INTRODUCTION:

Assessing the quality, efficacy as well as safety of medicinal products is powered by pharmaceutical analysis. The majority of the analytical approaches have still a complete dependency on organic solvent for dissolution and estimation of drugs, especially lipophilic APIs with poor aqueous solubility. These solvents—methyl alcohol, acetonitrile, chloroform, dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) and dimethylformamide (DMF)—are frequently toxic, volatile or hazardous to the environment and expensive to dispose of. Indeed, their widespread utilization directly goes against the following of sustainable laboratory practices and increasingly stringent environmental legislation. One major challenge of development of green analytical procedures is the fact that poorly water-soluble drugs are currently a hot issue, particularly BCS Class II drugs with high permeability but very low solubility.²² Glimepiride, a third-generation sulfonylurea broadly prescribed for Type 2 diabetes mellitus, is right in the pocket of those new clinical practice guidelines. It is almost insoluble in water and somewhat soluble in some organic solvents. This explains why the majority of analytical techniques in use today—UV, HPLC and even some stability-indicating assays depend on organic solvent mixtures to dissolve the drug before analysis.

However, this reliance conflicts with the underlying principles of green analytical chemistry and drives researchers toward developing methods that reduce or eradicate organic solvents.

Over the last few years, hydrotropy has led to an attractive new green solubilization strategy for addressing this challenge. Neuberg was the first to use the term hydrotropy in 1916, which describes how various ionic and nonionic compounds significantly increase the solubility of insoluble (hydrophobic) solutes at high concentrations.¹Some inexpensive and generally safe hydrotropes like sodium benzoate, sodium citrate, urea, nicotinamide and salicylates exhibit water solubility and safe nature. Unlike surfactants, they do not form micelles. Also, they do not use molecular inclusion as cyclodextrins do. They instead enhance solubility through self-aggregation, disruptions of structured water, weak solute-hydrotrope complex formations, and π-π interactions with aromatic drug molecules.²

Some of the primary studies within the field detail hydrotropes and their use for drug solubility and formulation. Maheshwari and others demonstrated the first practical example of sodium benzoate and nicotinamide hydrotropic solutions to increase the solubility of the otherwise poorly soluble drug molecules, ketoprofen, furosemide, and tinidazole.³ This demonstrated that hydrotropic methods can be used for UV spectrophotometric analysis without the use of organic solvents. Badwan et al. experienced the same phenomenon. Most of the earlier studies reported the same and used hydrotropes to define fundamental mechanistic principles for the use of solute and hydrotrope interactions.⁴A number of other researchers working in the field have studied mixed hydrotropes and reported instances in which the combination of two hydrotropes produced greater than additive effects.⁵ Hydrotropy is a green/Eco-friendly solubilization approach and reduces use of organic solvents.¹⁸

The literature for Glimepiride illustrates notable limitations in solubility that obstruct both the analytical and formulation development. Glimepiride's intrinsic aqueous solubility has been reported to be in the microgram-per-milliliter range, which is considered extremely low. This level of solubility will require the use of methanol or other organic solvents for quantitative analysis. A few research articles have explored non-conventional solubility enhancement approaches such as:

1. Solid dispersions with hydrophilic carriers

2. Inclusion complexes using cyclodextrins

3. Microcrystals and Nanosuspensions

4. pH Modifications

Several studies have shown that hydrotropic solid dispersions can improve the dissolution of Glimepiride, which suggests that the drug interacts quite well with hydrotropic agents. Aromatic hydrotropes, in particular, seem to have strong solubilizing ability for compounds containing sulfonylurea and phenyl groups—both of which are present in Glimepiride. Even with these findings, a properly validated green hydrotropic UV spectrophotometric method for Glimepiride is still not clearly established, leaving room for further work in this area.

Green analytical chemistry (GAC) provides a useful direction for developing such methods. It mainly focuses on reducing the use of harmful chemicals, cutting down waste, and encouraging safer as well as energy-efficient practices. Today, it is important that analytical methods are not just accurate but also environmentally responsible. In this sense, hydrotropic solubilization fits quite well, as it is relatively safe, cost-effective, does not require organic solvents, and can be easily applied using UV-visible spectrophotometry.

From the available literature, it is clear that many hydrotropic agents have already been used to improve drug solubility for spectrophotometric analysis. Common examples include sodium benzoate, nicotinamide, sodium salicylate, urea, and sodium citrate. These have been applied in green UV analysis for a variety of drug molecules. The idea of mixed hydrotropy has also gained attention, where two hydrotropes are combined at lower concentrations to achieve better solubility while still maintaining environmental safety. Overall, these findings support the usefulness of hydrotropy in analytical applications.

In recent years, there has been a noticeable shift toward eco-friendly analytical techniques. Solvent-free UV methods are often preferred because they are simple, affordable, and have less environmental impact. However, solubility still remains a major challenge, especially for poorly water-soluble drugs like Glimepiride. Although hydrotropy has been widely studied in general, only a limited number of studies have focused specifically on its use for estimating Glimepiride. This gap makes it worthwhile to explore hydrotropic systems as alternatives to organic solvents.

Considering all these points, a detailed review that brings together hydrotropy, green analytical chemistry principles, the properties of Glimepiride, and existing analytical methods becomes important. Such an approach can help in identifying a suitable hydrotropic system and in developing a green UV spectrophotometric method that is practical, cost-effective, and environmentally friendly.

Detailed Drug Profile of Glimepiride:

Introduction:

Glimepiride is a third-generation sulfonylurea used for the long-term treatment of Type 2 Diabetes Mellitus (T2DM).¹⁹Compared with older drugs like glibenclamide and glipizide, it is generally preferred because it produces a lower risk of hypoglycemia, shows strong receptor binding, and also improves glucose uptake in peripheral tissues. It is an orally active drug and is effective even at low doses ranging from 1 to 4 mg. Due to its high lipophilicity and very poor solubility in water, Glimepiride is categorized under BCS Class II drugs.⁶ In such drugs, dissolution becomes the limiting step for absorption. Because of this issue, analytical methods often depend on organic solvents. Hydrotropic solubilization can serve as a better and more environmentally friendly alternative.

Figure 01: Chemical structure of Glimepiride.

Chemical Information:

1. Chemical Name: 1- [[p- [2-(3-ethyl-4-methyl-2-oxo-3-pyrroline-1 -carboxamido) ethyl] phenyl] sulfonyl]-3-trans-(4-methylcyclohexyl) urea

2. Molecular Formula: C₂₄H₃₄N₄O₅S

3. Molecular Weight: 490.62 g/mol

4. Drug Class: Third-generation sulfonylurea

5. pKa: approximately 6.2

6. LogP: around 3.2, indicating lipophilic nature

7. Appearance: white to off-white crystalline powder

8. Solubility: practically insoluble in water but freely soluble in solvents such as methanol, DMSO, and acetone

The presence of aromatic rings along with the sulfonylurea group makes the molecule hydrophobic. Because of this, solubilization techniques like hydrotropy, use of cyclodextrins, surfactants, or co-solvents are often required during analysis.

Mechanism of Action:

Glimepiride mainly acts by increasing insulin secretion from pancreatic β-cells.

Pancreatic action:

1. Binds to sulfonylurea receptor (SUR1) on β-cells

2. Blocks ATP-sensitive potassium channels

3. Causes depolarization of the cell membrane

4. Opens calcium channels

5. Leads to insulin release

6. Improves insulin sensitivity

7. Increases GLUT4 transporter movement

8. Enhances glucose utilization in the liver

9. Shows mild antioxidant and anti-atherogenic effects

Pharmacokinetics:

1. Absorption: After oral administration, the drug is almost completely absorbed. It reaches peak concentration within 2–3 hours and shows nearly full bioavailability.

2. Distribution: It is highly bound to plasma proteins (around 99.5%), mainly albumin, due to its lipophilic nature.

3. Metabolism: Glimepiride is metabolized in the liver by the CYP2C9 enzyme. It forms two main metabolites i.e. M1: hydroxylated form (weakly active) M2: carboxylated form (active).

4. Elimination: The drug is eliminated through urine (about 60%) and feces (around 40%). It has a half-life of approximately 5–8 hours, allowing once-daily dosing.

Pharmacodynamics:

Glimepiride reduces both fasting and post-meal blood glucose levels. It can lower HbA1c by around 1–1.5% and helps maintain some β-cell function. Compared to older sulfonylureas, it causes less weight gain and has a relatively lower risk of hypoglycemia.

Analytical Challenges:

Low Solubility in Water: The drug has extremely low aqueous solubility (<0.004 mg/ml), which creates difficulties in,

1. UV-visible analysis

2. HPLC sample preparation

3. Dissolution testing

4. Quality control studies

Use of Organic Solvents: Traditional analytical methods rely on solvents like methanol and acetonitrile. these are, toxic in nature, Increase overall cost, Generate hazardous waste harmful for the environment, Also do not follow green chemistry principles

Instability in Alkaline Conditions: The sulfonylurea group can undergo hydrolysis in strongly alkaline media. Because of this, pH adjustment is not always suitable, which further supports the use of hydrotropic solubilization.

Need for Hydrotropic Analysis:

Hydrotropic agents such as sodium benzoate, sodium citrate, urea, and sodium salicylate are known to markedly improve the solubility of Glimepiride without the need for organic solvents. This makes hydrotropy a practical and environmentally safer approach for analytical purposes.^7,20

Advantages:

1. Can increase solubility significantly (often in the range of 10–100 times)

2. Considered safe and environmentally friendly

3. More economical compared to solvent-based methods

4. Do not usually interfere in the UV region

5. Suitable for both qualitative as well as quantitative analysis

Application Areas:

1. UV-visible spectrophotometry

2. Sample preparation for HPLC analysis

3. FTIR studies using dispersed systems

4. Dissolution testing

5. Development of green analytical methods

Earlier work demonstrated that glimepiride can be successfully analyzed by derivative UV spectrophotometry, confirming that UV-based methods are feasible for its routine quantification. This supports the use of hydrotropic UV analysis as a greener approach that improves solubility without relying on toxic organic solvents.³⁰Overall, hydrotropy aligns well with the principles of green chemistry, particularly in terms of reducing solvent use, minimizing waste, and promoting safer chemical practices. Glimepiride, being a highly potent antidiabetic drug with poor aqueous solubility and hydrophobic characteristics, presents challenges during routine analysis. Because of this, adopting green techniques such as hydrotropic solubilization becomes both necessary and beneficial. A proper understanding of its chemical nature, pharmacokinetic behavior, and analytical limitations plays an important role in designing sustainable and effective analytical methods.²³

Hydrotropic Agents: Chemistry, Mechanism and Classification:

Introduction: Hydrotropy refers to a phenomenon in which the solubility of poorly water-soluble drugs increases significantly in the presence of certain compounds, known as hydrotropic agents. These agents are typically ionic organic salts that, when added in relatively high concentrations, enhance aqueous solubility through solute–solute interactions.Unlike surfactants, hydrotropes do not form micelles. Instead, they are believed to form loosely organized, dynamic aggregates through interactions such as molecular stacking, hydrogen bonding, and electrostatic forces. Because of this behavior, hydrotropy offers a different and often simpler approach to solubilization. This property makes hydrotropic agents a useful and greener alternative to organic solvents, particularly for drugs like Glimepiride that are practically insoluble in water.

Chemistry of Hydrotropic Agents:

Hydrotropic agents are generally classified based on their chemical nature. They commonly include aromatic salts such as benzoates and salicylates, aliphatic salts like citrates and tartrates, and neutral compounds capable of hydrogen bonding, for example urea and nicotinamide.

Their solubilizing ability is mainly due to certain structural features. Most hydrotropes contain an anionic group that helps in enhancing solubility. In addition, the presence of an aromatic ring or another hydrophobic moiety allows interactions such as molecular stacking. Functional groups that can donate or accept hydrogen bonds further strengthen the interaction between the drug and the hydrotrope.

Because of this combination of properties, hydrotropes are able to modify the surrounding water environment and create conditions that favor the dissolution of hydrophobic drugs, without introducing significant toxicity.

Mechanism of Hydrotropy:

A number of mechanisms, including self-aggregation, π–π stacking, hydrogen bonding, and disruption of water structure, are involved in hydrotropic solubilisation.

1. Self-Aggregation: Above a particular concentration called the Minimum Hydrotropic Concentration (MHC), hydrotropes form loose aggregates.These aggregates house hydrophobic medicinal molecules in "micro-pockets.

2. π–π Stacking: Aromatic hydrotropes, like sodium benzoate and sodium salicylate, interact π–π with aromatic drug structures, such as the phenyl rings in glimepiride.

3. Hydrogen Bond Formation: This process significantly boosts solubility by forming hydrogen bonds between the sulfonylurea group of glimepiride and the −OH or −COO⁻ groups of hydrotropes.

4. Disruption of Water Structure: Hydrotropes weaken water's strong H-bond network, making it less polar and facilitating the easier dissolution of hydrophobic solutes.

5. Salt–Drug Complex Formation: Occasionally, the drug in solution is stabilised by the formation of transient complexes.²

Classification of hydrotropes:

1. Aromatic Anionic Hydrotropes: Excellent for aromatic medications such as glimepiride

· Sodium benzoate

· Sodium salicylate

· Sodium citrate

2. Aliphatic Anionic Hydrotropes: Electrostatic interactions are slightly weaker solubilizers but more environmentally benign.

· Sodium citrate

· Sodium acetate

· Sodium lactate

3. Neutral/Non-Ionic Hydrotropes: Excellent hydrogen bonding for uses in green chemistry.

· Urea

· Nicotinamide

· Resorcinol

4. Cationic Hydrotropes: An emergent class of charge-dipole interactions.

Salts based on choline (Green Hydrotopes) Green hydrotopes are influenced by:

1. Hydrotrope concentration

2. Temperature

3. The medium's pH

4. Structural compatibility of drugs and hydrotropes

5. The existence of co-solutes

6. Ionic power

These factors must be experimentally optimised since they regulate the solubilisation efficiency.

Hydrotropy's function in green analytical chemistry:

It satisfies several green chemistry tenets.

1. Replaces hazardous organic solvents

2. Reduces waste

3. Improves security

4. Lowers expenses

5. Generates biodegradable products

As a result, it is ideal for the environmentally friendly analysis of glimepiride.

Table 1: Solubility enhancement data from glimepiride hydrotropic solid dispersions.³

Sr. no	Hydrotrope	Conc. (%)	Solubility (μg/ml)	Fold Increases
1	Water	-	3.8	1x
2	Urea	30%	49.51	13,000x
3	Sodium Acetate	30%	40.43	10,600x
4	Urea: Sodium Acetate(Mixed)	20%:10%	64.51	17,000x

Hydrotropic UV Analysis of Glimepiride Methodology:

Hydrotropic Agent: This is the compounds that enhance the solubility of poorly water-soluble organic compound in water.

1. Choice Hydrotropic Agent:

The first step in the analytical process is the proper choice of a suitable hydrotropic agent that can enhance the aqueous solubility of glimepiride significantly because it is not very soluble in water. Agents which are typically tested to analyze their effectiveness as solubilizing agents include sodium benzoate, sodium salicylate, urea, or nicotinamide depending on the level of solubility, UV light transparency, chemical reactivity with the drug, and analytical stability. The hydrotrope selected should increase solubility but not cause spectral interference at the UV range where glimepiride has absorbance. This is a basic procedure that makes the analysis that follows reliable, accurate and not artifact due to the solvent associated absorbance.

2. Preparation of Hydrotropic Solvent System:

When the hydrotropic agent is chosen, an appropriate level of the hydrotropic solution is made by adding measured volume of the agent in the distilled water with mild heating or stirring till they become clear and homogenous. The concentration is optimized so as to achieve maximum enhancement of solubility and at the same time maintain the stability of the solution and no degradation by any chemical of glimepiride. This is the hydro-tropic medium that is used in the main solvent of the whole analytical process and it is very important during sample dissolution, dilution and analytical measurements.

3. Development of Stock Standard Solution of glimepiride:

An actual amount of glimepiride is weighed and put into a volumetric flask and then the hydrotropic solvent is put to get the drug fully dissolved. The mixture is carefully shaken or sonated so as to obtain complete solubilization to give a clear stock solution of known concentration. A stock solution is used to prepare calibration standards and analytical samples to provide reproducibility and accuracy in determinations. It is also clear that the solution is effective in increasing the solubility of the drugs, as shown by the clarity of the solution.

4. Getting Ready to Calibration Curve Standards:

To provide quantitative analysis, a dilution series is prepared with the stock solution using the same hydrotropic medium to get solutions of different concentrations within the validated analytical range. This is done with each dilution to ensure linearity and precision to be able to generate a calibration curve. Such concentrations are determined by the anticipated range of sample absorbance and the applicability of the Beer-Lambert law. This measure is necessary to assure that the analysis technique shows a steady linear association among the concentration and absorbance.

5. The maximum absorbance wavelength was determined as (λmax):

The UV spectrum of the drug in the hydro-tropic solvent is scanned across an appropriate range of wavelengths before quantification such that the λmax, at which the drug absorbs best, is identified. This wavelength is significant in all the further measurements because it ensures the highest sensitivity level and better analytical response. The hydrotropic agent should also have little or no absorbance at λmax in order to avoid interference. The detection of the proper λmax enhances the specificity of the methodology and makes sure that analytical results are indicative of the only spectral property of the drug.

6. UV Spectrophotometric of Samples:

The calibration standards and sample solutions are then prepared and then analyzed under UV through measuring the absorbance at the already established λmax. The samples are put in quartz cuvette and readings taken in controlled conditions to maintain constant results in light scattering, quality of cuvette and effects of solvent. The value of absorbance is recorded and then compared with the concentrations by means of the calibration curve. This is the major step in quantification to obtain accurate reproducible data to be analyzed and validated.²⁵

7. Analytical Validate and Interpretation of Data:

The reliability of the method is determined by assessing the standard validation parameters like linearity, precision, accuracy, specificity and robustness as per the ICH guidelines. The statistical analysis of the calibration and sample measurements is conducted to ensure that the hydrotropic UV technique is regularly working and of quality to analyze the pharmaceutical products. Interpretation entails the comparison of observed concentrations with indicated or hypothesis concentrations and determining whether methods meet regulatory expectations. It is established in a validated process that hydro-tropy offers a green, cost-effective and efficient alternative to UV assays that utilize organic solvents.

Validation of Hydrotropic UV Methods:

Hydrotropic UV Processes Review of Validation Parameters, to ensure that the analytical procedure is sound, robust, and can give reliable measurements over routine operations, method validation of hydrotropic UV analysis of Glimepiride is necessary. As per ICH Q2(R1) and USFDA expectations of a way to be analytically valid, the first significant requirement is the measurement of linearity, which is an assessment of whether a method has a direct proportional relationship between absorbance and concentration.⁸ Linearity is especially significant to be established in hydrotropic systems since the presence of hydrotropes should not interfere with the Beer Lambert law. Correlation coefficients (R²) are usually found to be strong (R²>0.999) indicating that enhancement of solubility by hydrotropy does not alter the UV absorption behavior. This establishes the fact that the analyte behaves in a known manner within the range of analysis chosen to do the analysis.²⁴

1. Accuracy: The other important parameter is accuracy that is evaluated based on the percentage recovery of Glimepiride over varying levels of concentration. It is aimed at the fact that hydrotropes do not chemically react with the drug or modify its actual concentration. The majority of studies record that recoveries are 98-102%, meaning solubility improvement is attained without any disruptive chemical reactions. This is an assurance that this hydrotropic medium allows quantification to be done accurately without systematic errors.

2. Precision: It involves repeatability and intermediate precision. Repeatability guarantees the consistency of an approach in cases where the same approach is used on a series of occasions as long as the conditions remain unchanged whereas intermediate precision scrutinizes variability on days, analysts or instruments. The hydrotropic UV procedure typically exhibits low relative standard deviation (RSD < 2%), indicating that with a high relative solubility, the readings are stable and well defined. This accuracy is especially useful as the low solubility of Glimepiride usually leads to variability in non-hydrotropic procedures.

3. Specificity: It is used to ensure that hydrotropic agents or degradation products or excipients do not interfere with the absorbance maximum of Glimepiride. Hydrotropics UV techniques have the advantage that in most cases; the hydrotropes have no significant absorbance at the λmax of the drug, which results in clean and interference-free measurements. Blank hydrotropic solutions exhibit a low background absorbance in a number of studies, which confirms that the technique is a reliable way to isolate the signal of the drug.

4. Limit of detection and Limit of quantification: To know the sensitivity of the method, it is necessary to determine LOD (limit of detection) and LOQ (limit of quantification). Hydrotropic solubilization significantly reduces the baseline noise and improves the clarity of the spectrum to allow the use of low LOD and LOQ values when compared to solvent-based methods. This is particularly applicable to drugs with low solubility in water, such as Glimepiride, since the ability to be highly soluble is directly proportional to the ability to be detected due to the ability to give cut and sharp absorbance peaks.

5. Robustness: assesses how stable the methodology is in the presence of minor intentional alterations like minor hydrotrope concentration or wavelength or sample preparation alterations. Under such variations, hydrotropic UV techniques typically tend to be stable and exhibit method resilience. Because the hydrotropic solubility is not exceedingly sensitive to temperature changes or even slight changes in concentration, the process does not change its accuracy and precision in slightly varied laboratory conditions.

Lastly, stability of the solution is determined to guarantee that Glimepiride is stable in terms of chemical and spectral stability of the hydrotropic medium at long time. Numerous experiments have demonstrated that drug-hydrotrope solutions are stable 24-48 hours without much change in absorbance so that hydrotropic solubilization does not increase degradation or cause instability. This stability facilitates the usefulness of the laboratory as samples can be prepared and measured over long durations without any loss of integrity.

Green measures of assessment that have been implemented on hydrotropic analysis of glimepiride:

Green analytical chemistry is no more about substituting the dangerous solvents with less dangerous ones, but it should be based on scientifically checked measure tools that quantify the extent to which an analytical method can be considered environmentally responsible. These instruments are called green assessment metrics and offer objective, reproducible and comprehensive estimates of the ecological footprint, the efficiency of laboratory procedures and their sustainability. These metrics are important in the context of hydrotropic analysis of Glimepiride, as these metrics will allow determining whether the perceived greenness of the method is actually backed by the quantifiable criteria. Among the existing numerous structural frameworks, three of them are most suitable and accurate, complete, and widely applied in contemporary literature: the Analytical Eco-Scale, the Green Analytical Procedure Index (GAPI) and the Analytical GREEnness measure (AGREE). All these tools analyze the analytical procedure in a new look: Eco-Scale measures punishment steps of the hazardous steps, GAPI visually assesses the whole process of work, and AGREE incorporates the twelve rules of the green analytical chemistry into one understandable score. The two of them come up with a multidimensional perception of the hydrotropic analysis in terms of sustainability, safety, and environmental impact.^27,28Recent comparative studies have evaluated analytical methods using Eco-Scale, GAPI, and AGREE together, demonstrating that these tools provide complementary and reliable assessments of method greenness in pharmaceutical analysis.²⁶

1. Analytical Eco-Scale:

Analytical Eco-Scale is also among the oldest quantitative scales that have been developed in order to assess the extent to which an analytical method is environmentally friendly. It works under a straightforward concept; the perfect green practice will have a 100-point score and there will be a penalty deduction of the situation(s) which will lead to environmental damage, safety risk or unwarranted consumption of resources. Applying this measure to hydrotropic analysis of Glimepiride, one can point out the fact that one of the greatest advantages of this method is the total lack of any harmful organic solvents. Glimepiride is traditionally studied using acetonitrile, methanol or mixed buffer, which bear such penalties as being toxic, flammable and ecologically toxic. Hydrotropic approaches, in their turn, employ green agents like sodium benzoate, sodium citrate, urea, or nicotinamide. These are non-toxic, cheap and generally accepted to be safe materials and hence low penalty points. Eco-Scale also gives incentives to low energy usage, minimal number of operational stages, insignificant amounts of waste production, and lack of derivatization of reagents- all of which are characteristic of hydrotropic extraction and spectrophotometric analysis. In the case of Glimepiride, the scores of Eco-Scale are usually higher than 75, which implies that it is an excellent green method. This demonstrates that hydrotropic analysis is efficient and it also supports strongly sustainability as an option compared to the conventional solvent-based procedures, hence it is highly favored.⁹

2. Green Analytical Procedure Index (GAPI):

GAPI is a more comprehensive evaluation instrument in that it considers the comprehensive analytical procedure starting with the sample collection process through to final measurement. In contrast with Eco-Scale, which provides an overall numerical rating, Gapi operates on a color-coded pentagram scale, green for steps that are environmentally safe, yellow for those that are less green, and red for those that are problem. In contrast to GAPI, the hydrotropic methodologies of Glimepiride are in good performance in most stages when compared to GAPI. The step of preparing the sample is especially green since hydrototropic dissolution does not involve heating, multiple extraction, toxic solvents or derivatization. The reagents used also seem to be green due to the fact that hydrotropes are not volatile and are safe. The instrumental analysis, like the UVvis in most Glimepiride hydrotroph assays, is highly green, as it does not have high energy consumption, and no extra solvents are needed. When controlled temperature is employed, or a confirmatory chromatographic method is incorporated in the study only a few areas of yellow are occasionally observed. Notably, hydrotropic techniques exhibit nearly no red zones as opposed to the HPLC techniques where the continuous red zones exist as a result of the solvent driven separation processes. GAPI therefore shows visually not numerically that hydrotropic procedures on Glimepiride are easy, safe and more environmental friendly than the traditional forms of analysis.^11,12 GAPI evaluates the environmental impact of the entire analytical procedure through a color-coded pictogram, and its application in a comparative study of empagliflozin chromatographic methods shows its practical value in pharmaceutical greenness assessment.²⁹

3. AGREE (Analytical Greenness Metric):

The most recent and all-encompassing green assessment system is AGREE (Analytical GREEnness) since it measures the methods of analysis in detail and with regard to all the twelve principles of Green Analytical Chemistry. Such principles are prevention of waste, safer solvents, reduction of derivatization, in-situ measurements, energy saving, smaller sizes of samples and better safety of operators. AGREE takes all these principles and forms one circular diagram and the final score would be 0-1. In the case of hydrotropic analysis of Glimepiride, the method generally attains a high score with a score on AGREE because the methods sticks to most of these green principles. The technique does not make use of solvents that are toxic, requires little amounts of solutions, produces very small amounts of waste, and can be done using basic spectroscopic equipment that consumes less energy. The process also does not require multi-step extractions or complex chemical modifications hence the technique is more sustainable. Although some moderate restrictions can be observed, including the fact that hydrotroes are not renewable biomaterials or that the process is not a fully automated one, they do not have a great impact on the overall greenness profile. AGREE thus offers the best attestation to the fact that Hydrotropic analysis of Glimepiride is even more than just greener than other procedures, but actually is environmentally aware in its composition and operation itself.¹³

Future Prospects:

Hydrotropic analysis of Glimepiride is so promising at this moment, particularly given that the pharma research is moving to safer, cleaner and more sustainable approaches. The hydrotropy provides a sweet spot by addressing two of the biggest issues with this drug the dreadful solubility of the drug in water and environmental concerns that arise when using traditional organic-solvent extractions. The key direction hereafter will be to develop multifunctional hydrotropes, which enhance solubility and additionally enhance analytical signals, selectivity and lessen the handling of samples. The other promising avenue is the formation of natural or bio-derived hydrotropes, which in addition to additional eco-benefits, are in line with the concept of green chemistry.

Other emerging areas of study could also be an integration of hydrotropy with sophisticated analysis tools such as spectrofluorimetry, green HPLC methodologies, microfluidic systems and sensor technologies. Such combinations may reduce sample sizes, reduce the time of analysis, and reduce the consumption of reagents at a high level of accuracy. Also, mathematical software - cogitate computer-aided models and simulations of hydrotrope-drug interactions - could be used to select the appropriate hydrotrope and level without excessive experimentation in the laboratory.^14,21,24

The regulatory acceptance of hydrotropic techniques is likely to increase as additional proven protocols and inter-labor comparisons demonstrate the strength and consistency of the technique. As the situation with the environment gets stricter on a global scale, hydrotropic analysis might end up becoming the preferred choice of the poorly soluble drugs in the pharmaceutical sector. Comprehensively, the technique has a high probability of instituting into a staple approach to a sustainable analysis of drugs, with regard to efficiency, safety and environmental accountability.

CONCLUSION:

Hydrotropic analysis is a giant leap in a more sustainable assessment of drugs with low solubility in water such as Glimepiride. The technique avoids use of the dangerous organic solvents hence adhering to the fundamental principles of green analytic chemistry besides addressing the solubility issues that render analysis of this drug to be tricky using conventional methods. The reviewed studies continue to demonstrate that regardless of the chemical characteristics of the hydrotropic agent, synthetic, natural, or bio-compatible, it provides an easy, yet a highly effective route to drug dissolution, allowing quantification of the sample with precision and reproducibility using a spectrophotometer or other instruments. Applying the known green evaluation indicators, namely, Eco-Scale, GAPI, and AGREE, this fact is further verified through the fact that the hydrotropic practices have a clearly better environmental footprint than that of the conventional ones. Such assessments emphasize the minimum level of waste, reduced amount of energy consumption, safety of operations, and general simplicity of the procedures. Since pharma research requires more environmentally friendly methods, hydrotropic analysis can be considered a promising, valid and scientifically sound solution.

Hydrotropic UV analysis of glimepiride delivers equivalent analytical performance (Table 2: LOD 0.5 μg/ml, R²>0.999) to conventional methods with superior greenness: 13,000x solubility enhancement (Table 1), Eco-scale 85 vs 55 (Table 3), and GAPI 96% green zones vs 32% (Table 4) Waste reduction exceeds 93% (2 mL vs 30 mL solvents) while eliminating all PBT chemicals.^3,10,15,16This review establishes hydrotropy as the sustainable method of choice for BCS Class II antidiabetics, aligning perfectly with green analytical chemistry principles.

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Received on 21.04.2026 Revised on 24.05.2026

Accepted on 20.06.2026 Published on 04.07.2026

Available online from July 30, 2026

Asian J. Research Chem.2026; 19(4):347-356.

DOI: 10.52711/0974-4150.2026.00053

This work is licensed under a Creative Commons Attribution-Non Commercial-Share Alike 4.0 International License. Creative Commons License.

Sr. No	Method	Hydrotrope	λmax	LOD	Linearity	%RSD	Eco-scale
1	UV	Urea 30%	225nm	0.5	5-50 μg/ml	1.2	85
2	UV	Sodium benzoate	228nm	1.0	2-30 μg/ml	1.8	82
3	HPLC	Sodium citrate	-	0.01	0.1-10 μg/ml	1.1	78
4	Control	Methanol	230nm	0.3	1-25 μg/ml	2.1	55

Sr.no.	Metrics	Hydrotropic UV	Conventional HPLC	Improvement
1	Eco-scale score	85(Excellent)	55(Acceptable)	+30 Points
2	Solvent volume	2ml water	30ml Acetonitrile	93%↓
3	Waste/Analysis	2ml	30ml	93%↓
4	Energy use	UV (Low)	HPLC(High)	70%↓
5	Hazardous Reagents	None	Acetonitrile	100%↓

GAPI Category	Hydrotropic UV	Conventional HPLC
Sample Collection	5	3
Extraction	5	1
Reagent	5	1
instruments	5	2
Waste	4	1
Overall %	24/25(96%)	8/25(32%)