| 1. |
- Van der Heijden, Lisa T., et al.
(författare)
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Development of a Therapeutic Drug Monitoring Strategy for the Optimization of Vincristine Treatment in Pediatric Oncology Populations in Africa
- 2023
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Ingår i: Therapeutic Drug Monitoring. - : Ovid Technologies (Wolters Kluwer Health). - 0163-4356 .- 1536-3694. ; 45:3, s. 354-363
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Tidskriftsartikel (refereegranskat)abstract
- Background:Recent studies have reported ethnic differences in vincristine exposure and outcomes such as toxicity. This resulted in the hypothesis of subtherapeutic dosing in African children. To optimize individual treatment, a strategy to identify subtherapeutic exposure using therapeutic drug monitoring is essential. The aim of the current study was to develop a strategy for therapeutic drug monitoring of vincristine in African children to meet the following criteria: (1) identify patients with low vincristine exposure with sufficient sensitivity (>70%), (2) determine vincristine exposure with a limited sampling strategy design of 3 samples, and (3) allow all samples to be collected within 4 hours after administration.Methods:An in silico simulation study was performed using a previously described population pharmacokinetic model and real-life demographic dataset of Kenyan and Malawian pediatric oncology patients. Two different therapeutic drug monitoring strategies were evaluated: (1) Bayesian approach and (2) pharmacometric nomogram. The sampling design was optimized using the constraints described above. Sensitivity analysis was performed to investigate the influence of missing samples, erroneous sampling times, and different boundaries on the nomogram weight bands.Results:With the Bayesian approach, 43.3% of the estimated individual exposure values had a prediction error of & GE;20% owing to extremely high shrinkage. The Bayesian approach did not improve with alternative sampling designs within sampling constraints. However, the pharmacometric nomogram could identify patients with low vincristine exposure with a sensitivity, specificity, and accuracy of 75.1%, 76.4%, and 75.9%, respectively. The pharmacometric nomogram performed similarly for different weight bands.Conclusions:The pharmacometric nomogram was able to identify patients with low vincristine exposure with high sensitivity, with 3 blood samples collected at 1, 1.5, and 4 hours after administration. Missing samples should be avoided, and the 3 scheduled samples should be collected within 15, 5, and 15 minutes of 1, 1.5, and 4 hours after administration, respectively.
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| 2. |
- Siebinga, Hinke, et al.
(författare)
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Population pharmacokinetic dosimetry model using imaging data to assess variability in pharmacokinetics of 177Lu-PSMA-617 in prostate cancer patients
- 2023
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Ingår i: CPT. - : John Wiley & Sons. - 2163-8306. ; 12:8, s. 1060-1071
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Tidskriftsartikel (refereegranskat)abstract
- Studies to evaluate and optimize [177Lu]Lu-PSMA treatment focus primarily on individual patient data. A population pharmacokinetic (PK) dosimetry model was developed to explore the potential of using imaging data as input for population PK models and to characterize variability in organ and tumor uptake of [177Lu]Lu-PSMA-617 in patients with low volume metastatic prostate cancer. Simulations were performed to identify the effect of dose adjustments on absorbed doses in salivary glands and tumors. A six-compartment population PK model was developed, consisting of blood, salivary gland, kidneys, liver, tumor, and a lumped compartment representing other tissue (compartment 1–6, respectively), based on data from 10 patients who received [177Lu]Lu-PSMA-617 (2 cycles, ~ 3 and ~ 6 GBq). Data consisted of radioactivity levels (decay corrected) in blood and tissues (9 blood samples and 5 single photon emission computed tomography/computed tomography scans). Observations in all compartments were adequately captured by individual model predictions. Uptake into salivary glands was saturable with an estimated maximum binding capacity (Bmax) of 40.4 MBq (relative standard error 12.3%) with interindividual variability (IIV) of 59.3% (percent coefficient of variation [CV%]). IIV on other PK parameters was relatively minor. Tumor volume was included as a structural effect on the tumor uptake rate constant (k15), where a two-fold increase in tumor volume resulted in a 1.63-fold increase in k15. In addition, interoccasion variability on k15 improved the model fit (43.5% [CV%]). Simulations showed a reduced absorbed dose per unit administered activity for salivary glands after increasing radioactivity dosing from 3 to 6 GBq (0.685 Gy/GBq vs. 0.421 Gy/GBq, respectively). All in all, population PK modeling could help to improve future radioligand therapy research.
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| 3. |
- Kreeftmeijer-Vegter, A. R., et al.
(författare)
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Population pharmacokinetics of levamisole in children with steroid-sensitive nephrotic syndrome
- 2015
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 0306-5251 .- 1365-2125. ; 80:2, s. 242-252
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Tidskriftsartikel (refereegranskat)abstract
- AimThe aim was to investigate the population pharmacokinetics of levamisole in children with steroid-sensitive nephrotic syndrome. MethodsNon-linear mixed effects modelling was performed on samples collected during a randomized controlled trial. Samples were collected from children who were receiving 2.5mg kg(-1) levamisole (or placebo) orally once every other day. One hundred and thirty-six plasma samples were collected from 38 children from India and Europe and included in the analysis. A one compartment model described the data well. ResultsThe apparent clearance rate (CL/F) and distribution volume (V/F) were 44l h(-1) 70kg(-1) and 236l 70kg(-1), respectively; estimated interindividual variability was 32-42%. In addition to allometric scaling of CL/F and V/F to body weight, we identified a significant proportional effect of age on CL/F (-10.1% per year). The pharmacokinetics parameters were not affected by gender, tablet strength or study centre. The median (interquartile range) maximum plasma concentration of levamisole was 438.3 (316.5-621.8) ng ml(-1), and the median area under the concentration-time curve was 2847 (2267-3761) ng ml(-1) h. Median t(max) and t(1/2) values were 1.65 (1.32-2.0) h and 2.60 (2.06-3.65) h, respectively. ConclusionsHere, we present the first pharmacokinetic data regarding levamisole in children with steroid-sensitive nephrotic syndrome. The pharmacokinetic profile of levamisole in children was similar to findings reported in adults, although the elimination rate was slightly higher in children.
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| 4. |
- Fortin, Anny, et al.
(författare)
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Pharmacokinetics and pharmacodynamics of oleylphosphocholine in a hamster model of visceral leishmaniasis
- 2016
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 71:7, s. 1892-1898
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: This study evaluated the pharmacokinetic properties of oleylphosphocholine (OlPC) in hamsters following a single oral dose. Its prophylactic activity was tested to establish exposure-activity relationships, while a 5+5 day oral regimen at 20 mg/kg with long post-treatment follow-up was performed to assess its curative potential. Methods: Single oral doses of 20, 50 and 100 mg/kg were administered for pharmacokinetic analysis while a 100 mg/kg single oral dose was given on day 7, 4 or 1, or 4 h prior to infection in the prophylactic efficacy study. The animals were infected on day 0 with Leishmania infantum and the resulting parasite burdens were measured in target organs on day 21. In the curative model, treatment started on day 21 post-infection at 20 mg/kg for 5+5 days and amastigote burdens were determined in target organs either on day 42 [10 days after the end of treatment (dpt)] or day 72 (40 dpt). Results: OlPC showed elimination t(1/2) of similar to 50 h and dose-proportional exposure. The prophylactic action of OlPC was in agreement with model-simulated drug exposures, showing dose-dependent residual activity. Interestingly, the 100 mg/kg single dose administered 4 days before infection (day -4) still reduced the overall parasite burden by similar to 50%. In the curative model, >99% clearance of infection was observed at 10 dpt in all OlPC-treated animals and remained so at 40 dpt. Conclusions: This study reveals that total plasma exposure (AUC(t-infinity)) correlates well with the prophylactic and curative efficacy of OlPC in the L. infantum hamster model.
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| 5. |
- Janssen, J. M., et al.
(författare)
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Semi-physiological Enriched Population Pharmacokinetic Modelling to Predict the Effects of Pregnancy on the Pharmacokinetics of Cytotoxic Drugs
- 2023
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Ingår i: Clinical Pharmacokinetics. - : Springer Nature. - 0312-5963 .- 1179-1926. ; 62:8, s. 1157-1167
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Tidskriftsartikel (refereegranskat)abstract
- Background and Objective As a result of changes in physiology during pregnancy, the pharmacokinetics (PK) of drugs can be altered. It is unclear whether under- or overexposure occurs in pregnant cancer patients and thus also whether adjustments in dosing regimens are required. Given the severity of the malignant disease and the potentially high impact on both the mother and child, there is a high unmet medical need for adequate and tolerable treatment of this patient population. We aimed to develop and evaluate a semi-physiological enriched model that incorporates physiological changes during pregnancy into available population PK models developed from non-pregnant patient data.Methods Gestational changes in plasma protein levels, renal function, hepatic function, plasma volume, extracellular water and total body water were implemented in existing empirical PK models for docetaxel, paclitaxel, epirubicin and doxorubicin. These models were used to predict PK profiles for pregnant patients, which were compared with observed data obtained from pregnant patients.Results The observed PK profiles were well described by the model. For docetaxel, paclitaxel and doxorubicin, an overprediction of the lower concentrations was observed, most likely as a result of a lack of data on the gestational changes in metabolizing enzymes. For paclitaxel, epirubicin and doxorubicin, the semi-physiological enriched model performed better in predicting PK in pregnant patients compared with a model that was not adjusted for pregnancy-induced changes.Conclusion By incorporating gestational changes into existing population pharmacokinetic models, it is possible to adequately predict plasma concentrations of drugs in pregnant patients which may inform dose adjustments in this population.
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| 6. |
- Lohy Das, Jesmin, 1979-, et al.
(författare)
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Population Pharmacokinetics of Artemether, Dihydroartemisinin, and Lumefantrine in Rwandese Pregnant Women Treated for Uncomplicated Plasmodium falciparum Malaria
- 2018
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Ingår i: Antimicrobial Agents and Chemotherapy. - : AMER SOC MICROBIOLOGY. - 0066-4804 .- 1098-6596. ; 62:10
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Tidskriftsartikel (refereegranskat)abstract
- The artemisinin-based combination therapy artemether-lumefantrine is commonly used in pregnant malaria patients. However, the effect of pregnancy-related changes on exposure is unclear, and pregnancy has been associated with decreased efficacy in previous studies. This study aimed to characterize the population pharmacokinetics of artemether, its active metabolite dihydroartemisinin, and lumefantrine in 22 Rwandese pregnant women in their second (n = 11) or third (n = 11) trimester with uncomplicated Plasmodium falciparum malaria. These patients were enrolled from Rwamagana district hospital and received the standard fixed oral dose combination of 80 mg of artemether and 480 mg of lumefantrine twice daily for 3 days. Venous plasma concentrations were quantified for all three analytes using liquid chromatography coupled with tandem mass spectroscopy, and data were analyzed using nonlinear mixed-effects modeling. Lumefantrine pharmacokinetics was described by a flexible but highly variable absorption, with a mean absorption time of 4.04 h, followed by a biphasic disposition model. The median area under the concentration-time curve from 0 h to infinity (AUC(0-infinity)) for lumefantrine was 641 h . mg/liter. Model-based simulations indicated that 11.7% of the study population did not attain the target day 7 plasma concentration (280 ng/ml), a threshold associated with increased risk of recrudescence. The pharmacokinetics of artemether was time dependent, and the autoinduction of its clearance was described using an enzyme turnover model. The turnover half-life was predicted to be 30.4 h. The typical oral clearance, which started at 467 liters/h, increased 1.43-fold at the end of treatment. Simulations suggested that lumefantrine pharmacokinetic target attainment appeared to be reassuring in Rwandese pregnant women, particularly compared to target attainment in Southeast Asia. Larger cohorts will be required to confirm this finding.
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| 7. |
- Damoiseaux, David, et al.
(författare)
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Physiologically‐based pharmacokinetic model to predict doxorubicin and paclitaxel exposure in infants through breast milk
- 2023
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Ingår i: CPT. - : John Wiley & Sons. - 2163-8306. ; 12:12, s. 1931-1944
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Tidskriftsartikel (refereegranskat)abstract
- Limited information is available concerning infant exposure and safety when breastfed by mothers receiving chemotherapy. Whereas defining distribution to breast milk is important to infer drug exposure, infant pharmacokinetics also determine to what extent the infant will be exposed to potential toxic effects. We aimed to assess the impact of chemotherapy containing breast milk on infants by predicting systemic and local (intestinal) exposure of paclitaxel and doxorubicin in infants through breast milk using a physiologically-based pharmacokinetic (PBPK) approach. Whole-body PBPK models of i.v. paclitaxel and doxorubicin were extended from the literature, with an oral absorption component to enable predictions in infants receiving paclitaxel or doxorubicin-containing breast milk. For safety considerations, worst-case scenarios were explored. Finally, paclitaxel and doxorubicin exposures in plasma and intestinal tissue of infants following feeding of breast milk from paclitaxel- or doxorubicin-treated mothers were simulated and breast milk discarding strategies were evaluated. The upper 95th percentile of the predicted peak concentrations in peripheral venous blood were 3.48 and 0.74 nM (0.4%–1.7% and 0.1%–1.8% of on-treatment) for paclitaxel and doxorubicin, respectively. Intestinal exposure reached peak concentrations of 1.0 and 140 μM for paclitaxel and doxorubicin, respectively. Discarding breast milk for the first 3 days after maternal chemotherapy administration reduced systemic and tissue exposures even further, to over 90% and 80% for paclitaxel and doxorubicin, respectively. PBPK simulations of chemotherapy exposure in infants after breastfeeding with chemotherapy containing breast milk suggest that particularly local gastrointestinal adverse events should be monitored, whereas systemic adverse events are not expected.
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| 8. |
- Byakika-Kibwika, Pauline, et al.
(författare)
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Lopinavir/ritonavir significantly influences pharmacokinetic exposure of artemether/lumefantrine in HIV-infected Ugandan adults.
- 2012
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 67:5, s. 1217-23
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Treatment of HIV/malaria-coinfected patients with antiretroviral therapy (ART) and artemisinin-based combination therapy has potential for drug interactions. We investigated the pharmacokinetics of artemether, dihydroartemisinin and lumefantrine after administration of a single dose of 80/480 mg of artemether/lumefantrine to HIV-infected adults, taken with and without lopinavir/ritonavir.METHODS: A two-arm parallel study of 13 HIV-infected ART-naive adults and 16 HIV-infected adults stable on 400/100 mg of lopinavir/ritonavir plus two nucleoside reverse transcriptase inhibitors (ClinicalTrials.gov, NCT 00619944). Each participant received a single dose of 80/480 mg of artemether/lumefantrine under continuous cardiac function monitoring. Plasma concentrations of artemether, dihydroartemisinin and lumefantrine were measured.RESULTS: Co-administration of artemether/lumefantrine with lopinavir/ritonavir significantly reduced artemether maximum concentration (C(max)) and area under the concentration-time curve (AUC) [median (range): 112 (20-362) versus 56 (17-236) ng/mL, P = 0.03; and 264 (92-1129) versus 151 (38-606) ng · h/mL, P < 0.01]. Dihydroartemisinin C(max) and AUC were not affected [66 (10-111) versus 73 (31-224) ng/mL, P = 0.55; and 213 (68-343) versus 175 (118-262) ng · h/mL P = 0.27]. Lumefantrine C(max) and AUC increased during co-administration [2532 (1071-5957) versus 7097 (2396-9462) ng/mL, P < 0.01; and 41,119 (12,850-125,200) versus 199,678 (71,205-251,015) ng · h/mL, P < 0.01].CONCLUSIONS: Co-administration of artemether/lumefantrine with lopinavir/ritonavir significantly increases lumefantrine exposure, but decreases artemether exposure. Population pharmacokinetic and pharmacodynamic trials will be highly valuable in evaluating the clinical significance of this interaction and determining whether dosage modifications are indicated.
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| 9. |
- Castro, María Del Mar, et al.
(författare)
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Pharmacokinetics of Miltefosine in Children and Adults with Cutaneous Leishmaniasis
- 2017
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Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 61:3
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Tidskriftsartikel (refereegranskat)abstract
- An open-label pharmacokinetics (PK) clinical trial was conducted to comparatively assess the PK and explore the pharmacodynamics (PD) of miltefosine in children and adults with cutaneous leishmaniasis (CL) in Colombia. Sixty patients, 30 children aged 2 to 12 years and 30 adults aged 18 to 60 years, were enrolled. Participants received miltefosine (Impavido) at a nominal dose of 2.5 mg/kg/day for 28 days. Miltefosine concentrations were measured in plasma and peripheral blood mononuclear cells by liquid chromatography-tandem mass spectrometry of samples obtained during treatment and up to 6 months following completion of treatment, when therapeutic outcome was determined. Fifty-two patients were cured, 5 pediatric patients failed treatment, and 3 participants were lost to follow-up. Leishmania (Viannia) panamensis predominated among the strains isolated (42/46; 91%). Noncompartmental analysis demonstrated that plasma and intracellular miltefosine concentrations were, overall, lower in children than in adults. Exposure to miltefosine, estimated by area under the concentration-time curve and maximum concentration, was significantly lower in children in both the central and intracellular compartments (P < 0.01). Leishmania persistence was detected in 43% of study participants at the end of treatment and in 27% at 90 days after initiation of treatment. Clinical response was not dependent on parasite elimination. In vitro miltefosine susceptibility was similar for Leishmania strains from adults and children. Our results document PK differences for miltefosine in children and adults with cutaneous leishmaniasis that affect drug exposure and could influence the outcome of treatment, and they provide bases for optimizing therapeutic regimens for CL in pediatric populations. (This study has been registered at ClinicalTrials.gov under identifier NCT01462500.).
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| 10. |
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