scholarly journals 977Mechanistic within-host modelling to fast-track the selection of new antimalarial combination therapies

2021 ◽  
Vol 50 (Supplement_1) ◽  
Author(s):  
Julie Simpson ◽  
Saber Dini ◽  
Sophie Zaloumis ◽  
David Price ◽  
James McCarthy ◽  
...  
Keyword(s):  
Drug Development ◽  
Dose Range ◽  
Model Parameters ◽  
Combination Therapies ◽  
Drug Concentrations ◽  
Dosing Regimens ◽  
Killing Action ◽  
Cure Rates ◽  
Emergence Of Resistance ◽  
Data Informed

Abstract Background The efficacy of artemisinin-based combination therapies (ACTs), currently the first-line antimalarial treatments, is declining due to the emergence of resistance of malaria parasites to these drugs. This has led drug development initiatives to search for novel combination therapies to replace the failing ACTs. We developed a biologically informed within-host model, validated against data from volunteer infection studies, to guide critical drug development decisions. Methods A within-host model was developed, linking drug concentrations of two novel antimalarial drugs, OZ439 and DSM265, to their combined killing action and accounting for differential killing of these compounds against stages of the parasite’s lifecycle. Data collected from malaria-infected volunteers treated with OZ439–DSM265 were used to estimate the model parameters in a hierarchical Bayesian framework. Posterior-predictive simulations of the model were used to determine the dosing regimen required to cure >90% patients. Results The results showed that 800 mg of OZ439 combined with 450 mg of DSM265, which are within the safe and tolerable dose range, can provide day 42 cure rates >90%, despite the estimated antagonistic interaction between the drugs. The importance of accommodating parasite age specificity of drug action was demonstrated. Conclusions The dosing regimens for the combination of OZ439-DSM265 determined from our data-informed in silico model suggest this compound may be a suitable candidate to replace failing ACTs. Key messages Assessing various scenarios within a simulation framework allows discovery of robust dosing regimens, accelerating the drug development process and ensuring efficient allocation of resources for phase 2 and 3 clinical trials.

scholarly journals Seeking an optimal dosing regimen for OZ439-DSM265 combination therapy for treating uncomplicated falciparum malaria

2020 ◽  
Author(s):  
Saber Dini ◽  
Sophie G Zaloumis ◽  
David J Price ◽  
Nathalie Gobeau ◽  
Anne Kümmel ◽  
...  
Keyword(s):  
Combination Therapy ◽  
Falciparum Malaria ◽  
Dose Range ◽  
Uncomplicated Falciparum Malaria ◽  
Model Parameters ◽  
Pharmacodynamic Interaction ◽  
Fast Tracking ◽  
Optimal Dosing ◽  
Dosing Regimens ◽  
Using Data

AbstractThe efficacy of Artemisinin-based Combination Therapies (ACTs), the first- line treatments of uncomplicated falciparum malaria, has been declining in malaria endemic countries due to the emergence of malaria parasites resistant to these com- pounds. Novel alternative therapies are needed urgently to prevent the likely surge in morbidity and mortality due to failing ACTs. This study investigates the efficacy of the combination of two novel drugs, OZ439 and DSM265, using a biologically informed within-host mathematical model that accounts for the pharmacodynamic interaction between the two drugs. Model parameters were estimated using data from healthy volunteers infected with falciparum malaria collected from four trials: three that administered OZ439 and DSM265 alone, and the fourth a combination of OZ439-DSM265. Posterior predictive simulations of the model were performed to determine efficacious dosing regimens. One such regimen that predicted at least 90% of infected individuals cured 42 days after the administration of the drugs, while within the tolerable dose range, is 800 mg of OZ439 and 450 mg of DSM265. Our model can be used to inform future phase 2 and 3 clinical trials of OZ439-DSM265, fast-tracking the deployment of this combination therapy in the regions where ACTs are failing.

scholarly journals The potential of microdialysis to estimate rifampicin concentrations in the lung of guinea pigs

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245922
Author(s):  
Faye Lanni ◽  
Neil Burton ◽  
Debbie Harris ◽  
Susan Fotheringham ◽  
Simon Clark ◽  
...  
Keyword(s):  
Drug Development ◽  
Guinea Pigs ◽  
Sampling Technique ◽  
Tissue Fluid ◽  
Experimental Conditions ◽  
Continuous Sampling ◽  
Drug Concentrations ◽  
The Impact

Optimised pre-clinical models are required for TB drug development to better predict the pharmacokinetics of anti-tuberculosis (anti-TB) drugs to shorten the time taken for novel drugs and combinations to be approved for clinical trial. Microdialysis can be used to measure unbound drug concentrations in awake freely moving animals in order to describe the pharmacokinetics of drugs in the organs as a continuous sampling technique. The aim of this work was to develop and optimise the microdialysis methodology in guinea pigs to better understand the pharmacokinetics of rifampicin in the lung. In vitro experiments were performed before progressing into in vivo studies because the recovery (concentration of the drug in the tissue fluid related to that in the collected dialysate) of rifampicin was dependent on a variety of experimental conditions. Mass spectrometry of the dialysate was used to determine the impact of flow rate, perfusion fluid and the molecular weight cut-off and membrane length of probes on the recovery of rifampicin at physiologically relevant concentrations. Following determination of probe efficiency and identification of a correlation between rifampicin concentrations in the lung and skeletal muscle, experiments were conducted to measure rifampicin in the sacrospinalis of guinea pigs using microdialysis. Lung concentrations of rifampicin were estimated from the rifampicin concentrations measured in the sacrospinalis. These studies suggest the potential usefulness of the microdialysis methodology to determine drug concentrations of selected anti-TB drugs to support new TB drug development.

Phase 1 Clinical Trials of Small Molecules: Evolution and State of the Art

2021 ◽  
Vol 16 ◽  
Author(s):  
John J. Sramek ◽  
Michael F. Murphy ◽  
Sherilyn Adcock ◽  
Jeffrey G. Stark ◽  
Neal R. Cutler
Keyword(s):  
Clinical Trials ◽  
Drug Development ◽  
Healthy Volunteers ◽  
Small Molecules ◽  
Phase 1 ◽  
Dose Range ◽  
Pharmacodynamic Modeling ◽  
Inpatient Setting ◽  
Conducting Phase ◽  
Safe Dose

Background: Phase 1 studies comprise the first exposure of a promising new chemical entity in healthy volunteers or, when appropriate, in patients. To assure a solid foundation for subsequent drug development, this first step must carefully assess the safety and tolerance of a new compound, and often provide some indication of potential effect, so that a safe dose or dose range can be confidently selected for the initial Phase 2 efficacy study in the target patient population. Methods: This review was based on a literature search using both Google Scholar and PubMed, dated back to 1970, using search terms including “healthy volunteers”, “Phase 1”, and “normal volunteers” , and also based on the authors’ own experience conducting Phase 1 clinical trials. This paper reviews the history of Phase 1 studies of small molecules and their rapid evolution, focusing on the critical single and multiple dose studies, their designs, methodology, use of pharmacokinetic and pharmacodynamic modeling, application of potentially helpful biomarkers, study stopping criteria, and novel study designs. Results: We advocate for determining the safe dose range of a new compound by conducting careful dose escalation in a well-staffed inpatient setting, defining the maximally tolerated dose (MTD) by reaching the minimally intolerated dose (MID). The dose immediately below the MID is then defined as the MTD. This is best accomplished by using appropriately screened patients for the target indication, as patients in many CNS indications often tolerate doses differently than healthy non-patients. Biomarkers for safety and pharmacodynamic measures can also assist in further defining a safe and potentially effective dose range for subsequent clinical trial phases. Conclusion: Phase 1 studies can yield critical insights to the pharmacology of a new compound in man and offer perhaps the only development period in which the dose range can be safely and thoroughly explored. Phase 1 studies often contain multiple endpoint objectives, the reconciliation of which can present a dilemma for drug developers and study investigators alike, but which can crucially determine whether a compound can survive to the next step in the drug development process.

scholarly journals Current Antimycotics, New Prospects, and Future Approaches to Antifungal Therapy

Antibiotics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 445 ◽  
Author(s):  
Gina Wall ◽  
Jose L. Lopez-Ribot
Keyword(s):  
Drug Development ◽  
Drug Interactions ◽  
Fungal Infections ◽  
Mortality Rates ◽  
Clinical Development ◽  
Antifungal Drugs ◽  
High Morbidity ◽  
Eukaryotic Organisms ◽  
Emergence Of Resistance ◽  
Compromised Patients

Fungal infections represent an increasing threat to a growing number of immune- and medically compromised patients. Fungi are eukaryotic organisms and, as such, there is a limited number of selective targets that can be exploited for antifungal drug development. This has also resulted in a very restricted number of antifungal drugs that are clinically available for the treatment of invasive fungal infections at the present time—polyenes, azoles, echinocandins, and flucytosine. Moreover, the utility of available antifungals is limited by toxicity, drug interactions and the emergence of resistance, which contribute to high morbidity and mortality rates. This review will present a brief summary on the landscape of current antifungals and those at different stages of clinical development. We will also briefly touch upon potential new targets and opportunities for novel antifungal strategies to combat the threat of fungal infections.

scholarly journals A Systems Biology Approach in Therapeutic Response Study for Different Dosing Regimens—a Modeling Study of Drug Effects on Tumor Growth using Hybrid Systems

2012 ◽  
Vol 11 ◽  
pp. CIN.S8185 ◽  
Author(s):  
Xiangfang Li ◽  
Lijun Qian ◽  
Michale L. Bittner ◽  
Edward R. Dougherty
Keyword(s):  
Systems Biology ◽  
Drug Development ◽  
Tumor Growth ◽  
Hybrid Systems ◽  
Anticancer Agents ◽  
Therapeutic Response ◽  
Therapeutic Effects ◽  
Systems Model ◽  
Optimal Drug ◽  
Dosing Regimens

Motivated by the frustration of translation of research advances in the molecular and cellular biology of cancer into treatment, this study calls for cross-disciplinary efforts and proposes a methodology of incorporating drug pharmacology information into drug therapeutic response modeling using a computational systems biology approach. The objectives are two fold. The first one is to involve effective mathematical modeling in the drug development stage to incorporate preclinical and clinical data in order to decrease costs of drug development and increase pipeline productivity, since it is extremely expensive and difficult to get the optimal compromise of dosage and schedule through empirical testing. The second objective is to provide valuable suggestions to adjust individual drug dosing regimens to improve therapeutic effects considering most anticancer agents have wide inter-individual pharmacokinetic variability and a narrow therapeutic index. A dynamic hybrid systems model is proposed to study drug antitumor effect from the perspective of tumor growth dynamics, specifically the dosing and schedule of the periodic drug intake, and a drug's pharmacokinetics and pharmacodynamics information are linked together in the proposed model using a state-space approach. It is proved analytically that there exists an optimal drug dosage and interval administration point, and demonstrated through simulation study.

scholarly journals Fungicidal Activity of Fluconazole against Candida albicans in a Synthetic Vagina-Simulative Medium

2004 ◽  
Vol 48 (1) ◽  
pp. 161-167 ◽  
Author(s):  
Mahomed-Yunus S. Moosa ◽  
Jack D. Sobel ◽  
Hussain Elhalis ◽  
Wenjin Du ◽  
Robert A. Akins
Keyword(s):  
Acetic Acid ◽  
Candida Albicans ◽  
Drug Development ◽  
Carboxylic Acids ◽  
Fungicidal Activity ◽  
Vaginal Candidiasis ◽  
Ph Range ◽  
Cure Rates ◽  
Systemic Infections

ABSTRACT Fluconazole (FLZ) has emerged as a highly successful agent in the management of systemic infections of Candida. Cure rates for symptomatic candidiasis following single 150-mg FLZ dose therapy exceed 90%. In vitro, however, FLZ is fungistatic only in a narrow pH range and is not effective at vaginal pH, 4.2. This study evaluated the effect of FLZ on Candida albicans under in vitro conditions resembling the vaginal microenvironment, using vagina-simulative medium (VS). We found that FLZ was fungicidal for C. albicans in VS, but not in other media at the same pH, 4.2. In VS, FLZ was fungicidal at concentrations of ≥8 μg/ml and reduced viability by greater than 99.9%. Analysis of the components of VS indicated that 17 mM acetic acid, a concentration achieved in the vagina, was responsible for the synergistic, fungicidal effect. This effect was not seen at neutral pH. Other substrates were not effective substitutes for acetic acid; however, short-chained carboxylic acids, glyoxylate and malonate, were effective. Most strains of C. albicans that were resistant to FLZ under standard conditions were killed by FLZ plus acetate. Other species of Candida were also killed, except C. krusei and C. glabrata. This study shows that FLZ has fungicidal activity for Candida species under in vitro conditions that mimic the vaginal microenvironment. This raises the possibility that FLZ may also have fungicidal effects during treatment of vaginal candidiasis. Elucidating the mechanism by which FLZ and acetate interact may disclose vulnerable pathways that could be exploited in drug development.

scholarly journals Triple artemisinin-containing combination anti-malarial treatments should be implemented now to delay the emergence of resistance: the case against

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Sanjeev Krishna
Keyword(s):  
Multidrug Resistant ◽  
Triple Combination ◽  
Combination Therapies ◽  
Combination Treatments ◽  
Emergence Of Resistance

Abstract Managing multidrug resistant malaria can be problematic if currently available artemisinin-containing anti-malarial combination treatments are not used appropriately. Here, I debate that the best way to manage multidrug resistant malaria is to make best use of existing treatments and to develop new classes of anti-malarial drugs and not to make ‘triple combination therapies’ when there is already resistance to one or more proposed components.

scholarly journals Therapeutic drug monitoring in special populations

1998 ◽  
Vol 44 (2) ◽  
pp. 415-419 ◽  
Author(s):  
Philip D Walson
Keyword(s):  
Therapeutic Drug Monitoring ◽  
Drug Monitoring ◽  
Diagnostic Testing ◽  
Drug Effects ◽  
Special Populations ◽  
Therapeutic Drug ◽  
Drug Reactions ◽  
Drug Concentrations ◽  
Dosing Regimens ◽  
Multiple Drugs

Abstract Therapeutic drug monitoring (TDM) is commonly used to maintain “therapeutic” drug concentrations. Even in compliant patients, with “average” drug kinetics, TDM is useful to identify the causes of unwanted or unexpected responses, prevent unnecessary diagnostic testing, improve clinical outcomes, and even save lives. TDM has greatest promise in certain special populations who are: (a) prone to under- or overrespond to usual dosing regimens, (b) least able to tolerate, recognize, or communicate drug effects, or who are (c) intentionally or accidentally misdosed. TDM is especially useful in patients at the extremes of age, in adolescents, and in patients who are either taking multiple drugs or expressing unusual pharmacokinetics as a result of physiological, environmental, or genetic causes. Less-well-appreciated uses of TDM include prevention of dangerousunderdosing of patients, investigation of adverse drug reactions, and identification of serious medication errors, even for a number of drugs that are not traditionally monitored. TDM can be useful for some drugs in any patient and for most drugs in some special populations.

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