A mechanism-based pharmacokinetic model of fenofibrate for explaining increased drug absorption after food consumption

The magnitude and associated factors of unused medications storage practice among households in Jimma city, southwest of Ethiopia: Community-based cross-sectional study

Background

Medicines are kept unused at home for many therapeutic reasons. Conversely, unused medication and subsequent wastage can be attributed to several primary factors such as medication change, death, and non-adherence. This study aimed to assess the magnitude and associated factors of unused medication storage practice among households in Jimma City, southwest Ethiopia.

Methods

A community-based cross-sectional study design was conducted among households (n = 397) in Jimma Town from July to August 2021. The data were collected using the pre-tested and interviewer-administered questionnaire. SPSS version 21.0 was used for data analysis. The multivariate logistic regression was used to determine the factors associated with the storage of unused medicine at a 5% level of significance.

Results

Out of 397 households that responded, (n = 90, 23%) of households were found to have unused medicine at home. This study showed that the majority of households dispose of unused drugs by burning them (32.2%) and burying them in the ground (29%). Antibiotics were the most (6.3%) unused medicines stored while the anti-diabetics (1.3%) were the least unused drugs stored among households. The presence of family members working in the health sector (AOR: 0.402, 95%, CI: 0.202, 0.800) and family size in households (AOR: 2.325, 95%, CI: 1.045, 5.174) were significantly associated with the magnitude of unused medicine storage.

Conclusion

The magnitude and improper disposal of unused medicines storage among households were significant in the study area. Therefore, it is important to educate the community and encourage health professionals to understand their role in problems and solutions.

Predicting gastric emptying of drug substances taken under postprandial conditions by combination of biorelevant dissolution and mechanistic in silico modeling

Physiologically based pharmacokinetic (PBPK) models can help to understand the effects of gastric emptying on pharmacokinetics and in particular also provide a platform for understanding mechanisms of food effects, as well as extrapolation between different postprandial conditions, whether standardized clinical or patient-oriented, non-clinical conditions. By integrating biorelevant dissolution data from the GastroDuo dissolution model into a previously described mechanistic model of fed-state gastric emptying, we simulated the effects of a high-calorie high-fat meal on the pharmacokinetics of sildenafil, febuxostat, acetylsalicylic acid, theobromine and caffeine. The model was able to simulate the variability in Cmax and tmax caused by the presence of the stomach road. The main influences investigated to affect the gastric emptying process were drug solubility (theobromine and caffeine), tablet dissolution rate (acetylsalicylic acid) and sensitivity to gastric motility (sildenafil and febuxostat). Finally, we showed how PBPK models can be used to extrapolate pharmacokinetics between different prandial states using theobromine as an example with results from a clinical study being presented.

Bridging the Gap between Food Effects under Clinical Trial Conditions and Real Life: Modeling Delayed Gastric Emptying of Drug Substances and Gastric Content Volume Based on Meal Characteristics

Delayed gastric emptying is known to have a major impact on drug absorption. While the test meal recommended by the FDA and EMA to study food effects represents a worst-case scenario, it does not reflect the reality of the patients. Physiologically based pharmacokinetic (PBPK) models could bridge the gap between clinical settings of food effect studies and the diverse nonclinical situations by simulating the effect of meals with different compositions and volumes. A mathematical equation based on a stretched exponential function was reparameterized to describe the gastric emptying process of mixed solid meals. The model was fitted to literature data including the gastric emptying data of 23 meals from 15 studies. Using a multiple linear regression model, we were able to predict the two function parameters from the meal characteristics caloric content and the percentage of calories derived from fat. After implementation into the PBPK software PK-Sim, the model, together with a separate compartment for liquid gastric contents, was compared to commercially available software. The model is able to simulate the gastric emptying of mixed solid meals containing drugs based on specific meal characteristics. A second compartment allows for distribution between liquid and solid components and rapid gastric emptying along the Magenstrasse.

Food effects on gastrointestinal physiology and drug absorption

Food ingestion affects the oral absorption of many drugs in humans. In this review article, we summarize the physiological factors in the gastrointestinal (GI) tract that affect the in vivo performance of orally administered solid dosage forms in fasted and fed states in humans. In particular, we discuss the effects of food ingestion on fluid characteristics (pH, bile concentration, and volume) in the stomach and small intestine, GI transit of water and dosage forms, and microbiota. Additionally, case examples of food effects on GI physiology and subsequent changes in oral drug absorption are provided. Furthermore, the effects of food, especially fruit juices (e.g., grapefruit, orange, apple) and green tea, on transporter-mediated permeation and enzyme-catalyzed metabolism of drugs in intestinal epithelial cells are also summarized comprehensively.

Potential Applications of Chitosan-Based Nanomaterials to Surpass the Gastrointestinal Physiological Obstacles and Enhance the Intestinal Drug Absorption

The small intestine provides the major site for the absorption of numerous orally administered drugs. However, before reaching to the systemic circulation to exert beneficial pharmacological activities, the oral drug delivery is hindered by poor absorption/metabolic instability of the drugs in gastrointestinal (GI) tract and the presence of the mucus layer overlying intestinal epithelium. Therefore, a polymeric drug delivery system has emerged as a robust approach to enhance oral drug bioavailability and intestinal drug absorption. Chitosan, a cationic polymer derived from chitin, and its derivatives have received remarkable attention to serve as a promising drug carrier, chiefly owing to their versatile, biocompatible, biodegradable, and non-toxic properties. Several types of chitosan-based drug delivery systems have been developed, including chemical modification, conjugates, capsules, and hybrids. They have been shown to be effective in improving intestinal assimilation of several types of drugs, e.g., antidiabetic, anticancer, antimicrobial, and anti-inflammatory drugs. In this review, the physiological challenges affecting intestinal drug absorption and the effects of chitosan on those parameters impacting on oral bioavailability are summarized. More appreciably, types of chitosan-based nanomaterials enhancing intestinal drug absorption and their mechanisms, as well as potential applications in diabetes, cancers, infections, and inflammation, are highlighted. The future perspective of chitosan applications is also discussed.

Development of a Nanocrystal Formulation of a Low Melting Point API Following a Quality by Design Approach

Preparation of nanocrystal formulations by wet media milling and spray-drying is a reliable technique to enhance dissolution and ameliorate absorption limitations of poorly soluble BCS II drugs. However, when thermosensitive compositions are dried at high temperatures, the risks of particle aggregation and thermal degradation must be considered. The present study investigates the effects of nanosuspension formulation variables when performing the spray drying process at equidistant temperatures above and below the melting point. Towards this purpose, Fenofibrate is exploited as a model drug of unfavorable pharmacokinetic profile and low melting point (79–82 °C), properties that render thermal processing a nontrivial task. Rationalizing the system’s behavior by combining molecular simulations with QbD methodology, the preparation of stable nanocrystals can be “steered” in order to avoid undesirable melting. The statistically resolved operational conditions showed that Fenofibrate Critical Quality Attribute–compliant nanosuspensions i.e., bearing hydrodynamic diameter and ζ-potential of 887 nm and −16.49 mV, respectively, were obtained by wet milling drug to Pharmacoat and mannitol weighted optimum ratios of 4.075% and 0.75%, after spray drying at the desired temperature of 77 °C. In conclusion, we present a quality assurance methodology of nano-comminution generally applicable for thermo-labile BCS II drugs.

The preparation of lipid-based drug delivery system using melt extrusion

Melt extrusion of lipids is versatile with high applicability in the pharmaceutical industry. The formulations prepared can be easily customized depending on the requirements, and have the potential to open a window on personalized medicine.

Food Effects on Oral Drug Absorption: Application of Physiologically-Based Pharmacokinetic Modeling as a Predictive Tool

The bioavailability of an orally administered small molecule is often dictated by drug-specific physicochemical characteristics and is influenced by many biological processes. For example, in fed or fasted conditions, the transit time within the gastrointestinal tract can vary, confounding the ability to predict the oral absorption. As such, the effects of food on the pharmacokinetics of compounds in the various biopharmaceutics classification system (BCS) classes need to be assessed. The consumption of food leads to physiological changes, including fluctuations in the gastric and intestinal pH, a delay in gastric emptying, an increased bile secretion, and an increased splanchnic and hepatic blood flow. Despite the significant impact of a drug's absorption and dissolution, food effects have not been fully studied and are often overlooked. Physiologically-based pharmacokinetic (PBPK) models can be used to mechanistically simulate a compound's pharmacokinetics under fed or fasted conditions, while integrating drug properties such as solubility and permeability. This review discusses the PBPK models published in the literature predicting the food effects, the models' strengths and shortcomings, as well as future steps to mitigate the current knowledge gap. We observed gaps in knowledge which limits the ability of PBPK models to predict the negative food effects and food effects in the pediatric population. Overall, the further development of PBPK models to predict food effects will provide a mechanistic basis to understand a drug's behavior in fed and fasted conditions, and will help enable the drug development process.

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

Losartan presents multiple peaks in the concentration-time profile. This characteristic can be attributed to gastric emptying, which is known to significantly affect the disposition of highly soluble and permeable compounds. The aim of this study was to develop a population pharmacokinetic model for losartan and its active metabolite (EXP-3174) in order to describe the effect of gastric emptying on their disposition. Population pharmacokinetic analysis was performed using concentration-time data derived from a crossover bioequivalence study in 31 volunteers after a single oral dose of 100 mg losartan potassium in the fasted state. Delay differential equations (DDEs) were explored for the description of losartan absorption and EXP-3174 formation, since when solved they result in oscillatory behaviour. A two-compartment model preceded by a pre-absorption compartment (referring to small intestine) adequately described the observed concentration-time profiles of losartan. In the final model, a sinusoidal equation was used for the description of gastric emptying in view of its simplicity, leading to enhanced stability of the model and its capacity to describe periodicity. In case of EXP-3174, a one-compartment model, with a delayed first-order formation rate from losartan's central compartment, best described its disposition. Using the model developed, it was shown through simulations that changes in gastric emptying parameters lead to changes in the C-t profiles of both compounds. In particular, plasma oscillations can be enhanced or completely suppressed, simply by changing parameters affecting gastric emptying.