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Further Validation of a Rapid Screening Semiquantitative Thin-Layer Chromatographic Method for Marketed Antimalarial Medicines for Adoption in Malawi.

ABSTRACT: A recently developed semiquantitative thin-layer chromatographic (SQ-TLC) assay has been employed in postmarketing surveillance of antimalarial medicines used in Malawi prior to HPLC assay. Both methods gave analogous results in a significant majority of the samples, with a good correlation (r?=?0.9012) for the active pharmaceutical ingredients of the dosage forms assayed. Artemether-containing medicines had the highest percentage (92.67%) of samples with comparable results for both assays. The lowest percentage (66.67%) was observed in artesunate-containing medicines. The SQ-TLC method was validated for specificity, accuracy, precision, linearity, and stability according to the International Conference on Harmonisation guidelines, with the results falling within acceptable limits. For specificity, retention factor values of the test samples and reference standards were comparable, while accuracy and precision of 91.1?±?5.7% were obtained for all samples. The method was linear in the range 1.0-2.0?µg/spot with a correlation coefficient of r?=?0.9783. Stability tests also fell within acceptable limits. In this study, we present the validation of the SQ-TLC method and propose its adoption as a rapid screening tool for field estimation of the quality of antimalarial and other essential medicines in Malawi and other parts of the developing world prior to a more accurate HPLC assay.

SUBMITTER: Osei-Safo D

PROVIDER: S-EPMC5954873 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Further Validation of a Rapid Screening Semiquantitative Thin-Layer Chromatographic Method for Marketed Antimalarial Medicines for Adoption in Malawi.

Osei-Safo Dorcas D Chikowe Ibrahim I Harrison Jerry Joe Ebow Kingsley JJEK Yeboah Daniel Konadu DK Addae-Mensah Ivan I

Journal of analytical methods in chemistry 20180502

A recently developed semiquantitative thin-layer chromatographic (SQ-TLC) assay has been employed in postmarketing surveillance of antimalarial medicines used in Malawi prior to HPLC assay. Both methods gave analogous results in a significant majority of the samples, with a good correlation (<i>r</i> = 0.9012) for the active pharmaceutical ingredients of the dosage forms assayed. Artemether-containing medicines had the highest percentage (92.67%) of samples with comparable results for both assay ...[more]

PMID: 29854558

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Project description:BackgroundAvailability and affordability of medicines are key determinants of universal health coverage, yet achieving them presents a major challenge especially in low-income countries. We here present an analysis of availability and prices of antimalarial and antibiotic medicines in public, faith-based and private health facilities in Malawi. Medicines are provided free of charge in the public health care system of Malawi. In contrast, facilities of the Christian Health Association of Malawi (CHAM) usually charge their patients for medicines, as do private for-profit facilities.MethodsAs part of a study on medicine quality, samples of six antimalarial and six antibiotic medicines were collected in 31 health facilities in four districts of southern Malawi. These included 15 public facilities (i.e. health centres, district hospitals and central hospitals), eight CHAM and eight private facilities. Random selection was used in choosing the included health facilities. The availability of medicines was recorded, including the number of units which could be collected of each medicine, as well as the prices of medicines which were charged in CHAM and private facilities. These data were analyzed using the standard methodology developed by the World Health Organization (WHO) and Health Action International (HAI).ResultsAvailability of the antimalarials artemether/lumefantrine and sulfadoxine/pyrimethamine, which are provided with financial support from international donors, was high in public and CHAM facilities (93% and 100%, respectively). However, availability of antibiotics was much lower (e.g. 40% availability of amoxicillin tablets/capsules in public health centres). Medicine prices were lower than reported from many other countries. The median price ratio (MPR) to a wholesale international procurement price was 2.8 in CHAM facilities and even lower in the private sector (MPR 2.3). Nevertheless, for 10 of the 12 investigated medicines the cost for one course of treatment exceeded the daily wage of a low-paid government worker in Malawi and therefore had to be considered as unaffordable for a major part of the population.ConclusionsContinued efforts are required to improve the availability of essential medicines in Malawi. The free provision of medicines in the public health care system remains important in order to achieve universal health coverage, due to the low income in this country.

Project description:Hydrogels are important structural and operative components of microfluidic systems, finding diverse utility in biological sample preparation and interrogation. One inherent challenge for integrating hydrogels into microfluidic tools is thermodynamic molecular partitioning, which reduces the in-gel concentration of molecular solutes (e.g., biomolecular regents), as compared to the solute concentration in an applied solution. Consequently, biomolecular reagent access to in-gel scaffolded biological samples (e.g., encapsulated cells, microbial cultures, target analytes) is adversely impacted in hydrogels. Further, biomolecular reagents are typically introduced to the hydrogel via diffusion. This passive process requires long incubation periods compared to active biomolecular delivery techniques. Electrotransfer is an active technique used in Western blots and other gel-based immunoassays that overcomes limitations of size exclusion (increasing the total probe mass delivered into gel) and expedites probe delivery, even in millimeter-thick slab gels. While compatible with conventional slab gels, electrotransfer has not been adapted to thin gels (50-250 μm thick), which are of great interest as components of open microfluidic devices (vs enclosed microchannel-based devices). Mechanically delicate, thin gels are often mounted on rigid support substrates (glass, plastic) that are electrically insulating. Consequently, to adapt electrotransfer to thin-gel devices, we replace rigid insulating support substrates with novel, mechanically robust, yet electrically conductive nanoporous membranes. We describe grafting nanoporous membranes to thin-polyacrylamide-gel layers via silanization, characterize the electrical conductivity of silane-treated nanoporous membranes, and report the dependence of in-gel immunoprobe concentration on transfer duration for passive diffusion and active electrotransfer. Alternative microdevice component layers─including the mechanically robust, electrically conductive nanoporous membranes reported here─provide new functionality for integration into an increasing array of open microfluidic systems.

Project description:We report an approach to the fabrication of superhydrophobic thin films that is based on the 'reactive' layer-by-layer assembly of azlactone-containing polymer multilayers. We demonstrate that films fabricated from alternating layers of the azlactone functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) and poly(ethyleneimine) (PEI) exhibit micro- and nanoscale surface features that result in water contact angles in excess of 150º. Our results reveal that the formation of these surface features is (i) dependent upon film thickness (i.e., the number of layers of PEI and PVDMA deposited) and (ii) that it is influenced strongly by the presence (or absence) of cyclic azlactone-functionalized oligomers that can form upon storage of the 2-vinyl-4,4-dimethylazlactone (VDMA) used to synthesize PVDMA. For example, films fabricated using polymers synthesized in the presence of these oligomers exhibited rough, textured surfaces and superhydrophobic behavior (i.e., advancing contact angles in excess of 150º). In contrast, films fabricated from PVDMA polymerized in the absence of this oligomer (e.g., using freshly distilled monomer) were smooth and only moderately hydrophobic (i.e., advancing contact angles of ~75º). The addition of authentic, independently synthesized oligomer to samples of distilled VDMA at specified and controlled concentrations permitted reproducible fabrication of superhydrophobic thin films on the surfaces of a variety of different substrates. The surfaces of these films were demonstrated to be superhydrophobic immediately after fabrication, but they became hydrophilic after exposure to water for six days. Additional experiments demonstrated that it was possible to stabilize and prolong the superhydrophobic properties of these films (e.g., advancing contact angles in excess of 150° even after complete submersion in water for at least six weeks) by exploiting the reactivity of residual azlactones to functionalize the surfaces of the films using hydrophobic amines (e.g., aliphatic or semi-fluorinated aliphatic amines). Our results demonstrate a straightforward and substrate-independent approach to the design of superhydrophobic and reactive polymer-based coatings of potential use in a broad range of fundamental and applied contexts.

Dataset Information

Further Validation of a Rapid Screening Semiquantitative Thin-Layer Chromatographic Method for Marketed Antimalarial Medicines for Adoption in Malawi.

Publications

Further Validation of a Rapid Screening Semiquantitative Thin-Layer Chromatographic Method for Marketed Antimalarial Medicines for Adoption in Malawi.

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