Changes in liver tests during 1-year treatment of patients with Type 2 diabetes with pioglitazone, metformin or gliclazide

AIMS

Patients with Type 2 diabetes are at increased risk of liver damage. Therefore, it is of particular importance to investigate the hepatic effects of drugs used to treat such patients.

METHODS

Liver testing results performed in four 1-year, randomized, double-blind studies comparing effects of pioglitazone, metformin or a sulphonylurea, gliclazide, in the treatment of over 3700 patients with Type 2 diabetes have been analysed.

RESULTS

Pioglitazone caused reductions in mean levels of hepatic enzymes of between 3 and 18%, whilst gliclazide caused small increases of between 3 and 13%. Metformin treatment showed either small mean increases or decreases. More patients receiving pioglitazone had liver tests within the normal range at the end of treatment (> or = 87%) compared with patients receiving metformin (> or= 80%) or gliclazide (> or = 75%). Slightly fewer patients with pioglitazone than with comparators showed a large increase (> 3 upper limit of normal) in alanine aminotransferase levels at any time during treatment (pioglitazone 0.9%, metformin 1.9%, gliclazide 1.9%).

CONCLUSIONS

During pioglitazone treatment there is a reduction in liver enzyme levels. Although the mechanism of this effect is not clear, the results demonstrate potential beneficial effects on the liver during treatment of patients with Type 2 diabetes with pioglitazone.

Pharmaceutical availability of gliclazide from selected matrix formulation tablets

BACKGROUND

Immediate release and modified release gliclazide formulation tablets are available on the market. We decided to measure the kinetics of gliclazide release from these tablets, and to propose our own technique for producing gliclazide matrix tablets, comparing their release kinetic profile with the gliclazide tablets available on the market.

MATERIAL/METHODS

A BP 2001 dissolution test was performed for selected gliclazide formulation tablets, and the water solubility of authentic gliclazide samples from different manufacturers was determined by UV spectrometry.

RESULTS

Diabezidum (Jelfa) and diabrezide (Molteni) tablets are classic gliclazide oral formulations, releasing the drug very rapidly in vivo and in vitro according to BP 2001 (approximately 99% at 100 min). However, diaprel tablets (Servier) are modified release formulations (67% released in in vitro conditions at 8 h). The matrix tablets (C) produced according to our own formula demonstrated a release profile similar to diaprel tablets. The MDT, calculated in order to classify the tablets we studied, ranged from 4.6 to 76.4 minutes for immediate release (IR) tablets (diabrezide, diabezidum, I and F), and from 279.6 to 701.2 minutes for sustained-release (SR) tablets (E, G, C, diaprel, J, B, D, H, K, A).

CONCLUSIONS

The dissolution process of immediate release gliclazide formulation tablets (diabrezide, diabezidum, F, I) obeys a first-order equation. However, the process for modified release formulation tablets (diaprel, diaprel MR, A, B, C, D G, H, J, K) proceeds according to a zero-order equation.

[Controversial therapeutic strategies in the treatment of type 2 diabetes mellitus]

At the time of the diagnosis insulin resistance is present in the majority of type 2 diabetics. Only in those type 2 diabetics who are of normal weight at diagnosis must a disturbance of insulin secretion be assumed. These pathophysiological facts, discovered in recent years, mandate a differentiated treatment of type 2 diabetics. The primary aim must be the treatment of the insulin resistance. Insulinotropic drugs are indicated only during the further course of the disease. The use of glitazones makes possible a largely causal treatment of insulin resistance. Over the long term better glycemic control is achieved with glitazones rather than sulfonylureas. As a secondary effect, the insulin-producing beta cells are protected, and such cardiovascular risk factors as diabetic dyslipoproteinemia, hypertension or microalbuminuria are favorably influenced.

Gliclazide modified release: results of a 2-year study in patients with type 2 diabetes

AIM

To evaluate the efficacy and safety of gliclazide modified release (MR), alone or combined with other oral antidiabetic drug(s) over 2 years in type 2 diabetic patients.

METHODS

Two consecutive periods: (i) a 10-month, double-blind comparative study, where 800 type 2 diabetic patients were randomized either to gliclazide MR (30-120 mg) once daily or to gliclazide (80-320 mg) twice daily. All the patients were then treated with gliclazide MR for a 2-month switch period; (ii) 549 patients were subsequently enrolled in a 12-month, open-label period on gliclazide MR alone or in combination according to glycaemic control, 507 of whom completed the study.

RESULTS

Glycated haemoglobin (HbA1c) significantly decreased from baseline over 2 years by -0.46 +/- 1.08% in the whole cohort of 2-year completed patients, -0.95% in the subgroup of diet-failed patients and by -0.34% in the subgroup of patients pretreated with one oral antidiabetic drug. HbA1c was reduced by -0.43 +/- 1.02% and by -0.51 +/- 1.16%, when gliclazide MR was used in monotherapy and in combination therapy, respectively. The overall incidence of symptoms suggestive of hypoglycaemia was 4.8 episodes/100 patient-year, with no severe episode. This incidence was similarly low in elderly patients and patients with impaired renal function.

CONCLUSION

Gliclazide MR alone or in combination with another oral antidiabetic drug significantly improved glycaemic control in type 2 diabetic patients over 2 years with a very good safety profile, notably in the elderly and in patients with impaired renal function.

[A prospective randomized study of sulphonylureas therapeutic interchange in patients with type 2 diabetes mellitus]

OBJECTIVE

To clinically assess effectiveness of therapeutic interchange from glibenclamide to gliclazide in the hospital setting.

METHODS

An open-label prospective, randomized study with two groups of patients: a reference group (patients still receiving their previous outpatient regimen of glibenclamide) and an interchange group (patients with gliclazide substituted for glibenclamide according to a hospital-approved interchange protocol). The efficacy endpoint used was blood glucose at 3 and 6 days post-intervention. A patient with blood glucose < 200 mg/L was considered clinically controlled, and blood glucose changes < or > 30 mg/dL were considered significant.

RESULTS

One hundred and sixteen patients were randomized. Blood glucose on the day before the intervention was 177.9 mg/dL +/- 63.4 in the reference group versus 171.3 mg/dL +/- 52.1 in the interchange group (p = 0.92). Mean blood glucose during the first 3 days post-intervention was 156.1 mg/dL +/- 47.5 and 177.7 mg/dL +/- 36.0 (p = 0.14) in the reference and interchange groups, respectively; and mean values for the first 6 days post-intervention were 142.1 mg/dL +/- 36.0 and 172.8 mg/dL +/- 28.2, respectively (p = 0.01). The overall analysis of blood glucose levels showed a better control in the reference group versus baseline values, which was not seen in the interchange group, where blood glucose remained stable and similar to baseline. In no case were 3-day and 6-day blood glucose mean levels above 200 mg/dL, which may be considered acceptable within the hospital setting.

CONCLUSIONS

Therapeutic interchange may be safely performed with no clinical impairment, but better controls were achieved in the reference group.

[Therapy objectives and daily practice--to which extent are blood sugar target values accessible in daily practice?]

The healthcare sector is characterized at present by increasingly ambitious therapeutic objectives and rising healthcare costs. The aim of the Swiss study was to explore ways of achieving these therapeutic objectives in the present healthcare environment via the use of cost-effective antidiabetic agents. With a therapeutic regimen based on gliclazide, it was possible to reduce fasting blood glucose levels to below 7.0 mol/l in 70% of the 94 type 2 diabetics included in the study. Fasting blood glucose levels returned to normal in 80% of the women taking part of the study; the normalization rate was significantly higher in this group than in the study population as a whole. The target HbA1c -value was attained in 7% of both the patient group receiving gliclazide monotherapy and the group receiving gliclazide in combination with metformin. Weight reduction was observed in all the treatment groups. Some 86% of the patients experienced an improvement in life quality as a result of the more effective management of their diabetes. The tolerability of the treatment was very high. A total of two episodes of mild symptomatic hypoglycemia were recorded. The per diem costs of gliclazide-based treatment are in the range of 1-2 Swiss francs.

GUIDE study: double-blind comparison of once-daily gliclazide MR and glimepiride in type 2 diabetic patients

BACKGROUND

Progressive beta-cell failure is a characteristic feature of type 2 diabetes; consequently, beta-cell secretagogues are useful for achieving sufficient glycaemic control. The European GUIDE study is the first large-scale head-to-head comparison of two sulphonylureas designed for once-daily administration used under conditions of everyday clinical practice.

DESIGN

Eight hundred and forty-five type 2 diabetic patients were randomized to either gliclazide modified release (MR) 30-120 mg daily or glimepiride 1-6 mg daily as monotherapy or in combination with their current treatment (metformin or an alpha-glucosidase inhibitor) according to a double-blind, 27-week, parallel-group design. Efficacy was evaluated by HbA1c and safety by hypoglycaemic episodes using the European Agency definition.

RESULTS

HbA1c decreased similarly in both groups from 8.4% to 7.2% on gliclazide MR and from 8.2% to 7.2% on glimepiride. Approximately 50% of the patients achieved HbA1c levels less than 7%, and 25% less than 6.5%. The mean difference between groups of the final HbA1c was -0.06% (noninferiority test P < 0.0001). No hypoglycaemia requiring external assistance occurred. Hypoglycaemia with blood glucose level < 3 mmol L(-1) occurred significantly less frequently (P = 0.003) with gliclazide MR (3.7% of patients) compared with glimepiride (8.9% of patients). The distribution of the sulphonylurea doses was similar in both groups.

CONCLUSIONS

This study provides new insights into therapeutic strategies using sulphonylureas. It shows that gliclazide MR is at least as effective as glimepiride, either as monotherapy or in combination. The safety of gliclazide MR was significantly better, demonstrating approximately 50% fewer confirmed hypoglycaemic episodes in comparison with glimepiride.

Efficacy and safety of once daily gliclazide (20 mg/day) compared with nateglinide

An open-label prospective cross-over trial was performed to compare the efficacy and safety of once daily low-dose gliclazide (20 mg/day) with that of nateglinide at the usual dosage (270 mg/day, 90 mg t.i.d.) in Japanese type 2 diabetics with relatively good glycemic control (HbA1c<7.0%). Eight patients received 20 mg/day of gliclazide and 16 received 270 mg/day of nateglinide. After at least 12 weeks of gliclazide or nateglinide therapy, the drugs were switched and treatment was continued for another 12 weeks. The final HbA1c value was modestly, but significantly, lower after gliclazide treatment than after nateglinide treatment (6.2% vs. 6.4%). However, symptoms related to hypoglycemia were significantly more common with gliclazide treatment than nateglinide treatment (7 vs. 0 cases), although there were no severe hypoglycemic events. While gliclazide acts as a free radical scavenger, there was no effect on parameters of oxidative stress such as malondialdehyde-modified low density lipoprotein and thiobarbituric acid-reactive substances at the low dosage tested. In conclusion, both drugs are reasonable options for early type 2 diabetes. Compared with the regular dose of nateglinide, 20 mg/day of gliclazide achieved modestly better glycemic control with an increased frequency of hypoglycemia in diabetic patients with relatively good glycemic control.

[The efficacy and safety of 30 mg slow-released-gliclazide in type 2 diabetes mellitus]

OBJECTIVE

To evaluate the efficacy and safety profile of a slow-released-gliclazide (Diamicron MR) in type 2 diabetes patients.

METHODS

159 patients with type 2 diabetes were parallelly assigned to a slow-released-gliclazide or gliclazide group in a randomized, open, multi-center phase III study to compare the efficacy of slow-released-gliclazide and gliclazide on overall diabetes control through HbA1c and the adverse events including hypoglycemic episodes and change of vital signs, electrocardiogram and clinical laboratory parameters after a 12-week treatment period.

RESULTS

No statistically significant difference was found in HbA1c levels between the slow-released-gliclazide and the gliclazide group (P = 0.66) after 12 weeks of treatment. HbA1c levels in the slow-released-gliclazide group were extremely close to those in the gliclazide group after 12 weeks of treatment (95% CI -0.15; +0.24%). Furthermore, plasma glucose area under curve/24 hours, mean daily plasma glucose and fasting serum insulin levels between these two groups were also not statistically different, indicating that the efficacy of treatment was similar. The number of patients reported to experience at least one episode of hypoglycemia, which was confirmed by capillary or venous glucose assessment, but by no means severe, was similar in both the treatment groups. The main reason for the hypoglycemic episodes was related to good plasma glucose control. No adverse event led to withdrawal of the medication. Systolic and diastolic blood pressure, heart rate and body weight did not change during the study. There was also no noticeable change in electrocardiogram, lipid profile, and parameters in blood biochemistry and hematologic testing during the study.

CONCLUSION

Slow-released-gliclazide and gliclazide had a similar efficacy and safety profile.

[Compliance and optimisation of oral antidiabetic therapy. A longitudinal study]

OBJECTIVE

To evaluate the impact of optimization of treatment and improvement in observance awareness in patients with type 2 diabetes on compliance with oral antidiabetic drug therapy and long-term glycemic control. Method Evaluation of compliance with oral antidiabetic therapy and of HbA1c levels in a cohort of 4 802 patients with type 2 diabetes followed by their general practitioner, before and after 6 Months on optimized treatment: reduction in percentage of combination treatments from 69.5 to 56.8%, and increase in percentage of once-daily dosing regimen from 12 to 58.4%.

RESULTS

Optimization of treatment led to an increase in the percentage of patients achieving optimal compliance with oral antidiabetic drug therapy from 44 to 69.5% after 6 Months (p<0.001). Metabolic control also improved, as evidenced by a decrease in HbA1c levels observed both in the whole cohort (7.5+/-1.6% to 6.9+/-1.2%; p<0.0005), as well as in individual therapeutic subgroups of patients (having switched from multiple-daily dosing to once-daily-dosing schedules and from gliclazide 80 to gliclazide 30 MR once-daily formulation).

CONCLUSION

These findings suggest that optimization of oral antidiabetic therapy favoring the use of oral antidiabetic agents with once-daily dosing administration modalities may improve metabolic control in patients with type 2 diabetes.

Erosion Induced Controllable Release of Gliclazide Encapsulated Inside Degradable Polymeric Particles

The microphase inversion of water-insoluble poly(L-lactide), "poly[(L-lactide)-co-glycolide] and polylactide-block-poly(ethylene oxide)-block-polylactide from THF to water can result in narrowly distributed stable particles. Gliclazide, a commercial drug, can be encapsulated inside during the process. The formation and degradation of such particles was studied by laser light scattering. In comparison with the corrosion of a bulk material, the degradation of each particle is so fast that we only detect the decrease of the particle number, not the corrosion of individual particles. Therefore, the degradation is a "one-by-one" random process, just like the chemical reaction of molecules in solution. The disappearing rate of the particle number is nearly independent of time, ideal for the controlled release of drugs encapsulated inside. The amount of encapsulated gliclazide depends on the copolymer's hydrophobicity (composition), while the releasing rate mainly is, directly related to the disappearing rate of the particles. The correlation between the fluorescence intensity and the degradation was used to study the kinetics of gliclazide releasing. The releasing pattern is controllable with a proper choice of the drug loading, copolymer composition, pH and temperature.

NIDDM: new once-daily intervention for type 2 diabetes mellitus: Diaprel MR

Pharmacological treatment of hyperglycemia should address to both abnormalities in T2DM treatment, that is reduction of insulin resistance and restoration of normal insulin secretion. Gliclazide is a sulfonylurea compound oral hypoglycemic drug that has a unique feature of restoring the first-phase insulin secretion, which is lost in T2DM being one of the early features of disease.

MATERIAL AND METHOD

Laboratoires Servier conducted in Romania a an open non randomized surveillance on the efficacy and safety of Diaprel MR in type 2 diabetic patients. 199 patients in 14 treatment centers were enrolled. Eligibility criteria were as it follows: men and women with diabetes, previously on diet alone and not treated with other OAD, over 35 years old with FPG (mg/dl) at enrollment between 126 and 180. The clinical trial lasted for 16 weeks. During this period the doctors examined the patients 6 times. First visits were at a 2 weeks interval and the last two visits at a 4 weeks interval. At each visit the doctor renewed the prescription for the subsequent period according to the following protocol: the starting dose was 30 mg Diaprel MR/day, if the FPG (mg/dl) was over 140 (at the next visit) the dosage was increased with 30 mg Diaprel MR/day, if the FPG (mg/dl) was under 140 the dosage remained the same as the previous dosage. The maximum dosage was 120 mg Diaprel MR/day. The following parameters were measured on first and last (seventh) visit: blood pressure (systolic and diastolic), heart rate (bpm), body mass index-BMI (kg/m2), fasting plasma glucose FPG (mg/dl and mmol/l), glycated hemoglobin HbA1c (%) and Hb-Hct (mg/dl-%), creatinine (mg/dl), SGPT (UI/I), cholesterol (mg/dl) and triglycerides (mg/dl). Blood pressure (systolic and diastolic), heart rate, BMI and FPG were measured from the second to sixth visit also. On each visit there was registered other data such as: associated illnesses, concomitant medication and adverse events.

RESULTS

Primary end points. The average values of end points HbA1c (%) and PFG (mg/dl) registered a significant decrease during the 16 weeks of medication, from the enrollment moment (S0) to the last week (S16). The decrease was significant on the total sample of the main analysis group but also on subsamples of age, gender and BMI. HbA1c (%) average values decreased in the main analysis group (S16 compared to S0): with 22% on the total sample (from 7.7 to 6.0); p < 0.05. FPG (mg/dl) average values decreased in the main analysis group (S16 compared to S0): with 21% on the total sample (from 159 to 126); p < 0.05. Secondary end points. There were no significant changes registered in the average level of cholesterol and triglycerides, BMI, diastolic blood pressure, heart rate, creatinine, SGPT. A significant decline of the average systolic blood pressure was registered.

CONCLUSION

Diaprel MR can be used safely in diabetic patients newly diagnosed, uncontrolled on diet or other oral antidiabetic drugs, overweight, safely in those with cardio-vascular disease, or in patients with creatinine clearance 50-80 ml/min.

[Medication of the month. Gliclazide modified release (Uni Diamicron)]

Gliclazide modified release that has been recently launched by Servier (Uni Diamicron 30 mg) is a new formulation of gliclazide to be given once daily. The original hydrophilic matrix improves the biodisponsibility of gliclazide and allows a progressive release of the drug that better parallels the 24-hour glycaemic profile of patients with type 2 diabetes mellitus. Such characteristics may explain the rather low risk of hypoglycaemic episodes and the morning administration should contribute to improve patient's compliance. As the common formulation of gliclazide, the modified release formulation is indicated in the treatment of type 2 diabetes, in adult subjects, when diet, exercise and weight loss are insufficient to restore an adequate metabolic control. It may be used alone or in combination with metformin, glitazones, acarbose or insulin, with the same general principles of use as for the classical formulation of gliclazide.

Gliclazide modified release: A critical review of pharmacodynamic, metabolic, and vasoprotective effects

Gliclazide modified release (MR) is a new formulation of the drug gliclazide and is given once daily. The specifically designed hydrophilic matrix of gliclazide MR leads to a progressive drug release that parallels the 24-hour glycemic profile in type 2 diabetic patients. Development studies showed a sustained efficacy over 2 years coupled with a very good acceptability. Gliclazide MR acts selectively on adenosine triphosphate-dependent potassium (K(ATP)) channels of the pancreatic beta cell. No interaction with cardiovascular K(ATP) channels has been shown, indicating that the drug can be safely used in patients with ischemic heart disease. In addition, gliclazide MR shows the ability to inhibit key mechanisms in diabetic angiopathy, independently of glycemic control.

Bioequivalence study of generic gliclazide and Diamicron formulations in healthy Thai male volunteers

The objective of this study was to compare the bioequivalence of 80 mg gliclazide in healthy Thai males. A single dose of each preparation was administered after an overnight fast in a 2-period crossover design with a 2-week washout period. Serial blood samples were collected over a period of 60 hours. Plasma gliclazide concentrations were determined using HPLC and the pharmacokinetic parameters were analyzed by non-compartmental analysis.

RESULTS

The median time to reach the maximal concentration (Tmax) for the test formulation was identical to that of the reference Diamicron (11.5 h). Similarly, the mean elimination half-lives (t1/2) for the test (20.4 +/- 7.8 h) and Diamicron (21.5 +/- 9.4 h) were comparable. Analysis of variance was carried out using logarithmic transformations of AUC(0-infinity) and Cmax as well as non-transformed Tmax. The mean (90% CI) of the difference in Tmax (h) was 0.08 ((-1.44)-1.61). The mean (90% CI) of the AUC(0-infinity) and Cmax ratios for (test/reference) were 1.08 (0.98-1.18) and 1.09 (0.89-1.34), respectively. Since these values fall within the bioequivalence criteria, our study demonstrates bioequivalence of the 2 products.

Population PKPD modelling of the long-term hypoglycaemic effect of gliclazide given as a once-a-day modified release (MR) formulation

AIMS

To study the relationship between the pharmacokinetics (PK) of gliclazide and its long-term pharmacodynamic (PD) effect in a large population of Type 2 diabetic patients and to identify factors predicting intersubject variability.

METHODS

A PKPD database of 634 Type 2 diabetic patients with a total of 5,258 fasting plasma glucose (FPG) samples was built up from the data collected during the clinical development of a modified release formulation of gliclazide (gliclazide MR). The PKPD analysis used a nonlinear mixed effect modelling approach. A mixture model was used to identify patients with a FPG response to treatment. In patients identified as responders, the decrease in FPG was related to gliclazide exposure (AUC) by an Emax relationship. An effect compartment was used to describe the link between PK and PD. A linear disease-progression model was used to assess the glycaemic deterioration observable over several months of treatment. Simulations were performed to evaluate the predictive performance of the PKPD model and to illustrate the time course of the antidiabetic effect of gliclazide MR.

RESULTS

Disease state was found to be the main explanatory factor for intersubject variability in response to gliclazide. The percentage of responders to gliclazide, used as monotherapy, increased inversely to the number of classes of antidiabetic agents received prior to entry in the studies. In responders, the initial dose (30 mg) of the gliclazide MR dosing regimen induced half of the maximum hypoglycaemic effect. The equilibration half-life between the PK and PD steady states was 3 weeks (intersubject variability of 84%). The rate of disease progression was 0.84 mmol l(-1) year(-1) (intersubject variability 143%). The PKPD model adequately predicted the FPG profiles of 234 patients who received the current formulation of gliclazide. Simulation of a 1-year parallel dose ranging clinical trial illustrated the influence of dose, time and type of previous antidiabetic treatment on the percentage of patients with clinically significant improvement of blood glucose control.

CONCLUSIONS

This population PKPD analysis has characterized the relationship between the exposure to gliclazide and its long-term hypoglycaemic effect, and has established that the intersubject variability in response is mostly related to disease state. These results underline the clinical interest of quickly increasing the dose of gliclazide MR according to the response to treatment in order to achieve effective blood glucose control.

Gliclazide modified release

Gliclazide modified release (MR) is a new formulation of the drug gliclazide and is given once daily. The hydrophilic matrix of hypromellose-based polymer in the new formulation effects a progressive release of the drug which parallels the 24-hour glycaemic profile in untreated patients with type 2 diabetes mellitus. The formulation shows high bioavailability and its absorption profile is unaffected by coadministration with food. Mean plasma glucose levels are significantly reduced over a 24-hour period in patients with type 2 diabetes mellitus treated with gliclazide MR once daily, in both fasting and postprandial states. No cardiovascular ATP-sensitive potassium channel interaction has been observed at therapeutic concentrations of gliclazide MR. Gliclazide MR has also demonstrated antioxidant properties that are independent of glycaemic control. In a randomised, double-blind, multicentre study, gliclazide MR 30 to 120 mg once daily showed similar efficacy to gliclazide immediate release (IR) 80 to 320 mg/day (in divided doses for doses >80 mg) in patients with type 2 diabetes mellitus over a 10-month period, reducing glycosylated haemoglobin (HbA(1c)) and fasting plasma glucose (FPG) to a similar extent. The drug appeared most efficacious in patients who had previously been treated by diet alone, where significant reductions in HbA(1c) from baseline of 0.9% and 0.95% were seen at 10 and 24 months. Similarly, a sustained effect of gliclazide MR was observed in a subgroup of elderly patients defined a priori; HbA(1c) was decreased to a similar degree to that observed in the general study population. Gliclazide MR showed similar tolerability to gliclazide IR after 10 months' treatment in the randomised trial. The most commonly observed adverse events were arthralgia, arthritis, back pain and bronchitis (each <5%). Bodyweight remained stable. In this study no episodes of nocturnal hypoglycaemia or hypoglycaemia requiring third party assistance were observed during treatment with gliclazide MR. Episodes of symptomatic hypoglycaemia were infrequent, occurring in approximately 5% of patients.

Bioequivalence evaluation of two brands of gliclazide 80 mg tablets (Glyzide & Diamicron)--in healthy human volunteers

A randomized, two-way, crossover, bioequivalence study in 24 fasting, healthy, male volunteers was conducted to compare two brands of gliclazide 80 mg tablets, Glyzide (Julphar, UAE) as test and Diamicron (Servier Industries, France) as reference product. The study was performed at the International Pharmaceutical Research Centre (IPRC), in joint venture with Speciality Hospital, Amman, Jordan. The drug was administered with 240 ml of 20% glucose solution after a 10 h overnight fasting. After dosing, serial blood samples were collected for a period of 48 h. Plasma harvested from blood was analyzed for gliclazide by validated HPLC method. Various pharmacokinetic parameters including AUC(0-t), AUC(0- proportional, variant), C(max), T(max), T(1/2), and elimination rate constant were determined from plasma concentrations of both formulations. Statistical modules (ANOVA and 90% confidence intervals) were applied to AUC(0-t), AUC(0- proportional, variant), and C(max) for bioequivalence evaluation of the two brands which revealed no significant difference between them, and 90% CI fell within US FDA accepted bioequivalence range of 80-125%. Based on these statistical inferences, Glyzide was judged bioequivalent to Diamicron.

Complete bioavailability and lack of food-effect on pharmacokinetics of gliclazide 30 mg modified release in healthy volunteers

A new modified release (MR) formulation containing 30 mg of gliclazide was developed to obtain a better predictable release of the active principle and to allow once-daily dosing regimen. An absolute bioavailability study was carried out to characterise the performance of the new formulation and the food-effect was also investigated in a separate study. Both studies were single dose, randomised, open label, two way cross over studies with a wash out period between doses. For the bioavailability study, each volunteer received 30 mg of gliclazide given either as a 1 h intravenous infusion or as a 30 mg MR tablet. For the food-effect study, the treatment was given either fasted or 10 min after the start of a standardised Melander breakfast. Blood samples were collected up to 72 h after administrations and plasma samples assayed for gliclazide concentrations using a reverse-phase HPLC method with UV detection. Mean absolute bioavailability of gliclazide was 97% and ranged between 79 and 110% showing complete absorption. A similar moderate to low variability was observed after IV and oral administration showing the MR formulation did not add to the overall variability which is solely due to the disposition parameters, in particular metabolism of gliclazide. No significant difference was observed in t(max), t(1/2z), C(max) and AUC of gliclazide after administration of the 30 mg MR tablet under fasted and fed conditions. In conclusion, after single oral administration of a 30 mg MR tablet, gliclazide was completely absorbed both under fasted and fed conditions. A consistent and optimal release of gliclazide from this formulation leads to a low to moderate overall variability of its pharmacokinetic parameters. Diamicron 30 mg MR can be given without regards to meals i.e. before, during or after breakfast.

[Free radical scavenging activity of sulfonylureas: a clinical assessment of the effectiveness of gliclazide]

In long-term clinical studies the beneficial effects of gliclazide on platelets have been related to a reduction in oxidative stress. This property is because of gliclazide's free radical scavenging ability that relates to the unique amino azabicyclo-octane ring, which is grafted on to the sulfonylurea. During a blinded clinical trial, the possible effects of gliclazide were assessed in 30 non-insulin-dependent diabetic patients. All patients had been treated for diabetes for more than 2 years (mean 8 years) and had been established on glibenclamide for over 2 years with or without adjunctive metformin therapy. Patients were studied for 6 months and randomized to continue either their present dose of glibenclamide or to be converted to an equipotent dose of gliclazide. Measurements were taken of hemostatic variables, the oxidative status of the plasma, and the redox status, both extracellularly as plasma albuminthiols (PSH) and lipid peroxides, and intracellularly as red blood cell superoxide dismutase activity (SOD). At 3 months, diabetic control was unaltered, but there were significant improvements in the oxidative status of the gliclazide-treated patients. Lipid peroxides decreased (8.3 +/- 1.1 to 7.0 +/- 0.06 mumol/l, P < 0.01) and red blood cell SOD increased (135 +/- 21 to 152 +/- 36 micrograms/ml, P < 0.05). PSH levels were unaltered at 453 +/- 38 mumol/l, whereas they had decreased significantly in the glibenclamide patients (414 +/- 34 mumol/l, P < 0.05), resulting in a significant difference between the 2 treatment groups (P < 0.004). Platelet reactivity to collagen also improved in the gliclazide-treated patients, decreasing from 65.1% +/- 14% to 50.8 +/- 24% (p < 0.01). The reactivity of the platelets remained unaltered in the glibenclamide patients. At 6 months, the significant differences between the 2 treatment groups remained. Hence, gliclazide was shown in a clinical study to have free radical scavenging activity independent of glycemic control.

Determination of gliclazide in pharmaceutical preparations by capillary gas chromatography with cool on-column injection and elimination of the matrix effect

Conditions were established for the identification and quantitation of gliclazide in pharmaceutical preparations by capillary gas chromatography with flame ionization detection and cool on-column injection. Gliclazide was extracted with methanol and, after filtration, assayed on a (25 m x 0.25 mm id, 0.2 microm film thickness) CP-WAX 58 (FFAP)-CB WCOT fused silica column. Because the available preparations were of various origins and, therefore, could differ in auxiliary substances and their qualitative parameters, the influence of the matrix constituents on the analytical results was taken into account. Good separation conditions were established for the developed method. The retention time of gliclazide is about 36 min and differs from the retention times of the internal standard (approximately 29 min) and additional peaks present in chromatograms (20-26 min), which were assigned to matrix constituents. The recoveries of gliclozide were high and reached 96.5%. The developed method is characterized by selectivity and precision (relative standard deviation 0.38-1.26%), a wide range of linearity (0.1-10.0 mg/mL), and a limit of detection of 30 ng. In addition, the results of chromatographic analyses calculated in 3 ways were compared with those obtained by UV spectrophotometry. The suggested technique of cool on-column injection, in contrast with split-splitless injection (used in preliminary investigations), reduces to a minimum the possibility of thermal decomposition of gliclazide.

Acute and short-term administration of a sulfonylurea (gliclazide) increases pulsatile insulin secretion in type 2 diabetes

The high-frequency oscillatory pattern of insulin release is disturbed in type 2 diabetes. Although sulfonylurea drugs are widely used for the treatment of this disease, their effect on insulin release patterns is not well established. The aim of the present study was to assess the impact of acute treatment and 5 weeks of sulfonylurea (gliclazide) treatment on insulin secretory dynamics in type 2 diabetic patients. To this end, 10 patients with type 2 diabetes (age 53 +/- 2 years, BMI 27.5 +/- 1.1 kg/m(2), fasting plasma glucose 9.8 +/- 0.8 mmol/l, HbA(1c) 7.5 +/- 0.3%) were studied in a double-blind placebo-controlled prospective crossover design. Patients received 40-80 mg gliclazide/placebo twice daily for 5 weeks with a 6-week washout period intervening. Insulin pulsatility was assessed by 1-min interval blood sampling for 75 min 1) under baseline conditions (baseline), 2) 3 h after the first dose (80 mg) of gliclazide (acute) with the plasma glucose concentration clamped at the baseline value, 3) after 5 weeks of treatment (5 weeks), and 4) after 5 weeks of treatment with the plasma glucose concentration clamped during the sampling at the value of the baseline assessment (5 weeks-elevated). Serum insulin concentration time series were analyzed by deconvolution, approximate entropy (ApEn), and spectral and autocorrelation methods to quantitate pulsatility and regularity. The P values given are gliclazide versus placebo; results are means +/- SE. Fasting plasma glucose was reduced after gliclazide treatment (baseline vs. 5 weeks: gliclazide, 10.0 +/- 0.9 vs. 7.8 +/- 0.6 mmol/l; placebo, 10.0 +/- 0.8 vs. 11.0 +/- 0.9 mmol/l, P = 0.001). Insulin secretory burst mass was increased (baseline vs. acute: gliclazide, 43.0 +/- 12.0 vs. 61.0 +/- 17.0 pmol. l(-1). pulse(-1); placebo, 36.1 +/- 8.4 vs. 30.3 +/- 7.4 pmol. l(-1). pulse(-1), P = 0.047; 5 weeks-elevated: gliclazide vs. placebo, 49.7 +/- 13.3 vs. 37.1 +/- 9.5 pmol. l(-1). pulse(-1), P < 0.05) with a similar rise in burst amplitude. Basal (i.e., nonoscillatory) insulin secretion also increased (baseline vs. acute: gliclazide, 8.5 +/- 2.2 vs. 16.7 +/- 4.3 pmol. l(-1). pulse(-1); placebo, 5.9 +/- 0.9 vs. 7.2 +/- 0.9 pmol. l(-1). pulse(-1), P = 0.03; 5 weeks-elevated: gliclazide vs. placebo, 12.2 +/- 2.5 vs. 9.4 +/- 2.1 pmol. l(-1). pulse(-1), P = 0.016). The frequency and regularity of insulin pulses were not modified significantly by the antidiabetic therapy. There was, however, a correlation between individual values for the acute improvement of regularity, as measured by ApEn, and the decrease in fasting plasma glucose during short-term (5-week) gliclazide treatment (r = 0.74, P = 0.014, and r = 0.77, P = 0.009, for fine and coarse ApEn, respectively). In conclusion, the sulfonylurea agent gliclazide augments insulin secretion by concurrently increasing pulse mass and basal insulin secretion without changing secretory burst frequency or regularity. The data suggest a possible relationship between the improvement in short-term glycemic control and the acute improvement of regularity of the in vivo insulin release process.