glucose-regulated protein 78 (GRP78) and c-Jun N-terminal kinases (JNK) mRNA transcription level in thoracic aorta vessel were determined by reverse-transcription polymerase chain reaction (RT-PCR). Results: Compared with model group, After drugs intervention, all administered groups could significantly decrease FPG (P

An atmospheric pressure chemical ionization liquid chromatographic-mass spectrometric (APCI-LC-MS) LC-MS assay is presented for fast and reliable screening and identification as well as precise and sensitive quantification of oral antidiabetics of the sulfonylurea-type (OADs) in plasma. It allowed the specific diagnosis of an overdose situation or a Munchausen syndrome caused by ingestion of OADs. After liquid-liquid extraction, the OADs glibenclamide, glibornuride, gliclazide, glimepiride, glipizide, gliquidone, glisoxepide, tolazamide and tolbutamide were separated using fast gradient elution. After screening and identification in the scan mode using our new LC-MS library, the OADs were quantified in the selected-ion mode. The quantification assay was validated according to the criteria established by the Journal of Chromatography B. All validation data were inside the required limits. The assay is part of a general LC-MS procedure for fast screening, identification and quantification of different toxicologically relevant compounds in plasma and has proven to be appropriate for OADs.

Aims/hypothesis. Vascular complications observed in diabetes are often related to altered platelet functions. The most widely used hypoglycaemic drugs for treating Type II (non-insulin-dependent) diabetes mellitus are sulphonylurea derivatives. The purposes of this study were to evaluate the inhibitory effects of hypoglycaemic agents on platelet aggregation, to measure their lipophilicity and identify their structural parameters which assess their antiaggregatory activity. Methods. An antiaggregatory test in vitro was carried out for 13 sulphonylurea derivatives. Aggregation of platelets, incubated with the agents at concentrations varying from 7.5 to 480 μmol/l, was induced by 10 μmol/l ADP. Drug lipophilicity parameter, log kw, was measured by gradient HPLC and the agents were subjected to molecular modelling. Results. The most pronounced inhibition of platelet aggregation was by glimepiride, gliclazide, gliquidone, glibenclamide and compound 2A. The IC25 values were 15.9, 18.6, 20.4, 28.5 and 34.7 μmol/l, respectively. Quantitative structure-activity relationships indicate that antiaggregatory activity is mainly affected by electronic and not by lipophilic properties of the agents. Conclusion/interpretation. Glimepiride appeared to be a more potent ADP-induced platelet aggregation inhibitor in vitro than gliclazide. Antiaggregatory activity was shown for gliquidone and confirmed for glibenclamide. The QSAR analysis supports the hypothesis of a free radical mechanism of action of sulphonylurea derivatives previously suggested for gliclazide.

Aims Sulfonylurea drugs exert an insulinotropic effect through ATP-sensitive potassium (K ATP ) channel inhibition in pancreatic islet cells. These channels are also expressed in cardiomyocytes and vascular smooth muscle cells (VSMCs), suggesting potential for adverse cardiovascular effects. We evaluated the effects of Gliquidone (Glq) on sulfonylurea receptors in HIT-T15 cells (SUR1), cardiomyocytes (SUR2A), and VSMCs (SUR2B). Methods The concentration-dependent effects of Glq (0.001–500 μM) on K ATP channels were assessed using whole-cell patch clamp in HIT-T15 cells, rat cardiomyocytes, and VSMCs. Parallel studies using Glibenclamide (Glb) (0.001–10 μM) and Gliclazide (Glc) (0.01–500 μM)were conducted as controls. Results In HIT–T15 cells, Glb exhibited the lowest IC 50 (0.03 μM), as compared to Glq (0.45 μM) and Glc (1.21 μM). However, Glq had higher IC 50 in cardiomyoctes and VSMCs, as compared to Glb (119.1 vs. 0.01 and 149.7 vs . 0.09 μM, respectively), suggesting that Glq is more selective to β-cells than Glb. Thus, Glq may have fewer side effects in cardiomyoctes and VSMCs. Conclusions Glq is a highly selective SUR secretagogue with moderate affinity to β-cells, but low affinity to cardiomyocytes and VSMCs. Our data also reveal the non-selective nature of Glb, as evidenced by high binding affinity to K ATP channels in all the three cell types examined.

The aim of this study was to investigate the effect of administering Glurenorm (gliquidone, 10 mg/kg) on the lenses and skins of streptozotocin-induced diabetic rats. The drug was given to both diabetic and control rats daily, until the end of the experiment, at day 42. The drug was administered to one diabetic and one control group from day 0 and for the other diabetic and control groups from day 14. On day 42, cardiac blood samples, skin samples, and lenses were taken from each rat. Blood glucose (BG) was measured by the o-toluidine method. The total protein, nonenzymatic glycosylation of proteins (NEG), lipid peroxidation (LPO), and glutathione (GSH) levels in the lens and skin homogenates were determined by the Lowry, thiobarbituric acid, Ledwozwy, and Ellman methods, respectively. Laemmli SDS polyacrylamide gel electrophoresis was also carried out on the lens or skin homogenates. After 42 d, Glurenorm given to the diabetic rats produced (i) significant reductions in BG, NEG, and total protein in the lenses; (ii) significant increases in GSH levels in the lenses; (iii) and no significant results in the skin. The body weights of the drug group dropped relative to day 0, but not significantly. SDS polyacrylamide gel electrophoresis revealed no significant differences in any of the protein bands between any of the groups. In the lenses, the gains in turns of reduced NEG and increased GSH may have been offset by the reduction in protein.

A HPLC method has been developed for determination of gliquidone in rat plasma. The assay involves combined extraction and precipitation with 1:1 methanol-acetonitrile, and separation of the analyte on a Shimpack ODS (C18) column with 75:25 (v/v) acetonitrile-0.1 M acetic acid as mobile phase. Detection at 229 nm was by photodiode-array detection. The assay was validated in accordance with international requirements and found to be specific, accurate and precise with a linearity range from 50 ng mL−1 to 10μg mL−1. The method was suitable for conducting pharmacokinetic studies in rats.

Sulfonylurea compounds are commonly used to treat type 2 diabetes mellitus. The case of an old alcoholic addicted diabetic patient treated with gliquidone developing recurrent and prolonged hypoglycaemias refractory to dextrose administration is related. According to the emergency literature, the use of octreotide in sulfonyurea-induced hypoglycaemia refractory to dextrose administration is related to overdoses of SUA. Use of octreotide with our patient allowed stabilization of the glycaemia.

In this double-masked study, we compared the effects of 2 sulfonylureas—gliquidone (Gd) and glibenclamide (Gl)—on metabolic control and on the interaction of insulin with its receptor. After a 3-week run-in period, 43 untreated patients with type 2 diabetes mellitus, aged 47 to 60 years, were randomly allocated to receive treatment with Gd (n = 22) or Gl (n = 21) for 4 months. Fasting plasma glucose levels decreased similarly in both treatment groups after 4 days and 4 months of treatment. After 4 months of treatment, a superimposable decrease in glycosylated hemoglobin A 1c concentrations was seen compared with baseline values (Gd, 7.9 ± 1.4% vs 6.5 ± 0.6%; Gl, 7.6 ± 1.5% vs 6.4 ± 0.9%). No significant changes were noted between treatment groups in body weight or in lipid or leptin levels. Total cell-associated insulin (TCAI) to monocytes increased significantly in the Gd group after 4 days and after 4 months compared with baseline (baseline, 2.13 ± 0.9%; 4 days, 3.14 ± 1.1%; 4 months, 4.33 ± 0.8%; P P P P P

1. The effect of intracerebroventricular (i.c.v.) administration of different potassium channel blockers (tetraethylammonium, apamin, charybdotoxin, gliquidone), potassium channel openers (pinacidil, minoxidil, cromakalim) and aODN to mKv1.1 on immobility time was evaluated in the mouse forced swimming test, an animal model of depression. 2. Tetraethylammonium (TEA; 5 microg per mouse i.c.v.), apamin (3 ng per mouse i.c.v.), charybdotoxin (1 microg per mouse i.c.v.) and gliquidone (6 microg per mouse i.c.v.) administered 20 min before the test produced anti-immobility comparable to that induced by the tricyclic antidepressants amitriptyline (15 mg kg(-1) s.c.) and imipramine (30 mg kg(-1) s.c.). 3. By contrast pinacidil (10-20 microg per mouse i.c.v.), minoxidil (10-20 microg per mouse i.c.v.) and cromakalim (20-30 microg per mouse i.c.v.) increased immobility time when administered in the same experimental conditions. 4. Repeated administration of an antisense oligonucleotide (aODN) to the mKv1.1 gene (1 and 3 nmol per single i.c.v. injection) produced a dose-dependent increase in immobility time of mice 72 h after the last injection. At day 7, the increasing effect produced by aODN disappeared. A degenerate mKv1.1 oligonucleotide (dODN), used as control, did not produce any effect in comparison with saline- and vector-treated mice. 5. At the highest effective dose, potassium channels modulators and the mKv1.1 aODN did not impair motor coordination, as revealed by the rota rod test, nor did they modify spontaneous motility as revealed by the Animex apparatus. 6. These results suggest that modulation of potassium channels plays an important role in the regulation of immobility time in the mouse forced swimming test.

1. The effect of i.c.v. administration of different potassium channel openers (minoxidil, pinacidil, cromakalim) and potassium channel blockers (tetraethylammonium, apamin, charybdotoxin, gliquidone, glibenclamide) on memory processes was evaluated in the mouse passive avoidance test. 2. The administration of minoxidil (10 microg per mouse i.c.v.), pinacidil (5-25 microg per mouse i.c.v.) and cromakalim (10-25 microg per mouse i.c.v.) immediately after the training session produced an amnesic effect. 3. Tetraethylammonium (TEA; 1-5 microg per mouse i.c.v.), apamin (10 ng per mouse i.c.v.), charybdotoxin (1 microg per mouse i.c.v.), gliquidone (3 microg per mouse i.c.v.) and glibenclamide (1 microg per mouse i.c.v.), administered 20 min before the training session, prevented the potassium channel opener-induced amnesia. 4. At the highest effective doses, none of the drugs impaired motor coordination, as revealed by the rota rod test, or modified spontaneous motility and inspection activity, as revealed by the hole board test. 5. These results suggest that the modulation of potassium channels plays an important role in the regulation of memory processes. On this basis, the potassium channel blockers could be useful in the treatment of cognitive deficits.

The influence of different sulfonylureas on the rate of acid and pepsinogen secretion was studied in isolated rabbit gastric glands. Neither tolbutamide (10-500 microM), chlorpropamide (10-500 microM), glibenclamide (1-50 microM) nor glipizide (1-50 microM) exerted a secretory effect. In contrast, gliquidone caused a marked and dose-dependent stimulation of acid production in gastric glands incubated under basal conditions and potentiated the stimulatory effect of both histamine and carbachol. Gliquidone also increased the rate of pepsinogen release in gastric glands incubated either under basal conditions or in the presence of cholecystokinin-octapeptide or isoproterenol. The secretory effects of gliquidone were associated with a significant increase in the glandular content of cyclic AMP, caused by a competitive inhibition of low-Km cyclic AMP phosphodiesterase. Our results indicate that, among the assayed sulfonylureas, only gliquidone, in the micromolar range, stimulates acid and pepsinogen secretion through a cyclic AMP-dependent mechanism.

A method is described for the separation, identification and quantification of six sulfonylureas in serum by liquid chromatography/mass spectrometry with atmospheric-pressure chemical-ionization (APCI LC/MS). The sample pretreatment is based on single-step liquid-liquid extraction, using the 4-methylcyclohexyl analogue of glibenclamide as internal standard. Carbutamide and tolbutamide have been chosen as representative sulfonylureas of the first generation and glipizide, glibornuride, glibenclamide and gliquidone as those of the second generation, widely used in the treatment of diabetes mellitus. This method allows a screening of these sulfonylureas in serum and subsequently the quantification of the serum level in one run of measurement. Accuracy, precision, specificity and sensitivity for each sulfonylurea are presented and discussed.

The monoethyl, monopropyl and monoisopropyl esters of succinic acid, administered intravenously at the dose of 2 micromol/g body weight, were found to increase the insulinotropic action of gliquidone (0.2 nmol/g body weight) in anaesthetized rats. The monoisopropyl ester of succinic acid also doubled the hypoglycemic action of gliquidone. These findings indicate that it is possible to design esters of succinic acid that are devoid of the risk of generating methanol by intracellular hydrolysis, and yet susceptible to increase both the insulinotropic and hypoglycemic responses to antidiabetic agents.