Chloroquine Concentrations Research Articles

Effect of chloroquine pre-treatment on the metoclopramide’s pharmacokinetics after their co-administration

ABSTRACT Background This study evaluated the pharmacokinetic interactions of orally administered chloroquine and metoclopramide. Methods The study employed a randomized and two-phase cross-over design with 4-week washout plan. Twelve healthy male volunteers were shortlisted according to the set criteria and were administered with metoclopramide 10 mg PO and chloroquine (a total of 1500 mg) at different intervals which were (500 mg at 0, 6, and 24 h). The concentration of chloroquine and metoclopramide in the blood samples was estimated using a validated HPLC-UV technique to affirm the maximum concentration (Cmax), time to reach Cmax (Tmax), and area under the curve (AUC). Results Cmax, T1/2, and AUC of metoclopramide were increased up to 20, 10, and 47.8%, respectively, by the concomitantly administering Chloroquine. Chloroquine-treated phase showed increased values of Cmax (ng/ml), AUC (ng.h/ml), and T½ (h), i.e. 41.35 ± 1.61, 504.12 ± 66.25, and 5.72 ± 2.63, as compared to that reference phase i.e. 34.52 ± 4.92, 341.14 ± 112.8, and 5.19 ± 1.14, respectively. Conclusions Chloroquine was found to attenuate CYP2D6 activity in healthy Pakistani male volunteers. Hence, patients that are prescribed with metoclopramide or other CYP2D6-substrate drugs require a dose adjustment when administered with chloroquine.

Chloroquine degradation in aqueous solution under electron beam irradiation

Abstract Pharmaceutically active compounds are the most widely produced and consumed consumer products that pose a substantial threat to the environment and living organisms owing to their pharmacokinetics, side effects, and contraindications. In this study, the degradation of chloroquine (CQ), a popular antimalarial and recently proposed COVID-19 drug, was investigated under electron beam (EB) irradiation of aqueous solutions. Both the hydroxyl radical and hydrated electron generated in the radiolysis of water contribute to the degradation of CQ in aqueous solution. The overall removal efficiency for 125 mg·L-1 of the CQ solution under EB treatment is reported to be >80% at neutral pH at a maximum irradiation dose of 7 kGy. Removal efficiency is further favored by acidic and slightly alkaline conditions where reactions with hydroxyl radicals and hydrated electrons are favored, respectively. Additionally, increments in the applied dose resulted in the increased removal efficiency for the same concentration of CQ. Conversely, the removal efficiency decreased with increasing concentration of CQ at the same irradiation dose. The initial solution pH, applied irradiation dose, and initial pollutant concentration play an important role in the EB-induced degradation of CQ by influencing the available oxidizing and reducing species. The chemical oxygen demand (COD) and total organic carbon (TOC) were not significantly decreased during the treatment process and indicated the formation of organic byproducts, which were not further degraded under the current experimental conditions.

Treatment of condylomata acuminata caused by low-risk human papillomavirus with chloroquine phosphate gel.

To observe the stability and therapeutic effect of chloroquine phosphate gel on human condylomata acuminata (CA) caused by low-risk human papillomavirus (HPV). The appearance, viscosity, pH, chloroquine concentration, deethylchloroquine concentration and content uniformity of chloroquine phosphate gel were examined for 24 months, the gel met the quality standards throughout the 24-month observation. A nude mouse model harboring CA xenografts was used to observe the therapeutic effect of this gel on CA in vivo. After 14 days of gel administration, compared with the control group, the treatment group had significantly smaller warts and significantly reduced DNA copy numbers of HPV6 and HPV11 in the wart tissues. Immunohistochemistry analysis of p53 protein expression in the wart tissues of the treatment group was significantly increased. Chloroquine phosphate gel was stable and effective against CA, possibly through the promotion of p53 protein expression to induce apoptosis, leading to the involution of warts.

Characterization of LysoTracker Red uptake by in vitro model cells of the outer blood-retinal barrier: Implication of lysosomal trapping with cytoplasmic vacuolation and cytotoxicity

Lysosomal trapping, a physicochemical process in which lipophilic cationic compounds are sequestered in lysosomes, can affect drug disposition and cytotoxicity. To better understand lysosomal trapping at the outer blood-retinal barrier (BRB), we investigated the distribution of LysoTracker Red (LTR), a probe compound for lysosomal trapping, in conditionally immortalized rat retinal pigment epithelial (RPE-J) cells. LTR uptake by RPE-J cells was dependent on temperature and attenuated by ammonium chloride and protonophore, which decreased the pH gradient between the lysosome and cytoplasm, suggesting lysosomal trapping of LTR in RPE-J cells. The involvement of lysosomal trapping in response to cationic drugs, including neuroprotectants such as desipramine and memantine, was also suggested by an inhibition study of LTR uptake. Chloroquine, which is known to show ocular toxicity, induced cytoplasmic vacuolization in RPE-J cells with a half-maximal effective concentration of 1.35 μM. This value was 59 times lower than the median lethal concentration (= 79.1 μM) of chloroquine, suggesting that vacuolization was not a direct trigger of cell death. These results are helpful for understanding the lysosomal trapping of cationic drugs, which is associated with drug disposition and cytotoxicity in the outer BRB.

Digoxin is a potent inhibitor of Bunyamwera virus infection in cell culture.

Drug repurposing is a valuable source of new antivirals because many compounds used to treat a variety of pathologies can also inhibit viral infections. In this work, we have tested the antiviral capacity of four repurposed drugs to treat Bunyamwera virus (BUNV) infection in cell cultures. BUNV is the prototype of the Bunyavirales order, a large group of RNA viruses that includes important pathogens for humans, animals and plants. Mock- and BUNV-infected Vero and HEK293T cells were treated with non-toxic concentrations of digoxin, cyclosporin A, sunitinib and chloroquine. The four drugs inhibited BUNV infection with varying potency in Vero cells, and all except sunitinib also in HEK293T cells, with digoxin rendering the lowest half maximal inhibitory concentration (IC50). Since digoxin rendered the best results, we selected this drug for a more detailed study. Digoxin is an inhibitor of the Na+/K+ ATPase, a plasma membrane enzyme responsible for the energy-dependent exchange of cytoplasmic Na+ for extracellular K+ in mammalian cells and involved in many signalling pathways. Digoxin was shown to act at an early time point after viral entry reducing the expression of the viral proteins Gc and N. Effects on the cell cycle caused by BUNV and digoxin were also analysed. In Vero cells, digoxin favoured the transition from G1 phase of the cell cycle to S phase, an effect that might contribute to the anti-BUNV effect of digoxin in this cell type. Transmission electron microscopy showed that digoxin impedes the assembly of the characteristic spherules that harbour the BUNV replication complexes and the morphogenesis of new viral particles. Both BUNV and digoxin induce similar changes in the morphology of mitochondria that become more electron-dense and have swollen cristae. The alterations of this essential organelle might be one of the factors responsible for digoxin-induced inhibition of viral infection. Digoxin did not inhibit BUNV infection in BHK-21 cells that have a digoxin-resistant Na+/K+ ATPase, which suggests that the effects of the blockade of this enzyme is a key factor of the antiviral activity of digoxin in BUNV-infected Vero cells.

Application of electrocoagulation process for the removal of chloroquine from an aqueous solution

AbstractUsing chloroquine (CQ) as a provisional treatment for COVID-19 patients generates more pharmaceutical waste, posing a potential environmental threat. The present study evaluates the feasibility of the electrocoagulation (EC) process in removing CQ from an aqueous solution. The experiment was performed in a laboratory-scale stirred tank reactor (STR). The effects of operating conditions were investigated. Equilibrium and kinetic experiments were also performed to describe CQ adsorption. The results showed that increasing both the applied current density and the EC reaction time increases the removal efficiency of CQ. The results showed that 95% of CQ removal efficiency was achieved at a current density of 66.89 mA/cm2, 600 rpm of agitation rate, 60 min of electrolysis time, an initial CQ concentration of 3 mg/L, and a pH of 6.5. For equilibrium and kinetic studies, the Langmuir isotherm and the pseudo-second-order provided the best fit to the experimental data. The optimal operating conditions led to a specific amount of dissolved aluminum electrodes and a specific energy consumption of 0.228 kg/m3 and 12.243 kWh/m3. These results suggest that the EC process is an excellent tool for effectively degrading CQ from wastewater with a low operating cost (2.48 USD/m3).

The effect of chloroquine on large yellow croaker (Larimichthys crocea): From autophagy, inflammation, to apoptosis

Chloroquine (CQ) is a common autophagy inhibitor but was few understood in marine fish. This study investigated the effects of different concentration of CQ on representative tissues of large yellow croakers (Larimichthys crocea) by setting 5 treatments: 2.52 μg/mL, 5.03 μg/mL, 12.58 μg/mL, 25.16 μg/mL, 50.32 μg/mL, and 251.60 μg/mL CQ groups. We found that the higher the concentration of CQ was, the more obvious the toxic effect it caused, exhibiting as high mortalities of large yellow croakers. The LC50 (24 h) to CQ was 17.14 μg/mL with the upper limit 34.84 μg/mL, the lower limit 8.43 μg/mL, and the standard error 0.16 μg/mL. The CQ treatment also led to the differential expressions of autophagy / inflammation / apoptosis-related genes in representative tissues. The inflammation-related genes IL8 / TNF-α1 (peaked mostly in 2.52 μg/mL and 5.03 μg/mL) and the autophagy-related genes Cx43 / LC3 (from 2.52 μg/mL to 25.16 μg/mL) were more sensitive to lower CQ concentration groups. The apoptosis-related genes BAX / Cas3 were more sensitive to medium CQ concentration (peaked around 25.16 μg/mL). The autophagy and apoptosis-related gene P62 in all tissues peaked in the highest CQ concentration 50.32 μg/mL group, and the expression pattern of P62 was more similar to autophagy genes under Control, but more similar to apoptosis genes in the CQ-treatment groups. In addition, we have newly identified an expression pattern of Cx43 similar to that of the autophagy marker gene LC3, which was also for the first time in marine fish. These data largely enriched our knowledge of the effects of CQ on marine fish and provided a solid basis for further studies on the autophagy regulation in large yellow croakers.

Lipid emulsion inhibits the cardiac toxicity caused by chloroquine via inhibition of reactive oxygen species production.

Lipid emulsion (LE) is effective in treating intractable cardiac depression induced by the toxicity of highly lipid-soluble drugs including local anesthetics. However, the effect of LE on chloroquine (CQ)-evoked cardiac toxicity remains unclear. This study aimed to examine the effect of Lipofundin MCT/LCT, an LE, on the cardiotoxicity caused by CQ in H9c2 rat cardiomyoblasts and elucidate the underlying cellular mechanism. The effects of CQ (1 × 10-4 M), LE, and the reactive oxygen species (ROS) scavengers mitotempo and N-acetyl-L-cysteine (NAC), alone or combined, on cell viability and migration, apoptosis, ROS production, calcium levels, mitochondrial membrane potential, and adenosine triphosphate (ATP) were examined. Additionally, the effects of LE on the activities of catalase (CAT), malondialdehyde (MDA), and superoxide dismutase (SOD) induced by CQ were assessed. Pretreatment with LE, mitotempo, or NAC reversed the reduction in cell migration and viability, mitochondrial membrane potential, and ATP levels evoked by CQ, and inhibited the increase in cleaved caspase-3, ROS, and calcium concentration induced by CQ. LE inhibited the increase in Bax expression, terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells, MDA activity, and late apoptosis, and reversed the reduction in SOD and CAT activity induced by CQ. CQ did not significantly affect cleaved caspase-8 expression, and LE did not significantly affect CQ concentration. Collectively, these results suggest that LE (Lipofundin MCT/LCT) inhibits the cardiotoxicity and late apoptosis induced by CQ toxicity via the intrinsic mitochondrial apoptotic pathway that is associated with direct inhibition of ROS production.

An Alternative Autophagy-Related Mechanism of Chloroquine Drug Resistance in the Malaria Parasite.

We generated highly chloroquine (CQ)-resistant (ResCQ) Plasmodium yoelii parasites by stepwise exposure to increasing concentrations of CQ and CQ-sensitive parasites (SenCQ) by parallel mock treatments. No mutations in genes that are associated with drug resistance were detected in ResCQ clones. Autophagy-related genes were highly upregulated in SenCQ compared to ResCQ parasites during CQ treatment. This indicates that CQ resistance can be developed in the malaria parasite by the inhibition of autophagy as an alternative drug resistance mechanism.

Epidemiological characterization and sensitivity to traditional antimalarials of Plasmodium spp. isolates from Porto Velho, western Amazon, Brazil

Objective: To describe the epidemiological profile of patients infected with malaria in Porto Velho and the susceptibility of Plasmodium spp. to different classes of drugs used in current treatment methods. Methods: 708 patients infected with malaria were treated at the Center of Tropical Medicine in Porto Velho, where they answered standard epidemiological questionnaires. Maps were built using place of residence information of 199 infected patients. In chemosensitivity assay, dihydroartemisinin, chloroquine, mefloquine and lumefantrine half maximal inhibitory concentration (IC50) was assessed by schizont maturation assay. Results: A higher prevalence of Plasmodium spp. infection among men, young people, with recurrent events of malaria and residents of urban area can be observed. The most prevalent malaria species was P. vivax followed by P. falciparum. Regarding treatment, it was observed that P. falciparum demonstrated resistance only to chloroquine (CQ) with a median of IC50 (MD of IC50) = 119.8 nM, whereas P. vivax demonstrated sensitivity to all drugs (MD IC50 < 10; 100; 30; and 150 nM for dihydroartemisinin, CQ, mefloquine and lumefantrine, respectively). Conclusion: This study contributes to the understanding of the disease by the city’s public health organs, to Plasmodium chemosensitivity literature and vigilance, and to decision making processes of city officials.

Clinical Toxicological Follow-Up Analysis of a Suicide Attempt Using Chloroquine.

Chloroquine, a drug approved for the treatment of malaria, is frequently used to commit suicide. We report about a suicide attempt by ingesting a high dose of chloroquine in combination with other drugs. Findings of the emergency toxicology screening of blood and urine and those of the follow-up analyses in blood are discussed. Systematic toxicological analysis approaches revealed the presence of chloroquine, butylscopolamine, cafedrine, diazepam, lorazepam, metoclopramide, nordazepam, norephedrine and 11-nor-9-carboxy-∆9-tetrahydroxycannabinol in blood and/or urine of the subject. Suicide due to a combination of chloroquine and benzodiazepines is known as the so-called "Kusch method" in German-speaking countries. The initial chloroquine plasma concentration was determined to be 9.6 mg/L after precipitation and analysis by liquid chromatography-high-resolution tandem mass spectrometry. The analytical procedure was developed ad hoc and validated in accordance with international recommendations. Clinical toxicological follow-up analyses in blood were performed over a period of 3 weeks. The chloroquine concentration remained above the therapeutic range (up to 0.5 mg/L) for 2 weeks and dropped to 0.3 mg/L after 3 weeks. Furthermore, monodesethylchloroquine (MDCQ) and bisdesethylchloroquine (BDCQ) were determined to be the most abundant metabolites in plasma. Within 3 weeks, the area ratios of MDCQ and chloroquine increased 4-fold (from 0.090 to 0.350), and those of BDCQ and chloroquine increased 100-fold (from 0.002 to 0.218). This information may help to estimate the chloroquine excretion progress in the future.

Chloroquine-susceptible and -resistant Plasmodium falciparum strains survive high chloroquine concentrations by becoming dormant but are eliminated by prolonged exposure.

Background Plasmodium falciparum strains that are resistant to standard-dose chloroquine can be treated by higher chloroquine concentrations maintained for a longer time in vivo.ObjectivesTo determine the relative importance of chloroquine concentrations versus exposure time for elimination of chloroquine-susceptible and -resistant P. falciparum in vitro.MethodsChloroquine-susceptible (3D7) and -resistant (FCR3) strains were exposed in vitro to 1, 2, 4, 8, 16 or 32 times their respective 90% inhibitory chloroquine concentrations for 3, 5, 7 or 14 days and then followed until recrudescence, or not, by 42 days after the end of exposure.ResultsExposure to chloroquine appeared to eliminate susceptible and resistant parasites, leaving small pyknotic apparently dead parasites. Chloroquine-susceptible and -resistant parasites recrudesced after 3 and 5 days of chloroquine exposure. Recrudescence occurred in one out of four 7 day exposure series but not after 14 days exposure. The median time to recrudescence was 13 to 28 days with a range of 8 to 41 days after the end of exposure. Time to recrudescence after the end of exposure increased with duration of exposure for susceptible and resistant strains (P < 0.001). Time to recrudescence did not correlate with concentrations greater than 1× IC90.ConclusionsChloroquine-susceptible and -resistant P. falciparum probably become dormant. Elimination of dormant parasites is primarily dependent upon the duration of chloroquine exposure. Exposure to effective drug concentrations for 7 days eliminates most parasites in vitro. The results support in vivo data indicating that elimination of chloroquine-resistant P. falciparum correlates with Day 7 chloroquine concentrations.

Pharmacokinetics of chloroquine and primaquine in healthy volunteers

BackgroundVivax malaria is a neglected disease. There is an irrefutable need for better treatments with higher acceptability and efficacy. The treatment efficacy is influenced by many factors, including bioavailability. Hence, a straightforward strategy to improve vivax malaria treatment efficacy is the deployment of good quality formulations of primaquine and chloroquine. As these treatments were developed more than 70 years ago, many of the available data on blood levels of both drugs are based on obsolete analytical methodologies or pharmaceutical formulations, which are not available anymore. Herein, the results of three bioequivalence studies are presented, providing individual pharmacokinetic data on chloroquine and primaquine of more than a hundred healthy volunteers and using up-to-date analytical methods.MethodsThree trials were designed as a single centre, randomized, single dose, open label, fasting, crossover bioequivalence studies comparing a new coated chloroquine tablet to the uncoated tablet, and 5 and 15 mg primaquine formulations to either an international reference product or the currently distributed tablets. Plasma concentrations of chloroquine and primaquine were measured using a validated HPLC–MS/MS method in accordance with current international regulatory requirements for bio-analytical methods.ResultsIn total, a hundred eleven healthy volunteers of both genders were included in the three studies (n = 32; 30 and 56 respectively). No serious adverse events occurred. Drugs levels were measured in 5,520 blood samples. The estimated ratio of the geometric means of Cmax, AUC0-t and AUC0-inf of test and reference drugs and their 90% CI for chloroquine 150 mg, primaquine 15 mg and primaquine 5 mg were: 95.33% (89.18; 101.90), 86. 85% (82.61; 91.31), and 84.45% (76.95; 92.67); 93.28% (81.76; 106.41), 94.52% (86.13; 103.73) and 93.93% (85.83; 102.79); 97.44% (90.60; 104.78), 93.70% (87.04; 100.87) and 91.36% (85.27; 97.89), respectively. As Cmax and AUC0-t 90% CI were within the acceptance interval of 80–125% in all cases, the formulations tested were bioequivalent.ConclusionsIn conclusion, the three studies provided detailed chloroquine and primaquine pharmacokinetic data in accordance with current regulatory standards. Together with other open data initiatives, this individual data may increase the accuracy of pharmacokinetic models guiding best dose, new combinations, regimens and formulations to optimize the current chloroquine and primaquine treatments for vivax malaria. The data presented here may support the deployment of high-quality drugs and evidence-based public health policies.

Translational Modeling of Chloroquine and Hydroxychloroquine Dosimetry in Human Airways for Treating Viral Respiratory Infections

PurposeChloroquine and hydroxychloroquine are effective against respiratory viruses in vitro. However, they lack antiviral efficacy upon oral administration. Translation of in vitro to in vivo exposure is necessary for understanding the disconnect between the two to develop effective therapeutic strategies.MethodsWe employed an in vitro ion-trapping kinetic model to predict the changes in the cytosolic and lysosomal concentrations of chloroquine and hydroxychloroquine in cell lines and primary human airway cultures. A physiologically based pharmacokinetic model with detailed respiratory physiology was used to predict regional airway exposure and optimize dosing regimens.ResultsAt their reported in vitro effective concentrations in cell lines, chloroquine and hydroxychloroquine cause a significant increase in their cytosolic and lysosomal concentrations by altering the lysosomal pH. Higher concentrations of the compounds are required to achieve similar levels of cytosolic and lysosomal changes in primary human airway cells in vitro. The predicted cellular and lysosomal concentrations in the respiratory tract for in vivo oral doses are lower than the in vitro effective levels. Pulmonary administration of aerosolized chloroquine or hydroxychloroquine is predicted to achieve high bound in vitro-effective concentrations in the respiratory tract, with low systemic exposure. Achieving effective cytosolic concentrations for activating immunomodulatory effects and adequate lysosomal levels for inhibiting viral replication could be key drivers for treating viral respiratory infections.ConclusionOur analysis provides a framework for extrapolating in vitro effective concentrations of chloroquine and hydroxychloroquine to in vivo dosing regimens for treating viral respiratory infections.Graphical abstract

An Integrated Strategy Designed To Explore the Common and Diverging Mechanisms of Potential Drugs against the Novel Coronavirus Pneumonia Based on Network Pharmacology and In Silico Molecular Docking Technology

Drug repositioning may be a promising way to find potential therapies against coronavirus disease 2019. Although chloroquine and hydroxychloroquine showed controversial results against the coronavirus disease 2019 disease, the potential common and diverging mechanisms of action are not reported and need to be dissected for better understanding them. An integrated strategy was proposed to systematically decipher the common and diverging aspects of mechanism of chloroquine and hydroxychloroquine against coronavirus disease 2019-disease network based on network pharmacology and in silico molecular docking. Potential targets of the two drugs and coronavirus disease 2019 related genes were collected from online public databases. Target function enrichment analysis, tissue enrichment maps and molecular docking analysis were carried out to facilitate the systematic understanding of common and diverging mechanisms of the two drugs. Our results showed that 51 chloroquine targets and 47 hydroxychloroquine targets were associated with coronavirus disease 2019. The core targets include tumor necrosis factor, glyceraldehyde 3-phosphate dehydrogenase, lymphocyte-specific protein-tyrosine kinase, beta-2 microglobulin, nuclear receptor coactivator 1, peroxisome proliferator-activated receptor gamma and glutathione disulfide reductase. Both chloroquine and hydroxychloroquine had good binding affinity towards tumor necrosis factor (affinity=-8.6 and -8.4 kcal/mol, respectively) and glyceraldehyde 3-phosphate dehydrogenase (-7.5 and -7.5 kcal/mol). Chloroquine and hydroxychloroquine both had good affinity with angiotensinconverting enzyme 2, 3-chymotrypsin-like protease and transmembrane serine protease 2. However, hydroxychloroquine manifested better binding affinity with the three proteins comparing with that of chloroquine. Chloroquine and hydroxychloroquine could have potential to inhibit over-activated immunity and inflammation. The potential tissue-specific regulation of the two drugs against severe acute respiratory syndrome coronavirus 2 infection may related with the lung, liver, brain, placenta, kidney, blood, eye, et al. In conclusion, our data systematically demonstrated chloroquine and hydroxychloroquine may have potential regulatory effects on coronavirus disease 2019 disease network, which may affect multiple organs, protein targets and pathways. Routine measurements of the chloroquine and hydroxychloroquine blood concentrations and tailored therapy regimen may be essential. But, further rigorous and high quality randomized controlled clinical trials are warranted to validate the antiviral effects of chloroquine and hydroxychloroquine against severe acute respiratory syndrome coronavirus 2. Our proposed strategy could facilitate the drug repurposing efforts for coronavirus disease 2019 treatment.

Enantioselective analyses of chloroquine and hydroxychloroquine in rat liver microsomes through chiral liquid chromatography-tandem mass spectrometry.

An efficient, sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) chiral analysis method was established for determination of chloroquine and hydroxychloroquine enantiomers in rat liver microsomes. Effects of polysaccharide chiral stationary phases and basic additives on chiral separations of two analytes were discussed in detail. Amylose tris(3, 5-dimethylphenylcarbamate)-coated chiral stationary phase showed the best separation performance for them with acetonitrile-diethylamine-ethanol-diethylamine mixture (90:0.1:10:0.1, v/v/v/v) among four chiral stationary phases. Then, multiple reaction monitoring mode was selected as the data acquisition for determination of two pairs of enantiomers. The proposed LC-MS/MS chiral analysis method was validated in terms of linearity, accuracy, precision, and specificity. Good linearity with correlation coefficient over 0.998 was obtained in the concentration range of 0.05-5 μM. Limits of quantification for chloroquine and hydroxychloroquine enantiomers were 5.0 and 1.0 nM, respectively. The recoveries ranged from 81.14% to 111.09%. The intra-day and inter-day relative standard deviation were less than 6.5%. Moreover, concentrations of chloroquine and hydroxychloroquine enantiomers in rat liver microsomes were determined through the proposed LC-MS/MS analysis method. After incubated with rat liver microsomes for 10 min, the enantiomeric factor of hydroxychloroquine decreased from 0.50 to 0.45 (p < 0.001). In brief, our developed determination method for chloroquine and hydroxychloroquine enantiomers through LC-MS/MS spectrometry showed the characteristics of high-efficiency, fast speed, and very low detection limit, and would be greatly beneficial for screening and quantitation of them in biological matrices.

Simultaneous Determination of Chloroquine and Pyrimethamine with Cetirizine in an Active Form and Human Serum by RP-HPLC.

A simple, accurate and precise RP-HPLC method was developed for the simultaneous determination of chloroquine, pyrimethamine and cetirizine hydrochloride concentrations in bulk drug and human serum. The assay was performed using a mobile phase of methanol: water (70:30) at pH of 2.8±0.05 on the Purospher C-18 column with UV detection at 230nm and rosuvastatin used as an internal standard. The retention times observed for chloroquine, pyrimethamine and cetirizine hydrochloride were 3.5, 2.5 and 5.5minutes, respectively. The method was found to be specific for the assayed drugs showing a linear response in the concentration range of 1-100μg mL-1 with coefficients of determination values of (r=0.999). The method was developed and validated according to ICH guidelines. The method was used to monitor the serum samples and was found to be sensitive for therapeutic purposes, showing the potential to be a useful tool for routine analysis in laboratories.

Chloroquine and hydroxychloroquine provoke arrhythmias at concentrations higher than those clinically used to treat COVID-19: A simulation study.

The risk of fatal arrhythmias is the major concern for using chloroquine (CQ) or hydroxychloroquine (HCQ) to treat coronavirus disease 2019 (COVID‐19), but the reported number of life‐threatening arrhythmic events or deaths is relatively small. The objective of this study was to assess the arrhythmogenic risk of these two drugs using a multiscale heart simulation, which allows testing even at high concentrations, including those that cause fatal arrhythmias. We measured the inhibitory action of CQ, HCQ, and HCQ with 30 μM azithromycin (AZ) on six ion currents (fast [INa] and late [INa,L] components of the sodium current, L‐type calcium current [ICa,L], rapid [IKr/hERG], and slow [IKs] components of delayed rectifier potassium, and inward rectifier potassium [IK1]) over a wide range of concentrations using the automated patch‐clamp system. Using the concentration–inhibition relationship that was thus obtained, we simulated the drug effects while increasing the concentration until the life‐threatening arrhythmia, torsade de pointes (TdP), was observed. The obtained threshold concentrations for TdP were 12.5, 35, and 22.5 μM for CQ, HCQ, and HCQ with AZ, respectively. Adding therapeutic concentrations of mexiletine or verapamil successfully prevented the occurrence of TdP, and verapamil was more effective. CQ, HCQ, and HCQ with AZ thresholds for TdP were larger than both antiviral concentrations that were reported by in vitro experiments and free plasma concentrations that were attained by the clinically used dosage. The current simulation data provided a safety margin to the currently used clinical dose for CQ and HCQ/AZ. Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? Despite the potent in vitro antiviral effect, clinical trials have failed to show the therapeutic effects of chloroquine (CQ) and hydroxychloroquine (HCQ)/azithromycin (AZ) to treat coronavirus disease 2019. Torsadogenic potentials may limit the dosage of these drugs, but the reported incidence of fatal arrhythmias is rare. WHAT QUESTION DID THIS STUDY ADDRESS? Our objective was to assess the arrhythmogenicity of CQ and HCQ/AZ over a wide range of drug concentrations using a multiscale heart simulation. WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE? Our study showed that CQ and HCQ/AZ do not induce fatal arrhythmias even at concentrations much higher than in vitro antiviral half‐maximal effective concentration (EC50) values at which QT prolongation exceeds 150 ms. We also found that estimated free plasma concentrations of CQ and HCQ/AZ achieved by currently used dosing protocols are lower than the antiviral EC50 for these drugs. HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE? Our simulation data provided a safety margin to the currently used clinical dose for CQ and HCQ/AZ.

Physiologically Based Pharmacokinetics of Lysosomotropic Chloroquine in Rat and Human.

A semimechanistic physiologically based pharmacokinetic (PBPK) model for chloroquine (CQ), a highly lysosomotropic weak base, was applied to digitized rat and human concentration versus time data. The PBPK model in rat featured plasma and red blood cell (RBC) concentrations, extensive and apparent nonlinear tissue distribution, fitted hepatic and renal intrinsic clearances, and a plasma half-life of about 1 day. Tissue-to-plasma CQ ratios at 50 hours after dosing were highest in lung, kidney, liver, and spleen (182-318) and lower in heart, muscle, brain, eye, and skin (11-66). The RBC-to-plasma ratio of 11.6 was assumed to reflect cell lipid partitioning. A lysosome-based extended model was used to calculate subcellular CQ concentrations based on tissue mass balances, fitted plasma, interstitial and free cytosol concentrations, and literature-based pH and pKa values. The CQ tissue component concentrations ranked as follows: lysosome > > acidic phospholipid > plasma = interstitial = cytosol ≥ neutral lipids. The extensive lysosome sequestration appeared to change over time and was attributed to lowering pH values caused by proton pump influx of hydrogen ions. The human-to-rat volume of distribution (Vss) ratio of 7 used to scale rat tissue partitioning to human along with estimation of hepatic clearance allowed excellent fitting of oral-dose PK (150-600 mg) of CQ with a 50-day half-life in humans. The prolonged PK of chloroquine was well characterized for rat and human with this PBPK model. The calculated intratissue concentrations and lysosomal effects have therapeutic relevance for CQ and other cationic drugs. SIGNIFICANCE STATEMENT: Sequestration in lysosomes is a major factor controlling the pharmacokinetics and pharmacology of chloroquine and other cationic drugs. This report provides comprehensive physiologic modeling of chloroquine distribution in tissues and overall disposition in rat and human that reveals expected complexities and inferences related to its subcellular association with various tissue components.

Exposure to chloroquine in male adults and children aged 9-11 years with malaria due to Plasmodium vivax.

Chloroquine is effective against the asexual blood stage of Plasmodium vivax. A high proportion of children are underdosed with the drug, but there are no studies comparing chloroquine exposure in adults and children aged 8-11 years old. The present study intends to compare these populations using the area under the curve (AUC) derived from the plasma concentration-time profile in patients with P. vivax. A prospective study of cases was performed on male children (aged 9-11 years) and adults with vivax malaria. Blood samples were collected after several days of treatment. Chloroquine was measured by high-performance liquid chromatography. A non-compartmental pharmacokinetic model was used to calculate the pharmacokinetic parameters of the drug. A total of 20 children and 25 adults were included in the study. Plasma concentrations of chloroquine in older children ranged from 67 to 1112 ng/ml, and in adults the value ranged from 74 to 1147 ng/ml. The AUC to the last measurable concentration and to infinite was significantly lower in children than in adults, indicating a lower exposure to the drug. These data demonstrate lower exposure to chloroquine in children, which corroborates the importance of optimising the doses of chloroquine in the study age band to ensure adequate exposure to the drug.