Influence of nicorandil on the pharmacodynamics and pharmacokinetics of gliclazide in rats and rabbits

Exploring the role of ATP-sensitive potassium channel, eNOS, and P-glycoprotein in mediating the hepatoprotective activity of nicorandil in methotrexate-induced liver injury in rats

BACKGROUND

Methotrexate (MTX) is a commonly used chemotherapeutic agent; however, its clinical use is challenged by various types of injuries, including hepatotoxic side effects. Therefore, finding new protective drugs against MTX-induced toxicities is a critical need. Moreover, the different mechanisms mediating such effects are still not clear. The current study aimed to evaluate the possible ameliorative action of nicorandil (NIC) in MTX-induced hepatotoxicity and examine the roles of the ATP-sensitive potassium channel (KATP), endothelial nitric oxide synthase (eNOS), and P-glycoprotein (P-gp).

MATERIALS AND METHODS

Thirty-six male Wistar albino rats were used. NIC (3 mg/kg/day) was given orally for 2 weeks, and hepatotoxicity was induced by a single intraperitoneal injection of MTX (20 mg/kg) on the 11th day of the experiment. We confirmed the role of KATP by co-administering glimepiride (GP) (10 mg/kg/day) 30 min before NIC. The measured serum biomarkers were [alanine transaminase (ALT) and aspartate transaminase (AST)], total antioxidant capacity (TAC), malondialdehyde (MDA), nitric oxide (NOx), tumor necrosis factor-alpha (TNFα), superoxide dismutase (SOD), and P-gp. Histopathology, eNOS, and caspase-3 immunoexpression were evaluated.

RESULTS

The MTX group displayed hepatotoxicity in the form of elevations of ALT, AST, MDA, NOx, and caspase-3 immunoexpression. Furthermore, the histopathological examination showed marked liver injury. TAC, SOD, P-gp, and eNOS immunoexpression showed significant inhibition. In the protective group, all parameters improved (P value < 0.05).

CONCLUSION

NIC has an ameliorative action against MTX-induced hepatotoxicity, most probably via its antioxidant, anti-inflammatory, and anti-apoptotic functions together with the modulation of the KATP channel, eNOS, and P-glycoprotein.

Gliclazide in Binary and Ternary Systems Improves Physicochemical Properties, Bioactivity, and Antioxidant Activity

The poor solubility of the antidiabetic drug gliclazide (Glc) is due to its hydrophobic nature. This research is aimed at improving Glc's solubility and drug release profile, as well as at investigating additional benefits such as bioactivity and antioxidant activity, by forming binary complexes with HPβCD at different w/w ratios (1 : 1, 1 : 2.5, 1 : 4, and 1 : 9) and ternary complexes with HPβCD and Tryp at 1 : 1 : 1, 1 : 1 : 0.27, 1 : 2.5 : 0.27, 1 : 3.6 : 3.6, 1 : 4 : 1, and 1 : 9 : 1, respectively. Complexes were prepared by the physical mixing (PM) and solvent evaporation (SE) methods. The prepared inclusion complexes were meticulously characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra. To verify our findings, the inclusion complexes were evaluated by equilibrium solubility, in vitro drug release profile, kinetic models, and antidiabetic and antioxidant activities in animal models. Our results demonstrated that the solubility and drug release profile were found to be enhanced through binary as well as ternary complexes. Notably, ternary complexes with a ratio of 1 : 9 : 1 showed the highest solubility and drug release profile compared to all other preparations. Data on antioxidant activity indicated that the ternary complex had the higher total antioxidant status (TAS), superoxide dismutase (SOD), and catalase (CAT) activity than the binary complex and Glc alone, in contrast to the diabetic group. In vivo antidiabetic activity data revealed a high percentage reduction in the blood glucose level by ternary complexes (49-52%) compared to the binary complexes (45-46%; p ≤ 0.05). HPβCD and Tryp provide a new platform for overcoming the challenges associated with poorly soluble Glc by providing greater complexing and solubilizing capabilities and imparting ancillary benefits to improve the drug's antidiabetic and antioxidant activities.

Effect of C. cyminum and L. sativum on Pharmacokinetics and Pharmacodynamics of Antidiabetic Drug Gliclazide

BACKGROUND

Numerous herbs are reported to have anti-hyperglycemic activity and are frequently used in combination with prescription drugs to lower the blood glucose levels in diabetic patients, without proper knowledge about the possibility of herb-drug interaction.

OBJECTIVES

To investigate the effect of cumin and garden cress on pharmacokinetics (PK) and pharmacodynamics (PD) of gliclazide (GLZ) in nicotinamide-streptozotocin diabetic model.

METHODS

Diabetic animals of groups II-IV were treated with GLZ, cumin, 'cumin + GLZ', garden cress and 'garden cress + GLZ'. Herb's treatments were given for two weeks, and GLZ was administered in a single dose. Blood glucose levels (BGLs) were measured at pre-determined time points. Plasma samples of pharmacokinetic study were analyzed using UPLC-MS/MS. GLZ fragment at m/z 324.1>127 was monitored.

RESULTS

Cumin and garden cress have shown 15.3% and 15.9% reduction in mean BGL (1-24h) (p-value < 0.001), respectively. GLZ reduced mean BGL by 30.0%, which was significantly better than cumin and garden cress (pvalue <0.05). Concurrently administered "garden cress + GLZ" demonstrated the highest reduction in mean BGL (by 40.46%) and showed a prolonged effect. There was no significant advantage of simultaneously administered 'cumin + GLZ'. Cumin did not affect PK of GLZ. Garden cress has significantly enhanced AUC_0-t (by 69.8%, pvalue 0.0013), but other PK parameters C_max, T_max, and Kel were close to the control group.

CONCLUSION

PK/PD-based herb-drug interaction was observed. Concurrently administered garden cress + GLZ showed improved antidiabetic effect and has enhanced GLZ bioavailability.

Nicorandil prevents the nephrotoxic effect of cyclosporine-A in albino rats through modulation of HIF-1α/VEGF/eNOS signaling

Despite that cyclosporine-A (CsA) is a widely used immunosuppressive drug, its nephrotoxic effect limits its long-term administration. Herein we tried to investigate its renal effect on endothelial dysfunction targeting the hypoxia-inducible factor (HIF-1α) / vascular endothelial growth factor (VEGF) / endothelial nitric oxide synthase (eNOS) pathway and the possible modulation by nicorandil. Eight groups of adult male Wistar rats were included: (1) control; (2) vehicle group (received oil); (3) glibenclamide 5 mg·kg-1·day-1 administered orally; (4) nicorandil 10 mg·kg-1·day-1 administered orally; (5) CsA 25 mg·kg-1·day-1 administered orally; (6) combined administration of CsA and nicorandil; (7) glibenclamide was added to CsA; and (8) both CsA and nicorandil were combined with glibenclamide. The treatment continued for six weeks. Combined nicorandil with CsA improved renal function deterioration initiated by CsA. CsA decreased the renal expression levels (P < 0.001) of HIF-1α, eNOS, and VEGF, inducing endothelial dysfunction and triggering inflammation, and upregulated the profibrotic marker transforming growth factor (TGF-β). Nicorandil fixed the disturbed HIF-1α/VEGF/eNOS signaling. Nicorandil corrected the renal functions, confirmed by the improved histological glomerular tuft retraction that was obvious in the CsA group, without significant influence by glibenclamide. Proper protection from CsA-induced nephrotoxicity was achieved by nicorandil. Nicorandil reversed the disturbed HIF-1α/VEGF/eNOS pathway created by CsA.

Population pharmacokinetics of gliclazide in normal and diabetic rabbits

Gliclazide is a second-generation sulphonylurea drug widely used in the treatment of type 2 diabetes. However, there is no single report to describe the population pharmacokinetics of gliclazide in animal models. This study was aimed to evaluate the population pharmacokinetics (PK) of gliclazide in normal and alloxan-induced diabetic rabbits using nonlinear mixed effects modeling. A total of 90 New Zealand white rabbits were administered with three doses (4.13, 8.27 and 16.53 mg/kg b.wt) of gliclazide by an oral route. Blood samples were collected up to 24 hr and the gliclazide concentrations in rabbit were determined using the HPLC method. The non-compartmental and classical compartmental PK analyses were performed using Phoenix WinNonlin. Population PK analysis of gliclazide was performed using nonlinear mixed-effects model software NONMEM and Phoenix NLME considering the weight, age, sex, health and dose as covariates. The final population values for clearance (CL), volume of distribution (V) and the absorption rate constant (k_a ) were 5270 ml/hr, 55700 ml and 0.708 hr^-1 , respectively. The inter-individual variability in gliclazide CL, V and k_a was 16.3%, 14.9% and 26.5%, respectively. There was no significant difference between NONMEM and Phoenix NLME pharmacokinetic results. The visual predictive check and bootstrap analysis confirmed the predictive ability, model stability and precision of the parameter estimates from this model. This population PK model demonstrated that gliclazide pharmacokinetics is best described by one-compartment model with first-order absorption in rabbits. Body weight is a covariate that significantly influences gliclazide kinetic disposition in rabbits.

Influence of aprepitant on the pharmacodynamics and pharmacokinetics of gliclazide in rats and rabbits

Background

Concomitant drug administration is a general phenomenon in patients with chronic diseases such as diabetes mellitus. Among the currently available oral antidiabetic drugs, gliclazide is a commonly prescribed drug considering its multiple benefits in diabetic patients. Aprepitant is a commonly prescribed antiemetic drug which is mainly metabolized by CYP3A4, reported to have modest inductive and inhibitory effects on CYP2C9 and CYP3A4, respectively. Since gliclazide is metabolized by CYP2C9 (major) and CYP3A4 (minor), it is very difficult to predict the influence of aprepitant and its metabolic interaction with gliclazide. Considering the complexity associated with the combination of aprepitant and gliclazide, this study was designed to evaluate the influence of aprepitant on the pharmacodynamics (PD) and pharmacokinetics (PK) of gliclazide in animal models.

Methods

The PD interaction studies were conducted in both rodent (normal and alloxan-induced diabetic rats) and non-rodent (rabbits) animal models (n = 6) while the PK interaction study was conducted in normal rabbits (n = 6). An extrapolated human therapeutic oral dose of gliclazide, aprepitant and their combination were administered to rats and rabbits with 7 days washout between each treatment. For the multiple-dose interaction study, the same groups were administered with an interacting drug (aprepitant) for 7 days and then the combination of aprepitant and gliclazide on the 8th day. From the collected animal blood samples, blood glucose (by Glucose-Oxidase/Peroxidase method), insulin (by ELISA method) and gliclazide concentration levels (by HPLC method) were determined. Non-compartmental PK analysis was conducted by Phoenix WinNonlin software to determine the PK parameters of gliclazide. Statistical analysis was performed by student’s paired t-test.

Results

The pharmacodynamic activity (blood glucose reduction and insulin levels) of gliclazide was significantly (p < 0.05) influenced by aprepitant in normal and diabetic condition without any convulsions in animals. There was a significant (p < 0.05) increase in concentration levels and Area Under the Curve of gliclazide while significant (p < 0.05) decrease in clearance levels of gliclazide in rabbits. The PK interaction with gliclazide is relatively more with the multiple dose treatment of aprepitant over single dose treatment.

Conclusion

In combination, aprepitant significantly influenced the pharmacodynamic activity of gliclazide in animal models. Considering this, care should be taken when this combination is prescribed for the clinical benefit in diabetic patients.

Interaction of p-synephrine on the pharmacodynamics and pharmacokinetics of gliclazide in animal models

Background

Type 2 diabetes is frequently seen in patients suffering from obesity. p-synephrine and gliclazide are widely used medicines for the treatment of obesity and diabetes, respectively.

Objectives

The present study was undertaken to determine the potential for interactions between p-synephrine and gliclazide, based on the relationship between obesity and diabetes.

Methods

Influence of p-synephrine on the activity of gliclazide was determined by conducting single and multiple dose interaction studies in animal models. Blood samples collected at pre-determined time intervals from experimental animals were used for the estimation of glucose and insulin levels. The insulin resistance and β-cell function were determined by homeostasis model assessment. Additionally, serum gliclazide levels in rabbits were analyzed by high-performance liquid chromatography (HPLC).

Results

Gliclazide alone showed peak reduction in blood glucose levels at 2 and 8 h after administration in rats and after 3 h in rabbits. The activity of gliclazide was not altered by a single dose treatment with p-synephrine. However, in multiple dose interaction studies, samples from all the time points analyzed showed significant changes in percent blood glucose reduction ranging from 19.73 to 44.18% in normal rats, 23.76–46.43% in diabetic rats and 16.36–38.34% in normal rabbits. The homeostasis model assessment parameters were also significantly altered in multiple dose interaction studies. The pharmacokinetics of gliclazide was not altered by either single or multiple dose p-synephrine treatments in rabbits.

Conclusion

The effect of multiple dose p-synephrine treatments upon gliclazide appeared to be pharmacodynamic in nature, indicating the need for periodic monitoring of glucose levels and dose adjustment as necessary when this combination is prescribed to obese patients.

Influence of curcumin on the pharmacodynamics and pharmacokinetics of gliclazide in animal models

Purpose

Patients suffering from obesity-related diseases use multiple prescription drugs to control their condition, and it is therefore essential to determine the safety and efficacy of any combination. Gliclazide is one of the most commonly used drug of choice for treatment of type 2 diabetes, and curcumin is a widely used herbal supplement to counter obesity condition. The objective of this study was to investigate the effect of oral administration of curcumin on pharmacodynamics and pharmacokinetics of gliclazide in rats and rabbits to further evaluate the safety and effectiveness of this combination.

Methods

Influence of curcumin on the activity of gliclazide was determined by conducting single- and multiple-dose interaction studies in rats (normal and diabetic) and rabbits. Blood samples collected at predetermined time intervals from experimental animals were used for the estimation of glucose and insulin levels by using automated clinical chemistry analyzer and radioimmunoassay method, respectively. The insulin resistance and β-cell function were determined by homeostasis model assessment. Additionally, serum gliclazide levels in rabbits were analyzed by high-performance liquid chromatography.

Results

Gliclazide showed peak reduction in blood glucose levels at 2 and 8 hours in rats and at 3 hours in rabbits. This activity of gliclazide was not altered by single-dose treatment with curcumin. However, in multiple-dose interaction studies, samples analyzed from all time points showed subtle but significantly greater reduction in percent blood glucose ranging from 23.38% to 42.36% in normal rats, 27.63% to 42.27% in diabetic rats, and 16.50% to 37.88% in rabbits. The pharmacokinetics of gliclazide was not altered by single- or multiple-dose curcumin treatments in rabbits.

Conclusion

The interaction of curcumin with gliclazide up on multiple-dose treatment was pharmacodynamic in nature, indicating the need for periodic monitoring of glucose levels and dose adjustment as necessary when this combination is prescribed to obese patients.

Effects of Thymoquinone on the Pharmacokinetics and Pharmacodynamics of Glibenclamide in a Rat Model

Glibenclamide and thymoquinone plasma concentrations were analysed using a sensitive RP-HPLC method, and non-compartmental model pharmacokinetic parameters were calculated. The maximum reduction in blood glucose level was observed 3 hours following glibenclamide administration, which reached 47.4% of baseline, whereas it was reduced by 53.0% to 56.2% when co-administrated with thymoquinone. Plasma concentration of glibenclamide was increased by 13.4% and 21.8% by the co-administration of thymoquinone as single and multiple doses, respectively ( P<0.05). The AUC and T1/2 of glibenclamide were also increased respectively by 32.0% and 17.4% with a thymoquinone single dose, and by 52.5% and 92.8% after chronic treatment. Furthermore, diabetic rats treated with thymoquinone demonstrated a marked decrease in hepatic protein expressions of CYP3A2 and CYP2C11 enzymes that are responsible for the metabolism of glibenclamide. The current data suggest that thymoquinone exhibits a synergistic effect with glibenclamide on glucose level, which could be explained by reducing CYP450 activity at the protein level.

In vivo and in vitro attenuation of naloxone-precipitated experimental opioid withdrawal syndrome by insulin and selective KATP channel modulator

RATIONALE

Opiate exposure for longer duration develops state of dependence in humans and animals, which is revealed by signs and symptoms of withdrawal precipitated by opioid receptor antagonists. The sudden withdrawal of opioids produces a withdrawal syndrome in opioid-dependent subjects. Insulin and ATP-sensitive potassium (KATP) channel-mediated glucose homeostasis have been shown to modulate morphine withdrawal.

OBJECTIVE

Present study has been structured to investigate the role of insulin and pharmacological modulator of KATP channel (gliclazide) in experimental morphine withdrawal syndrome, both invivo and invitro.

METHODS

In this study, naloxone-precipitated morphine withdrawal syndrome in mice (invivo) as well as in rat ileum (invitro) were utilized to assess opioid withdrawal phenomenon. Morphine withdrawal syndromes like jumping and rearing frequency, forepaw licking, circling, fore paw tremor, wet dog shake, sneezing, overall morphine withdrawal severity (OMWS), serum glucose, brain malondialdehyde (MDA), glutathione (GSH), nitrite/nitrate, and calcium (Ca(+2)) were assessed.

RESULTS

Naloxone has significantly increased morphine withdrawal syndrome, both invivo and invitro. Insulin and gliclazide have significantly attenuated, naloxone induced behavioral changes like jumping and rearing frequency, forepaw licking, wet dog shake, sneezing, straightening, circling, OMWS, and various biochemical impairments such as serum glucose, brain MDA, GSH, nitrite/nitrate, and Ca(+2) in morphine-dependent animals (invivo). In vitro, insulin and gliclazide have significantly reduced naloxone-induced contraction in morphine-withdrawn rat ileum preparation.

CONCLUSIONS

Insulin and gliclazide (KATP channel blocker) have attenuated naloxone-precipitated morphine withdrawal syndrome, both invivo and invitro. Thus, insulin and KATP channel modulation may provide new avenues for research in morphine withdrawal.

Influence of atorvastatin on the pharmacodynamic and pharmacokinetic activity of repaglinide in rats and rabbits

Dyslipidemia is common in patients with type 2 diabetes. Statins are used as the first choice in treatment of diabetic dyslipidemia. Atorvastatin represents a first-line treatment option, alongside other hydroxyl methylglutaryl coenzyme A reductase inhibitors. Repaglinide is a short-acting, oral, insulin secretagogue that is used in the treatment of type 2 diabetes mellitus. Both the category of drugs undergo extensive metabolism with cytochrome enzyme system. This may lead to drug-drug interaction problems with altered repaglinide activity which is cautious. Repaglinide/atorvastatin/atorvastatin + repaglinide were administered orally to normal, diabetic rats, and to normal rabbits. Blood samples were collected at different time intervals and were analyzed for blood glucose by GOD-POD method using commercial glucose kits and repaglinide estimation in plasma by HPLC method. Diabetes was induced by alloxan 100 mg/kg body weight administered by I.P route. In the presence of atorvastatin, repaglinide activity was increased and maintained for longer period in diabetic rats compared with repaglinide matching control. The present study concludes co-administration of atorvastatin was found to improve repaglinide responses significantly in diabetic rats and improved glucose metabolism of atorvastatin played an important role and increased repaglinide levels by competitive CYP 3A4 enzyme inhibition by atorvastatin could be added advantage for anti hyperglycemic activity.

Design and development of gliclazide-loaded chitosan microparticles for oral sustained drug delivery: in-vitro/in-vivo evaluation

Objectives

The objective of this study was to prepare gliclazide–chitosan microparticles with tripolyphosphate by ionic crosslinking.

Methods

Chitosan microparticles were produced by emulsification and ionotropic gelation. The effects of process variables including chitosan concentration, pH of tripolyphosphate solution, glutaraldehyde volume and release modifier agent such as pectin added to the tripolyphosphate crosslinking solution were evaluated. The microparticles were examined with scanning electron microscopy, infrared spectroscopy and differential scanning colorimetry. The serum glucose lowering effect of gliclazide microparticles was studied in streptozotocin-diabetic rabbits compared with the effect of pure gliclazide powder and gliclazide commercial tablets.

Key findings

The particle sizes of tripolyphosphate–chitosan microparticles were over the range 675–887 µm and the loading efficiency of drug was greater than 94.0%. In-vivo testing of the gliclazide–chitosan microparticles in diabetic rabbits demonstrated a significant antidiabetic effect of gliclazide–chitosan microparticles after 8 h that lasted for 18 h compared with gliclazide powder, which produced a maximum hypoglycaemic effect after 4 h.

Conclusions

The results suggests that gliclazide–chitosan microparticles are a valuable system for the sustained delivery of gliclazide.

Influence of non-nucleoside reverse transcriptase inhibitors (efavirenz and nevirapine) on the pharmacodynamic activity of gliclazide in animal models

BACKGROUND

Type 2 diabetes may occur as a result of HIV infection and/or its treatment. Gliclazide is a widely used drug for the treatment of type 2 diabetes. Efavirenz and nevirapine are widely used non-nucleoside reverse transcriptase inhibitors for the treatment of HIV infection. The role of Efavirenz and nevirapine on the pharmacodynamic activity of gliclazide is not currently known. The objective of this study was to examine the effect of oral administration of efavirenz and nevirapine on blood glucose and investigate their effect on the activity of gliclazide in rats (normal and diabetic) and rabbits to evaluate the safety and effectiveness of the combination.

METHODS

Studies in normal and alloxan induced diabetic rats were conducted with oral doses of 2 mg/kg bd. wt. of gliclazide, 54 mg/kg bd. wt. of efavirenz or 18 mg/kg bd. wt. of nevirapine and their combination with adequate washout periods in between treatments. Studies in normal rabbits were conducted with 5.6 mg/1.5 kg bd. wt. of gliclazide, 42 mg/1.5 kg bd. wt. of efavirenz or 14 mg/1.5 kg bd. wt. of nevirapine and their combination given orally. Blood samples were collected at regular time intervals in rats from retro orbital puncture and by marginal ear vein puncture in rabbits. All the blood samples were analysed for blood glucose by GOD/POD method.

RESULTS

Efavirenz and nevirapine alone have no significant effect on the blood glucose level in rats and rabbits. Gliclazide produced hypoglycaemic/antidiabetic activity in normal and diabetic rats with peak activity at 2 h and 8 h and hypoglycaemic activity in normal rabbits at 3 h. In combination, efavirenz reduced the effect of gliclazide in rats and rabbits, and the reduction was more significant with the single dose administration of efavirenz than multiple dose administration. In combination, nevirapine has no effect on the activity of gliclazide in rats and rabbits.

CONCLUSION

Thus, it can be concluded that the combination of efavirenz and gliclazide may need dose adjustment and care should be taken when the combination is prescribed for their clinical benefit in diabetic patients. The combination of nevirapine and gliclazide was safe. However, further studies are warranted.

Design and development of gliclazide mucoadhesive microcapsules: in vitro and in vivo evaluation

In this study an attempt was made to prepare mucoadhesive microcapsules of gliclazide using various mucoadhesive polymers designed for oral controlled release. Gliclazide microcapsules were prepared using sodium alginate and mucoadhesive polymer such as sodium carboxymethyl cellulose (sodium CMC), carbopol 934P or hydroxy propylmethyl cellulose (HPMC) by orifice-ionic gelation method. The microcapsules were evaluated for surface morphology and particle shape by scanning electron microscope. Microcapsules were also evaluated for their microencapsulation efficiency, in vitro wash-off mucoadhesion test, in vitro drug release and in vivo study. The microcapsules were discrete, spherical and free flowing. The microencapsulation efficiency was in the range of 65-80% and microcapsules exhibited good mucoadhesive property in the in vitro wash off test. The percentage of microcapsules adhering to tissue at pH 7.4 after 6 h varied from 12-32%, whereas the percentage of microcapsules adhering to tissue at pH 1.2 after 6 h varied from 35-68%. The drug release was also found to be slow and extended for more than 16 h. In vivo testing of the mucoadhesive microcapsules in diabetic albino rats demonstrated significant antidiabetic effect of gliclazide. The hypoglycemic effect obtained by mucoadhesive microcapsules was for more than 16 h whereas gliclazide produced an antidiabetic effect for only 10 h suggesting that mucoadhesive microcapsules are a valuable system for the long term delivery of gliclazide.