Cysteamine broadly improves the anti-plasmodial activity of artemisinins against murine blood stage and cerebral malaria.

BACKGROUND: The potential emergence and spread of resistance to artemisinins in the Plasmodium falciparum malaria parasite constitutes a major global health threat. Hence, improving the efficacy of artemisinins and of artemisinin-based combination therapy (ACT) represents a major short-term goal in the global fight against malaria. Mice defective in the enzyme pantetheinase (Vnn3) show increased susceptibility to blood-stage malaria (increased parasitaemia, reduced survival), and supplementation of Vnn3 mutants with the reaction product of pantetheinase, cysteamine, corrects in part the malaria-susceptibility phenotype of the mutants. Cysteamine (Cys) is a small, naturally occurring amino-thiol that has very low toxicity in vivo and is approved for clinical use in the life-long treatment of the kidney disorder nephropathic cystinosis. METHODS: The ability of Cys to improve the anti-plasmodial activity of different clinically used artemisinins was tested. The effect of different CYS/ART combinations on malarial phenotypes (parasite blood-stage replication, overall and survival from lethal infection) was assessed in a series of in vivo experiments using Plasmodium strains that induce either blood-stage (Plasmodium chabaudi AS) or cerebral disease (Plasmodium berghei ANKA). This was also evaluated in an ex vivo experimental protocol that directly assesses the effect of such drug combinations on the viability of Plasmodium parasites, as measured by the ability of tested parasites to induce a productive infection in vivo in otherwise naïve animals. RESULTS: Cys is found to potentiate the anti-plasmodial activity of artesunate, artemether, and arteether, towards the blood-stage malaria parasite P. chabaudi AS. Ex vivo experiments, indicate that potentiation of the anti-plasmodial activity of artemisinins by Cys is direct and does not require the presence of host factors. In addition, potentiation occurs at sub-optimal concentrations of artemisinins and Cys that on their own have little or no effect on parasite growth. Cys also dramatically enhances the efficacy and protective effect of artemisinins against cerebral malaria induced by infection with the P. berghei ANKA parasite. CONCLUSION: These findings indicate that inclusion of Cys in current formulations of ACT, or its use as adjunct therapy could improve the anti-plasmodial activity of artemisinin, decrease mortality in cerebral malaria patients, and prevent or delay the development and spread of artemisinin resistance.

Gas chromatographic method for the determination of lumefantrine in antimalarial finished pharmaceutical products.

A simple method has been developed and validated for quantitative determination of lumefantrine in antimalarial finished pharmaceutical products using gas chromatography coupled to flame ionization detector. Lumefantrine was silylated with N,O-bis(trimethyl-silyl)trifluoro-acetamide at 70°C for 30 minutes, and chromatographic separation was conducted on a fused silica capillary (HP-5, 30 m length × 0.32 mm i.d., 0.25 µm film thickness) column. Evaluation of the method within analytical quality-by-design principles, including a central composite face-centered design for the sample derivatization process and Plackett-Burman robustness verification of the chromatographic conditions, indicated that the method has acceptable specificity toward excipients and degradants, accuracy [mean recovery = 99.5%, relative standard deviation (RSD) = 1.0%], linearity (=0.9986), precision (intraday = 96.1% of the label claim, RSD = 0.9%; interday = 96.3% label claim, RSD = 0.9%), and high sensitivity with detection limits of 0.01 µg/mL. The developed method was successfully applied to analyze the lumefantrine content of marketed fixed-dose combination antimalarial finished pharmaceutical products.

UHPLC-MS/MS method for the determination of the cyclic depsipeptide mycotoxins beauvericin and enniatins in in vitro transdermal experiments.

Currently, dermal exposure data of cyclic depsipeptide mycotoxins beauvericin and enniatins are completely absent with a lack of local skin and systemic kinetics, despite their widespread skin contact and intrinsic hazard. Therefore a sensitive and specific bioanalytical high-throughput UHPLC-MS/MS method was developed for the quantitative and simultaneous determination of cyclic depsipeptide mycotoxins beauvericin and enniatins (A, A1, B, B1, D, E, C/F) in human skin Franz diffusion cell samples. The limits of detection ranged between 10 and 17pg/ml, while the total run time was only 4.5min. There was no significant effect of endogenous skin compounds on the mycotoxin MS signal observed, and the accuracy (0.68-24.68% bias) and precision (0.57-10.70% RSD) were considered acceptable for our purposes. Moreover, it was demonstrated that these cyclic depsipeptides are stable for at least 7 days when formulated in different organic or aqueous mixtures. Finally, adsorption to glass did occur: at least 50% ethanol or acetonitrile is required to prevent significant adsorption effects, which could be as high as 45%.

Investigation of active pharmaceutical ingredient loss in pharmaceutical compounding of capsules.

Pharmaceutical compounding of capsules is still an important corner stone in today's health care. It allows for a more patient specific treatment plan as opposed to the "one size fits all"-approach, used by the pharmaceutical industry when producing fixed dose finished drug products. However, loss of active pharmaceutical ingredient (API) powder during pharmaceutical capsule compounding can lead to under-dosed finished drug products and annul the beneficiary therapeutic effects for the patient. The amount and location of API loss was experimentally determined during capsule compounding of five different preparations: 10 and 20mg hydrocortisone capsules, 4mg triamcinolone capsules and 0.25mg dexamethasone capsules, using a 10% m/m self-made or commercial trituration. The total API amount present in the five capsule preparations varied between 90.8% and 96.6%, demonstrating that for certain preparations, significant API mass loss occurred during the pharmaceutical compounding of capsules. Swabbing results of the different compounding equipment and working areas indicated the mortar surface as the largest API loss location. An agate mortar accounted for the least amount of API loss, whereas an extensively used porcelain mortar accounted for the highest amount of API loss. Optical microscopy and roughness (Ra) determination by profilometry of the different mortar surfaces revealed a significant influence of the mortar surface wear and tear on the observed API loss. This observation can be explained by physical deformation, or scratch formation, of the relatively soft porcelain mortar surface, in which the API particles can become adsorbed. Furthermore, a small effect of the capsulation device material on the API loss was also observed. The presence of a chemical molecule effect on the API loss was demonstrated through data mining using a set of assay results containing 17 different molecules and 1922 assay values. The 17 median assay values were modeled in function of corresponding molecular descriptors, using stepwise multiple linear regression. The obtained MLR model, containing RDF060m, R6e(+) and R3m(+) variables, explained 92.5% of the observed variability between the 17 median assay values.

LC-UV/MS quality analytics of paediatric artemether formulations.

A highly selective and stability-indicating HPLC-method, combined with appropriate sample preparation steps, is developed for ß-artemether assay and profiling of related impurities, including possible degradants, in a complex powder for oral suspension. Following HPLC conditions allowed the required selectivity: a Prevail organic acid (OA) column (250 mm×4.6 mm, 5 µm), flow rate set at 1.5 mL/min combined with a linear gradient (where A=25 mM phosphate buffer (pH 2.5), and B=acetonitrile) from 30% to 75% B in a runtime of 60 min. Quantitative UV-detection was performed at 210 nm. Acetonitrile was applied as extraction solvent for sample preparation. Using acetonitrile-water mixtures as extraction solvent, a compartmental behaviour by a non-solving excipient-bound fraction and an artemether-solubilising free fraction of solvent was demonstrated, making a mobile phase based extraction not a good choice. Method validation showed that the developed HPLC-method is considered to be suitable for its intended regulatory stability-quality characterisation of ß-artemether paediatric formulations. Furthermore, LC-MS on references as well as on stability samples was performed allowing identity confirmation of the ß-artemether related impurities. MS-fragmentation scheme of ß-artemether and its related substances is proposed, explaining the m/z values of the in-source fragments obtained.

LC-UV/MS quality analytics of paediatric artemether formulations / 药物分析学报

A highly selective and stability-indicating HPLC-method, combined with appropriate sample preparation steps, is developed for β-artemether assay and profiling of related impurities, including possible degradants, in a complex powder for oral suspension. Following HPLC conditions allowed the required selectivity: a Prevail organic acid (OA) column (250 mm×4.6 mm, 5μm), flow rate set at 1.5 mL/min combined with a linear gradient (where A ? 25 mM phosphate buffer (pH 2.5), and B ? acetonitrile) from 30% to 75% B in a runtime of 60 min. Quantitative UV-detection was performed at 210 nm. Acetonitrile was applied as extraction solvent for sample preparation. Using acetonitrile-water mixtures as extraction solvent, a compartmental behaviour by a non-solving excipient-bound fraction and an artemether-solubilising free fraction of solvent was demonstrated, making a mobile phase based extraction not a good choice. Method validation showed that the developed HPLC-method is considered to be suitable for its intended regulatory stability-quality characterisation of β-artemether paediatric formulations. Furthermore, LC-MS on references as well as on stability samples was performed allowing identity confirmation of the β-artemether related impurities. MS-fragmentation scheme of β-artemether and its related substances is proposed, explaining the m/z values of the in-source fragments obtained.

A rapid stability-indicating, fused-core HPLC method for simultaneous determination of ß-artemether and lumefantrine in anti-malarial fixed dose combination products.

BACKGROUND: Artemisinin-based fixed dose combination (FDC) products are recommended by World Health Organization (WHO) as a first-line treatment. However, the current artemisinin FDC products, such as ß-artemether and lumefantrine, are inherently unstable and require controlled distribution and storage conditions, which are not always available in resource-limited settings. Moreover, quality control is hampered by lack of suitable analytical methods. Thus, there is a need for a rapid and simple, but stability-indicating method for the simultaneous assay of ß-artemether and lumefantrine FDC products. METHODS: Three reversed-phase fused-core HPLC columns (Halo RP-Amide, Halo C18 and Halo Phenyl-hexyl), all thermostated at 30°C, were evaluated. ß-Artemether and lumefantrine (unstressed and stressed), and reference-related impurities were injected and chromatographic parameters were assessed. Optimal chromatographic parameters were obtained using Halo RP-Amide column and an isocratic mobile phase composed of acetonitrile and 1 mM phosphate buffer pH 3.0 (52:48; V/V) at a flow of 1.0 ml/min and 3 µl injection volume. Quantification was performed at 210 nm and 335 nm for ß-artemether and for lumefantrine, respectively. In-silico toxicological evaluation of the related impurities was made using Derek Nexus v2.0®. RESULTS: Both ß-artemether and lumefantrine were separated from each other as well as from the specified and unspecified related impurities including degradants. A complete chromatographic run only took four minutes. Evaluation of the method, including a Plackett-Burman robustness verification within analytical QbD-principles, and real-life samples showed the method is suitable for quantitative assay purposes of both active pharmaceutical ingredients, with a mean recovery relative standard deviation (± RSD) of 99.7 % (± 0.7%) for ß-artemether and 99.7 % (± 0.6%) for lumefantrine. All identified ß-artemether-related impurities were predicted in Derek Nexus v2.0® to have toxicity risks similar to ß-artemether active pharmaceutical ingredient (API) itself. CONCLUSIONS: A rapid, robust, precise and accurate stability-indicating, quantitative fused-core isocratic HPLC method was developed for simultaneous assay of ß-artemether and lumefantrine. This method can be applied in the routine regulatory quality control of FDC products. The in-silico toxicological investigation using Derek Nexus® indicated that the overall toxicity risk for ß-artemether-related impurities is comparable to that of ß-artemether API.

Relative response factor determination of ß-artemether degradants by a dry heat stress approach.

During the stability evaluation of ß-artemether containing finished drug products, a consistent and disproportional increase in the UV-peak areas of ß-artemether degradation products, when compared to the peak area decline of ß-artemether itself, was observed. This suggested that the response factors of the formed ß-artemether degradants were significantly higher than ß-artemether. Dry heat stressing of ß-artemether powder, as a single compound, using different temperatures (125-150 °C), times (10-90 min) and environmental conditions (neutral, KMnO(4) and zinc), resulted in the formation of 17 degradants. The vast majority of degradants seen during the long-term and accelerated ICH stability study of the drug product, were also observed here. The obtained stress results allowed the calculation of the overall average relative response factor (RRF) of ß-artemether degradants, i.e. 21.2, whereas the individual RRF values of the 9 most prominent selected degradants ranged from 4.9 to 42.4. Finally, Ames tests were performed on ß-artemether as well as a representative stressed sample mixture, experimentally assessing their mutagenic properties. Both were found to be negative, suggesting no mutagenicity problems of the degradants at high concentrations. Our general approach and specific results solve the developmental quality issue of mass balance during stability studies and the related genotoxicity concerns of the key antimalarial drug ß-artemether and its degradants.