Publications by authors named "Rory Leisegang"

Immunogenicity is the propensity of a therapeutic protein to generate an immune response to itself. While reporting of antidrug antibodies (ADAs) is increasing, model-based analysis of such data is seldom performed. Model-based characterization of factors affecting the emergence and dissipation of ADAs may inform drug development and/or improve understanding in clinical practice.

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Background: Coformulated bictegravir, emtricitabine, and tenofovir alafenamide is a single-tablet regimen and was efficacious and well tolerated in children and adolescents with HIV (aged 6 years to <18 years) in a 48-week phase 2/3 trial. In this study, we report data from children aged at least 2 years and weighing 14 kg to less than 25 kg.

Methods: We conducted this open-label, multicentre, multicohort, single-arm study in South Africa, Thailand, Uganda, and the USA.

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Article Synopsis
  • The UNIVERSAL project aims to develop a fixed-dose combination of paediatric dolutegravir (DTG), emtricitabine (FTC), and tenofovir alafenamide (TAF) to improve dosing for children.
  • A study on 15 healthy volunteers tested the pharmacokinetics (PK) of these medications combined in various doses, assessing blood concentration differences over 48 hours.
  • Results indicated no significant PK interactions with DTG, FTC, and tenofovir (TFV), although TAF showed variability, leading to a conclusion that the formulations are safe for use without clinically relevant interactions.
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The prevalence of diabetes mellitus is increasing in resource limited settings. Simultaneously, there has been an increase in the number of novel therapies for the management of diabetes mellitus. However, use of novel antidiabetic therapies is limited because of major market access challenges in resource limited settings.

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Gliclazide was approved as a treatment for type 2 diabetes in an era before model-based drug development, and consequently, the recommended doses were not optimised with modern methods. To investigate various dosing regimens of gliclazide, we used publicly available data to characterise the dose-response relationship using pharmacometric models. A literature search identified 21 published gliclazide pharmacokinetic (PK) studies with full profiles.

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Real-world evidence (RWE) is derived from real-world data (RWD) sources including electronic health records, claims data, registries (disease, product) and pragmatic clinical trials. The importance of RWE derived from RWD has been once again demonstrated during the coronavirus disease 2019 (COVID-19) pandemic, as it can improve patient care by complementing information obtained from traditional clinical trial programs. Additionally, RWE can generate insights into disease mechanisms, epidemiology, patient flows in and out of healthcare systems, and drivers and barriers to optimal clinical care in real-world settings.

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Background: Dyslipidaemia is a major modifiable risk factor for atherosclerotic cardiovascular disease. At the time the study was conducted, guidelines recommended a low-density lipoprotein cholesterol (LDL-C) target of less than 1.8 mmol/l and a reduction of at least 50% if the baseline LDL-C was between 1.

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There is a paucity of information on real world management of African adult patients with type 1 diabetes mellitus (T1DM). We aimed to describe a cohort of African adults with T1DM.The International Diabetes Management Practices Study is an observational survey conducted from 2005 to 2017.

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Background: Proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors are a novel class of non-statin lipid lowering therapy that reduce LDL-cholesterol by 50 - 60%. PCSK9 inhibitors decrease LDL-cholesterol by preventing intracellular degradation of LDL receptors; subsequently, a greater number of LDL-receptors are available on the cell surface to extract circulating LDL.

Objective: To describe the origins of PCSK9 inhibitors and their current use in clinical practice.

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Article Synopsis
  • Tuberculosis significantly affects pregnant women, but there is limited information about how pregnancy impacts the effectiveness of common tuberculosis drugs like isoniazid, pyrazinamide, and ethambutol.
  • A study involving HIV-positive pregnant women in South Africa analyzed drug concentrations during pregnancy and postpartum, finding no major differences in drug clearance or effectiveness between the two periods.
  • The research concluded that pregnancy doesn't significantly alter drug exposure levels for these medications, suggesting the need for further studies to understand the pharmacokinetics of antituberculosis drugs in pregnant individuals.
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Background: Ivermectin is an older anthelminthic agent that is being studied more intensely given its potential for mass drug administration against scabies, malaria and other neglected tropical diseases. Its pharmacokinetics (PK) remain poorly characterized. Furthermore, the majority of PK trials are performed under fasted-state dosing conditions, and the effect of food is therefore not well known.

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Introduction: International guidelines support the use of low molecular weight heparins for the treatment of thromboembolism and thromboprophylaxis during pregnancy. However, evidence of the benefit and harm associated with specific low molecular weight heparins such as enoxaparin is dated. No current systematic review and meta-analysis describing the safety and efficacy of enoxaparin for thromboembolism and thromboprophylaxis during pregnancy exists.

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Background: Most adults with virological failure on second-line antiretroviral therapy (ART) in resource-limited settings have no major protease inhibitor (PI) resistance mutations. Therefore, empiric switches to third-line ART would waste resources. Genotypic antiretroviral resistance testing (GART) is expensive and has limited availability.

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Background: Incomplete adherence to antiretroviral therapy (ART) results in virologic failure and resistance. It remains unclear which adherence measure best predicts these outcomes. We compared six patient-reported and objective adherence measures in one ART-naïve cohort in South Africa.

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Efavirenz is the preferred nonnucleoside reverse transcriptase inhibitor (NNRTI) in first-line antiretroviral therapy (ART) regimens in low- and middle-income countries, where the prevalence of diabetes is increasing. Randomized control trials have shown mild increases in plasma glucose in participants in the efavirenz arms, but no association has been reported with overt diabetes. We explored the association between efavirenz exposure and incident diabetes in a large Southern African cohort commencing NNRTI-based first-line ART.

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Background: An increasing number of patients in Africa are experiencing virologic failure on second-line antiretroviral therapy (ART) and those who develop resistance to protease inhibitors (PI) will require third-line ART, but no data on the outcomes of third-line are available from the region. We assessed the virologic outcomes and survival of patients started on salvage ART in a Southern African private sector disease management programme.

Methods: Retrospective observational cohort study with linkage to the national death register.

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Background: Most patients who experience virologic failure (VF) on second line antiretroviral therapy (ART) in low-middle income countries fail due to poor adherence rather than antiretroviral resistance. A simple adherence tool designed to detect VF would conserve resources by rationally limiting need for viral load (VL) testing and, in those countries with access to third line ART, the need for resistance testing.

Methods: We conducted an observational cohort study of patients who initiated second line ART at a clinic in Kwazulu-Natal, South Africa.

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Introduction: Providing private antiretroviral therapy (ART) care for public sector patients could increase access to ART in low- and middle-income countries. We compared the costs and outcomes of a private-care and a public-care ART program in South Africa.

Methods: A novel Markov model was developed from the public-care program.

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Introduction: The prognosis of patients with HIV in Africa has improved with the widespread use of antiretroviral therapy (ART) but these successes are threatened by low rates of long-term retention in care. There are limited data on predictors of retention in care, particularly from rural sites.

Methods: Prospective cohort analysis of outcome measures in adults from a rural HIV care programme in Madwaleni, Eastern Cape, South Africa.

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Background: Despite concerns about affordability and sustainability, many models of the lifetime costs of antiretroviral therapy (ART) used in resource limited settings are based on data from small research cohorts, together with pragmatic assumptions about life-expectancy. This paper revisits these modelling assumptions in order to provide input to future attempts to model the lifetime costs and the costs of scaling up ART.

Methods: We analysed the determinants of costs and outcomes in patients receiving ART in line with standard World Health Organization (WHO) guidelines for resource poor settings in a private sector managed ART programme in South Africa.

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Background: Many drugs are eliminated by the kidneys and therefore may require dose adjustment in patients with renal impairment. The need for dose adjustment is frequently neglected by prescribers.

Methods: We reviewed folders of patients admitted to the Groote Schuur Hospital general medical wards between January and March 2008.

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Background: Antiretroviral therapy (ART) adherence predicts HIV disease progression and survival, but its effect on direct health care costs is unclear.

Objective: To determine the effect of ART adherence on direct health care costs among adults in a resource-limited setting.

Design: Cohort study.

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Background: There is a paucity of data on the health care costs of antiretroviral therapy (ART) programmes in Africa. Our objectives were to describe the direct heath care costs and establish the cost drivers over time in an HIV managed care programme in Southern Africa.

Methods/findings: We analysed the direct costs of treating HIV-infected adults enrolled in the managed care programme from 3 years before starting non-nucleoside reverse transcriptase inhibitor-based ART up to 5 years afterwards.

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