Effects of the new oral hypoglycaemic agent nateglinide on insulin secretion in Type 2 diabetes mellitus

Exemplary Practices in Cardiovascular Care: Results on Clinical Quality Measures from the EvidenceNOW Southwest Cooperative

BACKGROUND

Identifying characteristics of primary care practices that perform well on cardiovascular clinical quality measures (CQMs) may point to important practice improvement strategies.

OBJECTIVE

To identify practice characteristics associated with high performance on four cardiovascular disease CQMs.

DESIGN

Longitudinal cohort study among 211 primary care practices in Colorado and New Mexico. Quarterly CQM reports were obtained from 178 (84.4%) practices. There was 100% response rate for baseline practice characteristics and implementation tracking surveys. Follow-up implementation tracking surveys were completed for 80.6% of practices.

PARTICIPANTS

Adult patients, staff, and clinicians in family medicine, general internal medicine, and mixed-specialty practices.

INTERVENTION

Practices received 9 months of practice facilitation and health information technology support, plus biannual collaborative learning sessions.

MAIN MEASURES

This study identified practice characteristics associated with overall highest performance using area under the curve (AUC) analysis on aspirin therapy, blood pressure management, and smoking cessation CQMs.

RESULTS

Among 178 practices, 39 were exemplars. Exemplars were more likely to be a Federally Qualified Health Center (69.2% vs 35.3%, p = 0.0006), have an underserved designation (69.2% vs 45.3%, p = 0.0083), and have higher percentage of patients with Medicaid (p < 0.0001). Exemplars reported greater use of cardiovascular disease registries (61.5% vs 29.5%,), standing orders (38.5 vs 22.3%) or electronic health record prompts (84.6% vs 49.6%) (all p < 0.05), were more likely to have medical home recognition (74.4% vs 43.2%, p = 0.0006), and reported greater implementation of building blocks of high-performing primary care: regular quality improvement team meetings (3.0 vs 2.2), patient experience survey (3.1 vs 2.2), and resources for patients to manage their health (3.0 vs 2.3). High improvers (n = 45) showed greater improvement implementing team-based care (32.8 vs 11.7, p = 0.0004) and population management (37.4 vs 20.5, p = 0.0057).

CONCLUSIONS

Multiple strategies-registries, prompts and protocols, patient self-management support, and patient-team partnership activities-were associated with delivering high-quality cardiovascular care over time, measured by CQMs.

TRIAL REGISTRATION

ClinicalTrials.gov registration: NCT02515578.

Diabetes: the place of new therapies

Until the discovery of insulin in 1921 there were no effective treatments for diabetes mellitus. After the advent of long-acting insulin, the first oral agents, sulfonylureas became available in the mid-1950s, quickly followed (outside of the United States) by metformin. It was then another three decades before newer agents became available, with alpha glucosidase inhibitors, thiazolidinediones and meglitinides following in the 1990s. Since the turn of the century, several new classes have also been launched. But how do these agents fit into the management of type 2 diabetes? How does one choose which drug class to use after metformin? This review looks at the agents launched since 2000 and how and when they can be used. It also deals with some of the controversies that have arisen and how decisions have changed as a result, in particular moving away from the use of HbA1c as the driver for decision, but rather the cardiovascular safety of these agents and their use in the prevention of premature cardiovascular morbidity and mortality. Now that some of these agents have shown cardiovascular benefit, will this lead to a change in the treatment paradigm?

Understanding adaptations to patient-centered medical home activities: The PCMH adaptations model

Primary care practices have increasingly adopted the patient-centered medical home (PCMH) model and often adapted quality improvement efforts to fit local context. This paper implemented a modified framework for understanding adaptations in the context of primary care PCMH transformation efforts. We combined an adaptations model by Stirman et al. that categorized adaptations to evidence-based interventions in research studies with dimensions from the RE-AIM framework, as well as items specific to PCMH. The resulting constructs were translated into a "plain English" adaptations interview. We conducted interviews with 27 practices and used resulting descriptive categories to inform exploratory analyses of the relationships between adaptation characteristics and improvement outcomes in PCMH domains of team-based care and data capacity. Practices most commonly focused on development and use of disease registries and enhancements to team-based care (not disease-specific outcomes). Adaptations were common, with practices most frequently making changes to format or personnel. Adaptations were most often intended to increase effectiveness and based on pragmatic considerations. Generally similar adaptation themes emerged across different content topics (registry and quality improvement team). Adaptations initiated or carried out by the entire team or made in early to middle stages of the project were most related to outcome measures of team-based care and data capacity. This paper extends adaptation models from specific interventions in research studies to PCMH quality improvement efforts. Despite limitations, the PCMH Adaptations Model provided a useful framework to understand adaptations in this context.

Effect of nateglinide and glimepiride in reducing postprandial hyperglycaemia in patients with type 2 diabetes mellitus

Aim — The purpose of this study was to compare the effect of nateglinide on two-hour post-meal glucose levels with that of glimepiride in patients with type 2 diabetes mellitus. Methods — Glucose and insulin levels were measured during 14-hour profiles (comprising three meal challenges) and intravenous glucose tolerance tests performed before and after five-weeks of treatment with nateglinide (120 mg, a.c.) or glimepiride (1 mg, o.d.) in a randomised, two-centre, double-blind, crossover study in 26 patients with type 2 diabetes and fasting initial glucose levels < 13.9 mmol/L. Results — Mean two-hour postprandial glucose levels were significantly lower during nateglinide treatment than during glimepiride treatment (9.46 vs. 10.00 mmol/L, respectively; p<0.05). The 14-hour incremental glucose area under the curve was -2.2 mmol•h/L during nateglinide treatment and +6.2 mmol•h/L during glimepiride treatment (p<0.01). Nateglinide improved both the early insulin response during meals and the acute insulin response during intravenous glucose tolerance tests, restoring the biphasic insulin secretion pattern. Both insulin secretagogues improved intravenous glucose tolerance relative to the pre-treatment period, but only nateglinide restored a biphasic insulin profile. Conclusions — By restoring a more physiological post-load insulin response, nateglinide is more effective than glimepiride in controlling postprandial glucose excursions.

Comparison of the postprandial glucose and insulin profiles with nateglinide and gliclazide in type 2 diabetic patients

Aim

The aim of this study was to compare glucose, insulin and proinsulin profiles during nateglinide and gliclazide treatment over an extended postprandial period.

Materials and methods

This double-blind crossover trial was conducted in 23 type 2 diabetic patients (mean HbA1C 6.6%; range 6.0—7.4%) who received, for one week each, nateglinide 120 mg t.i.d., gliclazide 80 mg b.i.d. and placebo, with a one week wash out period between treatments.

Results

The 2-hour postprandial glucose concentration was markedly lower with nateglinide than with gliclazide (5.83 vs. 7.21 mmol/L; p<0.05), as was the post-meal peak glucose elevation (8.63 vs. 9.72 mmol/L; p=0.085), which was associated with earlier, higher and shorter-lived insulin and proinsulin secretory responses. However, 0—7-hour AUCs during standardised meal test for glucose and insulin between the two drugs did not statistically differ. No symptomatic hypoglycaemic events occurred during the 7-hour test period.

Conclusion

Nateglinide was more effective than gliclazide in controlling postprandial hyperglycaemia and showed a faster effect on insulin and proinsulin secretion.

Relative fasting bioavailability of two formulations of nateglinide 60 mg in healthy male Chinese volunteers: an open-label, randomized-sequence, single-dose, two-way crossover study

BACKGROUND

Nateglinide, N-(trans-4-isopropylcyclohexyl-carbonyl)-d-phenylalanine, is a potent insulin secretagogue designed to restore early-phase insulin secretion. It increases pancreatic insulin secretion by competitively binding to sulfonylurea receptors inhibiting adenosine triphosphate-sensitive potassium channels and thus reducing blood glucose levels. The drug has a rapid onset (causing immediate insulin release) and a short duration (allowing insulin to return to baseline levels between meals) of insulinotropic action.

OBJECTIVE

To meet the requirements for marketing a new generic product, this study was designed to compare the pharmacokinetic parameters and relative fasting bioavailability of new generic (test) formulation of nateglinide with the reference formulation of nateglinide in healthy Chinese male volunteers.

METHODS

This open-label, single-dose, randomized-sequence, 2-way crossover study was performed at Nanjing First Hospital of Nanjing Medical University. Eligible subjects were healthy male volunteers who were randomly assigned in a 1:1 ratio to receive a single 60-mg (0.88 mg/kg) dose of the 2 formulations, followed by a 1-week washout period and then administration of the alternate formulation. Study drugs were administered after a 10-hour overnight fast. Concentrations of nateglinide were determined by using a validated LC-MS method. For analysis of pharmacokinetic properties, including C(max), AUC(0-10), and AUC(0-∞), blood samples were obtained at intervals over the 10-hour period after study drug administration. As established by the State Food and Drug Administration, the formulations were assumed bioequivalent if 90% CIs for the test/reference ratios of ln-transformed values of C(max) and AUC (obtained by using ANOVA) were within the predetermined equivalence range (80%-125%). Tolerability was assessed by monitoring vital signs and laboratory tests (hematology, blood biochemistry, hepatic function, and urinalysis) and by questioning subjects about adverse events.

RESULTS

The 90% CIs for nateglinide were as follows: C(max), 98.4% to 118.6%; AUC(0-10), 99.5% to 110.3%. Both C(max) and AUC(0-10) met the predetermined criteria for assuming bioequivalence. The relative bioavailability of the test formulation was estimated to be 102.1% (13.5%). One volunteer (5%) experienced a headache after administration of the test formulation. This resolved spontaneously within 1 hour and was considered by the investigators to be mild. No serious adverse events were reported. No period or sequence effects were observed.

CONCLUSIONS

In this study of healthy Chinese male volunteers, a single 60-mg dose of nateglinide (test formulation) met the regulatory criteria for assuming bioequivalence to the established reference formulation. Both formulations were well tolerated. Chinese Clinical Trials registration number: ChiCTR-TRC-11001754.

Additive hypoglycaemic effect of nateglinide and exogenous glucagon-like peptide-1 in type 2 diabetes

We examined the postprandial glucose regulators nateglinide and GLP-1, separately and in combination, in people with type 2 diabetes. Nateglinide inhibited DPP-4 activity, reduced GLP-1 degradation and enhanced its insulinotropic and blood glucose lowering effect. Combining nateglinide and GLP-1 derivatives may effectively control postprandial glycaemia.

Determination of the L-enantiomer of nateglinide in pharmaceutical formulations by micellar electrokinetic chromatography

An analytical micellar electrokinetic chromatographic method was developed and validated for the determination of the L-enantiomer of nateglinide. Separations were carried out in a 50 μm, 64.5/56 fused-silica capillary. The optimized conditions included 75 mM borate buffer, pH 9.2, containing 50 mM of sodium dodecyl sulfate and 25 mg/mL of methyl-β-cyclodextrin as background electrolyte, an applied voltage of 20 kV and a temperature of 15, UV detector at 210 nm. The assay was validated for the L-enantiomer of nateglinide. The limit of detection and quantification were 0.07 and 0.2% respectively. Intraday precision was ranged between 0.12 and 1.7%. Interday precision ranged between 0.73 and 1.73%. The assay was applied to the determination of the L-enantiomer of nateglinide in pharmaceutical formulations.

Combination of nateglinide with thiazolidinediones in Type 2 diabetes

Insulin sensitivity and insulin secretion are reciprocally related such that insulin resistance is adapted by increased insulin secretion to maintain normal glucose and lipid homeostasis. Treatment of Type 2 diabetes should aim to restore and sustain the normal relationship between insulin sensitivity and secretion. Nateglinide is a rapid-onset, short-acting insulin-secretion enhancer that restores early-phase insulin secretion, reduces postprandial glucose excursions and prevents long-term hyperinsulinemia. Given its mechanism of action, it is evident that nateglinide would be more effective when used in combination with an insulin sensitizer, such as the thiazolidinediones. Thiazolidinediones do not stimulate insulin release and, therefore, are potentially suitable candidates for combination therapy with an insulin-secretion enhancer, such as nateglinide. Combination therapy of thiazolidinediones with nateglinide is effective, carries low risk of hypoglycemia and is suitable for patients with moderate renal impairment, although weight gain and edema are common side effects. Further studies are needed to determine whether nateglinide in combination with thiazolidinediones will help clinicians better achieve their treatment goals in targeting Type 2 diabetes. Moreover, comparative studies between nateglinide and medications targeting postprandial glycemia, such as dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 analogues, are necessary. This article summarizes data concerning the mechanism of action, efficacy and safety of therapy with nateglinide and thiazolidinediones as monotherapy and in combination treatment, and aims at a better understanding of the substrate defects their synergy hopes to defy.

Determination of nateglinide in human plasma by high-performance liquid chromatography with pre-column derivatization using a coumarin-type fluorescent reagent

A sensitive and selective high-performance liquid chromatographic method has been developed and validated for the determination of nateglinide in human plasma. Nateglinide and the internal standard, undecylenic acid, were extracted from plasma by liquid-liquid extraction using a mixture of ethyl acetate-diethyl ether, 50:50 (v/v). Pre-column derivatization reaction was performed using a coumarin-type fluorescent reagent, N-(7-methoxy-4-methyl-2-oxo-2H-6-chromenyl)-2-bromoacetamide. The derivatization proceeded in acetone in the presence of potassium carbonate and catalyzed by 18-crown-6 ether. The fluorescent derivatives were separated under isocratic conditions on a Hypersil BDS-C8 analytical column (250.0 mm x 2.1 mm i.d., particle size 5 microm) with a mobile phase that consisted of 65% acetonitrile in water and pumped at a flow rate of 0.50 mL min(-1). The excitation and emission wavelengths were set at 345 and 435 nm, respectively. The assay was linear over a concentration range of 0.05-16.00 microg mL(-1) for nateglinide with a limit of quantitation of 0.05 microg mL(-1). Quality control samples (0.05, 4.50 and 16.00 microg mL(-1)) in five replicates from five different runs of analysis demonstrated intra-assay precision (%coefficient of variation <6.8%), inter-assay precision (%coefficient of variation <1.6%) and an overall accuracy (%relative error) less than -3.4%. The method can be used to quantify nateglinide in human plasma covering a variety of pharmacokinetic or bioequivalence studies.

Meglitinide analogues for type 2 diabetes mellitus

BACKGROUND

In type 2 diabetes mellitus, impairment of insulin secretion is an important component of the disease. Meglitinide analogues are a class of oral hypoglycaemic agents that increase insulin secretion, in particular, during the early phase of insulin release.

OBJECTIVES

The aim of this review was to assess the effects of meglitinide analogues in patients with type 2 diabetes mellitus.

SEARCH STRATEGY

We searched several databases including The Cochrane Library, MEDLINE and EMBASE. We also contacted manufacturers and searched ongoing trials databases, and the American Diabetes Association (ADA) and European Association for the Study of Diabetes (EASD) websites.

SELECTION CRITERIA

We included randomised controlled, parallel or cross-over trials comparing at least 10 weeks of treatment with meglitinide analogues to placebo, head-to-head, metformin or in combination with insulin.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed trial quality.

MAIN RESULTS

Fifteen trials involving 3781 participants were included. No studies reported the effect of meglitinides on mortality or morbidity. In the eleven studies comparing meglitinides to placebo, both repaglinide and nateglinide resulted in a reductions in glycosylated haemoglobin (0.1% to 2.1% reduction in HbA1c for repaglinide; 0.2% to 0.6% for nateglinide). Only two trials compared repaglinide to nateglinide (342 participants), with greater reduction in glycosylated haemoglobin in those receiving repaglinide. Repaglinide (248 participants in three trials) had a similar degree of effect in reducing glycosylated haemoglobin as metformin. Nateglinide had a similar or slightly less marked effect on glycosylated haemoglobin than metformin (one study, 355 participants). Weight gain was generally greater in those treated with meglitinides compared with metformin (up to three kg in three months). Diarrhoea occurred less frequently and hypoglycaemia occurred more frequently but rarely severely enough as to require assistance.

AUTHORS' CONCLUSIONS

Meglitinides may offer an alternative oral hypoglycaemic agent of similar potency to metformin, and may be indicated where side effects of metformin are intolerable or where metformin is contraindicated. However, there is no evidence available to indicate what effect meglitinides will have on important long-term outcomes, particularly mortality.

Comparison of nateglinide and gliclazide in combination with metformin, for treatment of patients with Type 2 diabetes mellitus inadequately controlled on maximum doses of metformin alone

AIM

To compare the effects of nateglinide plus metformin with gliclazide plus metformin on glycaemic control in patients with Type 2 diabetes.

METHODS

Double-blind, double-dummy, parallel group, randomized, multicentre study over 24 weeks. Patients with inadequate glucose control on maximal doses of metformin were randomized to additionally receive nateglinide (n = 133) or gliclazide (n = 129). Changes from baseline in HbA1c, fasting plasma glucose (FPG) and mealtime glucose and insulin excursions were examined.

RESULTS

HbA1c was significantly (P < 0.001) decreased from baseline in both treatment groups (mean changes: nateglinide -0.41%, gliclazide -0.57%), but with no significant difference between treatments. Proportions of patients achieving a reduction of HbA1c >or= 0.5% or an end point HbA1c < 7% were also similar (nateglinide 58.1%, gliclazide 60.2%). Changes from baseline in FPG were similarly significant in both treatment groups (nateglinide -0.63, gliclazide -0.82 mmol/l). Reduction from baseline in maximum postprandial glucose excursion were significant in the nateglinide group only (nateglinide -0.71, gliclazide -0.10 mmol/l; P = 0.037 for difference). Postprandial insulin levels were significantly higher with nateglinide compared with gliclazide. The overall rate of hypoglycaemia events was similar in the nateglinide group compared with the gliclazide group.

CONCLUSIONS

No significant difference was seen between nateglinide plus metformin and gliclazide plus metformin in terms of HbA1c. However, the nateglinide combination demonstrated better postprandial glucose control.

Nateglinide--current and future role in the treatment of patients with type 2 diabetes mellitus

Therapy for type 2 diabetes mellitus should aim to control not only fasting, but also postprandial glucose levels. Nateglinide, a d-phenylalanine derivative, restores postprandial early phase insulin secretion in a transient and glucose-sensitive manner without affecting basal insulin levels. As nateglinide is administered immediately before meals it provides greater lifestyle flexibility than agents that require patients to eat to avoid hypoglycemic events (e.g. long-acting sulfonylureas). In randomised, double-blind trials in patients with type 2 diabetes, nateglinide monotherapy (mealtime treatment of 120 mg three times daily) significantly improved long-term glycaemic control by significantly reducing glyated haemoglobin (HbA 1c) and preventing mealtime glucose spikes. The combination of nateglinide with insulin-sensitising agents, for example, metformin and thiazolidinediones, addresses the dual defects of loss of insulin secretion and insulin resistance to provide optimal management of type 2 diabetes, and more patients achieve HbA 1c goal with nateglinide combination therapy rather than with monotherapy with other oral agents. Nateglinide also restores early insulin secretion and reduces postprandial hyperglycaemia in prediabetic subjects with impaired glucose tolerance (IGT) and appears similarly effective in elderly and non-elderly populations with type 2 diabetes. It has an excellent safety and tolerability profile, with a low propensity to cause hypoglycaemia due to its transient, selective effect on early phase insulin secretion. Nateglinide as monotherapy or combination therapy is an effective option to reduce mealtime glucose in patients with type 2 diabetes. The results of ongoing research into its potential role in delaying progression to overt diabetes, and protecting against cardiovascular events, in prediabetic patients with IGT are awaited.

Pharmacology of the meglitinide analogs: new treatment options for type 2 diabetes mellitus

The expression meglitinide analogs was introduced in 1995 to cover new molecules proposed as non-sulfonylurea insulinotropic agents and displaying structural analogy with meglitinide, such as repaglinide, nateglinide, and mitiglinide. Meglitinide analogs display, as judged by conformation analysis, a U-shaped configuration similar to that of antihyperglycemic sulfonylureas such as glibenclamide (glyburide) and glimepiride. In rat pancreatic islets incubated in the presence of 7.0 mmol/L D-glucose, repaglinide and mitiglinide demonstrate comparable concentration-response relationships for stimulation of insulin release, with a threshold value < 10 nmol/L and a maximal secretory response at about 10 nmol/L. Several findings indicate that meglitinide analogs provoke the closing of adenosine triphosphate-sensitive potassium channels, with subsequent gating of voltage-sensitive calcium channels. The effects of meglitinide analogs upon the binding of [3H]glibenclamide to islet cells membranes reinforces this concept. At variance, however, with other meglitinide analogs, the ionic and secretory response to repaglinide (10 micromol/L) is not rapidly reversible in perifused rat islets. In experiments conducted in vivo in control and diabetic rats, repaglinide provokes a greater and more rapid increase in plasma insulin concentration and an earlier fall in glycemia than glibenclamide or glimepiride. Onset of effect is also more rapid and duration of effect shorter with nateglinide versus glibenclamide. In clinical studies, single or repeated daily administration of repaglinide increased plasma insulin concentration in a dose-dependent manner, with an incremental peak reached about 2 hours after repaglinide intake. Plasma concentrations of repaglinide are about 5.0 microg/L 2-2.5 hours after oral intake of the drug. Despite the slow reversibility of repaglinide action in vitro, this drug offers advantages over glibenclamide in terms of the possible occurrence of hypoglycemia if a meal is missed. In volunteers receiving a single oral dose of nateglinide (120mg) 10 minutes before a standardized 800 Kcal breakfast, the plasma insulin concentration was higher 5, 10, and 20 minutes after meal intake than when they received a single dose of repaglinide (0.5 or 2.0mg) or placebo 10 minutes before breakfast. Peak plasma concentrations of nateglinide were reached within 2 hours in most volunteers. Peak plasma concentrations of mitiglinide were reached 30 minutes after a single oral dose in a representative volunteer. Mitiglinide significantly suppressed meal-induced elevations in blood glucose concentrations in a study of patients with type 2 diabetes. In conclusion, two obvious differences among these meglitinide analogs should be underlined. First, on a molar basis, nateglinide is somewhat less potent than repaglinide or mitiglinide, as an insulinotropic agent. The maximal secretory responses evoked by these three meglitinide analogs are, however, identical to one another. Secondly, and as already mentioned, the functional effects of nateglinide and mitiglinide are more rapidly reversible than those of repaglinide, for instance in perifused rat islets. The meglitinide analogs offer the advantage over the long-acting antihyperglycemic sulfonylurea glibenclamide of minimizing the risk of undesirable hypoglycemia.

Clinical pharmacokinetics of nateglinide: a rapidly-absorbed, short-acting insulinotropic agent

The prevalence and medical and economic impact of type 2 diabetes mellitus is increasing in Western societies. New agents have been developed that act primarily to reduce postprandial glucose excursions, which may be of particular significance now that postprandial glucose excursions are known to be correlated with cardiovascular morbidity and mortality. Nateglinide is a phenylalanine derivative that blocks K+ channels in pancreatic beta-cells, facilitating insulin secretion. Nateglinide sensitises beta-cells to ambient glucose, reducing the glucose concentration needed to stimulate insulin secretion. The pharmacokinetics of nateglinide are characterised by rapid absorption and elimination, with good (73%) bioavailability. Nateglinide is more rapidly absorbed when given 0-30 minutes prior to meal ingestion than if given during the meal. Nateglinide is extensively metabolised, primarily by cytochrome P450 2C9, and eliminated primarily by the kidney. Nateglinide pharmacokinetics are linear over the dose range 60-240 mg. No significant pharmacokinetic alterations occur in renally impaired patients, in the elderly, or in mildly hepatically impaired patients. Nateglinide administered prior to meals stimulates rapid, short-lived insulin secretion in a dose-dependent manner, thus decreasing mealtime plasma glucose excursions. Its effects on insulin secretion are synergistic with those of a meal. With increasing nateglinide doses, the risk of hypoglycaemia also increases, but its incidence is low. Even if a meal is missed, and the patient skips the dose of nateglinide (as recommended in the event of a missed meal), the incidence of subsequent hypoglycaemia remains low compared with long-acting agents. The postprandial insulinotropic effects of nateglinide are more rapid than those of repaglinide and more rapid and greater than those of glibenclamide (glyburide), while producing less prolonged insulin exposure and less risk of delayed hypoglycaemia. Further investigation is required to determine if nateglinide inhibition of postprandial glucose excursions will help to prevent diabetic complications or preserve pancreatic beta-cell function.

Cardiovascular risk in type 2 diabetics and pharmacological regulation of mealtime glucose excursions

In type 2 diabetic patients mealtime glucose fluctuations are important determinants of overall glucose control and overall risk of diabetes cardiovascular complications. In fact, acute elevation of plasma glucose concentrations trigger an array of tissue response that may contribute to development of such vascular complications since it may result in a thrombophilic condition, causes endothelial dysfunction (possibly through a reduction of nitric oxide availability) and is responsible for non-enzymatic glycation and production of free- radicals with ensuing oxidative stress. To keep post-prandial glucose with narrow range, metiglinide analogues drugs have been developed. In particular, repaglinide and nateglinide seem the most useful ones. In fact, both drugs improve 1(st) phase insulin release but they do not affect the total daily amount of insulin released by the pancreas. Due to the mechanism of action and to pharmacokinetic properties, repaglinide and nateglinide allow diabetic patients to get a more tight metabolic glucose control with a contemporary reduction in the cases of severe hypoglycaemia. In conclusions, repaglinide and nateglinide are new and powerful pharmacological tools not only for achieving a better metabolic glucose control but also for preventing the development of diabetes-related cardiovascular complications.

Pharmacokinetics of nateglinide in renally impaired diabetic patients

Treatment of hyperglycemia in patients with diabetes mellitus and renal insufficiency is complicated by altered pharmacokinetics of hypoglycemic agents. This study evaluated the pharmacokinetic profile and safety of nateglinide, an amino acid derivative that improves early phase insulin secretion and reduces mealtime glucose excursions. This open-label, single-dose, two-center study included patients (mean age = 57 +/- 10 years) with type 1 or 2 diabetes with impaired renal function (IRF) (n = 10) or with renal failure undergoing hemodialysis (n = 10). Both groups were compared with age-, sex-, height-, and weight-matched healthy controls (n = 20). All participants received a single 120-mg dose of nateglinide immediately before breakfast. Pharmacokinetic and safety evaluations were undertaken up to 48 hours postdose. All 40 subjects completed the study. Plasma nateglinide concentrations increased rapidly in patients undergoing dialysis and matched healthy subjects (tmax = 0.95 vs. 0.78 h, respectively) and was comparable with patients with IRF and matched healthy subjects (tmax = 0.80 vs. 0.65 h, respectively). There were no statistically significant differences for Cmax or AUC0-t between the groups. Nateglinide was eliminated rapidly in all groups (t1/2 = 1.9-2.8 h). There was no correlation between the level of renal function and systemic exposure. There was a low extent of renal excretion of nateglinide in healthy subjects (11%) and diabetic patients with IRF (3%). Nateglinide was well tolerated. These data suggest that nateglinide is suitable for use in diabetic patients with IRF or with renal failure undergoing dialysis. Given the comparable absorption and elimination profiles of nateglinide in renally impaired and healthy subjects, no dose adjustment appears necessary in the renally impaired.

Control of postprandial hyperglycemia: optimal use of short-acting insulin secretagogues

OBJECTIVE

This study was designed to compare the efficacy of acute premeal administration of glipizide versus nateglinide in controlling postprandial hyperglycemia in subjects with non-insulin-requiring type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 20 subjects (10 female, 10 male) with non-insulin-requiring type 2 diabetes were admitted overnight to the General Clinical Research Center on four occasions. In random order, 10 mg glipizide (30 min premeal), 120 mg nateglinide (15 min premeal), 10 mg glipizide plus nateglinide (30 and 15 min premeal, respectively), or placebo pills (30 and 15 min premeal) were administered in a double-blind fashion before a standardized breakfast. Blood was drawn for analysis of glucose, insulin, and C-peptide at -0.05, 0, 0.5, 1, 2, 3, and 4 h relative to the meal.

RESULTS

The subjects were aged 56 +/- 2 years and were moderately obese (BMI 31 +/- 1 kg/m(2)), with a mean HbA(1c) of 7.4 +/- 0.4%. The peak postprandial glucose excursion above baseline was higher with placebo (6.1 +/- 0.5 mmol/l) than glipizide (4.3 +/- 0.6 mmol/l, P = 0.002), nateglinide (4.2 +/- 0.4 mmol/l, P = 0.001), or glipizide plus nateglinide (4.1 +/- 0.5 mmol/l, P = 0.001). The area under the curve for the glucose excursion above baseline was also higher with placebo (14.1 +/- 1.8 mmol/h. l) compared with glipizide (6.9 +/- 2.4 mmol/h. l, P = 0.002), nateglinide (9.7 +/- 2 mmol/h. l, P = 0.004), or glipizide plus nateglinide (5.6 +/- 2.2 mmol/h. l, P < 0.001). Peak and integrated glucose excursions did not differ significantly between glipizide and nateglinide. However, by 4 h postmeal, plasma glucose levels were significantly higher with nateglinide (9 +/- 0.9 mmol/l) compared with the premeal baseline (7.8 +/- 0.6 mmol/l, P = 0.04) and compared with the 4-h postprandial glucose level after administration of glipizide (7.6 +/- 0.6 mmol/l, P = 0.02). Integrated postprandial insulin levels were higher with glipizide (1,556 +/- 349 pmol/h. l) than nateglinide (1,364 +/- 231 pmol/h. l; P = 0.03). Early insulin secretion, as measured by insulin levels at 30 min postmeal, did not differ between glipizide and nateglinide.

CONCLUSIONS

Acute premeal administration of nateglinide or glipizide has equal efficacy in controlling postbreakfast hyperglycemia in type 2 diabetes when each drug is administered at the optimum time before the meal. Glipizide causes a more pronounced and sustained postmeal insulin secretory response compared with nateglinide. Glipizide facilitates the return to near-fasting glucose levels at 4 h postmeal, but with the possible risk of increased frequency of postmeal hypoglycemia in drug-naive patients. The clinical decision to use glipizide versus nateglinide should be based on factors other than the control of postprandial hyperglycemia in type 2 diabetes.

No effect of the novel antidiabetic agent nateglinide on the pharmacokinetics and anticoagulant properties of warfarin in healthy volunteers

The novel hypoglycemic agent nateglinide is pharmacologically distinct from oral hypoglycemic agents such as sulfonylureas and repaglinide. The present study investigated the effects in healthy volunteers of multiple doses of nateglinide on the pharmacokinetics and pharmacodynamics of warfarin. The study comprised a randomized two-group, two-way crossover, open-label design in 12 healthy male subjects. One group of 6 subjects initially received a single oral dose of warfarin 30 mg and then, after a 7- to 14-day washout, received both warfarin and nateglinide (120 mgnateglinide, 10 min before meals for 4 days and a single dose of 30 mg warfarin on the second day). The alternate group of 6 subjects received treatments in the opposite order. Pharmacokinetic profiles were derived from plasma warfarin and nateglinide concentrations. Prothrombin measurements were evaluated in both periods as a measure of warfarin activity. When administered alone or in combination, there were no statistically significant differences in mean warfarin (R- and S-enantiomers) or nateglinide pharmacokinetic parameters. The concurrent administration of nateglinide and warfarin did not affect the maximal change in prothrombin time that follows warfarin administration. In this study, there was no evidence of an effect of coadministration of nateglinide on the pharmacodynamic action of warfarin or any pharmacokinetic interaction between warfarin and nateglinide.

Effects of nateglinide and glibenclamide on postprandial lipid and glucose metabolism in type 2 diabetes

BACKGROUND

Postprandial hyperlipemia and small, dense LDL particles are features of dyslipidemia in type 2 diabetes. The purpose of this study was (1) to determine whether the oral insulinotropic drugs, nateglinide and glibenclamide, can overcome the defect of insulin action to suppress the hepatic VLDL release after a meal and decrease the postprandial lipemia and (2) to evaluate the acute effect of postprandial hypertriglyceridemia on LDL particle size in subjects with type 2 diabetes.

METHODS

Forty-three subjects with type 2 diabetes and mean baseline HbA(1c) 7.6% (95% CI 7.3 to 7.9) were treated with nateglinide 120 mg three times daily or glibenclamide 5 mg once or twice daily for 12 weeks in a double-blind randomised trial. Insulin, glucose, and lipoprotein responses to a mixed fat-rich meal were determined for 8 h postprandially at baseline and at 12 weeks on-trial.

RESULTS

Nateglinide and glibenclamide significantly augmented the maximal response in serum insulin at 60 min postprandially compared with the response without the drug [additional increase 25.0 mU/l (95% CI 11.2-38.8) p = 0.001 and 12.5 mU/l (95% CI 4.6-20.3) p = 0.003, respectively] and reduced hyperglycemia. Neither drug affected fasting or postprandial lipid or lipoprotein levels. LDL size did not significantly change in the 8-h postprandial period.

CONCLUSIONS

Although nateglinide and glibenclamide increase postprandial insulin secretion and attenuate hyperglycemia, they do not alleviate postprandial lipemia in subjects with type 2 diabetes and good glycemic control. Although small LDL particle size is associated with chronic hypertriglyceridemia, LDL size does not change during acute postprandial hypertriglyceridemia.

Nateglinide improves glycaemic control when added to metformin monotherapy: results of a randomized trial with type 2 diabetes patients

AIMS/HYPOTHESIS

This study evaluated the addition of nateglinide, a d-phenylalanine derivative that restores early phase insulin release, to metformin in type 2 diabetes patients stabilized on high-dose metformin.

METHODS

This multicentre, double-blind, parallel group trial included 467 metformin-treated patients with glycosylated haemoglobin (HbA1c) between 6.8% and 11%. Patients were randomized to add nateglinide 60 mg, 120 mg or placebo before three meals to metformin 1000 mg b.i.d. for 24 weeks.

RESULTS

HbA1c was significantly reduced with nateglinide 60 mg and 120 mg plus metformin compared with metformin control (-0.36%, p = 0.003; -0.59%, p < 0.001 respectively). Greater benefits occurred if patients had elevated HbA1c at baseline (-1.38% with nateglinide 120 mg in patients with HbA1c > 9.5%). A modest fasting plasma glucose reduction was observed. Most symptoms suggestive of hypoglycaemia occurred in patients with low HbA1c levels (<or= 8%) at baseline, although no confirmed cases of hypoglycaemia occurred with nateglinide 60 mg in this patient group. Events suggestive of hypoglycaemia were confirmed in 1.1% of cases (plasma glucose <or= 3.3 mmol/l). Weight gain over 24 weeks was 0.9 kg with nateglinide 120 mg vs. metformin alone, and plasma lipids remained unchanged.

CONCLUSIONS/INTERPRETATION

In patients stabilized on high-dose metformin, the addition of nateglinide improved glycaemic control. The combination of these agents was well tolerated and both doses of nateglinide proved effective. The efficacy of nateglinide 60 mg and the low rate of hypoglycaemia observed at this dose make it suitable for patients close to their therapeutic target on metformin monotherapy.

Insulinotropic meglitinide analogues

The loss of early-phase insulin secretion is an important and early event in the natural history of type 2 diabetes. Because a normal pattern of insulin secretion is essential for the effective control of postprandial metabolism, a rational basis for the development of agents that target early-phase insulin release exists. Conventional oral hypoglycaemic agents do not target, or adequately control, postprandial glycaemia. The emergence of new classes of oral agent with a more specific mode of action provides, for the first time, an opportunity to restore early-phase insulin release. One such drug class is the meglitinide analogues (repaglinide, nateglinide, and mitiglinide). These drugs are ideally suited for combination use with metformin. They could also prove effective in combination with a thiazolidinedione, a drug class that targets insulin resistance. Exogenous insulin is frequently required in the late management of type 2 diabetes. However, one hope for newer combinations of diabetic drugs is that the functional life of the beta cell can be extended, thereby delaying the need for insulin injections.

Nateglinide therapy for type 2 diabetes mellitus

OBJECTIVE

To review the pharmacology, pharmacokinetics, dosing guidelines, adverse effects, drug interactions, and clinical efficacy of nateglinide.

DATA SOURCES

Primary and review articles regarding nateglinide were identified by MEDLINE search (from 1966 to January 2001); abstracts were identified through the Institute for Scientific Information Web of Science (from 1995 to January 2001) and the American Diabetes Association; additional information was obtained from the nateglinide product information.

STUDY SELECTION/DATA EXTRACTION

All articles and meeting abstracts identified from the data sources were evaluated and all information deemed relevant was included in this review. Much of the information was from abstracts or the product labeling, since few clinical studies have been published in the medical literature.

DATA SYNTHESIS

Nateglinide is a novel nonsulfonylurea oral antidiabetic agent that stimulates insulin secretion from the pancreas. It has a rapid onset and short duration of action, allowing administration before a meal to reduce postprandial hyperglycemia. Improvement in glycemic control with nateglinide monotherapy has been demonstrated in patients not previously treated with antidiabetic medications. Greater improvement in glycemic control was observed when nateglinide was administered in combination with metformin.

CONCLUSIONS

Nateglinide is similar to repaglinide, but has a quicker onset of action, quicker reversal, and does not usually require dosage titration. Based on the pharmacodynamics of nateglinide and repaglinide, nateglinide produces a more rapid postprandial increase in insulin secretion, and its duration of response is shorter than that of repaglinide. The risk of postabsorptive hypoglycemia should be lower than with either sulfonylureas or repaglinide.

Randomized dose ranging study of the reduction of fasting and postprandial glucose in type 2 diabetes by nateglinide (A-4166)

OBJECTIVE

This randomized crossover double-blind placebo-controlled study aimed to assess the efficacy of nateglinide (A-4166), a novel phenylalanine-derived insulin secretagogue, in type 2 diabetic subjects while fasting and 5 min before a standard meal.

RESEARCH DESIGN AND METHODS

A single dose of nateglinide (60, 120, or 180 mg) or placebo was given to eight diet-treated overnight-fasted type 2 diabetic patients and to seven patients 5 min before a standard breakfast. Plasma glucose, radioimmunoassay insulin, and nateglinide were measured at baseline and for a further 180 min.

RESULTS

The time-averaged 180-min postdose mean decrease in fasting plasma glucose concentration was greater after nateglinide (1.8 mmol/l; 95% CI 1.5-2.0) than after placebo (0.7 mmol/l; 95% CI 0.3-1.2) (P < 0.001). Hypoglycemia did not develop in any of the subjects. Insulin concentrations increased 1.5-, 1.8-, and 1.9-fold with the 60-, 120-, and 180-mg doses, respectively (P < 0.001), peaking approximately 30 min after the dose. Nateglinide concentrations peaked after approximately 30 min, decreasing to 21% of peak by 180 min. In the meal test, the mean increase (2.9 mmol/l, 2.3-3.6) in plasma glucose over 180 min after placebo was reduced by 1.8 mmol/l (P < 0.001) with the two higher doses of nateglinide.

CONCLUSIONS

A single dose of nateglinide administered to diet-treated type 2 diabetic patients with fasting hyperglycemia increased insulin secretion and reduced fasting glucose without hypoglycemia. Administered 5 min before a meal, nateglinide reduced the postprandial glucose excursion by 64%. With its rapid onset and short duration of action, nateglinide is a promising oral prandial therapy in type 2 diabetes.