INTRODUCTION:

Malaria is one of the most dangerous infectious diseases in the world, mostly found in tropical and subtropical areas.¹ The World Health Organization says millions of people get infected with Plasmodium falciparum each year, and this type is especially deadly.

Because traditional medicines like chloroquine and sulfadoxine-pyrimethamine are no longer as effective due to drug resistance, Artemisinin-based combination treatments (ACTs) are now the main way to treat uncomplicated malaria.² Among these, the combination of artemether and lumefantrine is considered the most effective. This fixed-dose combination has shown fewer chances of resistance and faster removal of the parasite from the body.

However, the high lipophilicity and poor water solubility of artemether and lumefantrine restrict their rate of dissolution, bioavailability, and accuracy of analytical measurement.³ Conventional analytical approaches for identifying these medications frequently depend on organic solvents and extraction procedures like solid-phase extraction (SPE) or liquid-liquid extraction (LLE), which are expensive, time-consuming, and environmentally toxic. Green, straightforward, and environmentally friendly analytical techniques that reduce solvent consumption while preserving sensitivity and accuracy are becoming more necessary in the era of sustainable pharmaceutical research. A possible substitute that offers improved water solubility for poorly soluble medications without the use of hazardous solvents is hydrotropic solubilization. Therefore, investigating Hydrotropy for the analysis of artemether and lumefantrine may be a crucial step in creating safer, more effective, and ecologically friendly analytical techniques for antimalarial medications.

Chemistry and Physicochemical Properties of Artemether and Lumefantrine:

Artemether is a semisynthetic derivative of artemisinin, a natural sesquiterpene lactone isolated from Artemisia annua (sweet wormwood) represented in Figure 1. Chemically, it is known as (3R, 5aS, 6R, 8aS, 9R, 10R, 12R, 12aR)-10, 11, 12-trimethyl-6,12-epoxy-3,12a,4-trioxatetracyclo [9.3.1.0³^,⁸.0⁵^,⁷] pentadecane with molecular formula C₁₆H₂₆O₅ and a molecular weight of 298.37g/mol.⁴ Artemether appears as white crystalline powder, practically insoluble in water but freely soluble in organic solvents such as dichloromethane, acetone, and ethyl acetate. It possesses a log P value of 2.8, indicating moderate lipophilicity, and lacks ionizable functional groups, which means it has no pKa value. These characteristics limit its aqueous solubility and contribute to variable absorption after oral administration. Artemether is metabolized in the liver by cytochrome P450 (CYP3A4) to its active metabolite dihydroartemisinin (DHA), which is responsible for its potent antimalarial activity.

Lumefantrine is an aryl amino alcohol derivative with the chemical name 2-dibutylamino-1-(2,7-dichloro-9-phenanthryl)-3-dimethylaminopropan-1-ol hydrochloride represented in Figure.2. It has the molecular formula C₃₀H₃₂Cl₃NO and molecular weight 528.94g/mol.⁵ It is a yellow crystalline powder, practically insoluble in water, but soluble in dichloromethane and slightly soluble in methanol. It exhibits two pKa values (8.7 and 13.4) due to its basic amino groups and has a very high log P value (~8.7), reflecting strong lipophilicity. This high lipophilicity results in slow and variable absorption from the gastrointestinal tract, with bioavailability highly dependent on dietary fat intake.

Figure 1. Artemether

Figure 2. Lumefantrine

Conventional Analytical Methods:

For estimating Artemether and Lumefantrine, there are several analytical methods like UV-visible, HPLC, UPLC, LC-MS, etc that have been validated for both bulk and combined pharmaceutical doses.

UV–visible spectrophotometric methods are easy, quick, and cheap for routine analysis. However, they often have low sensitivity and selectivity because the two drugs' absorption spectra overlap. These methods are generally good for rough estimates or studies of how well something dissolves, not for exact measurements.⁶

Because they are more accurate, reproducible, and have better resolution, HPLC and UPLC are the best ways to estimate artemether and lumefantrine at the same time. In reversed-phase HPLC, C18 columns are usually used with mobile phases that are made up of acetonitrile, methanol, and phosphate buffer. But these methods need a lot of toxic organic solvents, take a long time to analyze, and use expensive equipment, which makes them less eco-friendly and too expensive for places with few resources.

Pharmacokinetic and bioequivalence studies commonly employ LC-MS/MS techniques because of their high sensitivity and specificity. They are less feasible for routine quality control in developing nations due to their high operational costs, complex instrumentation, and use of volatile organic solvents, despite their analytical precision.^7,8

Before chromatographic analysis, extraction and sample preparation techniques like liquid-liquid extraction (LLE) and solid-phase extraction (SPE) are frequently used. These procedures lead to possible analyte loss and the production of environmental waste in addition to lengthening analysis times and using more solvent.⁹

LIMITATIONS:

All things considered, these traditional techniques main drawbacks are their excessive reliance on hazardous organic solvents (acetonitrile, methanol, chloroform, etc.), high maintenance costs, difficult sample preparation, and unsustainable environmental practices. Green and hydrotropic analytical methods for artemether and lumefantrine estimation are becoming more popular because of these difficulties, which highlight the pressing need for environmentally friendly analytical substitutes.

Green Analytical Chemistry Approach:

Green Analytical Chemistry basically is "developing analytical method that are environmentally friendly by reducing hazardous waste, minimizing use of toxic reagent, cutting down on energy consumption".

It sustains the accuracy, precision, and reliability. It is based on 12 principles proposed by koel and kaljurand which is mentioned in Figure 3.

Figure 3. The Twelve Principles of Green Chemistry.

Several changes have been made to pharmaceutical analysis to adhere to the GAC principles. Reducing and replacing solvents has been one of the simpler methods. Greener substitutes like ethanol, water, or aqueous buffer systems are used in place of more hazardous organic solvents like acetonitrile and methanol. Surfactant-based mobile phases, which are extremely selective and eco-friendly, have been used in micellar chromatography in place of organic solvents.¹⁰ Like this, high-efficiency separations with very little solvent waste and minimal toxicity are achieved when carbon dioxide is used as a mobile phase component in SFC.

The use of green metrics to assess the environmental performance of analytical techniques has drawn a lot of interest. The greenness of the analytical technique is quantitatively evaluated in terms of solvent type, energy consumption, waste generated, and operator safety using indicators such as the Analytical Eco-Scale, Green Analytical Procedure Index (GAPI), and Analytical Greenness Metric AGREE.¹¹ Method developers would be able to compare various processes and optimize them for both ecological sustainability and analytical efficiency with the use of these assessment tools.

To put it briefly, GAC is a groundbreaking development in contemporary pharmaceutical analysis that promotes resource conservation and environmental responsibility. GAC principles support global efforts toward green pharmaceutical quality control by encouraging the development of solvent-free, economical, and sustainable methods for the estimation of artemether and lumefantrine.

Hydrotropy-Based Analytical Techniques:

Hydrotropy is a fascinating technique used to enhance the solubility of drugs that don’t dissolve well in water. By adding a significant amount of a hydrotropic agent, we can boost the aqueous solubility of these tricky compounds. The way it works involves some gentle interactions like stacking and hydrophobic forces, which help create a better environment for the drugs to dissolve, all without forming micelles. In pharmaceutical analysis, a variety of hydrotropes have been utilized, such as sodium benzoate, sodium salicylate, urea, nicotinamide, sodium citrate, and caffeine. The great thing about these agents is that they’re non-toxic, affordable, and highly soluble in water.¹²

Hydrotropic solutions present an alternative to the use of toxic organic solvents, which has been the standard in UV-visible spectrophotometry and HPLC method development. For example, in spectrophotometry, hydrotropes have made it possible for drugs that are insoluble in water to provide clear solutions for subsequent absorbance measurements. For HPLC, hydrotropic media assist in sample solvation, while potentially reducing or eliminating the requirement for organic mobile phase components in sample preparation.¹³

Aside from a number of reports demonstrating hydrotropic solubilization of poorly soluble drugs. Several this literature includes examination of furosemide, aceclofenac, ketoprofen, hydrochlorothiazide, and diclofenac using sodium benzoate or urea to demonstrate sufficient hydrotropic solubilization of poorly soluble drugs and subsequently demonstrate sufficient analytical methods without the use of solvents. Examples of well-studied drugs command demonstrate the viability and hydrotropic solubilization of compounds with high lipophilicity and such as the compounds used in treatment of malaria (artemether and lumefantrine).¹⁴

In summary, hydrotropy presents several additional benefits, such as being safer than organic solvents compared with organic solvents, and can be less expensive, can be safer to work with, less hazardous to the environment, and aligns more with the principles of green analytical chemistry. Based on these criteria hydrotropic should be considered one of the better alternatives for development of aore and analytical procedures on poorly soluble antimalarial drugs.

Comparison of Conventional vs. Green/Hydrotropic Analytical Methods.

Table 1: Conventional vs. Green/Hydrotropic Analytical Methods.

Parameter	Conventional Method	Green Analytical Method
Solvent use	High (Acetonitrile, Methanol)	Very Low, or aqueous based
Cost	High, due to solvents & upkeep	Low; inexpensive hydrotropes
Toxicity	High (organic solvents)	Negligible; eco-friendly
Accuracy and Precision	Good	Comparable and acceptable
Sustainability	Not Good	Outstanding; low solvent waste & greener

Challenges and Future Prospects Challenges:

Challenges:

· Limited validation data is available for hydrotropic analytical methods.

· There are difficulties in scaling up and slower regulatory acceptance compared to conventional methods.

Future Prospects:

· There is strong potential for integration with QbD (Quality by Design) approaches.

· The development of hybrid green hydrotropic RP-HPLC methods can improve sustainability and performance.

CONCLUSION:

The increasing demand for green and eco-friendly analytical methodologies calls for consideration of greener approaches for pharmaceutical analysis. Hydrotropy combined with the principles of green chemistry offers a potent alternative to conventional solvent-intensive methods due to its remarkable reduction of environmental impact, operation cost, and toxicity. Considering various advantages, strengthening method validation, robustness, and regulatory acceptance requires further research. Continuing efforts towards global exploration and implementation of hydrotropic and hybrid green analytical methodologies will create a path for safer, cleaner, and more sustainable pharmaceutical analytics.

REFERENCES:

1. Wahajuddin, Raju KS. Bioanalysis of antimalarials using liquid chromatography. TrAC Trends Anal Chem. 2013; 42:186–204. doi: 10.1016/j.trac.2012.09.014.

2. Ramakrishna K, Shiffali DR, Pani Kumar AD. Estimation of pioglitazone hydrochloride in bulk drug and pharmaceutical dosage forms by hydrotropy technique and oxidative-coupling reaction. Asian J Res Chem. 2013; 6(2): 172–176.

3. Parashar D, Kumar A, Aditya NP, Rayasa RM. Simultaneous estimation of artemether and lumefantrine in pharmaceutical dosage forms using derivative spectrophotometry. Asian J Res Chem. 2013;6(3):226–231.

4. World Health Organization. The International Pharmacopoeia. 7th ed. Geneva: World Health Organization; 2017.

5. Chemical Abstracts Service. SciFinder: artemether and lumefantrine. Columbus (OH): American Chemical Society; 2018.

6. Shrivastava A, Nagori BP, Saini P, Issarani R, Gaur SS. New simple and economical spectrophotometric method for estimation of artemether in pharmaceutical dosage forms. Asian J Res Chem. 2008; 1(1): 19–21.

7. Khuda F, Iqbal Z, Shah Y, Abbas M, Zakiullah, Hassan M. A high-resolution LC-MS/MS method for the quantitative determination of artemether and its metabolite dihydroartemisinin in human plasma and its application to pharmacokinetic studies. Chromatographia. 2022.

8. Hilhorst MJ, Hendriks G, de Vries R, Hillewaert V, Verhaege T, van de Merbel NC. A high-performance liquid chromatography–tandem mass spectrometry method for the determination of artemether and dihydroartemisinin in human plasma. J Chromatogr B Analyt Technol Biomed Life Sci. 2014; 965:45–53. doi: 10.1016/j.jchromb.2014.06.006.

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10. Peys E, Vandenkerckhove J, Van Hemel J, Sas B. Simultaneous determination of artemether and its metabolite dihydroartemisinin in human plasma and urine by a high-performance liquid chromatography–mass spectrometry assay using electrospray ionization. Chromatographia. 2005; 61: 637–641.

11. Duthaler U, Keiser J, Huwyler J. Development and validation of a liquid chromatography and ion spray tandem mass spectrometry method for the quantification of artesunate, artemether and their major metabolites dihydroartemisinin and dihydroartemisinin-glucuronide in sheep plasma. J Mass Spectrom. 2011; 46: 172–181.

12. Gurumurthy V, Deveswaran R, Bharath S, Basavaraj BV, Madhavan V. Application of hydrotropic solubilisation in simultaneous estimation of atenolol and amlodipine besylate. Asian J Res Chem. 2012; 5(1): 57–60.

13. Kothapalli LP, Vighne KS, Nanda RK, Thomas AB. Development and validation of a stability indicating HPTLC method for estimation of artemether in bulk and formulated dosage form. Asian J Res Chem. 2015; 8(10): 635–642.

Received on 28.11.2025 Revised on 31.12.2025

Accepted on 29.01.2026 Published on 10.04.2026

Available online from April 13, 2026

Asian J. Research Chem.2026; 19(2):143-146.

DOI: 10.52711/0974-4150.2026.00024

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

INTRODUCTION:

Malaria is one of the most dangerous infectious diseases in the world, mostly found in tropical and subtropical areas.1 The World Health Organization says millions of people get infected with Plasmodium falciparum each year, and this type is especially deadly.

Malaria is one of the most dangerous infectious diseases in the world, mostly found in tropical and subtropical areas.¹ The World Health Organization says millions of people get infected with Plasmodium falciparum each year, and this type is especially deadly.