| 1. |
- Blessborn, Daniel, et al.
(författare)
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Determination of pyronaridine in whole blood by automated solid-phase extraction and high-performance liquid chromatography
- 2003
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Ingår i: Therapeutic Drug Monitoring. - : Ovid Technologies (Wolters Kluwer Health). - 0163-4356 .- 1536-3694. ; 25:3, s. 264-270
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Tidskriftsartikel (refereegranskat)abstract
- A new extraction procedure for the analysis of pyronaridine in whole blood is presented. A weak cation exchanger with a carboxylic acid (CBA) sorbent was found to be a suitable solid phase sorbent for the extraction of pyronaridine. High-performance liquid chromatography with UV detection at 278 nm and an electrochemical detector at +0.75 V is used. The electrochemical detector gives higher selectivity than the UV detector. The separation was performed using a C18 reversed phase column with mobile phase of acetonitrile-phosphate buffer (0.01 mol/L, pH 2.5)- sodium perchlorate (1.0 mol/L; 22:77:1, v/v/v). The within-day RSDs were below 5% at all concentration levels between 75 nmol/L and 1500 nmol/L, and the between-day RSDs were below 14% at all concentration levels. The limit of quantification was about 50 nmol/L in 1000 microL whole blood with an RSD of 20% or less on a day-to-day basis. The stability of pyronaridine is increased if the pH is less than 3 in water solutions. In whole blood, the concentration decreases by about 10% for each freeze-thaw cycle performed. At room temperature (about 22 degrees C), pyronaridine concentration in whole blood decreases by about 10% within 12 to 24 hours.
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| 2. |
- Blessborn, Daniel, et al.
(författare)
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Development and validation of an automated solid-phase extraction and liquid chromatographic method for determination of lumefantrine in capillary blood on sampling paper
- 2007
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Ingår i: Journal of Pharmaceutical and Biomedical Analysis. - : Elsevier BV. - 0731-7085 .- 1873-264X. ; 45:2, s. 282-287
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Tidskriftsartikel (refereegranskat)abstract
- A bioanalytical method for the determination of lumefantrine in 100 μl blood applied onto sampling paper, by solid-phase extraction and liquid chromatography, has been developed and validated. Whatman 31 ET Chr sampling paper was pre-treated with 0.75 M tartaric acid before sampling capillary blood to enable a high recovery of lumefantrine. Lumefantrine was extracted from the sampling paper, then further purified using solid-phase extraction and finally quantified with HPLC. The between-day variation was below 10% over the range 0.4-25 μM. The lower limit of quantification was 0.25 μM in 100 μl capillary blood. No decrease in lumefantrine concentration in dried blood spot is seen after 4 months storage at 22 °C. The method was also evaluated in field samples from patients in Tanzania after treatment with lumefantrine/artemether. Lumefantrine could be estimated accurately enough to assess bioavailability and treatment compliance on day 7 (i.e. 4 days after the last dose) after a standard regimen with the lumefantrine/artemether combination.
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| 3. |
- Ngasala, Billy E., et al.
(författare)
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Effectiveness of artemether-lumefantrine provided by community health workers in under-five children with uncomplicated malaria in rural Tanzania : an open label prospective study
- 2011
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 10, s. 64-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Home-management of malaria (HMM) strategy improves early access of anti-malarial medicines to high-risk groups in remote areas of sub-Saharan Africa. However, limited data are available on the effectiveness of using artemisinin-based combination therapy (ACT) within the HMM strategy. The aim of this study was to assess the effectiveness of artemether-lumefantrine (AL), presently the most favoured ACT in Africa, in under-five children with uncomplicated Plasmodium falciparum malaria in Tanzania, when provided by community health workers (CHWs) and administered unsupervised by parents or guardians at home. Methods: An open label, single arm prospective study was conducted in two rural villages with high malaria transmission in Kibaha District, Tanzania. Children presenting to CHWs with uncomplicated fever and a positive rapid malaria diagnostic test (RDT) were provisionally enrolled and provided AL for unsupervised treatment at home. Patients with microscopy confirmed P. falciparum parasitaemia were definitely enrolled and reviewed weekly by the CHWs during 42 days. Primary outcome measure was PCR corrected parasitological cure rate by day 42, as estimated by Kaplan-Meier survival analysis. This trial is registered with ClinicalTrials.gov, number NCT00454961. Results: A total of 244 febrile children were enrolled between March-August 2007. Two patients were lost to follow up on day 14, and one patient withdrew consent on day 21. Some 141/241 (58.5%) patients had recurrent infection during follow-up, of whom 14 had recrudescence. The PCR corrected cure rate by day 42 was 93.0% (95% CI 88.3%-95.9%). The median lumefantrine concentration was statistically significantly lower in patients with recrudescence (97 ng/mL [IQR 0-234]; n = 10) compared with reinfections (205 ng/mL [114-390]; n = 92), or no parasite reappearance (217 [121-374] ng/mL; n = 70; p <= 0.046). Conclusions: Provision of AL by CHWs for unsupervised malaria treatment at home was highly effective, which provides evidence base for scaling-up implementation of HMM with AL in Tanzania.
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| 4. |
- Ngasala, Billy E., et al.
(författare)
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Efficacy and Effectiveness of Artemether-Lumefantrine after Initial and Repeated Treatment in Children < 5 Years of Age with Acute Uncomplicated Plasmodium falciparum Malaria in Rural Tanzania : A Randomized Trial
- 2011
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Ingår i: Clinical Infectious Diseases. - : Oxford University Press (OUP). - 1058-4838 .- 1537-6591. ; 52:7, s. 873-882
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Tidskriftsartikel (refereegranskat)abstract
- Background. We assessed the efficacy, effectiveness and safety of artemether-lumefantrine, which is the most widely used artemisinin-based combination therapy in Africa, against Plasmodium falciparum malaria during an extended follow-up period after initial and repeated treatment. Methods. We performed an open-label randomized trial of artemether-lumefantrine with supervised (n 5 180) and unsupervised intake (n = 179) in children <5 years of age with uncomplicated falciparum malaria in rural Tanzania. Recurrent infections between day 14 and day 56 were retreated within the same study arm. Main end points were polymerase chain reaction (PCR)-corrected cure rates by day 56 and day 42 after initial and repeated treatment, respectively, as estimated by survival analysis. Results. The PCR-corrected cure rate after initial treatment was 98.1% (95% confidence interval [CI], 94.2%-99.4%) after supervised and 95.1% (95% CI, 90.7%-98.1%) after unsupervised intake (P = .29). After retreatment of recurrent infections, the cure rates were 92.9% (95% CI, 81.8%-97.3%) and 97.6% (95% CI, 89.3%-98.8%), respectively (P = .58). Reinfections occurred in 46.9% (82 of 175) versus 50.9 % of the patients (relative risk [RR], 0.92 [95% CI, 0.74-1.14]; P 5.46) after initial therapy and 32.4% (24 of 74) versus 39.0% (32 of 82) (RR, 0.83 [95% CI, 0.54-1.27]; P 5.39) after retreatment. Median blood lumefantrine concentrations in supervised and unsupervised patients on day 7 were 304 versus 194 ng/ mL (P <.001) after initial treatment and 253 versus 164 ng/ mL (P 5.001) after retreatment. Vomiting was the most commonly reported drug-related adverse event (in 1% of patients) after both initial and repeated treatment. Conclusions. Artemether-lumefantrine was highly efficacious even after unsupervised administration, despite significantly lower lumefantrine concentrations, compared with concentration achieved with supervised intake, and was well-tolerated and safe after initial and repeated treatment.
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| 5. |
- Ursing, Johan, et al.
(författare)
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Chloroquine Is Grossly Overdosed and Overused but Well Tolerated in Guinea-Bissau
- 2009
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Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 53:1, s. 180-185
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Tidskriftsartikel (refereegranskat)abstract
- High chloroquine doses are commonly prescribed in Guinea-Bissau. Double-dose chloroquine has been shown to be more efficacious (92% efficacy) than the standard dose (80% efficacy). However, chloroquine is toxic when overdosed, and it was not known if the high doses prescribed in Guinea-Bissau were taken or whether they caused adverse effects. We aimed to determine the dosage of chloroquine commonly prescribed, the doses commonly taken, and whether concentration-dependent adverse events occurred in routine practice. Chloroquine prescriptions by eight physicians and chloroquine intake by 102 children were recorded. Chloroquine intake and adverse events were assessed by questioning. Chloroquine concentrations in whole blood were measured. The median total chloroquine dose prescribed and that reportedly taken were 81 and 77 mg kg(-1), respectively. The total dose was usually split into two to three daily doses of 6.6 mg kg(-1) each. These were taken unsupervised for a median of 5 days. Forty percent of the study children had chloroquine concentrations in the same range as those found in a previous study in which double the normal dose (50 mg kg(-1)) of chloroquine was taken. Only 3/102 children had Plasmodium falciparum in the blood at the time of diagnosis and treatment. No severe adverse events were reported. No adverse events were associated with higher chloroquine concentrations. High doses of chloroquine are commonly taken and well tolerated in Guinea-Bissau. Malaria diagnostics are poor, and chloroquine is commonly prescribed to children without parasitemia. Use of high-dose chloroquine is concurrent with an exceptionally low prevalence of chloroquine-resistant P. falciparum.
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| 6. |
- Ursing, Johan, et al.
(författare)
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Chloroquine is grossly under dosed in young children with malaria : implications for drug resistance
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Plasmodium falciparum malaria is treated with 25 mg/kg of chloroquine (CQ) irrespective of age. Theoretically, CQ should be dosed according to body surface area (BSA). The effect of dosing CQ according to BSA has not been determined but doubling the dose per kg doubled the efficacy of CQ in children aged <15 years infected with P. falciparum carrying CQ resistance causing genes typical for Africa. The study aim was to determine the effect of age on CQ concentrations.Methods and Findings: Day 7 whole blood CQ concentrations were determined in 150 and 302 children treated with 25 and 50 mg/kg, respectively, in previously conducted clinical trials. CQ concentrations normalised for the dose taken in mg/kg of CQ decreased with decreasing age (p<0.001). CQ concentrations normalised for dose taken in mg/m(2) were unaffected by age. The median CQ concentration in children aged <2 years taking 50 mg/kg and in children aged 10-14 years taking 25 mg/kg were 825 (95% confidence interval [CI] 662-988) and 758 (95% CI 640-876) nmol/l, respectively (p = 0.67). The median CQ concentration in children aged 10-14 taking 50 mg/kg and children aged 0-2 taking 25 mg/kg were 1521 and 549 nmol/l. Adverse events were not age/concentration dependent.Conclusions: CQ is under-dosed in children and should ideally be dosed according to BSA. Children aged <2 years need approximately double the dose per kg to attain CQ concentrations found in children aged 10-14 years. Clinical trials assessing the efficacy of CQ in Africa are typically performed in children aged <5 years. Thus the efficacy of CQ is typically assessed in children in whom CQ is under dosed. Approximately 3 fold higher drug concentrations can probably be safely given to the youngest children. As CQ resistance is concentration dependent an alternative dosing of CQ may overcome resistance in Africa.
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| 7. |
- Ursing, Johan, et al.
(författare)
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High-Dose Chloroquine for Treatment of Chloroquine-Resistant Plasmodium falciparum Malaria
- 2016
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 213:8, s. 1315-1321
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Tidskriftsartikel (refereegranskat)abstract
- Background. Due to development of multidrug-resistant Plasmodium falciparum new antimalarial therapies are needed. In Guinea-Bissau, routinely used triple standard-dose chloroquine remained effective for decades despite the existence of "chloroquine-resistant" P. falciparum. This study aimed to determine the in vivo efficacy of higher chloroquine concentrations against P. falciparum with resistance-conferring genotypes. Methods. Standard or double-dose chloroquine was given to 892 children aged < 15 years with uncomplicated malaria during 3 clinical trials (2001-2008) with >= 35 days follow-up. The P. falciparum resistance-conferring genotype (pfcrt 76T) and day 7 chloroquine concentrations were determined. Data were divided into age groups (< 5, 5-9, and 10-14 years) because concentrations increase with age when chloroquine is prescribed according to body weight. Results. Adequate clinical and parasitological responses were 14%, 38%, and 39% after standard-dose and 66%, 84%, and 91% after double-dose chloroquine in children aged < 5, 5-9, and 10-14 years, respectively, and infected with P. falciparum genotypes conferring chloroquine resistance (n = 195, P < .001). In parallel, median chloroquine concentrations were 471, 688, and 809 nmol/L for standard-dose and 1040, 1494, and 1585 nmol/L for double-dose chloroquine. Conclusions. Chloroquine resistance is dose dependent and can be overcome by higher, still well-tolerated doses.
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| 8. |
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| 9. |
- Blessborn, Daniel, et al.
(författare)
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Assay for screening for six antimalarial drugs and one metabolite using dried blood spot sampling, sequential extraction and ion-trap detection
- 2010
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Ingår i: Bioanalysis. - : Future Science Ltd. - 1757-6180 .- 1757-6199. ; 2:11, s. 1839-1847
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Tidskriftsartikel (refereegranskat)abstract
- Background: More parasites are becoming resistant to antimalarial drugs, and in many areas a change in first-line drug treatment is necessary. The aim of the developed assay is to help determine drug use in these areas and also to be a complement to interviewing patients, which will increase reliability of surveys.Results: This assay detects quinine, mefloquine, sulfadoxine, pyrimethamine, lumefantrine, chloroquine and its metabolite desethylchloroquine in a 100-mu l dried blood spot. Most of the drugs also have long half-lives that make them detectable at least 7 days after administration. The drugs are extracted from the dried blood spot with sequential extraction (due to the big differences in physicochemical properties), solid-phase extraction is used as sample clean-up and separation is performed with gradient-LC with MS ion-trap detection.Conclusion: Detection limits (S/N > 5:1) at 50 ng/ml or better were achieved for all drugs except lumefantrine (200 ng/ml), and thus can be used to determine patient compliance. A major advantage of using the ion-trap MS it that it will be possible to go back into the data and look for other drugs as needed.
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| 10. |
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