Search

Abstract: A cost-effective HPLC method for determination of pyrimethamine (PYR) in human whole blood samples dried on filter paper (Whatman®) is reported. Trimethoprim (TMP) was used as an internal standard. Whole blood spiked with PYR was transferred (100μl) onto filter paper and dried at room temperature. Capillary blood samples (100μl) after ingestion of three tablets of sulfadoxine-pyrimethamine (SP) by one subject were also tested. PYR and an internal standard (IS) TMP were extracted into di-isopropyl ether as bases and then re-extracted with 150μl mobile phase. A C-18 column was used and the mobile phase consisted of phosphate buffer (0.05M, pH 5):acetonitrile:concentrated perchloric acid (750:300:2.5, v/v/v). The absorbances of PYR and IS were monitored at 270nm. The limit of quantification was 40ng/ml. The within- and between-assay coefficient of variations were <10% at the limit of quantification. [Copyright &y& Elsevier]

Objective: To study case management of malaria in children under 5 years of age at primary health care facilities in Kibaha district, Tanzania and to evaluate the accuracy of self-reported mothers'/guardians' information on chloroquine use in children.Method: A random sample of 652 mothers/guardians with sick children under 5 years of age attending 10 primary health care facilities was observed and interviewed. Blood samples for determination of chloroquine levels were taken from all children and thick smears for detection of malaria parasites were taken from the children who were prescribed chloroquine. Information on diagnoses and prescriptions was collected from recording books.Results: Fever and respiratory problems were the most common complaints and accounted for 75% and 46% of the presenting conditions, respectively (some complained of both). Fifty-four per cent of the children received medication at home, most commonly antipyretics and chloroquine, 20% had been taken to another health facility and 3% to traditional healers before coming to the health facilities. There was a significantly higher use of antipyretics among home treated children compared with those taken previously to health facilities (P or= 1000 nmol/l). Of those prescribed chloroquine, 16% already had high blood concentrations of the drug.Conclusion: Health care services, i.e. presumptive malaria diagnosis, consultation time and procedure for physical examination need to be improved. [ABSTRACT FROM AUTHOR]

Objective: World Health Organization/International Network of Rational use of Drugs (WHO/INRUD) indicators are widely used to assess medicine use. However, there is limited evidence on their validity in Namibia's primary health care (PHC) to assess the quality of prescribing. Consequently, our aim was to address this.Design, Setting, Participants and Interventions: An analytical cross-sectional survey design was used to examine and validate WHO/INRUD indicators in out-patient units of two PHC facilities and one hospital in Namibia from 1 February 2015 to 31 July 2015. The validity of the indicators was determined using two-by-two tables against compliance to the Namibian standard treatment guidelines (NSTG). The receiver operator characteristics for the WHO/INRUD indicators were plotted to determine their accuracy as predictors of compliance to agreed standards. A multivariate logistic model was constructed to independently determine the prediction of each indicator.Main Outcomes and Results: Out of 1243 prescriptions; compliance to NSTG prescribing in ambulatory care was sub-optimal (target was >80%). Three of the four WHO/INRUD indicators did not meet Namibian or WHO targets: antibiotic prescribing, average number of medicines per prescription and generic prescribing. The majority of the indicators had low sensitivity and/or specificity. All WHO/INRUD indicators had poor accuracy in predicting rational prescribing. The antibiotic prescribing indicator was the only covariate that was a significant independent risk factor for compliance to NSTGs.Conclusion: WHO/INRUD indicators showed poor accuracy in assessing prescribing practices in ambulatory care in Namibia. There is need for appropriate models and/or criteria to optimize medicine use in ambulatory care in the future. [ABSTRACT FROM AUTHOR]

Liquid chromatography (LC) and mass spectral behavior and analytical performance characteristics of efavirenz (EFV), emtricitabine (EMT) and tenofovir (TFV), i.e., individual components of Atripla®, were probed. Thiswas followed by estimation of their analytical performance characteristics employing LC and a parallel direct infusion sample introduction procedure. Performance characteristics using both types of sample introduction procedures were compared. Using liquid chromatography- mass spectrometry (LC-MS), linearities, i.e., correlation coefficients of the calibration curves of EFV, EMT and TFV, ranged between 0.9300 and 0.9990 in the full scan, selected ion monitoring and mass spectrometry/mass spectrometry (MS-MS) modes. The limits of detection (LODs) ranged between 0.5 and 11.6 μg/L. The lower limits of quantification (LLOQs) and the upper limits of quantification (ULOQs) were in the ranges of 0.9-23.2 and 1.6-38.7 μg/L, respectively. The LODs ranged between 0.8 and 114.7 μg/L. The LLOQs and the ULOQs were in the ranges of 1.6-29.4 and 2.7- 49.0 μg/L, respectively. In the case of EMT, sodiated molecular ion at m/z 270 was used to adduce analytical performance characteristics from which lower detection limits were obtained compared with those in the literature where [M+H]+ at m/z 248 was used. [ABSTRACT FROM AUTHOR]

Highlights: [•] We have compared three analytical techniques, i.e. GC–MS, LC–MS and LC–UV for the determination of nevirapine in human plasma. [•] We have compared the performance of helium and hydrogen as carrier gases in GC–MS. [•] Helium gave lower detection limits but comparable to hydrogen and both were found suitable for therapeutic drug monitoring. [•] QuEChERS extraction technique gave good recoveries in both GC–MS and LC–MS. [•] Analytical performance characteristics were the same or better than those obtaining in literature. [Copyright &y& Elsevier]

Introduction Sample preparation in bio analytical chemistry poses a challenge because it can be compound dependent. We compared six sample extraction techniques i.e. QuEChERS (Q), liquid extraction (LE), protein precipitation (PPT), Q-PPT, Q-LE and LE-PPT for the extraction of antiretroviral drugs emtricitabine, tenofovir, efavirenz, lopinavir and rotinavir in human blood plasma. Method A multiple reaction monitoring liquid chromatography- tandem mass spectrometry method for the determination of the same antiretroviral drugs developed and validated in this laboratory was used. Comparisons were based on the efficiencies of extraction, the precisions and accuracies. Using United States Food and Drug Administration guidelines, analytical performance characteristics i.e. limits of detection, lower limits of quantification and upper limits of quantification were also compared. Results The percent mean recoveries ranged between 68.8 and 81.2% for single modes and 52.4–70.5% for mixed mode techniques. The precisions of all the extraction techniques were within the Using United States Food and Drug Administration guidelines acceptable range of < 15% at all concentration levels for all analytes. Accuracy ranged between 8.73 and 65.94% for single mode techniques and between 21.73 and 51.59% for mixed mode techniques. Discussion The mixed modes gave slightly lower recoveries but Q-LE compared well with the single modes at slightly higher spike levels. Limits of detection for all the six sample preparation techniques fell below the clinically relevant therapeutic range of approximately 3–8 ppm. Therefore all techniques can be employed for routine therapeutic drug monitoring studies. [ABSTRACT FROM AUTHOR]

Objectives In 2005, Tanzania changed its policy for uncomplicated malaria treatment from sulphadoxine-pyrimethamine ( SP) to artemisinin-based combination therapy ( ACT), specifically artemether-lumefantrine ( ALU). SP remains the medicine of choice for intermittent preventive treatment in pregnancy ( IPTp). There is a need to assess dispensers' knowledge regarding the treatment of uncomplicated malaria and IPTp in Tanzania given appreciable self-purchasing to improve future care. Methods Descriptive cross-sectional design with structured questionnaires to capture quantitative data, with qualitative data captured using focus groups. The study was performed at 32 private pharmacies and 33 Accredited Drug Dispensing Outlets in the Nyamagana and Sengerema Districts in Tanzania, with 20 dispensers included in the qualitative discussions. Key findings The knowledge level of dispensers in the private medicine outlets was variable. Most dispensers knew ALU was first-line treatment in uncomplicated malaria, however variable knowledge about taking ALU with fatty meals. Generally, dispensers had poor knowledge about dosing intervals for SP in IPTp and variable knowledge regarding treatments in the first trimester. Overall, 49% had good knowledge and 48% had moderate knowledge of ACT in uncomplicated malaria. There was a significant relationship between dispenser type and knowledge of ACT but no statistical relationship between the level of knowledge on IPTp and the dispenser. Conclusions The majority of dispensers in private medicines outlets have good knowledge on ACT policy in the treatment of uncomplicated malaria; however, few dispensers had good knowledge on IPTp, which may contribute to irrational dispensing of SP. This needs addressing given the extent of self-purchasing in Tanzania. [ABSTRACT FROM AUTHOR]

Background: Cholera outbreaks have occurred in Tanzania since 1974. To date, the genetic epidemiology of these outbreaks has not been assessed.Methods: 96 Vibrio cholerae O1 isolates from five regions were characterized, and their genetic relatedness assessed using multi-locus variable-number tandem-repeat analysis (MLVA) and whole genome sequencing (WGS).Results: Of the 48 MLVA genotypes observed, 3 were genetically unrelated to any others, while the remaining 45 genotypes separated into three MLVA clonal complexes (CCs) - each comprised of genotypes differing by a single allelic change. In Kigoma, two separate outbreaks, 4 months apart (January and May, 2015), were each caused by genetically distinct strains by MLVA and WGS. Remarkably, one MLVA CC contained isolates from both the May outbreak and ones from the 2011/2012 outbreak in Dar-es-Salaam. However, WGS revealed the isolates from the two outbreaks to be distinct clades. The outbreak that started in August 2015 in Dar-es-Salaam and spread to Morogoro, Singida and Mara was comprised of a single MLVA CC and WGS clade. Isolates from within an outbreak were closely related differing at fewer than 5 nucleotides. All isolates were part of the 3rd wave of the 7th pandemic and were found in four clades related to isolates from Kenya and Asia.Conclusions: We conclude that genetically related V. cholerae cluster in outbreaks, and distinct strains circulate simultaneously. [ABSTRACT FROM AUTHOR]

We have discerned some characteristics of protonated and sodiated forms of emtricitabine tenofovir and tenofovir disoproxil fumarate in aqueous solutions using mass spectrometry/mass spectrometry (MS/MS), nuclear magnetic resonance spectroscopy (NMR) and Ab initio calculations. Protonated species exhibited different mass spectral characteristics from sodiated species for the three antiretroviral drugs. Sodiation of the three compounds yields extremely stable conformers which require high excitation energies to detach the sodium cation using MS/MS. In the case of emtricitabine (FTC), collision induced dissociation (CID) of the protonated species with m / z 248 yielded m / z 130 as the major product ion by losing 2-ethyl-1,3-oxathiolane. MS/MS of the sodiated molecular ion [M + Na] + with m / z 270 would be expected to yield [M + H] + i.e. m / z 248 by losing the Na + cation but instead lost 2-ethyl-1,3-oxathiolane and left the Na + cation well sequestered within the ionic complex. Similar observations were made with tenofovir disoproxil fumarate (TDF) and tenofovir (TFV). Ab initio calculations showed in the case of sodiated TDF and TFV that, the sodium could only be cleaved when a nucleophilic species i.e. PO 2 to which it was coordinated to, fragmented requiring activation energy of 1.5 eV. The potential energy barrier to remove the Na + cation alone was too high to allow the cleavage to proceed. NMR data showed that when TFV or TDF coordinates with Na + ions at one of the nitrogens at position 1 in the purine moiety of the molecule, it also interacts with oxygens of the phospho group to form an ionic complex and perturbs the chemical environments of several atoms in the periphery. The abundance of sodium cations and their strong interactions with the core structures of FTC, TDF and TFV make sodiated species as the best candidates for their quantitation using MS/MS especially in biological fluids. Evidence for improved sensitivity when sodiated species of some of the antiretroviral (ARV) drugs were used for quantitation exists in the literature. [ABSTRACT FROM AUTHOR]

Background: Early diagnosis and prompt, effective treatment of uncomplicated malaria is critical to prevent severe disease, death and malaria transmission. We assessed the impact of rapid malaria diagnostic tests (RDTs) by community health workers (CHWs) on provision of artemisinin-based combination therapy (ACT) and health outcome in fever patients. Methodology/Principal Findings: Twenty-two CHWs from five villages in Kibaha District, a high-malaria transmission area in Coast Region, Tanzania, were trained to manage uncomplicated malaria using RDT aided diagnosis or clinical diagnosis (CD) only. Each CHW was randomly assigned to use either RDT or CD the first week and thereafter alternating weekly. Primary outcome was provision of ACT and main secondary outcomes were referral rates and health status by days 3 and 7. The CHWs enrolled 2930 fever patients during five months of whom 1988 (67.8%) presented within 24 hours of fever onset. ACT was provided to 775 of 1457 (53.2%) patients during RDT weeks and to 1422 of 1473 (96.5%) patients during CD weeks (Odds Ratio (OR) 0.039, 95% CI 0.029-0.053). The CHWs adhered to the RDT results in 1411 of 1457 (96.8%, 95% CI 95.8-97.6) patients. More patients were referred on inclusion day during RDT weeks (10.0%) compared to CD weeks (1.6%). Referral during days 1-7 and perceived non-recovery on days 3 and 7 were also more common after RDT aided diagnosis. However, no fatal or severe malaria occurred among 682 patients in the RDT group who were not treated with ACT, supporting the safety of withholding ACT to RDT negative patients. Conclusions/Significance: RDTs in the hands of CHWs may safely improve early and well-targeted ACT treatment in malaria patients at community level in Africa. [ABSTRACT FROM AUTHOR]

Background: Prescribing antimalarial medicines based on parasite confirmed diagnosis of malaria is critical to rational drug use and optimal outcome of febrile illness. The impact of microscopy-based versus clinical-based diagnosis of childhood malaria was assessed at primary health care (PHC) facilities using a cluster randomized controlled training intervention trial. Methods: Sixteen PHC facilities in rural Tanzania were randomly allocated to training of health staff in clinical algorithm plus microscopy (Arm-I, n = 5) or clinical algorithm only (Arm-II, n = 5) or no training (Arm-III, n = 6). Febrile under-five children presenting at these facilities were assessed, treated and scheduled for follow up visit after 7 days. Blood smears on day 0 were only done in Arm-I but on Day 7 in all arms. Primary outcome was antimalarial drug prescription. Other outcomes included antibiotic prescription and health outcome. Multilevel regression models were applied with PHC as level of clustering to compare outcomes in the three study arms. Results: A total of 973, 1,058 and 1,100 children were enrolled in arms I, II and III, respectively, during the study period. Antimalarial prescriptions were significantly reduced in Arm-I (61.3%) compared to Arms-II (95.3%) and III (99.5%) (both P < 0.001), whereas antibiotic prescriptions did not vary significantly between the arms (49.9%, 54.8% and 34.2%, respectively). In Arm-I, 99.1% of children with positive blood smear readings received antimalarial prescriptions and so did 11.3% of children with negative readings. Those with positive readings were less likely to be prescribed antibiotics than those with negative (relative risk = 0.66, 95% confidence interval: 0.55, 0.72). On day 7 follow-up, more children reported symptoms in Arm-I compared to Arm-III, but fewer children had malaria parasitaemia (p = 0.049). The overall sensitivity of microscopy reading at PHC compared to reference level was 74.5% and the specificity was 59.0% but both varied widely between PHCs. Conclusion: Microscopy based diagnosis of malaria at PHC facilities reduces prescription of antimalarial drugs, and appears to improve appropriate management of non-malaria fevers, but major variation in accuracy of the microscopy readings was found. Lack of qualified laboratory technicians at PHC facilities and the relatively short training period may have contributed to the shortcomings. [ABSTRACT FROM AUTHOR]

To determine the effect of artesunate (AT) on the disposition kinetics of sulfadoxine/pyrimethamine (SP) in humans. In a randomized cross-over study, 16 healthy volunteers were given a dose of three SP tablets containing 500 mg of sulfadoxine (SDX) and 25 mg of pyrimethamine (PYR) (=SP group), while the second arm received three SP tablets + two AT tablets of 200 mg in total followed by 100 mg AT for the next 4 days (SP+AT group). Blood samples (100 μl) were collected by means of a finger prick and dried on filter paper. The blood spots were wrapped in polythene folders and stored at room temperature until analysis. The samples were assayed using high-performance liquid chromatographic methods. The peak concentration Cmax), time required to attain peak concentration (Tmax), half-life ( t ½) and area under the plasma concentration-time curve (AUC) were determined. The Cmax of SDX were 92.9 and 98.9 μg/ml for the SP and SP+AT arms, respectively; for PYR, these were 0.86 and 0.79 μg/ml, respectively. The Tmax of SDX were 10 and 8 h for the SP and SP+AT arms, respectively; for PYR, these were 4.0 and 3.0 h, respectively. The AUC0–288 of SDX were 15,840 and 18,876 μg/ml h for the SP and SP+AT arms, respectively; for PYR, they were 124 and 112 μg/ml h, respectively. The t ½ of values for SDX were 165 and 180 h for the SP and SP+AT arms, respectively; for PYR, these were 158 and 177 h, respectively. There was no statistically significant difference between the Cmax, Tmax, AUC0–288 and t ½ between the two arms ( p > 0.05). Taking AT concomitantly with SP does not have any impact in the disposition of SP. [ABSTRACT FROM AUTHOR]

Summary Objective: There are several independent reports in Tanzania of treatment failures with commercially available sulphadoxine/pyrimethamine (SP) and amodiaquine (AQ) brands. The aim of this work was to assess the quality of SP and AQ tablets marketed by wholesale pharmacies in Dar Es Salaam, Tanzania. Methods: All eight wholesale pharmacies authorized to import medicines and located in Dar Es Salaam were included in the study. From each pharmacy, samples of all SP and AQ brands available at the time of sampling were bought, provided they had a shelf-life of at least 1 year. A sample was either an intact box of 100 tablets or a sealed tin of 100 tablets. To ensure blinding, 30 tablets of each sample were removed from their original containers, coded and sent to the quality control laboratory for analysis. The name, strength, batch number, manufacturer and the expiry dates of the tablets were recorded. In total 15 AQ and 18 SP samples were collected. Identity, assay for content of active ingredients and dissolution assay were performed as described in the United States Pharmacopoeia (USP). Results: All samples passed the identity test. Among the AQ samples collected, two of 15 (13%) failed the dissolution test but all passed the assay for content, whereas two of 18 (11%) and eight of 18 (44%) SP samples failed the assay for content and dissolution tests, respectively. None of the pharmacies stocked all AQ and SP brands. Conclusion: This work reveals the availability of poor quality antimalarial drugs on the Tanzanian market. Use of substandard drugs could have serious clinical consequences to patients. The results support the need for continuous monitoring of the quality of marketed drugs to ensure safety and efficacy of these products in the treatment of malaria in endemic areas. [ABSTRACT FROM AUTHOR]

Investigate the absorption and quality of a sugar-coated chloroquine marketed in Tanzania. Legislation to control drug sale and use of substandard; Implication of poor quality antimalarial drugs lead to drug resistance and treatment failures; Variability in dissolution rate and criteria.

Presents field tests for rational drug use in twelve developing countries. Efforts to improve drug-use practices and prescribing behavior; Objective and standard method of assessment; Description of practical applications.