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.

Quadruple isotope dilution gas chromatography-mass spectrometry after simultaneous derivatization and spraying based fine droplet formation liquid phase microextraction method for the accurate and sensitive quantification of chloroquine phosphate in human serum, urine and saliva samples at trace levels.

This study presents an accurate and precise analytical strategy for the determination of chloroquine phosphate at trace levels in human body fluids (urine, serum, and saliva). Simultaneous derivatization-spraying based fine droplet formation-liquid phase microextraction (SD-SFDF-LPME) method was used to derivatize and preconcentrate the analyte prior to gas chromatography-mass spectrometry (GC-MS) measurements. Acetic anhydride was employed as derivatizing agent in this study. After optimizing the SD-SFDF-LPME method, the limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.16 and 0.53 mg/kg, respectively. Quadruple isotope dilution (ID4) was coupled to the SD-SFDF-LPME method in order to alleviate matrix effects and promote accuracy/precision of the method. Chloroquine acetamide-d3 was firstly synthesized in our research laboratory and used as the isotopic analogue of the analyte in the ID4 experiments. Superior percent recovery results (99.4% - 101.0%) with low standard deviation values were obtained for the spiked samples. This validated the developed SD-SFDF-LPME-ID4-GC-MS method as highly accurate and precise for the determination of chloroquine phosphate at trace levels. In addition, the isotopic analogue of the analyte was obtained via the acetamide derivative of the analyte, which is an alternative to obtain isotopic analogues of organic compounds that are not accessible or commercially available.

Evidence of Self-Medication with Chloroquine before Consultation for Malaria in the Southern Pacific Coast Region of Colombia.

Self-medication with antimalarial drugs is a major factor in the development of drug resistance, exerting subtherapeutic drug pressure on circulating parasite populations. Data on self-medication with antimalarials from the Southern Pacific coast region of Colombia, where 4-aminoquinolines resistance and political instability prevail, are vital to elimination strategies. We present results of an exploratory study of 254 individuals having malaria symptoms who sought malaria diagnosis in two hospitals in Tumaco, Department of Nariño, Colombia. Thirty-two percent (82/254) of participants had positive Saker-Solomons urine tests, indicating self-medication with chloroquine (CQ) before consultation for diagnosis. Notably, among 30 pregnant women participating in the study, 43% were Saker--Solomons positive. Molecular analysis of the K76T position encoded by the pfcrt gene revealed the mutant allele in all four samples that were both positive for Plasmodium falciparum and positive for the Saker-Solomons test, suggesting persistent CQ pressure. The high frequency of self-medication, particularly among pregnant women merits attention by public health authorities and comprehensive investigation.

Cloroquina como instrumento de suicidio / Use of chloroquine in suicides

El empleo de la cloroquina con fines suicidas no es frecuente en España. En los últimos años, en algunos países europeos se ha incrementado el número de suicidios por cloroquina, por la difusión del conocimiento de esta sustancia por activistas en defensa del suicidio asistido a través de diferentes medios de comunicación. Presentamos 3casos de suicidio con cloroquina estudiados en el IMLCF de Alicante en los últimos 7 años. Hemos obtenido en la autopsia resultados inespecíficos, al igual que lo publicado en otros trabajos. El estudio toxicológico confirmó la intoxicación por cloroquina. En 2de los 3casos habían consultado la mezcla de sustancias y dosis empleadas en páginas web. En el tercer caso en un libro de ayuda al suicidio. Es fundamental obtener la máxima información durante el levantamiento del cadáver, a fin de realizar la autopsia y dirigir el estudio toxicológico para poder llegar al diagnóstico de intoxicación por cloroquina

The use of chloroquine to commit suicide is not common in Spain. However, the number of suicides by chloroquine has increased in some European countries in recent years due to the awareness raised about this substance through various media by assisted-suicide defence activists. We present 3cases of suicide with chloroquine studied at the Institute of Forensic Medicine and Forensic Sciences (IMLCF) of Alicante in the last 7years. Consistent with other published studies, our autopsies yielded nonspecific results but the toxicological study confirmed chloroquine poisoning. In 2of the 3cases, the victims had looked up the mixture of substances and dose used online. In the third case, a suicide help book was used. It is essential to obtain as much information as possible upon initial examination of the body in order to perform the autopsy and to prompt the toxicological study to reach the diagnosis of chloroquine poisoning

Cross-Reactivity of Chloroquine and Hydroxychloroquine With DRI Amphetamine Immunoassay.

BACKGROUND: Chloroquine and hydroxychloroquine are medical drugs used to treat the chemoprophylaxis of malaria and a second-line anti-inflammatory drug. METHODS: We performed a study of cross-reactivity of chloroquine and hydroxychloroquine in the DRI Amphetamine Assay inspired by a case report of a self-ingestion of chloroquine after a family dispute, that involved the following: (1) an in vitro study with control samples of healthy subjects, (2) an in vivo study with samples of patients with rheumatoid arthritis, and (3) an evaluation of the cross-reactivity of chloroquine and hydroxychloroquine in 3 additional immunoassays. RESULTS: In the case report, the Amphetamine DRI assay resulted positive both at 1000 ng/mL cutoff (1507 and 1137 ng/mL) and at 500 ng/mL cutoff (1178 and 642 ng/mL). Chloroquine urine levels were 103,900 and 100,900 ng/mL at 5 and 9 hours after ingestion. The results with control samples showed a positive cross-reactivity of chloroquine in the DRI Amphetamine Assay (approximately 0.74% and 0.89% at cutoff of 1000 and 500 ng/mL, respectively). Hydroxychloroquine did not cross-react with the DRI Amphetamine Assay up to 1,000,000 ng/mL. In patients treated with chloroquine or hydroxychloroquine, DRI Amphetamine did not produce false-positive results. The comparative assay study showed a positive cross-reactivity of chloroquine in the Emit II Plus Amphetamines Assay with control samples. CONCLUSIONS: Chloroquine can cause false-positive results in the DRI Amphetamine Assay when it is present at high concentrations. Hydroxychloroquine did not produce false-positive results neither in the DRI Amphetamine Assay nor in the others immunoassays evaluated.

A simple qualitive procedure for the detection of chloroquine in urine for use in clinical analytical toxicology in resource poor settings.

Objective: To develop and validate a simple procedure for the qualitative determination of chloroquine in urine with potential for use in developing countries lacking sophisticated analytical equipment and expensive reagents. Design: This was a laboratory based study making use of which combines a colorimetric test, Dill-Glazko's test, and UV/Visible absorbance spectrometry to confirm the presence of chloroquine. The spectrophotometric method was cross validated with the standard Baselt's method for quantification of chloroquine in biological fluids. Setting: Pharmacology laboratory at the Department of Clinical Pharmacology, College of Health Sciences, University of Zimbabwe. Main Outcome Measures: Recovery of the methods was assessed by comparing the peak absorbances and the resolution of the peaks at 329nm and 343nm. Sensitivity and specificity was determined by analysing in a blinded manner. The limits of detection of both the Dill-Glazko's test and the confirmatory test was determined. Results: In the prevalidation procedures increasing the volume of the ethylacetate and the volume of the lower aqueous layer extracted was found to increase the recovery of the confirmatory test. There was a significant difference between both the peak absorbances and the peak resolution for the two methods (p<0.0001). The confirmatory test had a sensitivity of 90% and a specificity of 100%, whereas the Baselt's method had a sensitivity of 83.3% and a specificity of 96.7%. The limit of detection of the Dill-Glazko's test was 15mg/Land that of the confirmatory test was 5mg/L. Conclusions: The confirmatory test had better recovery and was more sensitivity compared with the Baselt's method. The limit of detection of the combination method (Dill-Glazko's plus confirmatory test) was 15mg/L. The combination test showed appreciable sensitivity to be suitable for application to clinical toxicology.

Chronic use of chloroquine disrupts the urine concentration mechanism by lowering cAMP levels in the inner medulla.

Chloroquine, a widely used anti-malaria drug, has gained popularity for the treatment of rheumatoid arthritis, systemic lupus erythematosus (SLE), and human immunodeficiency virus (HIV). Unfortunately, chloroquine may also negatively impact renal function for patients whose fluid and electrolyte homeostasis is already compromised by diseases. Chronic administration of chloroquine also results in polyuria, which may be explained by suppression of the antidiuretic response of vasopressin. Several of the transporters responsible for concentrating urine are vasopressin-sensitive including the urea transporters UT-A1 and UT-A3, the water channel aquaporin-2 (AQP2), and the Na(+)-K(+)-2Cl(-) cotransporter (NKCC2). To examine the effect of chloroquine on these transporters, Sprague-Dawley rats received daily subcutaneous injections of 80 mg·kg(-1)·day(-1) of chloroquine for 4 days. Twenty-four hour urine output was twofold higher, and urine osmolality was decreased by twofold in chloroquine-treated rats compared with controls. Urine analysis of treated rats detected the presence chloroquine as well as decreased urine urea and cAMP levels compared with control rats. Western blot analysis showed a downregulation of AQP2 and NKCC2 transporters; however, UT-A1 and UT-A3 abundances were unaffected by chloroquine treatment. Immunohistochemistry showed a marked reduction of UT-A1 and AQP2 in the apical membrane in inner medullary collecting ducts of chloroquine-treated rats. In conclusion, chloroquine-induced polyuria likely occurs as a result of lowered cAMP production. These findings suggest that chronic chloroquine treatment would exacerbate the already compromised fluid homeostasis observed in diseases like chronic kidney disease.

[Different assays for hingamine in the study of biological fluids].

The authors present a method of hingamine identification in non-biological substances (tablets, powder, syringes) and biological fluids (blood, urine). Isolation was made with chloroform in pH 10. Identification was conducted with thin-layer chromatography, gas chromatography/mass-spectrometry, high-performance liquid chromatography, spectrophotometry in UV region. The quantity was estimated with spectrophotometry in UV region, high-performance liquid chromatography and high-performance thin-layer chromatography. The results of the three methods are comparable.

Is chloroquine chemoprophylaxis still effective to prevent low birth weight? Results of a study in Benin.

BACKGROUND: In areas of stable transmission, malaria during pregnancy is associated with severe maternal and foetal outcomes, especially low birth weight (LBW). To prevent these complications, weekly chloroquine (CQ) chemoprophylaxis is now being replaced by intermittent preventive treatment with sulfadoxine-pyrimethamine in West Africa. The prevalence of placental malaria and its burden on LBW were assessed in Benin to evaluate the efficacy of weekly CQ chemoprophylaxis, prior to its replacement by intermittent preventive treatment. METHODS: In two maternity clinics in Ouidah, an observational study was conducted between April 2004 and April 2005. At each delivery, placental blood smears were examined for malaria infection and women were interviewed on their pregnancy history including CQ intake and dosage. CQ was measured in the urine of a sub-sample (n = 166). Multiple logistic and linear regression were used to assess factors associated with LBW and placental malaria. RESULTS: Among 1090 singleton live births, prevalence of placental malaria and LBW were 16% and 17% respectively. After adjustment, there was a non-significant association between placental malaria and LBW (adjusted OR = 1.43; P = 0.10). Multiple linear regression showed a positive association between placental malaria and decreased birth weight in primigravidae. More than 98% of the women reported regular chemoprophylaxis and CQ was detectable in 99% of urine samples. Protection from LBW was high in women reporting regular CQ prophylaxis, with a strong duration-effect relationship (test for linear trend: P < 0,001). CONCLUSION: Despite high parasite resistance and limited effect on placental malaria, a CQ chemoprophylaxis taken at adequate doses showed to be still effective in reducing LBW in Benin.

A simple technique for the detection of anti-malarial drug formulations and their presence in human urine.

A simple, sensitive, specific assay technique for the detection and semi-quantification of chloroquine, amodiaquine, quinine, primaquine, sulfadoxine and pyrimethamine in formulations and in human urine by using thin layer chromatography (TLC) was developed and tested in the laboratory. The method involved developing test samples spotted on TLC chromatogram by diethylamine-toluene-isopropanol (1:4:5 v/v/v) as the eluting solvent. The solvent system diethylamine-toluene-isopropanol (1:4:5 v/v/v) enabled the elution and detection of all the tested antimalarial drugs in solution and those spiked in human urine. Detection limits for chloroquine, amodiaquine, quinine and primaquine were the lowest at 0.00025 mg/ml. Sulfadoxine exhibited a detection limit of 0.0005 mg/ml whereas that of pyrimethamine was 0.001 mg/ml. The results indicate the suitability of this technique in antimalarial drug quality and bioavailability studies. It is envisaged that this technique will adequately address the role of drug absorption and excretion in the chemotherapy of malaria as well as to detect types of antimalarial drugs commonly used in the community.

Simultaneous determination of quinine and chloroquine anti-malarial agents in pharmaceuticals and biological fluids by HPLC and fluorescence detection.

Even nowadays millions of people suffer and even die each year from malaria and hundreds of millions of people especially in tropical countries. Quinine (Q) a natural occurring alkaloid and chloroquine (CQ) a synthetic drug are widely used as anti-malarial agents. Herein an isocratic reversed-phase high performance liquid chromatographic (RP-HPLC) method is described for the simultaneous determination of quinine and chloroquine, at low concentrations, in pharmaceuticals and biological fluids. The present method is characterized by higher sensitivity and analytes are separated in less time than the already published methods. The analytical column, an MZ Kromasil, C18, 5 microm, 250 x 4mm, was operated at ambient temperature with backpressure values of 230 kg/cm(2). Mobile phase consisted of methanol-acetonitrile-0.1 mol/L ammonium acetate, (45:15:40 v/v) at a flow rate of 1.0 mL/min. Fluorescence detection was performed at excitation 325 nm and emission 375 nm, respectively. Salicylic acid was used as internal standard at a concentration of 0.5 ng/microL, resulting in a detection limit of 0.3 ng, while upper limit of linear range was 0.7 ng/microL for quinine and 0.5 ng/microL for chloroquine. Separation was completed within 5 min. The statistical evaluation of the method was examined performing intra-day (n=8) and inter-day calibration (n=8) and was found to be satisfactory, with high accuracy and precision results. Solid phase extraction provided high relative extraction recoveries from biological matrices: 92.1% for quinine and 105.4% for chloroquine from blood serum and 101.8% for quinine and 90.7% for chloroquine from urine.

Pharmacokinetic interaction of chloroquine and methylene blue combination against malaria.

OBJECTIVE: The combination of chloroquine and methylene blue is potentially effective for the treatment of chloroquine-resistant malaria caused by Plasmodium falciparum. The aim of this study was to investigate whether methylene blue influences the pharmacokinetics of chloroquine. METHODS: In a randomized, placebo-controlled, parallel group design, a 3-day course of therapeutic oral doses of chloroquine (total 2.5 g in male, 1.875 g in female participants) with oral co-administration of placebo or 130 mg methylene blue twice daily for 3 days was administered to 24 healthy individuals. Chloroquine, desethylchloroquine, and methylene blue concentrations were determined by means of HPLC/UV or LC/MS/MS assays in whole blood, plasma, and urine for 28 days after the last dose. RESULTS: During methylene blue exposure, the area under the chloroquine whole blood concentration-time curve normalized to body weight (AUC(0-24 h)/BW) yielded a trend of reduction (249+/-98.2 h mug l(-1) kg(-1) versus 315+/-65.0 h mug l(-1) kg(-1), P=0.06). The AUC(0-24 h)/BW of desethylchloroquine was reduced by 35% (104+/-40.3 h mug l(-1) kg(-1) versus 159+/-66.6 h mug l(-1) kg(-1), P=0.03), whereas the metabolic ratio between chloroquine and desethylchloroquine remained unchanged (2.25+/-0.49 versus 1.95+/-0.42, P=0.17). The renal clearance of chloroquine and the ratio between chloroquine in whole blood and plasma remained unchanged (P>0.1). CONCLUSION: Oral co-administration of methylene blue appears to result in a small reduction of chloroquine exposure which is not expected to be clinically relevant and thus represents no concern for further development as an anti-malarial combination.

High-performance liquid chromatographic method for determination of amodiaquine, chloroquine and their monodesethyl metabolites in biological samples.

A high-performance liquid chromatographic method for determination of amodiaquine (AQ), desethylamodiaquine (DAQ), chloroquine (CQ) and desethylchloroquine (DCQ) in human whole blood, plasma and urine is reported. 4-(4-Dimethylamino-1-methylbutylamino)-7-chloroquinoline was used as internal standard. The drugs and the internal standard were extracted into di-isopropyl ether as bases and then re-extracted into an acidic aqueous phase with 0.1 M phosphate buffer at pH 4.0 for AQ samples and at pH 2.5 for CQ filter paper samples. A C(18) column was used and the mobile phase consisted of methanol-phosphate buffer (0.1 M, pH 3)-perchloric acid (250: 747.5:2.5, v/v). The absorbance of the drugs was monitored at 333 nm and no endogenous compound interfered at this wavelength. The limit of quantification in whole blood, plasma and urine was 100 nM for AQ and DAQ (sample size 100 microliter) as well as for CQ and DCQ in blood samples dried on filter paper. For 1000 microliter AQ and DAQ samples, the limit of quantification was 10 nM in all three biological fluids. The within-assay and between-assay coefficients of variations were always <10% at the limits of quantification. Plasma should be preferred for the determination of AQ and DAQ since use of whole blood may be associated with stability problems.

Plasmodium falciparum pfcrt and pfmdr1 polymorphisms are associated with the pfdhfr N108 pyrimethamine-resistance mutation in isolates from Ghana.

The Plasmodium falciparum chloroquine resistance transporter gene (pfcrt) T76 and multidrug resistance gene analogue (pfmdr1) Y86 mutations are associated with chloroquine(CQ)-resistance. In isolates from 172 pregnant women living in the area of Agogo, Ghana, pfcrt T76 was detected in 69% and pfmdr1 Y86 in 66%. Pfcrt T76 but not pfmdr1 Y86 was more prevalent in samples from women with residual CQ in urine or serum. Parasite densities and multiplicity of infection of pfmdr wild type but not of resistant isolates were reduced by CQ. Adjusted for CQ and pyrimethamine (PYR) in urine, the P. falciparum dihydrofolate reductase (pfdhfr) N108 mutation which confers PYR-resistance was 3.1 and 3 times, respectively, more likely to be detected in isolates containing pfcrt and pfmdr1 mutations than in those comprising wild type alleles. Pfcrt, pfmdr, and pfdhfr mutations are frequent in P. falciparum from this part of Ghana which may limit the choice of drugs for the prevention of malaria in pregnancy. The association of CQ- and PYR-resistance mutations independent of recent drug use could indicate accelerated development of resistance to structurally unrelated drugs. Alternatively, it may reflect selection of resistance in persisting infections due to no longer detectable drug pressure.

Comparative in vitro and in vivo study of a sugar-coated chloroquine preparation marketed in Tanzania versus an ordinary brand.

OBJECTIVE: To investigate the absorption and the quality of a sugar-coated chloroquine (CQ) marketed in Tanzania. METHOD: Twenty healthy volunteers were randomised to take either the test brand (group A) or a control chloroquine phosphate (group B). Each subject received 300 mg chloroquine base. Whole blood dried on filter papers were collected at time 0 and at 15 and 30 min and at 1, 2, 3, 4, 6, 8, 24, 36, 48, 72 and 168 h after drug intake. Urine samples were collected at time 0, 0-4 h, 4-8 h, 8-24 h, 24-48 h and 48-72 h after drug administration. In an in vitro study, six tablets from each of the two CQ preparations were checked for the amount of active drug contained in each tablet and their dissolution rates. RESULTS: The blood concentration Area Under the Curve (AUC) of group B was about 10% larger than that of group A. The total amounts of CQ plus deethylchloroquine excreted with the urine during the 72-h study period were 5% for group A and 6% for group B. None of the pharmacokinetic parameters were significantly different between the two groups. All the tablets contained the labelled amount of chloroquine; however, one tablet from the test drug failed to fulfil the required dissolution rate. CONCLUSION: We found no major difference between the AUCs of the two CQ preparations, but the sugar-coated brand has shown to have variable dissolution rate.

Pharmacokinetic aspects of chloroquine-induced pruritus: influence of dose and evidence for varied extent of metabolism of the drug.

The significance of a pharmacokinetics basis in chloroquine (CQ)-induced pruritus was investigated by determining the disposition of the drug in two groups of volunteers; pruritus positive and pruritus negative. Single oral dose of 600 mg CQ was administered to each of 36 volunteers, 18 for each of the two groups. After a washout period of 9 months, 150 mg single oral dose of the drug was given to 12 of the same volunteers, six each from the two groups. Blood and urine samples were collected at predetermined times following administration of each dose. Concentrations of CQ and its major metabolite, desethylchloroquine (CQM), were measured in plasma and urine using an established HPLC method. Results showed that the ratio, AUC (CQ)/AUC (CQM), as well as AUC(0-48 h) and 24-h urinary CQ excretion were all significantly higher (P<0.05) in pruritus-positive compared to pruritus-negative volunteers, following administration of the 600-mg CQ dose. Also, urinary drug-metabolite ratios monitored over 0-48 h postdose were markedly higher in the pruritus positive group. However, after administration of the 150-mg dose, 24-h urinary CQ collection and urinary drug-metabolite ratios were highly comparable between the two groups (P>0.1). This study indicates that there might be a decreased metabolism of CQ in subjects susceptible to CQ-induced pruritus following ingestion of a therapeutic dose. It also suggests that the extent of metabolism of CQ in this group may be influenced by the dose of the drug. Comparatively higher CQ levels in pruritus susceptible subjects may possibly be responsible for the pruritus experienced by such individuals when given therapeutic regimen.

Sensitive ELISA dipstick test for the detection of chloroquine in urine under field conditions.

OBJECTIVE: To evaluate a new enzyme-linked immunosorbent assay (ELISA) dipstick test for detecting chloroquine (CQ) in urine in a malaria-endemic region of north-western Namibia. METHOD: Urine samples from 92 patients attending the outpatient department of Kamhaku Hospital with suspected malaria infection were tested for CQ with both the Dill-Glazko test and the ELISA dipstick test. Results were compared to the history of CQ intake as documented in the patients' health passes. RESULTS: The dipstick test proved an easy-to-handle and very sensitive tool for the detection of CQ with a lower limit of detection at 120 nmol/l. It showed high agreement with the history of CQ intake within the last 6 months. The specificity in a negative control group was 100%. The Dill-Glazko test was far less sensitive and specific with a lower detection limit of 150 micromol/l. CONCLUSION: The dipstick test can be used in pharmacological studies to evaluate the use of CQ, and as an inclusion criterion for in vivo and in vitro sensitivity tests, whereas the Dill-Glazko test is appropriate to test compliance during and a few days after CQ intake.

[Determination of chloroquine in human urine].

A GC method was established for qualitative and quantitative determination of chloroquine in human urine. The chloroquine is extracted from 2 ml urine with 2 x 2 ml cyclohexame: chloroform (8:2). The retention time of chlorquine is 9.44 min. The linear of quantitation is 0-50 micrograms/ml. The recovery of the procedure in 25 micrograms g/ml is 87.0%, CV = 7. 9% (n = 5). The limit of the determination is 200 ng/ml. The method can also be used in blood. A case is reported here. In that, we detected chloroquine in urine and blood. The quantitation of chloroquine in urine and blood is 0.475 mg/ml and 3.68 micrograms/ml, respectively. A metabolite of chloroquine-desethylchloroquine is also found in the urine.