Label: NATEGLINIDE- nateglinide tablet, coated

Mechanism of Action

Nateglinide is an amino-acid derivative that lowers blood glucose levels by stimulating insulin secretion from the pancreas. This action is dependent upon functioning beta-cells in the pancreatic islets. Nateglinide interacts with the ATP-sensitive potassium (K+ ATP) channel on pancreatic beta-cells. The subsequent depolarization of the beta cell opens the calcium channel, producing calcium influx and insulin secretion. The extent of insulin release is glucose dependent and diminishes at low glucose levels. Nateglinide is highly tissue selective with low affinity for heart and skeletal muscle.

Pharmacokinetics

Pharmacodynamics

Nateglinide is rapidly absorbed and stimulates pancreatic insulin secretion within 20 minutes of oral administration. When nateglinide is dosed three times daily before meals there is a rapid rise in plasma insulin, with peak levels approximately 1 hour after dosing and a fall to baseline by 4 hours after dosing.

In a double-blind, controlled clinical trial in which nateglinide was administered before each of three meals, plasma glucose levels were determined over a 12-hour, daytime period after 7 weeks of treatment. Nateglinide was administered 10 minutes before meals. The meals were based on standard diabetic weight maintenance menus with the total caloric content based on each subject’s height. Nateglinide produced statistically significant decreases in fasting and postprandial glycemia compared to placebo.

CLINICAL STUDIES

A total of 3,566 patients were randomized in nine double-blind, placebo-or active-controlled studies 8 to 24 weeks in duration to evaluate the safety and efficacy of nateglinide. 3,513 patients had efficacy values beyond baseline. In these studies nateglinide was administered up to 30 minutes before each of three main meals daily.

Nateglinide Monotherapy Compared to Placebo

In a randomized, double-blind, placebo-controlled, 24-week study, patients with Type 2 diabetes with HbA1c ≥6.8% on diet alone were randomized to receive either nateglinide (60 mg or 120 mg three times daily before meals) or placebo. Baseline HbA1c ranged from 7.9% to 8.1% and 77.8% of patients were previously untreated with oral antidiabetic therapy. Patients previously treated with antidiabetic medications were required to discontinue that medication for at least 2 months before randomization. The addition of nateglinide before meals resulted in statistically significant reductions in mean HbA1c and mean fasting plasma glucose (FPG) compared to placebo (see Table 1). The reductions in HbA1c and FPG were similar for patients naïve to, and those previously exposed to, antidiabetic medications.

In this study, one episode of severe hypoglycemia (plasma glucose <36 mg/dL) was reported in a patient treated with nateglinide 120 mg three times daily before meals. No patients experienced hypoglycemia that required third party assistance. Patients treated with nateglinide had statistically significant mean increases in weight compared to placebo (see Table 1).

In another randomized, double-blind, 24-week, active-and placebo-controlled study, patients with Type 2 diabetes were randomized to receive nateglinide (120 mg three times daily before meals), metformin 500 mg (three times daily), a combination of nateglinide 120 mg (three times daily before meals) and metformin 500 mg (three times daily), or placebo. Baseline HbA1c ranged from 8.3% to 8.4%. Fifty-seven percent of patients were previously untreated with oral antidiabetic therapy. Nateglinide monotherapy resulted in significant reductions in mean HbA1c and mean FPG compared to placebo that were similar to the results of the study reported above (see Table 2).

Nateglinide Monotherapy Compared to Other Oral Antidiabetic Agents

Glyburide

In a 24-week, double-blind, active-controlled trial, patients with Type 2 diabetes who had been on a sulfonylurea for ≥ 3 months and who had a baseline HbA1c ≥6.5% were randomized to receive nateglinide (60 mg or 120 mg three times daily before meals) or glyburide 10 mg once daily. Patients randomized to nateglinide had significant increases in mean HbA1c and mean FPG at endpoint compared to patients randomized to glyburide.

Metformin

In another randomized, double-blind, 24-week, active- and placebo-controlled study, patients with Type 2 diabetes were randomized to receive nateglinide (120 mg three times daily before meals), metformin 500 mg (three times daily), a combination of nateglinide 120 mg (three times daily before meals) and metformin 500 mg (three times daily), or placebo. Baseline HbA1c ranged from 8.3% to 8.4%. Fifty-seven percent of patients were previously untreated with oral antidiabetic therapy. Patients previously treated with antidiabetic medications were required to discontinue medication for at least 2 months before randomization. The reductions in mean HbA1c and mean FPG at endpoint with metformin monotherapy were significantly greater than the reductions in these variables with nateglinide monotherapy (see Table 2). Relative to placebo, nateglinide monotherapy was associated with significant increases in mean weight whereas metformin monotherapy was associated with significant decreases in mean weight. Among the subset of patients naïve to antidiabetic therapy, the reductions in mean HbA1c and mean FPG for nateglinide monotherapy were similar to those for metformin monotherapy (see Table 2). Among the subset of patients previously treated with other antidiabetic agents, primarily glyburide, HbA1c in the nateglinide monotherapy group increased slightly from baseline, whereas HbA1c was reduced in the metformin monotherapy group (see Table 2).

Nateglinide Combination Therapy

Metformin

In the active and placebo-controlled study of metformin and nateglinide described above, the combination of nateglinide and metformin resulted in statistically significantly greater reductions in HbA1c and FPG compared to either nateglinide or metformin monotherapy (see Table 2). Nateglinide, alone or in combination with metformin, significantly reduced the prandial glucose elevation form pre-meal to 2-hours post-meal compared to placebo and metformin alone.

In this study, one episode of severe hypoglycemia (plasma glucose ≤36 mg/dL) was reported in a patient receiving the combination of nateglinide and metformin and four episodes of severe hypoglycemia were reported in a single patient in the metformin treatment arm. No patient experienced an episode of hypoglycemia that required third party assistance. Compared to placebo, nateglinide monotherapy was associated with a statistically significant increase in weight, while no significant change in weight was observed with combined nateglinide and metformin therapy (see Table 2).

In another 24-week, double-blind, placebo-controlled trial, patients with Type 2 diabetes with HbA1c ≥6.8% after treatment with metformin (≥1500 mg daily for ≥1 month) were first entered into a four-week run-in period of metformin monotherapy (2000 mg daily) and then randomized to receive nateglinide (60 mg or 120 mg three times daily before meals) or placebo in addition to metformin. Combination therapy with nateglinide and metformin was associated with statistically significantly greater reductions in HbA1c compared to metformin monotherapy (-0.4% and -0.6% for nateglinide 60 mg and nateglinide 120 mg plus metformin, respectively).

Rosiglitazone

A 24-week, double blind multicenter, placebo-controlled trial was performed in patients with Type 2 diabetes not adequately controlled after a therapeutic response to rosiglitazone monotherapy 8 mg daily. The addition of nateglinide (120 mg three times per day with meals) was associated with statistically significantly greater reductions in HbA1c compared to rosiglitazone monotherapy. The difference was -0.77% at 24 weeks. The mean change in weight from baseline was about +3 kg for patients treated with nateglinide plus rosiglitazone vs about +1 kg for patients treated with placebo plus rosiglitazone.

Glyburide

In a 12-week study of patients with Type 2 diabetes inadequately controlled on glyburide 10 mg once daily, the addition of nateglinide (60 mg or 120 mg three times daily before meals) did not produce any additional benefit.

Information for Patients

Patients should be informed of the potential risks and benefits of nateglinide and of alternative modes of therapy. The risks and management of hypoglycemia should be explained. Patients should be instructed to take nateglinide 1 to 30 minutes before ingesting a meal, but to skip their scheduled dose if they skip the meal so that the risk of hypoglycemia will be reduced. Drug interactions should be discussed with patients. Patients should be informed of potential drug-drug interactions with nateglinide.

Laboratory Tests

Response to therapies should be periodically assessed with glucose values and HbA1c levels.

Drug Interactions

Nateglinide is highly bound to plasma proteins (98%), mainly albumin. In vitro displacement studies with highly protein-bound drugs such as furosemide, propranolol, captopril, nicardipine, pravastatin, glyburide, warfarin, phenytoin, acetylsalicylic acid, tolbutamide, and metformin showed no influence on the extent of nateglinide protein binding. Similarly, nateglinide had no influence on the serum protein binding of propranolol, glyburide, nicardipine, warfarin, phenytoin, acetylsalicylic acid and tolbutamide in vitro. However, prudent evaluation of individual cases is warranted in the clinical setting.

Certain drugs, including nonsteroidal anti-inflammatory agents (NSAIDs), salicylates, monoamine oxidase inhibitors, and non-selective beta-adrenergic-blocking agents, guanethidine, and CYP2C9 inhibitors (e.g., fluconazole, amiodarone, miconazole, oxandrolone) may potentiate the hypoglycemic action of nateglinide and other oral antidiabetic drugs.

Certain drugs including thiazides, corticosteroids, thyroid products, sympathomimetics, somatropin, rifampin, phenytoin and dietary supplements (St. John’s wort) may reduce the hypoglycemic action of nateglinide and other oral antidiabetic drugs. Somatostatin analogues may potentiate or attenuate the hypoglycemic action of nateglinide.

When these drugs are administered to or withdrawn from patients receiving nateglinide, the patient should be observed closely for changes in glycemic control.

Drug/Food Interactions

The pharmacokinetics of nateglinide were not affected by the composition of a meal (high protein, fat, or carbohydrate). However, peak plasma levels were significantly reduced when nateglinide was administered 10 minutes prior to a liquid meal. Nateglinide did not have any effect on gastric emptying in healthy subjects as assessed by acetaminophen testing.

Carcinogenesis and Mutagenesis and Impairment of Fertility

Carcinogenicity: A two-year carcinogenicity study in Sprague-Dawley rats was performed with oral doses of nateglinide up to 900 mg/kg/day, which produced AUC exposures in male and female rats approximately 30 and 40 times the human therapeutic exposure respectively with a recommended nateglinide dose of 120 mg, three times daily before meals. A two-year carcinogenicity study in B6C3F1 mice was performed with oral doses of nateglinide up to 400 mg/kg/day, which produced AUC exposures in male and female mice approximately 10 and 30 times the human therapeutic exposure with a recommended nateglinide dose of 120 mg, three times daily before meals. No evidence of a tumorigenic response was found in either rats or mice.

Mutagenesis: Nateglinide was not genotoxic in the in vitro Ames test, mouse lymphoma assay, chromosome aberration assay in Chinese hamster lung cells, or in the in vivo mouse micronucleus test.

Impairment of Fertility: Fertility was unaffected by administration of nateglinide to rats at doses up to 600 mg/kg (approximately 16 times the human therapeutic exposure with a recommended nateglinide dose of 120 mg three times daily before meals).

Pregnancy

Labor and Delivery

The effect of nateglinide on labor and delivery in humans is not known.

Nursing Mothers

Studies in lactating rats showed that nateglinide is excreted in the milk; the AUC 0-48h ratio in milk to plasma was approximately 1:4. During the peri- and postnatal period body weights were lower in offspring of rats administered nateglinide at 1000 mg/kg (approximately 60 times the human therapeutic exposure with a recommended nateglinide dose of 120 mg, three times daily before meals). It is not known whether nateglinide is excreted in human milk. Because many drugs are excreted in human milk, nateglinide should not be administered to a nursing woman.

Pediatric Use

Clinical trials to demonstrate the safety and effectiveness in pediatric patients have not been conducted.

Geriatric Use

No differences were observed in safety or efficacy of nateglinide between patients age 65 and over, and those under age 65. However, greater sensitivity of some older individuals to nateglinide therapy cannot be ruled out.

Laboratory Abnormalities

Uric Acid:There were increases in mean uric acid levels for patients treated with nateglinide alone, nateglinide in combination with metformin, metformin alone, and glyburide alone. The respective differences from placebo were 0.29 mg/dL, 0.45 mg/dL, 0.28 mg/dL, and 0.19 mg/dL. The clinical significance of these findings is unknown.

Monotherapy and Combination with Metformin or a Thiazolidinedione

The recommended starting and maintenance dose of nateglinide, alone or in combination with metformin or a thiazolidinedione, is 120 mg three times daily before meals.

The 60 mg dose of nateglinide, either alone or in combination with metformin or a thiazolidinedione, may be used in patients who are near goal HbA1c when treatment is initiated.

Dosage in Geriatric Patients

No special dose adjustments are usually necessary. However, greater sensitivity of some individuals to nateglinide therapy cannot be ruled out.

Dosage in Renal and Hepatic Impairment

No dosage adjustment is necessary in patients with mild-to-severe renal insufficiency or in patients with mild hepatic insufficiency. Dosing of patients with moderate-to-severe hepatic dysfunction has not been studied. Therefore, nateglinide should be used with caution in patients with moderate-to-severe liver disease (see PRECAUTIONS, Hepatic Impairment).