Current Issue : January-March Volume : 2025 Issue Number : 1 Articles : 5 Articles
Background: In clinical practice, the prevalent problem of polypharmacy could result in increased risks of drug–drug interactions. Regorafenib (REG) is commonly co-administered with paracetamol (PA) as a treatment protocol in cancer patients with pain therapy. Purpose: This study aimed to demonstrate the effect of paracetamol on the pharmacokinetic parameters of regorafenib and its metabolites following a single administration of both substances in rats. Additionally, the influence of REG and its metabolites on the pharmacokinetics of paracetamol was also determined. Methods: Twenty-four rats were divided randomly into three groups: REG group (IIREG, regorafenib 20 mg/kg, n = 8), PA group (IIIPA, paracetamol 100 mg/kg, n = 8), and REG+PA co-administration group (IREG+PA, REG 20 mg/kg and PA 100 mg/kg, n = 8). The concentrations of regorafenib, regorafenib-N-oxide (M-2), and N-desmethyl-regorafenib-N-oxide (M-5) were determined using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS). The plasma concentrations of PA and its glucuronide (GPA) and sulfate (SPA) metabolites were measured using the validated high-performance liquid chromatography method with ultraviolet detection (HPLC– UV). The pharmacokinetic parameters were calculated using a non-compartmental model. The statistical evaluation was performed in the SAS program. Results: After the administration of PA, the Cmax and AUC0–∞ of REG increased by 890% and 1140%, respectively; for M-2, they increased by 220% and 170%, and for M-5, by 2130% and 1730% (Cmax and AUC0–∞, respectively). A difference in the ratio of M-2/REG for AUC0–∞ and Cmax between the groups was observed, but not for M- 5/REG. The AUC0–∞ for PA and GPA decreased by 20.7% and 51.1%, respectively, when PA was co-administered with REG. But the AUC0–∞ for SPA increased by 91.35% in the IREG+PA group. A difference in the ratio of GPA/PA for Cmax and for SPA/PA for AUC0–t and AUC0–∞ between the groups was observed. Conclusions: Paracetamol increased the plasma exposure of regorafenib, M-2, and M-5, which may exacerbate the drug’s side effects. In contrast, REG reduced paracetamol exposure and contributed to its faster elimination, which may reduce the analgesic and antipyretic effects of paracetamol. These findings suggest clinical relevance for oncology patients requiring analgesic treatment....
P. aeruginosa is the most common microorganism involved in many ICU-acquired infections. A correct dosage regimen is pivotal to avoiding resistance development, worse outcomes and higher mortality rates. The aim of this study was to perform a pharmacokinetic–pharmacodynamic (PK/PD) evaluation of recommended dosing regimens of ceftazidime–avibactam (CAZ–AVI) in ICU patients with different degrees of renal function for a specific strain of Pseudomonas aeruginosa. A semimechanistic PK/PD model has been developed. It allows for the simulation of CAZ–AVI steady-state plasma level curves and the evolution of bacterial growth curves. The percentage of bacterial load reduction and the value of the recommended PK/PD indices have been taken into account to define the success or failure of the regimens. Probabilistic analysis was performed using Monte Carlo simulations of two populations: control and ICU. In both populations, dosing regimens endorsed for patients with CLcr higher than 10 mL/min reach the PK/PD indices recommended, T > MIC > 90% and Cmin/MIC > 1.3. While dosage regimens endorsed for patients with CLcr of 10 mL/min or lower fail (T > MIC < 60% and Cmin/MIC < 0.35). However, proposed dosing regimens based on shortening dosing intervals for these patients would be successful, increasing bacterial load reduction by almost 50% and reaching the proposed PK/PD indices. Therefore, CAZ–AVI dosing strategies based on model-informed precision dosing (MIPD) could directly influence the efficacy of results in ICU patients with renal insufficiency....
Background: Hydroxyurea (HU), also known as hydroxycarbamide, is an oral ribonucleotide reductase inhibitor. In 1999, the United States Food and Drug Administration (FDA) approved HU for the treatment of sickle cell disease (SCD). Since then, it has become the cornerstone in the management of SCD patients, helping to reduce vaso-occlusive crises, acute chest syndrome, the need for blood transfusions, hospitalizations and mortality. There is considerable variability among individuals in HU pharmacokinetic (Pk) parameters that can influence treatment efficacy and toxicity. The objective of this work is part of a clinical study aimed at investigating HU Pk and determining the optimal sampling time to estimate the Area Under the Curve (AUC) in SCD patients. Methods: HU plasma concentration in 80 patients at various time points (2, 4, 6, 24 h) following a 48-h drug washout was quantified using High-Pressure Liquid Chromatography (HPLC) coupled with an ultraviolet (UV) detection method previously described in the literature and adapted to new conditions with partial modifications. Results: The mean HU administered dose was 19.5 ± 5.1 mg/kg (range: 7.7–37.5 mg/kg). The median AUC quantified in plasma patients was 101.3 mg/L/h (Interquartile Range (IQR): 72.5–355.9) and it was not influenced by the weight-based dose. However, there was a strong positive correlation between AUC and Body Mass Index (BMI) as well as dose per Body Surface Area (BSA). Along with a three-point approach for AUC determination present in the literature, we show results obtained from a four-point sampling strategy, which is more useful and effective for better optimizing dose escalation to the maximum tolerated dose (MTD). Moreover, we observed that most patients achieved the maximum HU plasma concentration two hours after drug administration, regardless of age differences. Conclusions: HU treatment, which represents a milestone in the treatment of SCD due to its ability to reduce disease complications and improve patients’ quality of life, requires careful monitoring to optimize the individual dose for saving potential side effects and/or adverse events....
Tafenoquine (TQ) is a new 8-aminoquinoline antimalarial drug developed by the US Army for Plasmodium vivax malaria treatment. Modeling and simulation are essential tools for drug development and improving rationality in pharmacotherapy, and different modeling approaches are used. This study aims to summarize and explore the pharmacokinetic (PK) models available for tafenoquine in the literature. An integrative methodology was used to collect and review published data. Fifteen articles were identified using three modeling approaches: non-compartmental analysis (NCA), population pharmacokinetic analysis (popPK), and pharmacokinetic/pharmacodynamic analysis (PK/PD). An NCA was mainly used to describe the PK profile of TQ and to compare its PK profile alone to those obtained in association with other drugs. PopPK was used to assess TQ population PK parameters, covariates’ impact, and dose selection. PK/PD helped understand the relationship between TQ concentrations, some adverse events common for 8-aminoquilones, and the efficacy assessment for Plasmodium falciparum. In summary, pharmacokinetic models were widely used during TQ development. However, there is still a need for different modeling approaches to support further therapeutic questions, such as treatment for special populations and potential drug–drug interactions....
Remimazolam, widely used for procedural sedation and general anesthesia, is a new ultra short-acting benzodiazepine for intravenous sedation and anesthesia. We aim to characterize the pharmacokinetics/pharmacodynamics (PK/PD) of remimazolam and its metabolite CNS 7054 in healthy Chinese volunteers using population analysis and suggest an optimal dosing regimen for sedation therapy. Data were collected from a single-center, placebo-controlled, randomized, and dose–escalation clinical pharmacology study. Forty-six healthy volunteers received a single infusion dose of remimazolam, while nine healthy subjects received a continuous infusion of remimazolam. A population PK/PD model was established and RxODE and Shiny in R were used to design the remimazolam dosing regimens. A three-compartment model best described the PK of remimazolam and a two-compartment model with one transit compartment was adopted for CNS 7054. The relationship between exposure and the bispectral index was best described using an effect compartment model with an inhibitory sigmoid model. Additionally, a web-based dashboard was developed to provide individualized dosing regimens, complemented by a graphical illustration of the PK/PD profiles of the proposed dosing regimen. The established population PK/PD model characterized the dose–exposure–response relationship of remimazolam well, which could be applied to optimize individual dosing regimens....
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