Development of a generic micellar electrokinetic chromatography method for the separation of 15 antimalarial drugs as a tool to detect medicine counterfeiting

Antimalarial analysis of pharmaceutical formulations and biological samples by capillary electrophoresis: the state of the art and applications

Malaria is a serious public health problem, being an endemic disease in 84 countries, mainly in Africa. This review explores the application of capillary electrophoresis (CE) techniques for analyzing antimalarial drugs, highlighting methods from 2000 to 2023 for the analysis of pharmaceutical formulations and human biological samples. The versatility, selectivity, high efficiency, cost-effectiveness, and high analytical frequency of CE techniques have become attractive choices for pharmaceutical analysis, focusing on quality control and impurity analysis applications. The evolution of achiral and chiral electromigration methods has been described based on the features of each mode of separation: capillary zone electrophoresis (CZE), micellar electrokinetic chromatography, microemulsion electrokinetic chromatography, and capillary electrochromatography. As expected, CZE is reported in most articles owing to its compatibility with drug properties and separation mode. However, it is necessary to perform other separation modes for a few drugs that are present in neutral form. After exhaustive research using different databases and statistical analyses, 27 articles using CE techniques for antimalarial drug analysis were found and are mentioned in this review.

Cinchonine: A Versatile Pharmacological Agent Derived from Natural Cinchona Alkaloids

BACKGROUND

Cinchonine is one of the Cinchona alkaloids that is commercially extracted from the Peruvian bark of Cinchona officinalis L. (Family: Rubiaceae). It is also obtained in much lower quantities from other species of Cinchona, such as Cinchona calisaya, Cinchona succirubra, and Cinchona pubescens, and in some other plants, such as Remijia peruviana. Cinchonine has been historically used as an anti-malarial agent. It also has a wide range of other biological properties, including anti-cancer, anti-obesity, anti-inflammatory, anti-parasitic, antimicrobial, anti-platelet aggregation, and anti-osteoclast differentiation.

AIM AND OBJECTIVE

This review discusses the pharmacological activity of cinchonine under different experimental conditions, including in silico, in vitro, and in vivo. It also covers the compound's physicochemical properties, toxicological aspects, and pharmacokinetics.

METHODOLOGY

A comprehensive literature search was conducted on multiple online databases, such as PubMed, Scopus, and Google Scholar. The aim was to retrieve a wide range of review/research papers and bibliographic sources. The process involved applying exclusion and inclusion criteria to ensure the selection of relevant and high-quality papers.

RESULTS

Cinchonine has numerous pharmacological properties, making it a promising compound for various therapeutic applications. It induces anti-cancer activity by activating caspase-3 and PARP-1, and triggers the endoplasmic reticulum stress response. It up-regulates GRP78 and promotes the phosphorylation of PERK and ETIF-2α. Cinchonine also inhibits osteoclastogenesis, inhibiting TAK1 activation and suppressing NFATc1 expression by regulating AP-1 and NF-κB. Its potential anti-inflammatory effects reduce the impact of high-fat diets, making it suitable for targeting obesity-related diseases. However, research on cinchonine is limited, and further studies are needed to fully understand its therapeutic potential. Further investigation is needed to ensure its safety and efficacy in clinical applications.

CONCLUSION

Overall, this review article explains the pharmacological activity of cinchonine, its synthesis, and physicochemical properties, toxicological aspects, and pharmacokinetics.

Counterfeit formulations: analytical perspective on anorectics

Purpose

This paper examines the scope of anorectics in counterfeit weight-reducing formulations and provides insight into the present state of research in determining such adulterants. Analytical techniques utilised in profiling adulterants found in slimming products, including limitations and mitigation steps of these conventional methods are also discussed. The current legal status of the anorectics and analogues routinely encountered in non-prescription slimming formulations is also explored.

Methods

All reviewed literature was extracted from Scopus, Web of Science, PubMed, and Google Scholar databases using relevant search terms, such as, ‘counterfeit drugs’, ‘weight loss drugs’, ‘weight-reducing drugs’, ‘slimming drugs’, ‘anorectic agents’, and ‘counterfeit anorexics’. Legislation related to anorectics was obtained from the portals of various government and international agencies.

Results

Anorectics frequently profiled in counterfeit slimming formulations are mostly amphetamine derivatives or its analogues. Five routinely reported pharmacological classes of adulterants, namely anxiolytics, diuretics, antidepressants, laxatives, and stimulants, are mainly utilised as coadjuvants in fake weigh-reducing formulations to increase bioavailability or to minimise anticipated side effects. Liquid and gas chromatography coupled with mass spectrometric detectors are predominantly used techniques for anorectic analysis due to the possibility of obtaining detailed information of adulterants. However, interference from the complex sample matrices of these fake products limits the accuracy of these methods and requires robust sample preparation methods for enhanced sensitivity and selectivity. The most common anorectics found in counterfeit slimming medicines are either completely banned or available by prescription only, in many countries.

Conclusions

Slimming formulations doped with anorectic cocktails to boost their weight-reducing efficacy are not uncommon. Liquid chromatography combined with mass spectrometry remains the gold standard for counterfeit drug analysis, and requires improved preconcentration methods for rapid and quantitative identification of specific chemical constituents. Extensive method development and validation, targeted at refining existing techniques while developing new ones, is expected to improve the analytical profiling of counterfeit anorectics significantly.

Simultaneous separation of artesunate and mefloquine in fixed-dose combination tablets by CZE-UV

A novel method was proposed for simultaneous determination of artesunate (ATS) and mefloquine (MFQ) in fixed-dose combination tablets by capillary zone electrophoresis with simultaneous direct and indirect detection by ultraviolet (CZE-UV). The background electrolyte, consisting of 30/15 mmol L^-1 TRIS/3,5-dinitrobenzoic acid buffer at pH 8.2, a chromophore buffer, was selected taking into account a detailed study involving the effective mobility vs. pH curves of the analytes and electrolyte compounds in association with the very low molar absorptivity of ATS. Suitable separation conditions, considering voltage, temperature and buffer concentration as factors, were achieved through the 3³ Box-Behnken design investigation. The optimum baseline separation conditions were: injection pressure of 30 mbar for 10 s, cartridge temperature of 22.5 °C and positive voltage of +30 kV. The method proved to be rapid (5 minutes), simple, selective, linear (r² > 0.98), precise (relative standard deviation (RSD): ATS < 2.9% and MFQ < 2.2%) and accurate (recoveries: ATS 98.13-102.96% and MFQ 98.75-106.77%), proving to be suitable for routine quality control analysis.

Photoluminescent and Chromic Nanomaterials for Anticounterfeiting Technologies: Recent Advances and Future Challenges

Counterfeiting and inverse engineering of security and confidential documents, such as banknotes, passports, national cards, certificates, and valuable products, has significantly been increased, which is a major challenge for governments, companies, and customers. From recent global reports published in 2017, the counterfeiting market was evaluated to be $107.26 billion in 2016 and forecasted to reach $206.57 billion by 2021 at a compound annual growth rate of 14.0%. Development of anticounterfeiting and authentication technologies with multilevel securities is a powerful solution to overcome this challenge. Stimuli-chromic (photochromic, hydrochromic, and thermochromic) and photoluminescent (fluorescent and phosphorescent) compounds are the most significant and applicable materials for development of complex anticounterfeiting inks with a high-security level and fast authentication. Highly efficient anticounterfeiting and authentication technologies have been developed to reach high security and efficiency. Applicable materials for anticounterfeiting applications are generally based on photochromic and photoluminescent compounds, for which hydrochromic and thermochromic materials have extensively been used in recent decades. A wide range of materials, such as organic and inorganic metal complexes, polymer nanoparticles, quantum dots, polymer dots, carbon dots, upconverting nanoparticles, and supramolecular structures, could display all of these phenomena depending on their physical and chemical characteristics. The polymeric anticounterfeiting inks have recently received significant attention because of their high stability for printing on confidential documents. In addition, the printing technologies including hand-writing, stamping, inkjet printing, screen printing, and anticounterfeiting labels are discussed for introduction of the most efficient methods for application of different anticounterfeiting inks. This review would help scientists to design and develop the most applicable encryption, authentication, and anticounterfeiting technologies with high security, fast detection, and potential applications in security marking and information encryption on various substrates.

An overview of the use of microchips in electrophoretic separation techniques: fabrication, separation modes, sample preparation opportunities, and on-chip detection

This chapter is intended as a basic introduction to microchip-based capillary electrophoresis to set the scene for newcomers and give pointers to reference material. An outline of some commonly used setups and key concepts is given, many of which are explored in greater depth in later chapters.

Development of a specific monoclonal antibody-based ELISA to measure the artemether content of antimalarial drugs

Artemether is one of the artemisinin derivatives that are active ingredients in antimalarial drugs. Counterfeit and substandard antimalarial drugs have become a serious problem, which demands reliable analytical tools and implementation of strict regulation of drug quality. Structural similarity among artemisinin analogs is a challenge to develop immunoassays that are specific to artemisinin derivatives. To produce specific antibodies to artemether, we used microbial fermentation of artemether to obtain 9-hydroxyartemether, which was subsequently used to prepare a 9-O-succinylartemether hapten for conjugation with ovalbumin as the immunogen. A monoclonal antibody (mAb), designated as 2G12E1, was produced with high specificity to artemether. 2G12E1 showed low cross reactivities to dihydroartemisinin, artemisinin, artesunate and other major antimalarial drugs. An indirect competitive enzyme linked immunosorbent assay (icELISA) developed showed a concentration causing 50% of inhibition for artemether as 3.7 ng mL⁻¹ and a working range of 0.7-19 ng mL⁻¹. The icELISA was applied for determination of artemether content in different commercial drugs and the results were comparable to those determined by high-performance liquid chromatography analysis. In comparison with reported broad cross activity of anti-artemisinin mAbs, the most notable advantage of the 2G12E1-based ELISA is its high specificity to artemether only.

Pharmacokinetic properties and bioequivalence of two sulfadoxine/pyrimethamine fixed-dose combination tablets: a parallel-design study in healthy Chinese male volunteers

BACKGROUND

Sulfadoxine/pyrimethamine fixed-dose combination (FDC) tablet is the long-acting portion of the antimalaria product Artecospe(®), coblister containing artesunate tablets plus sulfadoxine/pyrimethamine FDC tablets. This study was conducted to support the efficacy and tolerability of the sulfadoxine/pyrimethamine FDC tablet in the World Health Organization's (WHO) Prequalification of Medicines Programme, as well as to obtain marketing authorization in China.

OBJECTIVE

The aim of the present study was to compare the pharmacokinetic profiles between a new generic and the branded reference formulation of sulfadoxine/pyrimethamine FDC tablets, and to assess the bioequivalence of the 2 products in healthy Chinese volunteers.

METHODS

This single-dose, open-label, randomized, parallel-group study was conducted in healthy Chinese male volunteers who were randomly assigned (1:1) to receive a single 1500/75-mg dose (3 × 500/25-mg tablets) of either the test or reference formulation after a 12-hour overnight fast. Seventeen blood samples were obtained over a 168-hour interval, and plasma concentrations of sulfadoxine and pyrimethamine were determined by 2 separate validated liquid chromatography-isotopic dilution mass spectrometry methods. Pharmacokinetic properties (C(max), AUC(0-72), AUC(0-168), and T(max)) were calculated and analyzed statistically. The 2 formulations were to be considered bioequivalent if 90% CIs for the log-transformed ratios of C(max) and AUC(0-72) were within the predetermined bioequivalence range of 80% to 125%, in accordance with the guidelines of WHO and China's Food and Drug Administration (FDA). Tolerability was evaluated throughout the study by vital signs, physical examinations, clinical laboratory tests, 12-lead ECGs, and subject interviews on adverse events (AEs).

RESULTS

Forty-six healthy subjects completed the study. The mean values of sulfadoxine C(max) (183.07 and 165.15 mg/L), AUC(0-72) (11,036.52 and 10,536.78 mg/L/h), and AUC(0-168) (22,247.05 and 21,761.02 mg/L/h) were not significantly different between the test and reference formulations, respectively. The same was true for pyrimethamine (0.55 and 0.58 mg/L, 29.85 and 31.44 mg/L/h, and 56.18 and 59.27 mg/L/h, respectively). The 90% CIs for the log-transformed ratios of C(max), AUC(0-72), and AUC(0-168) of both sulfadoxine (105.4%-116.6%, 99.3%-110.6%, and 96.4%-108.1%) and pyrimethamine (88.8%-100.9%, 89.5%-101.0%, and 88.3%-101.6%) were within the acceptance limits for bioequivalence. A total of 7 mild AEs were reported in 7 subjects (15.2%).

CONCLUSIONS

The findings from this single-dose (1500/75-mg) study suggest that the test and reference formulations of sulfadoxine/pyrimethamine FDC 500/25-mg tablet have similar pharmacokinetic profiles both in terms of rate and extent of absorption. The formulations met WHO's and China's FDA regulatory criteria for bioequivalence in these healthy Chinese volunteers under fasting conditions. Both formulations were generally well-tolerated.