Pharmacokinetic-pharmacodynamic modeling of severity levels of extrapyramidal side effects with markov elements

A major problem in the treatment of schizophrenic patients with current antipsychotic drugs, mainly acting as dopamine-2 receptor antagonists, is the occurrence of side effects such as extrapyramidal symptoms (EPS). Meta-analyses of summary data of EPS occurrence, and receptor occupancies inferred from mean plasma concentrations, have shown the incidence of EPS to rise when receptor occupancy is above ~80%. In this analysis, individual longitudinal EPS data from 2,630 patients participating in one of seven different trials and treated with haloperidol, paliperidone, ziprasidone, olanzapine, JNJ-37822681, or placebo were analyzed using a continuous time probability model with Markov elements. The developed pharmacokinetic-pharmacodynamic model describes the longitudinal changes of spontaneously reported EPS-related adverse events and their severity levels rated by clinicians. Individual steady-state concentrations and occupancy levels were found to be predictors for EPS. The results confirm 80% occupancy as a level of increased EPS occurrence rates, also at the individual level.CPT: Pharmacometrics & Systems Pharmacology (2012) 1, e1; doi:10.1038/psp.2012.9; advance online publication 26 September 2012

Comparative Pharmacokinetics of Tixagevimab/Cilgavimab (AZD7442) Administered Intravenously Versus Intramuscularly in Symptomatic SARS-CoV-2 Infection

AZD7442 (Evusheld) is a combination of two human anti-severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) monoclonal antibodies (mAbs), tixagevimab (AZD8895) and cilgavimab (AZD1061). Route of administration is an important consideration to improve treatment access. We assessed pharmacokinetics (PKs) of AZD7442 absorption following 600 mg administered intramuscularly (i.m.) in the thigh compared with 300 mg intravenously (i.v.) in ambulatory adults with symptomatic COVID-19. PK analysis included 84 of 110 participants randomized to receive i.m. AZD7442 and 16 of 61 randomized to receive i.v. AZD7442. Serum was collected prior to AZD7442 administration and at 24 hours and 3, 7, and 14 days later. PK parameters were calculated using noncompartmental methods. Following 600 mg i.m., the geometric mean maximum concentration (Cmax) was 38.19 μg/mL (range: 17.30–60.80) and 37.33 μg/mL (range: 14.90–58.90) for tixagevimab and cilgavimab, respectively. Median observed time to maximum concentration (Tmax) was 7.1 and 7.0 days for tixagevimab and cilgavimab, respectively. Serum concentrations after i.m. dosing were similar to the i.v. dose (27–29 μg/mL each component) at 3 days. The area under the concentration-time curve (AUC)0–7d geometric mean ratio was 0.9 for i.m. vs. i.v. Participants with higher weight or body mass index were more likely to have lower concentrations with either route. Women appeared to have higher interparticipant variability in concentrations compared with men. The concentrations of tixagevimab and cilgavimab after administration i.m. to the thigh were similar to those achieved with i.v. after 3 days from dosing. Exposure in the i.m. group was 90% of i.v. over 7 days. Administration to the thigh can be considered to provide consistent mAb exposure and improve access

Population pharmacokinetics of cutamesine in rats using NONMEM, 11C-SA4503, and microPET

Cutamesine (SA4503) is a selective sigma-1 receptor agonist, currently in Phase II clinical trials for depression and post stroke neurological disturbances. Cutamesine has been found to be effective in several rodent models of amnesia and depression. We used data obtained with carbon-11-labeled cutamesine (11CSA4503) in rats to develop a population pharmacokinetic (PK) model. Nonlinear mixed effects modeling (NONMEM) provides a tool for analyzing repeated measurements data in which the relationship between the explanatory and response variables can be modeled as a single function, allowing the parameters to differ between individuals. This modeling framework can be useful to scale preclinical drug kinetic information to clinical settings. METHODS: MicroPET scans of the brain region of male Wistar Hannover rats (age 1.5-32 months) were made and11C-SA4503 time-activity curves were obtained for the entire brain, A femoral artery cannula was used for blood sampling, and metabolite-corrected plasma time-activity curves were obtained. The PK model using NONMEM was constructed in two steps. In the first step, one-, two- or three-compartment PK models were explored to describe the plasma time course. In the second step, the model was extended to include brain11C-SA4503 time course data, while allowing brain distribution to influence plasma PK and vice versa. Bootstrap resampling (n=1000) technique was used as a model evaluation tool. The effects of covariates (age, weight, presence or absence of pituitary tumors) on PK parameters will be investigated for the final model. RESULTS: Plasma PK was best described by a twocompartment model. When brain PK was included, a three-compartment model performed best. The three compartments were: a central compartment (plasma) and two brain compartments (free and bound). Population PK parameters (relative standard error), not accounting for covariates are: central clearance (CL) 17.4 ml min-1(13%), central volume of distribution (VC) 25.3 ml (23%), brain volume of distribution (Vbr) 84.9 ml (23%), clearance into brain (Qin) 61.8 ml min-1(12%), clearance out of brain (Qout) 14.4 ml min-1(38%), clearance into bound compartment (Qon) 5.83 ml min-1(27%), clearance out of bound compartment (Qoff) 1.55 ml min-1(4%). Population estimates of the model are in close agreement with the median values of successful bootstrap replicates. CONCLUSION: Population PK modelling can be used successfully to analyze PET data of11C-labeled cutamesine

Asenapine pharmacokinetics and tolerability in a pediatric population

Peter Dogterom,1 Robert Riesenberg,2 Rik de Greef,1 Justin Dennie,3 Martin Johnson,1 Venkatesh Pilla Reddy,1 André MM Miltenburg,1 Robert L Findling,4 Abhijeet Jakate,5 Timothy J Carrothers,5 Matthew D Troyer3 1Early Stage Development, Merck Sharp and Dohme, Oss, the Netherlands; 2Atlanta Center for Medical Research, Atlanta, GA, 3Merck, Kenilworth, NJ, 4Kennedy Krieger Institute, Johns Hopkins University, Baltimore, MD, 5Allergan, Madison, NJ, USA Purpose: This study aimed to characterize the pharmacokinetic (PK) properties, safety, and tolerability of asenapine, and to develop a population PK model in pediatric patients with schizophrenia, bipolar disorder, or other psychiatric disorders. Methods: Two Phase I multiple ascending-dose studies were conducted to evaluate the PK, safety, and tolerability of sublingual asenapine in pediatric patients (age 10–17 years) with schizophrenia or bipolar I disorder. Patients received asenapine 1–10 mg twice daily for up to 12 days. PK parameters (maximum concentration [Cmax], area under the curve from 0 to 12 hours [AUC0–12], time to Cmax [Tmax], and half-life) were summarized for asenapine with descriptive statistics, and safety parameters were collected. A population PK model, which included the two Phase I studies and two additional Phase III efficacy studies (asenapine 2.5–10 mg twice daily for up to 8 weeks, age 10–17 years), was developed using nonlinear mixed-effect modeling based on a previously developed adult PK model. The final model was used in simulations to obtain asenapine-exposure estimates across pediatric subgroups and to determine if intrinsic covariates warrant dose adjustments. Results: The PK of asenapine showed rapid absorption (Tmax ~1 hour) with an apparent terminal half-life between 16 and 32 hours. Increases in mean Cmax and AUC0–12 appeared to be dose-proportional in one study and near dose-proportional in the second study. Steady state was attained within 8 days. The most frequently occurring treatment-emergent adverse events were dysgeusia, sedation, and oral hypoesthesia. Simulation-based estimates of Cmax and AUC0–12 were similar for pediatric and adult patients; age, body-mass index, race, and sex were not associated with changes in asenapine exposure. Conclusion: Asenapine was generally safe and well tolerated in pediatric patients aged 10–17 years. PK and safety data were similar to that observed in the adult population. Intrinsic factors had no significant impact on asenapine exposure, indicating there is no need for dose adjustments in the pediatric population. Keywords: asenapine, pharmacokinetics, schizophrenia, bipolar disorder, child and adolescent, atypical antipsychoti

Pediatric Pharmacokinetics and Dose Predictions: A Report of a Satellite Meeting to the 10th Juvenile Toxicity Symposium

Contains fulltext : 232077.pdf (Publisher’s version ) (Open Access)On April 24, 2019, a symposium on Pediatric Pharmacokinetics and Dose Predictions was held as a satellite meeting to the 10th Juvenile Toxicity Symposium. This symposium brought together scientists from academia, industry, and clinical research organizations with the aim to update each other on the current knowledge on pediatric drug development. Through more knowledge on specific ontogeny profiles of drug metabolism and transporter proteins, integrated into physiologically-based pharmacokinetic (PBPK) models, we have gained a more integrated understanding of age-related differences in pharmacokinetics (PKs), Relevant examples were presented during the meeting. PBPK may be considered the gold standard for pediatric PK prediction, but still it is important to know that simpler methods, such as allometry, allometry combined with maturation function, functions based on the elimination pathway, or linear models, also perform well, depending on the age range or the mechanisms involved. Knowledge from different methods and information sources should be combined (e.g., microdosing can reveal early read-out of age-related differences in exposure), and such results can be a value to verify models. To further establish best practices for dose setting in pediatrics, more in vitro and in vivo research is needed on aspects such as age-related changes in the exposure-response relationship and the impact of disease on PK. New information coupled with the refining of model-based drug development approaches will allow faster targeting of intended age groups and allow more efficient design of pediatric clinical trials

Comparative Pharmacokinetics of Tixagevimab/Cilgavimab (AZD7442) Administered Intravenously Versus Intramuscularly in Symptomatic SARS-CoV-2 Infection.

AZD7442 (Evusheld) is a combination of two human anti-severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) monoclonal antibodies (mAbs), tixagevimab (AZD8895) and cilgavimab (AZD1061). Route of administration is an important consideration to improve treatment access. We assessed pharmacokinetics (PKs) of AZD7442 absorption following 600 mg administered intramuscularly (i.m.) in the thigh compared with 300 mg intravenously (i.v.) in ambulatory adults with symptomatic COVID-19. PK analysis included 84 of 110 participants randomized to receive i.m. AZD7442 and 16 of 61 randomized to receive i.v. AZD7442. Serum was collected prior to AZD7442 administration and at 24 hours and 3, 7, and 14 days later. PK parameters were calculated using noncompartmental methods. Following 600 mg i.m., the geometric mean maximum concentration (Cmax ) was 38.19 μg/mL (range: 17.30-60.80) and 37.33 μg/mL (range: 14.90-58.90) for tixagevimab and cilgavimab, respectively. Median observed time to maximum concentration (Tmax ) was 7.1 and 7.0 days for tixagevimab and cilgavimab, respectively. Serum concentrations after i.m. dosing were similar to the i.v. dose (27-29 μg/mL each component) at 3 days. The area under the concentration-time curve (AUC)0-7d geometric mean ratio was 0.9 for i.m. vs. i.v. Participants with higher weight or body mass index were more likely to have lower concentrations with either route. Women appeared to have higher interparticipant variability in concentrations compared with men. The concentrations of tixagevimab and cilgavimab after administration i.m. to the thigh were similar to those achieved with i.v. after 3 days from dosing. Exposure in the i.m. group was 90% of i.v. over 7 days. Administration to the thigh can be considered to provide consistent mAb exposure and improve access