Rapid and specific drug quality testing assay for artemisinin and its derivatives using a luminescent reaction and novel microfluidic technology

Voltammetric methods for electrochemical characterization and quantification of artemether-based antimalarials

Every year substandard and falsified (SF) artemisinin derivative-based antimalarials are responsible for the loss of 450 000 deaths and billions of GBP. The lack of infrastructure and funds to support pharmaceutical quality control in many low-and-middle-income countries contributes to this problem. This work assesses fitness for purpose of voltammetric methods for identification and quantification of artemether in the presence of excipients. Electrochemical characterization of artemether using cyclic voltammetry shows that the reduction of artemether is chemically irreversible within the potential range of -0.4 V to -1.4 V. A chronocoulometric quantification algorithm for artemether is created and tested with pure artemether, as well as filtered and unfiltered Riamet® tablets. Filtration of Riamet® tablets provides no additional benefit for the quantification of artemether in Riamet®. In addition, artemether's response to pH indicates possible protonation and coupled homogeneous chemistry. Finally, sodium sulfite is an effective means of removing dissolved oxygen and improving artemether signal resolution in air-equilibrated PBS. This concludes that electrochemical analysis is a promising method for artemether identification and quantification.

Detection of ascorbic acid based on its quenching effect on luminol-artemisinin chemiluminescence

We find that luminol can react with artemisinin (ART) to produce chemiluminescence (CL) in the absence of a catalyst and ascorbic acid (AA) can quench luminol-ART CL. Based on its efficient inhibition effect on luminol-ART CL, a new AA detection method is established. The calibration curve for the determination of AA is in the linear range of 5 × 10^-7 M to 1 × 10^-4 M with a detection limit of 50 nM, which is more sensitive than many other reported methods. This CL approach was utilized to detect AA in vitamin C tablets by applying the standard addition method, and the recoveries of 104.0%, 96.8% and 103.4% were obtained, respectively, at concentrations of 1 μM, 5 μM and 10 μM with a RSD value of less than 3.6%. This developed method for AA assay is distinguished by its fastness, reproducibility, easy operation and good selectivity.

Target-Catalyzed Self-Growing Spherical Nucleic Acid Enzyme (SNAzyme) as a Double Amplifier for Ultrasensitive Chemiluminescence MicroRNA Detection

Portable chemiluminescence (CL) imaging with a smartphone has shown a great promise for point-of-care testing of diseases, especially for acute myocardial infarction (AMI), which may occur abruptly. A challenge remains how to improve the imaging sensitivity that usually is several orders of magnitude lower than those of counterpart methodologies using the sophisticated equipment. Toward this goal, here, we report the target-triggered in situ growth of AuNP@hairpin-DNA nanoprobes into spherical nucleic acid enzymes (SNAzymes), which serve as both nanolabels and amplifiers for portable CL imaging of microRNAs (miRNAs) with an ultrahigh sensitivity comparable to that of the instrumental measurement under same conditions. A G-quadruplex (G4) DNA dense layer is dynamically produced on the gold nanocore via a DNAzyme machine-driven hairpin cleaving and captures the cofactor hemin to form the SNAzymes with higher peroxidase activity and stronger nuclease resistance than the commonly used G4 DNAzymes. The matured SNAzymes are then utilized as catalytic labels in a luminol-artesunate CL system for miRNA imaging with a smartphone as the portable detector. In this way, two AMI-related miRNAs, miRNA-499 and miRNA-133a, are successfully detected in real patients' serum with a naked eye-visualized CL change at 10 fM, showing a 5 order of magnitude improvement on the sensitivity of visualizing the same disease markers in clinical circulating blood as compared to the reported strategy. In addition, a good selectivity of our developed CL imaging platform is demonstrated. These unique features make it promising to employ this portable imaging platform for clinical AMI diagnosis.

Application of delayed luminescence method on measuring of the processing of Chinese herbal materials

BACKGROUND

Based on the principle of tradition Chinese medicine, the processing refers to various techniques that alter the overall properties of herbal materials to meet the requirements of therapeutic applications. However, the standards of quality control and scientific standard operation protocol for processing manufacturing are largely unknown and there is a huge demand for the development of scientific tools for evaluating the quality during and after the processing. The key challenge in evidence-based medicine is to characterize the processing of herbal materials from system-based perspective.

METHODS

Delayed luminescence (DL) as a rapid, direct, systemic tool was used to characterize the properties of raw and processed materials of Rehmanniae radix and Ginseng radix et rhizome. Hyperbolic function was used to extract four parameters from DL curves of herbal materials. Statistical tools, including one-way analysis of variance and principal component analysis, were used to differentiate raw and processed herbal materials.

RESULTS

Our results showed DL properties were able to reliably identify raw and processed materials of Rehmanniae radix and Ginseng radix et rhizoma, respectively. In addition, the results indicated that after four cycles of processing for Rehmanniae radix, there was no much significant change in DL parameters which resembles the results obtained from chemical analyses (after five cycles) using 1HNMR and gas chromatography-mass spectrometry in previous studies.

CONCLUSION

DL may serve as a fast, robust and sensitive tool for evaluating processing on herbs and may be used as part of a comprehensive platform for assessing the quality of herbal materials.

Quantitative bioassay to identify antimicrobial drugs through drug interaction fingerprint analysis

Drug interaction analysis, which reports the extent to which the presence of one drug affects the efficacy of another, is a powerful tool to select potent combinatorial therapies and predict connectivity between cellular components. Combinatorial effects of drug pairs often vary even for drugs with similar mechanism of actions. Therefore, drug interaction fingerprinting may be harnessed to differentiate drug identities. We developed a method to analyze drug interactions for the application of identifying active pharmaceutical ingredients, an essential step to assess drug quality. We developed a novel approach towards the identification of active pharmaceutical ingredients by comparing drug interaction fingerprint similarity metrics such as correlation and Euclidean distance. To expedite this method, we used bioluminescent E. coli in a simplified checkerboard assay to generate unique drug interaction fingerprints of antimicrobial drugs. Of 30 antibiotics studied, 29 could be identified based on their drug interaction fingerprints. We present drug interaction fingerprint analysis as a cheap, sensitive and quantitative method towards substandard and counterfeit drug detection.

Public health interventions to protect against falsified medicines: a systematic review of international, national and local policies

BACKGROUND

Falsified medicines are deliberately fraudulent drugs that pose a direct risk to patient health and undermine healthcare systems, causing global morbidity and mortality.

OBJECTIVE

To produce an overview of anti-falsifying public health interventions deployed at international, national and local scales in low and middle income countries (LMIC).

DATA SOURCES

We conducted a systematic search of the PubMed, Web of Science, Embase and Cochrane Central Register of Controlled Trials databases for healthcare or pharmaceutical policies relevant to reducing the burden of falsified medicines in LMIC.

RESULTS

Our initial search identified 660 unique studies, of which 203 met title/abstract inclusion criteria and were categorised according to their primary focus: international; national; local pharmacy; internet pharmacy; drug analysis tools. Eighty-four were included in the qualitative synthesis, along with 108 articles and website links retrieved through secondary searches.

DISCUSSION

On the international stage, we discuss the need for accessible pharmacovigilance (PV) global reporting systems, international leadership and funding incorporating multiple stakeholders (healthcare, pharmaceutical, law enforcement) and multilateral trade agreements that emphasise public health. On the national level, we explore the importance of establishing adequate medicine regulatory authorities and PV capacity, with drug screening along the supply chain. This requires interdepartmental coordination, drug certification and criminal justice legislation and enforcement that recognise the severity of medicine falsification. Local healthcare professionals can receive training on medicine quality assessments, drug registration and pharmacological testing equipment. Finally, we discuss novel technologies for drug analysis which allow rapid identification of fake medicines in low-resource settings. Innovative point-of-purchase systems like mobile phone verification allow consumers to check the authenticity of their medicines.

CONCLUSIONS

Combining anti-falsifying strategies targeting different levels of the pharmaceutical supply chain provides multiple barriers of protection from falsified medicines. This requires the political will to drive policy implementation; otherwise, people around the world remain at risk.

Combating poor-quality anti-malarial medicines: a call to action

The circulation of poor-quality medicines continues to undermine the fight against many life-threatening diseases. Anti-malarial medicines appear to have been particularly compromised and present a major public health threat in malaria-endemic countries, negatively affecting individuals and their communities. Concerted collaborative efforts are required from global, regional and national organizations, involving the public and private sectors, to address the problem. While many initiatives are underway, a number of unmet needs deserve urgent and increased multisector attention. At the global level, there is a need for an international public health legal framework or treaty on poor-quality medicines, with statutes suitable for integration into national laws. In addition, increased international efforts are required to strengthen the governance of global supply chains and enhance cooperation between national medicine regulation authorities and law enforcement bodies. Increased investment is needed in innovative technologies that will enable healthcare teams to detect poor-quality medicines at all levels of the supply chain. At the regional level, a number of initiatives would be beneficial—key areas are standardization, simplification, and reciprocal recognition of registration processes and development of quality control capacity in regional centres of excellence that are better aligned with public health needs; improved surveillance methods and creation of a framework for compulsory and transparent reporting of poor-quality medicines; additional support for national medicine regulation authorities and other national partner authorities; and an increase in support for regional laboratories to boost their capabilities in detecting poor-quality medicines. It is vital that all stakeholders involved in efforts against poor-quality anti-malarial medicines extend and strengthen their actions in these critical areas and thus effectively support global health development and malaria elimination programmes.