Comparison of bioavailability between the most available generic tablet formulation containing artemether and lumefantrine on the Tanzanian market and the innovator's product

Determination of antimalarial drugs in pharmaceutical formulations and human blood by liquid chromatography: a review

Malaria is a life-threatening disease being treated by oral medication. This is the best treatment to reduce morbidity and mortality, prevent disease progression to the most severe form, lower the transmission of the disease and hinder the appearance of strains resistant to antimalarials. According to the World Health Organization, the most common antimalarial drugs are chloroquine, primaquine, mefloquine, lumefantrine, artemether, and artesunate in single dosage forms or fixed-dose combination. Within this context, the present review aims to show the evolution of different analytical methods that have been applied to the determination of these antimalarial drugs in pharmaceutical formulations and human blood by liquid chromatography in the last 10 years, along with statistical analyses of the methods.

Compliance of private pharmacies in Uganda with controlled prescription drugs regulations: a mixed-methods study

Background

Controlled prescription drug use disorders are a growing global health challenge in Sub-Saharan Africa. Effective supply chain regulations on dispensing and stock control are important for controlling this epidemic. Since compliance with these regulations in resource-limited countries is poor, there is need to understand its predictors in order to reduce the risk of prescription drug use disorders.

Methods

A mixed-methods study utilizing a structured questionnaire and a simulated client guide was undertaken in Kampala and Mbale towns in Uganda. The questionnaire recorded self-reported dispensing and verified stock control practices and their covariates from 101 private pharmacies. The guide recorded actual dispensing practices from 27 pharmacies. Snowball sampling was done to enrich the sample with pharmacies that stock opioids. The mean compliance with good dispensing and stock control practices was calculated. Multivariate logistic regression analyses were applied to identify predictors of compliance.

Results

The mean compliance with dispensing and stock control requirements was 82.9% and 23%, respectively. Twenty percent and 40% of the pharmacies dispensed pethidine without a prescription and with invalid prescriptions, respectively. Having a pharmacist on duty (OR = 5.17; p = 0.02), prior in-service training on narcotics regulations (OR = 3.51; p = 0.04), and previous narcotics audits by the regulator (OR = 5.11; p = 0.01) were independent predictors of compliance with stock control requirements. Pharmacies with a previous history of poor compliance with dispensing requirements were less likely to demonstrate good compliance (OR = 0.21; p = 0.01).

Conclusions

There is suboptimal compliance to controlled prescription drug regulations among Uganda’s pharmacies. A previous history of poor compliance to dispensing requirements predicted low compliance in subsequent assessments. Training and regulatory audits increased compliance in stock control but not dispensing. Expansion of training and audits to more pharmacies and/or incentives for compliance are necessary.

Usefulness of day 7 lumefantrine plasma concentration as a predictor of malaria treatment outcome in under-fives children treated with artemether-lumefantrine in Tanzania

Background

Day 7 plasma lumefantrine concentration is suggested as a predictor for malaria treatment outcomes and a cut-off of ≥ 200 ng/ml is associated with day 28 cure rate in the general population. However, day 7 lumefantrine plasma concentration can be affected by age, the extent of fever, baseline parasitaemia, and bodyweight. Therefore, this study assessed the usefulness of day 7 lumefantrine plasma concentration as a predictor of malaria treatment outcome in under-fives children treated with generic or innovator drug-containing artemether-lumefantrine (ALu) in Tanzania.

Methods

This study was nested in an equivalence prospective study that aimed at determining the effectiveness of a generic ALu (Artefan^®) in comparison with the innovator’s product (Coartem^®). Children with uncomplicated malaria aged 6–59 months were recruited and randomized to receive either generic or innovator’s product. Children were treated with ALu as per World Health Organization recommendations. The clinical and parasitological outcomes were assessed after 28 days of follow up. PCR was performed to distinguish recrudescence and re-infections among children with recurrent malaria. Analysis of day 7 lumefantrine plasma concentration was carried out using a high-performance liquid chromatographic method with UV detection.

Results

The PCR corrected cure rates were 98.7% for children treated with generic and 98.6% for those treated with the innovator product (p = 1.00). The geometric mean (± SD) of day 7 plasma lumefantrine concentration was 159.3 (± 2.4) ng/ml for the generic and 164 (± 2.5) ng/ml for the innovator groups, p = 0.87. Geometric mean (± SD) day 7 lumefantrine plasma concentration between cured and recurrent malaria was not statistically different in both treatment arms [158.5 (± 2.4) vs 100.0 (± 1.5) ng/ml, (p = 0.28) for generic arm and 158.5 (± 2.3) vs 251.2 (± 4.2) ng/ml, (p = 0.24) for innovator arm]. Nutritional status was found to be a determinant of recurrent malaria (adjusted hazardous ratio (95% confidence interval) = 3(1.1–8.2), p = 0.029.

Conclusion

Using the recommended cut-off point of ≥ 200 ng/ml, day 7 plasma lumefantrine concentration failed to predict malaria treatment outcome in children treated with ALu in Tanzania. Further studies are recommended to establish the day 7 plasma lumefantrine concentration cut-off point to predict malaria treatment outcome in children.

Comparison of malaria treatment outcome of generic and innovator's anti-malarial drugs containing artemether-lumefantrine combination in the management of uncomplicated malaria amongst Tanzanian children

Background

In 2006, artemether–lumefantrine (ALU), specifically Coartem^® (Novartis Pharma AG, Basel Switzerland), was approved as the first-line drug for treatment of uncomplicated malaria in Tanzania. Due to poor availability and affordability of the innovator’s product, the government of Tanzania in 2013 prequalified the use of generic anti-malarial drugs, whereby Artefan^® (Ajanta, Pharma Ltd, India) was the first to be approved.

Methods

This was an equivalence prospective study that aimed to determine the effectiveness of anti-malarial generic Artefan^® in comparison with innovator’s product Coartem^®. Patients aged 6 to 59 months with uncomplicated malaria were recruited and randomized to either receive Artefan^® or Coartem^® as a control. Participants were required to revisit clinic five times as follow up to monitor treatment outcome as per World Health Organization recommendations. On each visit, thick and thin blood smears, dried blood spot (DBS), haemoglobin concentrations and auxiliary temperature were performed and documented.

Results

Out of 230 recruited participants, 200 met inclusion criteria and were randomized equally to receive Artefan^® and Coartem^®. The overall PCR uncorrected cure rate were 80% for Artefan^® and 75% for Coartem^® (p = 0.44). Adequate clinical and parasitological response were 82.1% for Artefan^® and 74.7% for Coartem^®, and there was no early treatment failure (ETF) observed in both arms of treatment. Both drugs showed excellent early parasite clearance, whereby no participants had peripheral parasitaemia on day 3. Late clinical failures (LCF) were 3.6% for Artefan^® and 1.3% for Coartem^® (p = 0.31), and late parasitological failure (LPF) were 15.4% for Artefan^® and 22.7% for Coartem^® (p = 0.32). Mean haemoglobin (g/dl) concentrations observed on day 28 were higher compared to day 0 for both drugs, although not statistically significant. Only one (1.3%) participant on Artefan^® had temperature ≥ 37.5 °C on day 3.

Conclusion

The findings of this study indicate that both Artefan^® and Coartem^® are equivalent and effective in the management of uncomplicated malaria amongst children in the Coast part of Tanzania.

Semi-quantitative measurement of the antimalarial lumefantrine from untreated dried blood spots using LC-MS/MS

Study of the clinical effects of combination therapy for malaria is aided by the ability to measure concentrations of individual partner drugs. Existing methods for measurement of the antimalarial drug lumefantrine (LF) in dried blood spots (DBS) on filter paper rely on chemical pretreatment of the paper to facilitate drug elution. However, in the absence of pretreatment, DBS may still offer some utility for semi-quantitative measurements and pharmacokinetic-pharmacodynamic (PK-PD) analyses. We present a method for semi-quantitation of LF in DBS on untreated filter paper using liquid chromatography tandem mass spectrometry. Optimal recovery was achieved by extraction with acetone-water-formic acid (90:5:5). The range of quantitation was 100-20,000ng/ml. Mean intra- and inter-day accuracy values were 86.6% (coefficient of variation [CV]: 10.1%) and 91.8% (CV: 16.1%), therefore we propose the assay as semi-quantitative. Clinical application was demonstrated in exploratory PK-PD analyses of a drug efficacy trial of artemether-lumefantrine in children with uncomplicated falciparum malaria using post-treatment day 7 samples, parasite clearance times estimated from serial blood smears, and recurrence of malaria out to 35days. The median day 7 concentration among children (n=71) was 111ng/ml (interquartile range: 100-194ng/ml). We used a truncated calibration curve of 100-5000ng/ml for calculations due to low observed concentrations. Calculations using the full calibration curve yielded similar values (+1% avg. deviation). Controlling for participant age, sex, and parasite burden, each log increase in LF day 7 concentration corresponded to a decrease of 7.1h in mean parasite clearance time (95% confidence interval: 0.1-14.3h, P=0.05). A nested case-control study of participants (n=18) with and without recurrent malaria showed mean post-treatment day 7 concentrations of 181ng/ml and 235ng/ml, respectively, but the difference was not significant (P=0.64). A method for semi-quantitation of LF from post-treatment day 7 collections of DBS on untreated filter paper demonstrated clinical application in exploratory PK-PD analyses of parasite clearance and reinfection. Use of DBS will endure in certain study settings by virtue of their ease of collection and resilience. Their utility should continue to be explored as our instruments gain in sensitivity and as clinical pharmacology inquiries are pursued to the field.

Pharmacokinetic considerations for use of artemisinin-based combination therapies against falciparum malaria in different ethnic populations

INTRODUCTION

Artemisinin-based combination therapy (ACT) is used extensively as first-line treatment for uncomplicated falciparum malaria. There has been no rigorous assessment of the potential for racial/ethnic differences in the pharmacokinetic properties of ACTs that might influence their efficacy. Areas covered: A comprehensive literature search was performed that identified 72 publications in which the geographical origin of the patients could be ascertained and the key pharmacokinetic parameters maximum drug concentration (C_max), area under the plasma concentration-time curve (AUC) and elimination half-life (t_½β) were available for one or more of the five WHO-recommended ACTs (artemether-lumefantrine, artesunate-amodiaquine, artesunate-mefloquine, dihydroartemisinin-piperaquine and artesunate-sulfadoxine-pyrimethamine). Comparisons of each of the three pharmacokinetic parameters of interest were made by drug (artemisinin derivative and long half-life partner), race/ethnicity (African, Asian, Caucasian, Melanesian, South American) and patient categories based on age and pregnancy status. Expert opinion: The review identified no evidence of a clinically significant influence of race/ethnicity on the pharmacokinetic properties of the nine component drugs in the five ACTs currently recommended by WHO for first-line treatment of uncomplicated falciparum malaria. This provides reassurance for health workers in malaria-endemic regions that ACTs can be given in recommended doses with the expectation of adequate blood concentrations regardless of race/ethnicity.

Bioavailability of Lumefantrine Is Significantly Enhanced with a Novel Formulation Approach, an Outcome from a Randomized, Open-Label Pharmacokinetic Study in Healthy Volunteers

The artemether-lumefantrine combination requires food intake for the optimal absorption of lumefantrine. In an attempt to enhance the bioavailability of lumefantrine, new solid dispersion formulations (SDF) were developed, and the pharmacokinetics of two SDF variants were assessed in a randomized, open-label, sequential two-part study in healthy volunteers. In part 1, the relative bioavailability of the two SDF variants was compared with that of the conventional formulation after administration of a single dose of 480 mg under fasted conditions in three parallel cohorts. In part 2, the pharmacokinetics of lumefantrine from both SDF variants were evaluated after a single dose of 480 mg under fed conditions and a single dose of 960 mg under fasted conditions. The bioavailability of lumefantrine from SDF variant 1 and variant 2 increased up to ∼48-fold and ∼24-fold, respectively, relative to that of the conventional formulation. Both variants demonstrated a positive food effect and a less than proportional increase in exposure between the 480-mg and 960-mg doses. Most adverse events (AEs) were mild to moderate in severity and not suspected to be related to the study drug. All five drug-related AEs occurred in subjects taking SDF variant 2. No clinically significant treatment-emergent changes in vital signs, electrocardiograms, or laboratory blood assessments were noted. The solid dispersion formulation enhances the lumefantrine bioavailability to a significant extent, and SDF variant 1 is superior to SDF variant 2.

Building Capability for Clinical Pharmacology Research in Sub-Saharan Africa

A strong scientific rationale exists for conducting clinical pharmacology studies in target populations because local factors such as genetics, environment, comorbidities, and diet can affect variability in drug responses. However, clinical pharmacology studies are not widely conducted in sub-Saharan Africa, in part due to limitations in technical expertise and infrastructure. Since 2012, a novel public-private partnership model involving research institutions and a pharmaceutical company has been applied to developing increased capability for clinical pharmacology research in multiple African countries.

Anti-malarial medicine quality field studies and surveys: a systematic review of screening technologies used and reporting of findings

BACKGROUND

Assessing the quality of medicines in low-middle income countries (LMICs) relies primarily on human inspection and screening technologies, where available. Field studies and surveys have frequently utilized screening tests to analyse medicines sampled at the point of care, such as health care facilities and medicine outlets, to provide a snap shot of medicine quality in a specific geographical area. This review presents an overview of the screening tests typically employed in surveys to assess anti-malarial medicine quality, summarizes the analytical methods used, how findings have been reported and proposes a reporting template for future studies.

METHODS

A systematic search of the peer-reviewed and grey literature available in the public domain (including national and multi-national medicine quality surveys) covering the period 1990-2016 was undertaken. Studies were included if they had used screening techniques to assess the quality of anti-malarial medicines. As no standardized set of guidelines for the methodology and reporting of medicine quality surveys exist, the included studies were assessed for their standard against a newly proposed list of criteria.

RESULTS

The titles and abstracts of 4621 records were screened and only 39 were found to meet the eligibility criteria. These 39 studies utilized visual inspection, disintegration, colorimetry and Thin Layer Chromatography (TLC) either as components of the Global Pharma Health Fund (GPHF) MiniLab^® or as individual tests. Overall, 30/39 studies reported employing confirmatory testing described in international pharmacopeia to verify the quality of anti-malarials post assessment by a screening test. The authors assigned scores for the 23 criteria for the standard of reporting of each study.

CONCLUSIONS

There is considerable heterogeneity in study design and inconsistency in reporting of field surveys of medicine quality. A lack of standardization in the design and reporting of studies of medicine quality increases the risk of bias and error, impacting on the generalizability and reliability of study results. The criteria proposed for reporting on the standard of studies in this review can be used in conjunction with existing medicine quality survey guidelines as a checklist for designing and reporting findings of studies. The review protocol has been registered with PROSPERO (CRD42015026782).

Research progress in electroanalytical techniques for determination of antimalarial drugs in pharmaceutical and biological samples

The review focusses on the role of electroanalytical methods for determination of antimalarial drugs in biological matrices and pharmaceutical formulations with a critical analysis of published voltammetric and potentiometric methods.

Adherence to artemether-lumefantrine drug combination: a rural community experience six years after change of malaria treatment policy in Tanzania

Background

Adherence to multidosing is challenging worldwide. This study assessed the extent of adherence to multidosing artemether-lumefantrine (ALu) in a rural community in Tanzania, six years after switching from single dose policy of sulphadoxine-pyrimethamine.

Methods

This study was a prospective observational, open label, non-randomized study involving 151 patients with uncomplicated malaria recruited at Fukayosi dispensary in Bagamoyo district in Tanzania. Patients treated with ALu were visited at home on day 3 for interview on drug intake, capillary blood sample collection for microscopy and ALu tablets count. Venous blood samples (2 ml) for determination of blood lumefantrine concentrations and blood slides for microscopy were collected on day-7. Kappa’s coefficient was used to assess agreement between pill count and self-report. Adherence was categorized depending on the tablets remaining and what the patient reported. Only those with empty blister pack available but no tablet remaining and reported taking all six doses of ALu at a correct dose and correct time were regarded as definite adherent. The rest were either probable adherent or probable non-adherent.

Results

Only 14.9% of the patients were definite adherent the rest took the drug at incorrect time or did not finish the tablets. Out of 90 patients with analysed plasma samples for lumefantrine blood concentrations, 13/90 (14.4.0%) had lumefantrine concentrations <175 ng/ml. There was no difference in mean lumefantrine concentration in the patients who stated to have taken all doses as required (561.61 ng/ml 95% CI = 419.81-703.41) compared to those who stated to have not adhered well to drug intake (490.95 ng/ml, 95% CI = 404.18-577.7074 (p = 0.643). None of the patients had detectable parasites by microscopy on day-3 and day-7 regardless of adherence status and the level of day-7 blood lumefantrine. There was strong agreement between the self-reported responses on drug intake and pill-counts (kappa coefficient = 0.955). Age, sex, education and place where first dose was taken were associated with adherence.

Conclusions

The overall adherence six years after the change of malaria treatment policy was low. It is, therefore, important to continuously monitor the level of adherence to treatment in order to get the current situation and institute corrective measures on time.