HPLC analysis of anti-malaria agent, chloroquine in blood and tissue from forensic autopsy cases in Tanzania

Analytical Methods on Determination in Pharmaceuticals and Biological Materials of Chloroquine as Available for the Treatment of COVID-19

With the outbreak caused by the severe acute respiratory syndrome coronavirus (COVID-19), people's health and existing economies on a global scale are seriously threatened. Currently, most of the countries all over the world are studying extensively to better understand the antimalarial chloroquine (CQ) and hydroxychloroquine (HCQ) for therapeutic purposes due to the COVID-19 outbreak. However, CQ and HCQ can have serious side effects, from psychiatric effects to sudden death. Therefore, a faster and more effective detection method is needed to monitor drug concentrations. In this review, a large study was conducted on the detection techniques and quantitative determination methods of CQ and its related metabolites. In this review, chromatography, electrophoresis, electroanalytical, spectroscopic, and immunological methods for CQ and related metabolites are discussed extensively. It is hoped that a better understanding of the CQ used for therapeutic purposes in the COVID-19 outbreak will be provided.

Improvement of antimalarial activity of a 3-alkylpiridine alkaloid analog by replacing the pyridine ring to a thiazole-containing heterocycle: Mode of action, mutagenicity profile, and Caco-2 cell-based permeability

The development of new antimalarial drugs is urgent to overcome the spread of resistance to the current treatment. Herein we synthesized the compound 3, a hit-to‑lead optimization of a thiazole based on the most promising 3-alkylpyridine marine alkaloid analog. Compound 3 was tested against Plasmodium falciparum and has shown to be more potent than its precursor (IC₅₀ values of 1.55 and 14.7 μM, respectively), with higher selectivity index (74.7) for noncancerous human cell line. This compound was not mutagenic and showed genotoxicity only at concentrations four-fold higher than its IC₅₀. Compound 3 was tested in vivo against Plasmodium berghei NK65 strain and inhibited the development of parasite at 50 mg/kg. In silico and UV-vis approaches determined that compound 3 acts impairing hemozoin crystallization and confocal microscopy experiments corroborate these findings as the compound was capable of diminishing food vacuole acidity. The assay of uptake using human intestinal Caco-2 cell line showed that compound 3 is absorbed similarly to chloroquine, a standard antimalarial agent. Therefore, we present here compound 3 as a potent new lead antimalarial compound.

Development and validation of an HILIC-MS/MS method by one-step precipitation for chloroquine in miniature pig plasma

Background:

Quantification of polar compounds such as chloroquine by revered-phase LC is a challenge because of poor retention and silanol interactions with stationary phase. Strong ion-pairing reagents added to mobile phases to improve reversed-phase retention and improve peak shape can be harmful for MS.

Results:

This new approach provides a rapid and sensitive method for the detection of chloroquine using hydrophilic interaction LC coupled to MS/MS (HILIC–MS/MS). Ammonium formate and formic acid were added to mobile phase to attain good peak shapes and the salified chloroquine as well retained in an HILIC column. Linearity, intra- and inter-day precision, accuracy, recovery, matrix effect and stability were evaluated during the validation process.

Conclusion:

The validated method has been successfully used in a PK study in miniature pigs, and paves way for future development.

Hair analysis of an unusual case of Chloroquine intoxication

A dead body of middle aged man was exhumed from 6.5 month earth-grave. Autopsy findings were non-specific as the body was completely putrefied. Deceased's scalp hair and kidney was sent for toxicological analysis. Hair sample (50mg) was incubated with 1M NaOH (2 ml). Chloroquine was detected in hair and kidney during basic drug screen performed on GC/MS. For confirmation and quantitation, chloroquine was extracted using Hypersep verify CX SPE cartridges while mass detector was operated in SIM mode using the ions of m/z 245.0, 290.1, 319.0 for chloroquine while ions of m/z 260 and 455 were monitored for nalorphine (internal standard). Chloroquine was present in high concentration in hair (211 ng/mg) as well as in kidney (37.3mg/kg). Moreover, chloroquine was not detected in the wash solvents, suggesting ingestion of the drug rather than an external contamination of hair. These findings strongly suggested the acute exposure of higher doses of chloroquine to the deceased before death.

Chloroquine-N-oxide, a major oxidative degradation product of chloroquine: identification, synthesis and characterization

Chloroquine (CQ) (1) which has endured as one of the most powerful antimalarial drugs was subjected to oxidative stress conditions and the degradation profile was studied. The oxidative stress condition of CQ furnished one major degradation product along with other minor degradation products. The unknown major degradation product was identified in HPLC and pure impurity was isolated using column chromatography. The structure of this major product was elucidated using UV, FT-IR, (1)H NMR, (13)C NMR, 2D NMR (HSQC) and mass spectral data. Based on the results obtained from the different spectroscopic studies, it was confirmed that the N-oxide was formed at the tertiary amine nitrogen instead of the pyridine nitrogen. Subsequently, an efficient and simple synthetic approach was developed for the synthesis of chloroquine-N-oxide using a work-up procedure that does not require chromatography techniques for further purification. It was observed that the spectral data of the isolated degradation product coincided appropriately with the synthesized product spectral data.

Quality evaluation of chloroquine, quinine, sulfadoxine-pyrimethamine and proguanil formulations sold on the market in East Congo DR

OBJECTIVE

Drug quality may be poor in many regions of the world. Our first aim was to verify whether the dose of the active compounds in various antimalarial medicines on the market in East Congo conforms to the quality requirements of the European Pharmacopoeia (Ph. Eur.). The second aim was to check the extent to which simple methods of analysis could be used to evaluate drug quality.

METHODS

The formulations analysed included tablets, injections and syrups of chloroquine (CQ), quinine, sulfadoxine-pyrimethamine (SP) and proguanil. Ultraviolet (UV) spectrophotometry was used to quantify CQ and quinine in tablets and injections. Thin layer chromatography was used to identify the preservative(s) in the syrups. As the drug form (base or salt) in the tablets, is rarely declared, the estimated dose was calculated using both forms. High-performance liquid chromatography (HPLC) was used to check for assay interference and for measuring SP combinations.

RESULTS AND DISCUSSION

When the dose declaration on the label was assumed to be of the salt form, 33% of CQ batches were underdosed and two of eight batches of quinine were underdosed by about 25% and 15% respectively. When the base form was assumed, only one batch of CQ tablets conformed. The underdosed batches contained about 50-66% of the claimed amount for CQ. The dose of quinine in the different batches of tablets was in the range 62-86%. For the CQ syrup, interference by the preservative Nipagin, confirmed by HPLC-UV, was observed with UV-spectrophotometry at 257 nm but not at 342 nm. The results for CQ syrup using UV-spectrophotometry at 342 nm and HPLC-UV at 257 nm were comparable and showed compliance with the European Pharmacopoeia limits of 95-105%. One of two batches of CQ injections and one of four batches of quinine injections were overdosed by about 14% and 8% respectively. The SP tablets were analysed by using HPLC-UV only. All five batches were underdosed in sulfadoxine (91-94%) but still met the United States Pharmacopeial (USP) limit of 90-110%. Two batches were slightly overdosed in pyrimethamine (106% and 108% respectively) while one batch contained neither active ingredient. The one batch of proguanil analysed, met the Ph. Eur. quality requirement (98.7%).

CONCLUSION

Simple methods of analysis like UV-spectrophotometry can be used to check drug quality routinely. A substantial proportion of the antimalarial drugs sold on the Congo DR market is of poor quality. Some batches contain little or no drug. This is a serious threat to public health in the region of Congo DR.

Immunohistochemical demonstration of the distribution of chloroquine (CQ) and its metabolites in CQ-poisoned mice

Chloroquine (CQ) distribution in tissues of acutely poisoned mice was demonstrated by immunohistochemistry using anti-CQ polyclonal antibodies (PAC). PAC recognized 4-amino-7-chloro-quinoline structure and sufficiently reacted with CQ and CQ's metabolite bisdesethyl-chloroquine. In the brain, CQ and its metabolites (CQs) localized in the region of the choroids plexus, indicating an important role in the blood-cerebrospinal barrier system. In the heart, most regions showed diffused positive staining, and relatively strong reaction was observed in Purkinje cells, indicating an important role in acute CQ toxicity. In the lungs, CQs were observed in the bronchial epithelium, type II pneumocytes, and on the surface of alveolar walls. It was suggested that CQs were excreted to the alveolar wall with surfactant phospholipids, which are produced by type II pneumocytes. In the liver, CQs were concentrated in the centrolobular area rather than in the periportal area, in agreement with CQ's metabolic pathway. In the kidneys, tubular cells were strongly stained compared to glomerular capsules, and the distal part of renal tubules was better stained than the proximal tubules. These findings suggested that CQs were predominantly excreted or reabsorbed through the distal tubules and the collecting duct. Distribution of CQs in tissues presented here were mostly consistent with the physico-chemical properties of CQ and its metabolites. However, the elucidation of CQs' localization in Purkinje cells remains open. Further experimental studies at the level of microorganella will be needed to clarify the present result.

Sensitive and rapid liquid chromatography/tandem mass spectrometric assay for the quantification of chloroquine in dog plasma

A simple, sensitive and rapid liquid chromatography/tandem mass spectrometric (LC-MS/MS) method was developed and validated for quantification of chloroquine, an antimalarial drug, in plasma using its structural analogue, piperazine bis chloroquinoline as internal standard (IS). The method is based on simple protein precipitation with methanol followed by a rapid isocratic elution with 10 mM ammonium acetate buffer/methanol (25/75, v/v, pH 4.6) on Chromolith SpeedROD RP-18e reversed phase chromatographic column and subsequent analysis by mass spectrometry in the multiple reaction monitoring mode (MRM). The precursor to product ion transitions of m/z 320.3-->247.2 and m/z 409.1-->205.2 were used to measure the analyte and the IS, respectively. The assay exhibited a linear dynamic range of 2.0-489.1 ng/mL for chloroquine in dog plasma. The limit of detection (LOD) and lower limit of quantification (LLOQ) were 0.4 and 2.0 ng/mL, respectively in 0.05 mL plasma. Acceptable precision and accuracy were obtained for concentrations over the standard curve range of 2.0-489.1 ng/mL. A run time of 2.0 min for a sample made it possible to achieve a throughput of more than 400 plasma samples analyzed per day. The validated method was successfully used to analyze samples of dog plasma during non-clinical study of chloroquine.