Modelling gastric emptying: A pharmacokinetic model simultaneously describing distribution of losartan and its active metabolite EXP-3174

Efficacy and safety evaluation of Allisartan Isoproxil in patients with hypertension: a meta-analysis

Objective

This study aimed to evaluate the effectiveness and safety of Allisartan Isoproxil in the management of hypertension.

Methods

A comprehensive search was conducted across both English and Chinese databases, including the Cochrane Library, Embase, PubMed, Web of Science, Chinese Journal Full Text Database (CNKI), Wanfang Digital Periodical Full Text Database, and VIP Chinese Periodical Database (VIP), up to March 24, 2024. Randomized controlled trials (RCTs) investigating alisartan axetil for hypertension management were selected. Literature quality was assessed, and data were extracted for meta-analysis using Stata 15.1 software. The quality of evidence for outcome indicators was evaluated using the GRADE system level.

Results

Six RCTs involving 767 participants were included. Meta-analysis revealed that, compared to placebo, the Allisartan Isoproxil group exhibited a significant reduction in systolic blood pressure (SBP) [WMD = -8.08, 95% CI (-11.81, 4.10), p = 0.000] and brachial-ankle pulse wave velocity (baPWV) [SMD = -0.69, 95% CI (-1.17, 0.20), p = 0.006]. However, the reduction in diastolic blood pressure (DBP) was not statistically significant [WMD = -5.48, 95% CI (-11.07, 0.10), p = 0.054]. Additionally, compared to calcium channel blockers (CCB) and angiotensin II receptor blockers (ARB), Allisartan Isoproxil did not significantly affect SBP [WMD = 0.20, 95% CI (-3.71, 4.10), p = 0.921] or DBP [WMD = 0.16, 95% CI (-2.11, 2.43), p = 0.891]. Allisartan Isoproxil demonstrated superior effects in increasing nitric oxide (NO) levels and decreasing endothelin (ET) levels compared to control groups [WMD = 9.56, 95% CI (6.42, 12.71), p = 0.000], [WMD = -7.42, 95% CI (-11.13, -3.71), p = 0.000], and showed a higher effective control rate of blood pressure [RR = 1.26, 95% CI (1.13, 1.41), p = 0.000]. Subgroup analysis did not reveal significant differences. Regarding safety, there were no statistically significant differences in adverse events between the Allisartan Isoproxil group and the control groups [RR = 0.99, 95% CI (0.74, 1.32), p = 0.928], and no fatal adverse events were reported.

Conclusion

Allisartan Isoproxil is effective in reducing SBP and baPWV, increasing NO, decreasing ET, and achieving a higher control rate of blood pressure in patients with essential hypertension. These benefits are achieved with minimal adverse reactions.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023467869, identifier PROSPERO CRD42023467869.

Bioavailability and daily requirement of vitamin B12 in adult humans: an observational study of its colonic absorption and daily excretion as measured by [13C]-cyanocobalamin kinetics

BACKGROUND

Clinical and biochemical vitamin B12 (B12) deficiency is lower than anticipated in vegetarians. Extraileal absorption, such as from the colon, as well as reduced daily excretion, may be adaptive mechanisms to maintain B12 homeostasis with marginal intakes.

OBJECTIVE

To measure the absorption of B12 from the small and large intestine, and its daily rate of excretion from the body, using a [13C]-cyanocobalamin tracer.

METHODS

Oral B12 bioavailability was measured over 12 h after administration of [13C]-cyanocobalamin tracer (2.5 μg) in normal participants. The colonic B12 bioavailability was evaluated by direct instillation of [13C]-cyanocobalamin (5 μg) into the ascending colon. Bioavailability was calculated from 2-compartmental modeling of the tracer appearance in plasma. The excretion rate of B12 was measured from [13C]-cyanocobalamin elimination from the body over 4 wk after oral dosing (5 μg).

RESULTS

The oral B12 bioavailability (n = 11) was 63% ± 10% measured over 12 h. A late absorption peak, accounting for 12% of the absorption, was observed after an average lag time of 8.7 h from dosing. The colonic B12 bioavailability (n = 10) was 7% ± 5% over 4 h. The daily B12 excretion rate (n = 4) was 0.7 ± 0.2 μg/d. The minimum daily requirement of B12 in these participants was derived at 1 μg /d.

CONCLUSIONS

B12 is absorbed in the human colon. This observation confirms the potential contribution of the colon in daily B12 nutriture, and along with a possible lower requirement, could explain the absence of clinical deficiency in populations with marginal B12 intakes.

TRIAL REGISTRATION NUMBER

This study was registered in Clinical Trials Registry of India (CTRI) with the registration number CTRI/2018/04/012957, available from https://ctri.nic.in/Clinicaltrials/showallp.php?mid1=49319&EncHid=&userName=029108.

Physiological Dynamics in the Upper Gastrointestinal Tract and the Development of Gastrointestinal Absorption Models for the Immediate-Release Oral Dosage Forms in Healthy Adult Human

This review is a revisit of various oral drug absorption models developed in the past decades, focusing on how to incorporate the physiological dynamics in the upper gastrointestinal (GI) tract. For immediate-release oral drugs, GI absorption is a critical input of drug exposure and subsequent human body response, yet difficult to model largely due to the complex GI environment. One of the biggest hurdles lies at capturing the high within-subject variability (WSV) of bioavailability measures, which can be mechanistically explained by the GI physiological dynamics. A thorough summary of how GI dynamics is handled in the absorption models would promote the development of mechanism-based oral drug absorption models, aid in the design of clinical studies regarding dosing regimens and bioequivalence studies based on WSV, and advance the decision-making on formulation selection.

The [13 C]octanoic acid breath test for gastric emptying quantification: A focus on nutrition and modeling

Gastric emptying (GE) is the process of food being processed by the stomach and delivered to the small intestine where nutrients such as lipids are absorbed into the blood circulation. The combination of an easy and inexpensive method to measure GE such as the CO₂ breath test using the stable isotope [¹³C]octanoic acid with semi‐mechanistic modeling could foster a wider application in nutritional studies to further understand the metabolic response to food. Here, we discuss the use of the [¹³C]octanoic acid breath test to label the solid phase of a meal, and the factors that influence GE to support mechanistic studies. Furthermore, we give an overview of existing mathematical models for the interpretation of the breath test data and how much nutritional studies could benefit from a physiological based pharmacokinetic model approach.

Validation of population pharmacokinetic models: a comparison of internal and external validation approaches for hydrochlorothiazide

1. Model evaluation is an important issue in population analyses. Our aim was to perform and illustrate metrics and techniques for internal and external evaluation with an application to population pharmacokinetics of hydrochlorothiazide (HCTZ).2. A nonlinear mixed effects model was used to study the pharmacokinetics of HCTZ. In addition, different types of internal assessment tools and external metrics were used for model evaluation. External evaluation was performed using an alternative dataset that included data from an independent group of subjects. For comparison, a previously published population pharmacokinetic model for HCTZ was applied to the same data.3. A two-compartment model with first-order oral absorption using a constant time delay between administration and absorption and first-order elimination best described HCTZ pharmacokinetics. Age had a statistically significant effect on HCTZ clearance. The final model performed adequately in the internal and external assessment tests. The final model showed better predictive performance than the other previously published HCTZ model.4. Finally, a robust population pharmacokinetic model for HCTZ in adults was constructed and validated internally and externally. Incorporating analytical assessment of nonlinear pharmacokinetics into the modelling may be a promising approach to improve the predictive power of the model.

Investigating the Impact of Gastric Emptying on Pharmacokinetic Parameters Using Delay Differential Equations and Principal Component Analysis

BACKGROUND AND OBJECTIVES

Losartan presents multiple peaks after single oral administration, which can be attributed to gastric emptying. The aim of this study was to describe the multiple peak phenomenon of losartan using a delay differential model and a model with sine function. The impact of gastric emptying on pharmacokinetic parameters was investigated by applying principal component analysis to the individual parameter estimates.

METHODS

Using Monolix^TM, two population pharmacokinetic models were developed to describe the multiple peak phenomenon; the first using delay differential equations and the second using a sine function. Matlab^® delay differential equation solver was used to arithmetically solve both functions. Principal component analysis and all statistical analyses were performed in the R language.

RESULTS

The description of losartan multiple peaks can be achieved by the use of either delay differential equations or typical sine wave functions. Principal component analysis unveiled the impact of gastric emptying on the pharmacokinetic parameters. In the case of the delay differential equation model, a negative relationship was found between the constant delay tau1 and the parameters reflecting rate and extent of absorption (i.e., area under the curve [AUC], peak plasma concentration [C_max], and the absorption rate constant). Similar results were obtained from the sine model, where a higher amplitude and lower period (i.e., higher frequency) of gastric emptying were associated with higher AUC and C_max values.

CONCLUSIONS

The observed multiple peaks for certain drugs like losartan can be attributed to gastric emptying. Parameters describing gastric emptying can be associated with pharmacokinetic metrics like AUC and C_max.

Delay differential equations for the description of Irbesartan pharmacokinetics: A population approach to model absorption complexities leading to dual peaks

Irbesartan is a poorly soluble BCS class II compound with weak acidic properties. After oral administration, dual peaks are noted in its concentration (C) - time (t) profile, a phenomenon that may be attributed to enterohepatic recirculation, gastric emptying and/or other absorption complexities related to its pH- and buffer capacity-dependent dissolution behavior. A population pharmacokinetic model, encompassing delay differential equations, was found the most appropriate approach to describe dual peaks in irbesartan's C-t profiles. Parameters estimated were: the absorption rate constant in the central compartment (ka = 0.304 h^-1), the constant time delay between the administration and the absorption (T=1.68 h), the apparent volume of distribution of the central (V1/F = 13.8 L) and peripheral (V2/F = 85.8 L) compartment, the apparent clearance from the central compartment (CL/F = 13.5 L/h), and the inter-compartmental clearance (Q/F = 17.7 L/h). Using simulations, it was made evident that changing the time delay results in significant changes of peak plasma concentrations but not of its blood pressure-lowering effect. In conclusion, delay differential equations may be useful to model dual peaks arising from absorption complexities, while changes of the time delay that reflect physiological processes that take place before absorption may have significant implications in proving bioequivalence.