Publications by authors named "Tim Cressey"

This sub-study sought to characterize the pharmacokinetics (PK) of favipiravir (FPV) within Thai adults and quantitatively assess differences in exposure to those previously reported in other populations as a basis to understand putative differences in efficacy between studies conducted in different regions. It was nested within a prospective trial of adults with symptomatic COVID-19 infection without pneumonia receiving 1800 mg FPV twice-daily on day 1 and 800 mg twice-daily thereafter. Individual PK profiles were fitted with a one-compartment disposition model (first-order absorption).

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: Rivaroxaban and dabigatran are commonly used for thromboembolic disease management in active cancer patients. However, limited research explores the impact of concurrent chemotherapy on the pharmacodynamics of direct oral anticoagulants (DOAC). The aim of our study was to evaluate the impact of combined chemotherapy with rivaroxaban and dabigatran on the pharmacodynamics in patients with diffuse large B-cell lymphoma (DLBCL).

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Treatment options for children living with HIV have historically been less effective, less practical and more difficult to implement compared with those for adults, as the research and development of new drugs for children has lagged behind. Significant progress has been achieved in response to the paediatric HIV epidemic over the last decade. Several optimised paediatric antiretroviral formulations are currently available or in development, including fixed-dose combination tablets containing a complete World Health Organization-recommended regimen.

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Objectives: To develop a pragmatic twice daily lamivudine dosing strategy for preterm infants from 24 to 37 completed weeks of gestation.

Methods: Data were combined from eight pharmacokinetic studies in neonates and infants receiving lamivudine oral solution. A population pharmacokinetic model was developed using non-linear mixed effects regression.

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Introduction: Dolutegravir (DTG) dispersible tablet (DTG-DT) is a pediatric-friendly formulation. We aimed to describe the pharmacokinetics and virologic responses of generic DTG-DT in children weighing <20 kg.

Methods: Children living with HIV-1 and <7 years of age weighing 6 to <20 kg were eligible.

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Article Synopsis
  • A study on a fixed-dose combination of abacavir, dolutegravir, and lamivudine for children with HIV analyzed existing pediatric pharmacokinetic (PopPK) models to assess drug dosage effectiveness using dispersible tablets and standard tablets.
  • Data from the IMPAACT 2019 Phase I/II study showed that previous PopPK models accurately predicted drug concentration and exposure after evaluating samples from young children over 48 weeks.
  • The findings confirmed that the dosing recommendations for this combination therapy in children weighing 6 kg or more are appropriate and within target ranges for safe and effective use.
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  • Ravidasvir (RDV) is a new drug that effectively inhibits the hepatitis C virus (HCV) replication and has shown promising results when combined with Sofosbuvir (SOF) in trials involving adults, including those co-infected with HIV.
  • In a study conducted in Thailand and Malaysia, RDV was given to both patients with and without cirrhosis for various durations, and pharmacokinetics (how the drug behaves in the body) were evaluated through blood sampling at different intervals.
  • The analysis revealed that RDV levels were influenced by several factors; however, these variations were not significant enough to impact the drug's effectiveness across the diverse group of participants, and there were no significant drug interactions for
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Gram-negative bacteria (GNB) are a major cause of neonatal sepsis in low- and middle-income countries (LMICs). Although the World Health Organization (WHO) reports that over 80% of these sepsis deaths could be prevented through improved treatment, the efficacy of the currently recommended first- and second-line treatment regimens for this condition is increasingly affected by high rates of drug resistance. Here we assess three well known antibiotics, fosfomycin, flomoxef and amikacin, in combination as potential antibiotic treatment regimens by investigating the drug resistance and genetic profiles of commonly isolated GNB causing neonatal sepsis in LMICs.

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Background: There is increasing interest in utilising two-drug regimens for HIV treatment with the goal of reducing toxicity and improve acceptability. The D3 trial evaluates the efficacy and safety of DTG/3TC in children and adolescents and includes a nested pharmacokinetics(PK) substudy for paediatric drug licensing.

Methods: D3 is an ongoing open-label, phase III, 96-week non-inferiority randomised controlled trial(RCT) conducted in South Africa, Spain, Thailand, Uganda and the United Kingdom.

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Introduction: There are gaps in knowledge and experience of antiretroviral pre-exposure prophylaxis (PrEP) delivery in adolescents.

Methods: This pilot study enrolled Thai adolescents 14-20 year-old without HIV who reported risk behaviour. All participants were offered daily tenofovir/emtricitabine (TDF-FTC) and followed for 24 weeks.

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Background: Existing solid antiretroviral fixed-dose combination formulations are preferred over liquid formulations in children, but their suitability for neonates is unknown. We evaluated the pharmacokinetics and safety of paediatric abacavir-lamivudine fixed-dose dispersible tablets and ritonavir-boosted lopinavir granules in neonates.

Methods: In this open-label, two-stage, single-arm, phase 1/2, pharmacokinetic and safety trial, generic abacavir- lamivudine (120:60 mg) double-scored dispersible tablets and lopinavir boosted with ritonavir (40:10 mg) granules were studied.

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Article Synopsis
  • Antiretroviral therapy for children under 3 years with HIV often uses a liquid formulation of lopinavir/ritonavir (LPV/r), but it has taste issues and requires refrigeration, which led to the development of LPV/r oral pellets that can be mixed with food and don't need cooling.
  • The study assessed the drug exposure of these LPV/r oral pellets in Kenyan and Ugandan children using pharmacokinetic modeling to understand how body weight affects drug clearance and effectiveness.
  • Analysis of data from 514 children indicated that the pellets achieved the desired drug levels across different weight bands as defined by the World Health Organization, suggesting they are a suitable treatment option for young children with HIV.
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Background: Study of liquid lopinavir/ritonavir (LPV/r) in young infants has been limited by concerns for its safety in neonates.

Methods: International Maternal Pediatric Adolescent AIDS Clinical Trials Network P1106 was a phase IV, prospective, trial evaluating the safety and pharmacokinetics of antiretroviral medications administered according to local guidelines to South African preterm and term infants <3 months of age. Safety evaluation through 24-week follow-up included clinical, cardiac and laboratory assessments.

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Darunavir (DRV) is an HIV protease inhibitor commonly used as part of antiretroviral treatment regimens globally for children and adolescents. It requires a pharmacological booster, such as ritonavir (RTV) or cobicistat. To better understand the pharmacokinetics (PK) of DRV in this younger population and the importance of the RTV boosting effect, a population PK substudy was conducted within SMILE trial, where the maintenance of HIV suppression with once daily integrate inhibitor + darunavir/ritonavir in children and adolescents is evaluated.

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Background: Clinical interpretation of the reduced dolutegravir (DTG) plasma concentrations reported during pregnancy is complicated by its high plasma protein binding. Plasma proteins significantly decrease during pregnancy, and understanding changes in DTG protein binding and its therapeutically active unbound concentrations are necessary to evaluate the impact of pregnancy changes on DTG pharmacokinetics.

Methods: Retrospective assessment of plasma samples from pregnant women living with HIV enrolled in the International Maternal Pediatric Adolescent AIDS Clinical Trials Network P1026s study receiving 50 mg DTG film-coated tablets once daily as part of clinical care.

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Physiological changes during pregnancy may alter the pharmacokinetics (PK) of antituberculosis drugs. The International Maternal Pediatric Adolescent AIDS Clinical Trials Network P1026s was a multicenter, phase IV, observational, prospective PK and safety study of antiretroviral and antituberculosis drugs administered as part of clinical care in pregnant persons living with and without HIV. We assessed the effects of pregnancy on rifampin, isoniazid, ethambutol, and pyrazinamide PK in pregnant and postpartum (PP) persons without HIV treated for drug-susceptible tuberculosis disease.

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Background: The pharmacokinetics of abacavir (ABC) in African children living with HIV (CLHIV) weighing <14 kg and receiving pediatric fixed dose combinations (FDC) according to WHO weight bands dosing are limited. An ABC population pharmacokinetic model was developed to evaluate ABC exposure across different World Health Organization (WHO) weight bands.

Methods: Children enrolled in the LIVING study in Kenya and Uganda receiving ABC/lamivudine (3TC) dispersible tablets (60/30 mg) according to WHO weight bands.

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Background: Child-friendly fixed-dose combination (FDC) antiretroviral therapy (ART) options are limited. We evaluated the pharmacokinetics, safety, and tolerability of dispersible and immediate-release FDC abacavir, dolutegravir, and lamivudine taken once per day in children younger than 12 years with HIV.

Methods: IMPAACT 2019 was an international, phase 1-2, multisite, open-label, non-comparative dose-confirmation study of abacavir, dolutegravir, and lamivudine in children younger than 12 years.

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Article Synopsis
  • The SMILE trial investigated the effectiveness and safety of switching children living with HIV to a treatment regimen of integrase inhibitor (INSTI) and boosted darunavir (DRV/r), compared to continuing standard triple antiretroviral therapy (SOC).
  • The trial enrolled 318 participants aged 6-18 from multiple regions, finding that switching to the new regimen showed non-inferiority in maintaining low HIV-RNA levels after 48 weeks.
  • The results indicated no significant differences in safety between the two groups, but the INSTI + DRV/r group had greater increases in weight and BMI compared to those on SOC.
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Background: There is limited data on antibiotic treatment in hospitalized neonates in low- and middle-income countries (LMICs). We aimed to describe patterns of antibiotic use, pathogens, and clinical outcomes, and to develop a severity score predicting mortality in neonatal sepsis to inform future clinical trial design.

Methods And Findings: Hospitalized infants <60 days with clinical sepsis were enrolled during 2018 to 2020 by 19 sites in 11 countries (mainly Asia and Africa).

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Despite progress in providing antiretroviral therapy to pregnant women living with HIV, a substantial number of vertical transmissions continue to occur. Novel approaches leveraging modern potent, safe, and well-tolerated antiretroviral drugs are urgently needed.

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Article Synopsis
  • The SMILE trial investigated the effectiveness and safety of switching HIV-infected youth to a daily dual therapy of dolutegravir and ritonavir-boosted darunavir compared to standard ART.
  • A pharmacokinetic substudy analyzed dolutegravir levels in youth by collecting blood samples and developing a model to describe its concentrations.
  • Results showed that the once-daily 50 mg dolutegravir dosage resulted in adequate levels for effective treatment, comparable to adult dosages.
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Background: In sub-Saharan Africa (SSA), adolescent girls and young women (AGYW) ages 15 to 24 years represent <10% of the population yet account for 1 in 5 new HIV infections. Although oral pre-exposure prophylaxis (PrEP) with tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) can be highly effective, low persistence in PrEP programs and poor adherence have limited its ability to reduce HIV incidence among women.

Methods And Findings: A total of 336 AGYW participating in the PEPFAR-funded DREAMS PrEP program in western Kenya were enrolled into a study of PrEP use conducted between 6/2019 to 1/2020.

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  • Tenofovir disoproxil fumarate (TDF) is linked to a higher risk of chronic kidney disease (CKD), particularly in Asian patients, based on a study involving data from the Thai national health insurance system.
  • In a cohort of 27,313 patients undergoing antiretroviral therapy, the incidence of CKD was found to be low at 0.9%, but those on certain TDF combinations had significantly increased risk compared to those on a standard regimen.
  • Specifically, patients using TDF with lopinavir/ritonavir or nevirapine had a much greater risk of developing CKD compared to those taking alternative treatments.
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