A population pharmacokinetic and pharmacokinetic-pharmacodynamic analysis of vupanorsen from phase I and phase II studies.

Vupanorsen (PF-07285557) is a second-generation ligand-conjugated 2'O-methoxyethyl modified antisense oligonucleotide designed to target angiopoietin-like 3 (ANGPTL3) mRNA expressed by the liver, shown to reduce lipids and apolipoproteins in subjects with dyslipidemia. Using pooled data from two phase I studies of participants with elevated triglycerides (Western: n = 48 and Japanese: n = 12), and two phase II studies of patients with hypertriglyceridemia, diabetes, and nonalcoholic fatty liver disease (n = 105), and statin-treated patients with dyslipidemia (n = 286), we developed population pharmacokinetic (PK) and PK/pharmacodynamic (PK/PD) models. Efficacy target values were set a priori to -75%, -60%, and -35% for ANGPTL3, triglyceride (TG), and non-high-density lipoprotein-cholesterol (non-HDL-C), respectively.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamic Effects of PF-06751979, a Potent and Selective Oral BACE1 Inhibitor: Results from Phase I Studies in Healthy Adults and Healthy Older Subjects.

PF-06751979 is a selective inhibitor of the beta-site amyloid precursor protein cleaving enzyme-1, which is a key aspartyl protease in the generation of amyloid-β (Aβ) peptides, thought to be critical for the cerebral degeneration observed in Alzheimer's disease. Two Phase I studies (NCT02509117, NCT02793232) investigated the safety/tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of PF-06751979. Single-ascending doses up to 540 mg and multiple-ascending doses up to 275 mg once daily (QD) in healthy adults, and multiple doses of 50 mg or 125 mg QD in healthy older subjects were assessed.

Pharmacokinetic and Pharmacodynamic Effects of a γ-Secretase Modulator, PF-06648671, on CSF Amyloid-β Peptides in Randomized Phase I Studies.

γ-Secretase modulators (GSMs) represent a promising therapy for Alzheimer's disease by reducing pathogenic amyloid-β (Aβ) peptide production. Three phase I studies (NCT02316756, NCT02407353, and NCT02440100) investigated the safety/tolerability, pharmacokinetics (PKs), and pharmacodynamics (PDs) of the oral GSM, PF-06648671. A PK/PD indirect-response model was developed (using biomarker data) to simultaneously characterize differential effects of PF-06648671 on multiple Aβ species in cerebrospinal fluid (CSF).

Iron supplements in nursing home patients associated with reduced carbamazepine absorption.

Unlabelled: Persons in nursing homes receive a number of medications that may interfere with the pharmacokinetics of carbamazepine (CBZ). The aim of our study was to determine factors that may affect the pharmacokinetics of CBZ in elderly nursing home patients.

Methods: CBZ concentration data collected from 60 nursing homes across the US were evaluated.

Modeling of the parathyroid hormone response after calcium intake in healthy subjects.

Plasma ionized calcium (Ca(2+)) concentrations are tightly regulated in the body and maintained within a narrow range; thus it is challenging to quantify calcium absorption under normal physiologic conditions. This study aimed to develop a mechanistic model for the parathyroid hormone (PTH) response after calcium intake and indirectly compare the difference in oral calcium absorption from PTH responses. PTH and Ca(2+) concentrations were collected from 24 subjects from a clinical trial performed to evaluate the safety and calcium absorption of Geumjin Thermal Water in comparison with calcium carbonate tablets in healthy subjects.

Modeling longitudinal daily seizure frequency data from pregabalin add-on treatment.

The purpose of this study was to describe longitudinal daily seizure count data with respect to the effects of time and pregabalin add-on therapy. Models were developed in a stepwise manner: base model, time effect model, and time and drug effect (final) model, using a negative binomial distribution with Markovian features. Mean daily seizure count (λ) was estimated to be 0.

Longitudinal aggregate data model-based meta-analysis with NONMEM: approaches to handling within treatment arm correlation.

Literature data are often reported as multiple (longitudinal) mean outcomes observed in several groups of patients within a study. Observations within a study are correlated because the patients come from a common population, and the mean observations over time within a treatment arm are correlated because they are based on the same set of patients. As a result, model-based meta-analysis may require more than two levels of random effects to correctly characterize this correlation structure.

Likelihood based approaches to handling data below the quantification limit using NONMEM VI.

Purpose: To evaluate the likelihood-based methods for handling data below the quantification limit (BQL) using new features in NONMEM VI.

Methods: A two-compartment pharmacokinetic model with first-order absorption was chosen for investigation. Methods evaluated were: discarding BQL observations (M1), discarding BQL observations but adjusting the likelihood for the remaining data (M2), maximizing the likelihood for the data above the limit of quantification (LOQ) and treating BQL data as censored (M3), and like M3 but conditioning on the observation being greater than zero (M4).

Population pharmacokinetics of valproic acid concentrations in elderly nursing home residents.

The objective of this study was to identify factors that affect valproic acid (VPA) apparent clearance (CL/F) in elderly nursing home residents. Inclusion criteria included residency in a nursing home for at least 2 months, aged 65 years or older, a stable dosing regimen of VPA for at least 4 weeks, VPA concentration, and complete dosing information. CL/F was analyzed by a nonlinear mixed effects model.

Inherent correlation between dose and clearance in therapeutic drug monitoring settings: possible misinterpretation in population pharmacokinetic analyses.

During the course of therapeutic drug monitoring (TDM), doses are adjusted to attain a target concentration range and a correlation between clearance (CL) and dose is introduced. In population pharmacokinetic analyses of such TDM data, CL has frequently been modeled as a function of dose. This paper demonstrates by simulation methodology that the TDM process does indeed introduce a correlation between dose and CL which can be interpreted as a nonlinearity.