Repaglinide

Synthetic Routes and Reaction Conditions

Repaglinide can be synthesized through a multi-step process involving several key intermediates. One common method involves the following steps :

Esterification: 3-hydroxyphenylacetic acid is esterified to form ethyl 3-hydroxyphenylacetate.

Formylation: The ester is then formylated to produce ethyl 3-formyl-4-hydroxyphenylacetate.

Oxidation: The formyl group is oxidized to a carboxylic acid, yielding ethyl 3-carboxy-4-hydroxyphenylacetate.

Etherification: The hydroxyl group is etherified to form ethyl 3-carboxy-4-ethoxyphenylacetate.

Selective Hydrolysis: The ester is selectively hydrolyzed to produce 3-carboxy-4-ethoxyphenylacetic acid, a key intermediate in the synthesis of this compound.

Industrial Production Methods

Industrial production of this compound involves optimizing the reaction conditions to maximize yield and purity. This includes controlling reaction temperature, time, solvent, and substrate ratios . The process is designed to be scalable and environmentally friendly, with minimal impurities.

Types of Reactions

Repaglinide undergoes several types of chemical reactions, including:

Oxidation: this compound can be oxidized to form various metabolites.

Reduction: Reduction reactions can modify the functional groups on the this compound molecule.

Substitution: Substitution reactions can occur at various positions on the aromatic ring and side chains.

Common Reagents and Conditions

Common reagents used in the synthesis and modification of this compound include:

Oxidizing Agents: Such as potassium permanganate and hydrogen peroxide.

Reducing Agents: Such as sodium borohydride and lithium aluminum hydride.

Substitution Reagents: Such as halogens and alkylating agents.

Major Products

The major products formed from these reactions include various metabolites and derivatives of this compound, which can be characterized using techniques such as FT-IR, NMR, and UV-Vis spectroscopy .

Repaglinide is an oral antihyperglycemic agent primarily used to manage type 2 diabetes mellitus . It helps regulate blood glucose levels by stimulating the pancreas to release insulin . It is particularly effective in controlling postprandial glucose levels .

Monotherapy

This compound can be used as a monotherapy to manage blood sugar levels. A study comparing this compound monotherapy to nateglinide monotherapy showed that this compound was more effective in reducing HbA1c and fasting plasma glucose (FPG) values after 16 weeks of treatment . After 16 weeks, the mean reduction in HbA1c was significantly greater with this compound than with nateglinide (-1.57% vs -1.04%; P=0.002). Additionally, the mean changes in FPG demonstrated greater efficacy for this compound than nateglinide (-57 vs -18 mg/dl; P<0.001) .

Combination Therapy

This compound can be used in combination with other oral anti-diabetic drugs . this compound is also effective in lowering blood glucose concentrations in both sulfonylurea-treated patients and those who are new to oral hypoglycemic agents .

Glycemic Efficacy

Studies have demonstrated that reductions in A1c levels achieved with meglitinides like this compound are similar to, or slightly less than, those observed with sulfonylurea or metformin treatment when used as monotherapy . In a study comparing this compound to nateglinide in patients with type 2 diabetes, this compound was more effective in reducing A1c levels (1.57% vs. 1.04%) .

Safety and Tolerability

This compound is generally well-tolerated . However, like sulfonylureas, meglitinides can cause hypoglycemia, although the risk of severe hypoglycemia is less . Weight gain is another potential side effect .

Dosage and Administration

The recommended starting dose of this compound for patients with an A1c less than 8% is 0.5 mg before each meal (1-30 minutes prior). For those with an A1c of 8% or greater, the starting dose is 1 or 2 mg orally before each meal. The dose can be doubled up to 4mg with each meal until satisfactory glycemic control is achieved, with a one-week interval between dose increases. The maximum daily dose is 16 mg per day . this compound should be taken with meals, and doses should be skipped if a meal is skipped .

This compound vs. Nateglinide

Repaglinide exerts its effects by binding to ATP-sensitive potassium channels on the β cells of the pancreas. This binding inhibits the efflux of potassium ions, leading to depolarization of the cell membrane. The depolarization opens voltage-dependent calcium channels, allowing calcium ions to enter the cell. The influx of calcium ions triggers the exocytosis of insulin granules, resulting in increased insulin release . This mechanism is glucose-dependent, meaning that insulin release is stimulated only in the presence of glucose, reducing the risk of hypoglycemia .

Repaglinide is often compared with other antidiabetic drugs, such as:

Nateglinide: Another meglitinide with a similar mechanism of action but a shorter duration of effect.

Sulfonylureas: Such as glibenclamide and glimepiride, which also stimulate insulin release but have a longer duration of action and higher risk of hypoglycemia.

Metformin: A biguanide that reduces hepatic glucose production and improves insulin sensitivity but does not stimulate insulin release

This compound is unique in its rapid onset and short duration of action, making it particularly effective for controlling postprandial blood glucose levels without causing prolonged hypoglycemia .

Repaglinide is an oral antidiabetic medication belonging to the class of meglitinides, primarily used for managing type 2 diabetes mellitus. Its mechanism of action involves stimulating insulin secretion from pancreatic β-cells in response to elevated blood glucose levels. This article delves into the biological activity of this compound, supported by data tables, case studies, and detailed research findings.

This compound functions by inhibiting ATP-sensitive potassium channels (K-ATP channels) in pancreatic β-cells. This inhibition leads to membrane depolarization, opening L-type calcium channels, and subsequently increasing intracellular calcium concentrations. The rise in calcium levels triggers the exocytosis of insulin granules, enhancing insulin secretion in a glucose-dependent manner. Unlike sulfonylureas, this compound's effect is minimal in the absence of glucose, making it particularly effective for postprandial blood glucose control .

Pharmacokinetics

The pharmacokinetic profile of this compound is characterized by rapid absorption and a short duration of action:

• Absorption : Rapidly absorbed with peak plasma concentrations reached within 0.5 to 1.4 hours after oral administration.
• Bioavailability : Approximately 56%, indicating that a significant portion of the drug reaches systemic circulation.
• Volume of Distribution : About 31 L following intravenous administration.
• Protein Binding : Over 98%, primarily to albumin and α1-acid glycoprotein .

Case Studies and Clinical Trials

• Efficacy in Type 2 Diabetes Management :
  A phase II multicenter trial involving 99 patients demonstrated that this compound significantly reduced glycosylated hemoglobin (HbA1c) levels from 8.5% to 7.8% compared to an increase from 8.1% to 9.3% in the placebo group (P < 0.0001). Additionally, fasting plasma glucose levels decreased significantly in the this compound group .
• Comparison with Other Antidiabetics :
  In a study comparing this compound with nateglinide over 16 weeks, this compound resulted in a greater reduction in HbA1c (1.57% vs. 1.04%, P = 0.002) and was more effective at controlling postprandial glucose levels .
• Pharmacogenomic Studies :
  Research involving newly diagnosed type 2 diabetes patients indicated that genetic factors could influence the efficacy of this compound, with significant associations found between genetic scores and reductions in fasting glucose and HbA1c levels .

Safety Profile

This compound is generally well tolerated, with common adverse effects including:

• Hypoglycemia : Occurred in approximately 16% of patients, similar to other sulfonylureas but without increased risk when meals were missed.
• Other Adverse Events : Upper respiratory infections (10%), rhinitis (7%), bronchitis (6%), and headache (9%) were also reported .

Summary Table of Key Findings

Basic Research Questions

Q. What are the key methodological considerations when designing preclinical studies to evaluate repaglinide’s pharmacokinetics and safety?

• Methodological Answer : Preclinical studies must adhere to NIH guidelines for experimental rigor and reproducibility. Key factors include:

• Sample Size and Power Analysis : Use statistical tools (e.g., G*Power) to determine adequate sample sizes, minimizing Type I/II errors .
• In Vivo Model Selection : Rodent models should be justified based on metabolic similarities to humans, with documentation of strain, age, and housing conditions .
• Dosage Rationale : Align with human-equivalent doses (HED) derived from body surface area scaling, as per FDA guidance.
• Ethical Compliance : Include Institutional Animal Care and Use Committee (IACUC) approval details .

Q. How can researchers formulate focused research questions for optimizing this compound formulations using frameworks like PICO or FINER?

• Methodological Answer :

• PICO Framework : Define Population (e.g., diabetic rat models), Intervention (e.g., floating tablets with HPMC K-100M), Comparison (e.g., immediate-release formulations), and Outcome (e.g., gastric retention time) .
• FINER Criteria : Ensure questions are Feasible (e.g., lab resources for sustained-release testing), Interesting (e.g., novel polymer combinations), Novel (e.g., addressing gaps in floating mechanisms), Ethical, and Relevant (e.g., clinical translation potential) .

Q. What strategies ensure rigorous literature reviews for identifying gaps in this compound delivery systems?

• Methodological Answer :

• Systematic Search : Use databases (PubMed, Scopus) with Boolean operators (e.g., "this compound AND floating tablets NOT metformin").
• Quality Assessment : Apply PRISMA guidelines to filter studies by robustness (e.g., peer-reviewed journals, sample size >30) .
• Gap Analysis : Map existing studies using tools like VOSviewer to visualize under-researched areas (e.g., long-term stability of gastroretentive formulations) .

Advanced Research Questions

Q. How do response surface methodologies (RSM) such as Central Composite Design (CCD) and D-Optimal Design compare in optimizing this compound formulations?

• Methodological Answer :

• Model Accuracy : CCD typically achieves R² > 0.85 but requires more runs (e.g., 20 runs for 3 factors), whereas D-Optimal reduces runs (e.g., 15) with comparable predictive power (relative error < 4%) .
• Diagnostic Tools : Use ANOVA for model significance (p < 0.05), residual plots for variance homogeneity, and leverage 3D contour plots to visualize interactions (e.g., HPMC K-100M concentration vs. floating lag time) .
• Software : Implement Design-Expert® or JMP® for automated optimization, prioritizing "desirability functions" to balance conflicting responses (e.g., drug release vs. buoyancy) .

Q. What statistical approaches resolve contradictions in this compound’s pharmacokinetic data across heterogeneous patient cohorts?

• Methodological Answer :

• Mixed-Effects Modeling : Account for inter-individual variability (e.g., CYP2C8 polymorphism) using NONMEM® or Monolix® .
• Sensitivity Analysis : Identify covariates (e.g., BMI, renal function) via stepwise covariate modeling (SCM) .
• Meta-Regression : Pool data from multiple studies (e.g., Cochrane Library) to adjust for confounders like dosing regimens .

Q. How should researchers structure the Methods section to meet reproducibility standards for complex this compound formulations?

• Methodological Answer :

• Granularity : Specify excipient sources (e.g., Eudragit RSPO from Evonik Industries), tablet hardness (e.g., 8–10 kp), and dissolution conditions (e.g., USP Apparatus II, 50 rpm, 37°C) .
• Validation : Include HPLC parameters (column: C18, 5 µm; mobile phase: acetonitrile-phosphate buffer) and validation metrics (e.g., LOD/LOQ, recovery rate 98–102%) .
• Ethnography for Adherence Studies : For patient-centric research, detail interview protocols (e.g., semi-structured questionnaires) and coding frameworks (e.g., NVivo® for thematic analysis) .

Q. Data Analysis & Interpretation

Q. What advanced techniques validate the robustness of this compound’s in vitro-in vivo correlation (IVIVC)?

• Methodological Answer :

• Level A IVIVC : Use deconvolution methods (e.g., Wagner-Nelson) to correlate dissolution profiles (e.g., f2 similarity factor >50) with plasma concentration-time curves .
• Bootstrap Validation : Resample data 1000x to compute 95% confidence intervals for predicted AUC and C_max .

Q. How can machine learning improve this compound formulation development?

• Methodological Answer :

• Feature Engineering : Input variables include polymer viscosity, drug-polymer ratio, and compression force.
• Algorithm Selection : Compare Random Forest (interpretability) vs. Neural Networks (nonlinearity handling) using metrics like RMSE .
• Validation : Apply k-fold cross-validation (k=10) to prevent overfitting .