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Characterizing the non-linear pharmacokinetics of miltefosine in paediatric visceral leishmaniasis patients from Eastern Africa.

ABSTRACT: BACKGROUND:Conventional miltefosine dosing (2.5?mg/kg/day) for treatment of visceral leishmaniasis (VL) is less effective in children than in adults. A higher allometric dose (median 3.2?mg/kg/day) was therefore investigated in paediatric VL patients in Eastern Africa. Results of this trial showed an unforeseen, lower than dose-proportional increase in exposure. Therefore, we performed a pooled model-based analysis of the paediatric data available from both dosing regimens to characterize observed non-linearities in miltefosine pharmacokinetics (PK). METHODS:Fifty-one children with VL were included in this analysis, treated with either a conventional (n?=?21) or allometric (n?=?30) miltefosine dosing regimen. PK data were analysed using non-linear mixed-effects modelling. RESULTS:A two-compartment model following first-order absorption and linear elimination, with two separate effects on relative oral bioavailability, was found to fit these data best. A 69% lower bioavailability at treatment start was estimated, presumably due to initial malnourishment and malabsorption. Stagnation in miltefosine accumulation in plasma, hampering increased drug exposure, was related to the increase in cumulative dose (mg/kg/day). However, the allometric regimen increased exposure 1.7-fold in the first treatment week and reduced the time to reach the PK target by 17.4%. CONCLUSIONS:Miltefosine PK in children suffering from VL are characterized by dose-dependent non-linearities that obstruct the initially expected exposure levels. Bioavailability appeared to be affected by the cumulative dose, possibly as a consequence of impaired absorption. Despite this, allometric dosing led to a faster target achievement and increased exposure compared with conventional dosing.

SUBMITTER: Palic S

PROVIDER: S-EPMC7566410 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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Characterizing the non-linear pharmacokinetics of miltefosine in paediatric visceral leishmaniasis patients from Eastern Africa.

Palić Semra S Kip Anke E AE Beijnen Jos H JH Mbui Jane J Musa Ahmed A Solomos Alexandra A Wasunna Monique M Olobo Joseph J Alves Fabiana F Dorlo Thomas P C TPC

The Journal of antimicrobial chemotherapy 20201101 11

<h4>Background</h4>Conventional miltefosine dosing (2.5 mg/kg/day) for treatment of visceral leishmaniasis (VL) is less effective in children than in adults. A higher allometric dose (median 3.2 mg/kg/day) was therefore investigated in paediatric VL patients in Eastern Africa. Results of this trial showed an unforeseen, lower than dose-proportional increase in exposure. Therefore, we performed a pooled model-based analysis of the paediatric data available from both dosing regimens to characteriz ...[more]

PMID: 32780098

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Project description:Miltefosine unresponsive and relapse cases of visceral leishmaniasis (VL) are increasingly being reported. However, there has been no laboratory confirmed reports of miltefosine resistance in VL. Here, we report two laboratory confirmed cases of VL from India.Two patients with VL were referred to us with suspected VL. The first patient was a native of the VL endemic state of Bihar, but residing in Delhi, a VL non-endemic area. He was treated with broad-spectrum antibiotics and antipyretics but was unresponsive to treatment. The second patient was from Jharkhand state in eastern India (adjoining Bihar), another endemic state for VL. He was refractory to anti-leishmanial treatment, which included administration of miltefosine. Following investigation, both patients were serologically positive for VL, and blood buffy coat from both patients grew Leishmania donovani. The isolates derived from both cases were characterized for their drug susceptibility, genetically characterised, and SNPs typed for LdMT and LdROS gene expression. Both patients were successfully treated with amphotericin B.The in vitro drug susceptibility assays carried out on both isolates showed good IC50 values to amphotericin B (0.1?±?0.0004 ?g/ml and 0.07?±?0.0019 ?g/ml). One isolate was refractory to SbIII with an IC50 of > 200 ?M while the second isolate was sensitive to SbIII with an IC50 of 36.70?±?3.2 ?M. However, in both the isolates, IC50 against miltefosine was more than 10-fold higher (> 100 ?M) than the standard strain DD8 (6.8?±?0.1181 ?M). Furthermore, genetic analyses demonstrated single nucleotide polymorphisms (SNPs) (354Tyr?Phe and 1078Phe?Tyr) in the LdMT gene of the parasites.Here, we document two laboratory confirmed cases of miltefosine resistant VL from India. Our finding highlights the urgent need to establish control measures to prevent the spread of these strains. We also propose that LdMT gene mutation analysis could be used as a molecular marker of miltefosine resistance in L. donovani.

Project description:BackgroundThere is a continued need to develop effective and safe treatments for visceral leishmaniasis (VL). Preclinical studies on pharmacokinetics and pharmacodynamics of anti-infective agents, such as anti-bacterials and anti-fungals, have provided valuable information in the development and dosing of these agents. The aim of this study was to characterise the pharmacokinetic and pharmacodynamic properties of the anti-leishmanial drugs AmBisome and miltefosine in a preclinical disease model of VL.Methodology / principal findingsBALB/c mice were infected with L. donovani (MHOM/ET/67/HU3) amastigotes. Groups of mice were treated with miltefosine (orally, multi-dose regimen) or AmBisome (intravenously, single dose regimen) or left untreated as control groups. At set time points groups of mice were killed and plasma, livers and spleens harvested. For pharmacodynamics the hepatic parasite burden was determined microscopically from tissue impression smears. For pharmacokinetics drug concentrations were measured in plasma and whole tissue homogenates by LC-MS. Unbound drug concentrations were determined by rapid equilibrium dialysis. Doses exerting maximum anti-leishmanial effects were 40 mg/kg for AmBisome and 150 mg/kg (cumulatively) for miltefosine. AmBisome displayed a wider therapeutic range than miltefosine. Dose fractionation at a total dose of 2.5 mg/kg pointed towards concentration-dependent anti-leishmanial activity of AmBisome, favouring the administration of large doses infrequently. Protein binding was >99% for miltefosine and amphotericin B in plasma and tissue homogenates.Conclusion / significanceUsing a PK/PD approach we propose optimal dosing strategies for AmBisome. Additionally, we describe pharmacokinetic and pharmacodynamic properties of miltefosine and compare our findings in a preclinical disease model to available knowledge from studies in humans. This approach also presents a strategy for improved use of animal models in the drug development process for VL.

Dataset Information

Characterizing the non-linear pharmacokinetics of miltefosine in paediatric visceral leishmaniasis patients from Eastern Africa.

Publications

Characterizing the non-linear pharmacokinetics of miltefosine in paediatric visceral leishmaniasis patients from Eastern Africa.

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