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Food Effects on Oral Drug Absorption: Application of Physiologically pharmaceutics Review Food Effects on Oral Drug Absorption: Application of Physiologically-Based Pharmacokinetic Modeling as a Predictive Tool Lisa Cheng and Harvey Wong * Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada; [email protected] * Correspondence: [email protected]; Tel.: +1-604-822-4707 Received: 21 June 2020; Accepted: 15 July 2020; Published: 17 July 2020 Abstract: 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. Keywords: food effects; physiologically-based pharmacokinetic model; oral absorption; mathematical modeling 1. Introduction Oral administration is the most common route of drug delivery because of the convenience, relative cost-effectiveness, and ease of administration. These combined factors promote patient compliance. Despite its many advantages, it is often difficult to predict the drug’s oral pharmacokinetic profile in vivo. Specifically, there exists intra- and interindividual variabilities in oral drug absorption which affects bioavailability and impacts the therapeutic outcome. Drug-specific physicochemical characteristics (i.e., solubility and permeability) dictate the drug’s ability to travel across or through the intestinal wall into the hepatic portal vein and offers an initial understanding of its oral pharmacokinetics. Furthermore, complex biological processes including fluctuations in pH, gastric and intestinal movement, rate of blood flow, and bile salt secretion can impact the orally administered drug’s rate of absorption. The gastrointestinal tract’s physiology influences drug absorption and it is therefore imperative to ensure that any situations deterring the digestive system from homeostasis are explored. Food ingestion is known to alter the gastrointestinal environment, and individuals typically consume three meals a Pharmaceutics 2020, 12, 672; doi:10.3390/pharmaceutics12070672 www.mdpi.com/journal/pharmaceutics Pharmaceutics 2020, 12 2 of 19 The gastrointestinal tract’s physiology influences drug absorption and it is therefore imperative Pharmaceuticsto ensure that2020 ,any12, 672 situations deterring the digestive system from homeostasis are explored. 2Food of 18 ingestion is known to alter the gastrointestinal environment, and individuals typically consume three meals a day. This could affect the frequency at which drugs can be administered and when they can day.be taken This. couldAccording affect to the the frequency Food and at Drug which Administration drugs can be administered (FDA), drug andadministration when they canin the be fasted taken. Accordingcondition occurs to the Foodwhen and there Drug is Administrationan overnight fast (FDA), lasting drug for administration a minimum of in 10 the h fastedand no condition food is occursconsumed when until there after is an at overnightleast 4 h of fast drug lasting dosing for [1] a minimum. In comparison, of 10 h anda fed no state food is isachieved consumed by untilfollowing after atthe least same 4 hovernight of drug dosing fast, but [1]. patients In comparison, are advised a fed to state take isa achievedmeal within by following30 min before the same administration overnight fast,with butno patientseating until are adviseda minimum to take of 4 a h meal afterward within [1] 30. minConcomitant before administration food consumption with no and eating oral untildrug aadministration minimum of 4can h afterward affect drug [1]. Concomitantabsorption, thereby food consumption impacting its and safety oral drugand administrationefficacy. Increased can asystemicffect drug exposure absorption, can therebyenhance impacting efficacy, but its safetyalso increases and efficacy. the probability Increased systemicof experiencing exposure dose can- enhancerelated toxicities. efficacy, but Alternatively, also increases an the inefficient probability absorption of experiencing decreases dose-related the bioavailability, toxicities. Alternatively, potentially anresulting inefficient in reduced absorption efficacy decreases or no efficacy the bioavailability, at subtherapeutic potentially levels. resultingAn ideal drug in reduced would enotfficacy exhibit or noany e ffisignificantcacy at subtherapeutic meal-induced changes, levels. An allowing ideal drug patients would to adhere not exhibit to their any prescription significant meal-inducedwithout being changes,concerned allowing about their patients prandial to adhere state. to However, their prescription this is not without always being possi concernedble, and aboutpatients their need prandial to be state.aware However, of any concerns this is notthat always come with possible, simultaneous and patients food need and todrug be awareadministration. of any concerns that come with simultaneousThe food effects food (Figure and drug 1) on administration. oral drug absorption can be investigated through preclinical and clinicalThe pharmacokinetic food effects (Figure studies1) on, by oral determin drug absorptioning whether can oral be investigatedtherapeutics throughexhibit consequential preclinical and or clinicalinconsequential pharmacokinetic effects when studies, administered by determining withwhether food. Historically, oral therapeutics the inability exhibit consequentialto accurately orcharacterize inconsequential a drug’s eff pharmacokineticsects when administered resulted within many food. drug Historically, development the failures inability and to, along accurately with characterizeit, billions of a dollars drug’s in pharmacokinetics losses. Traditionally, resulted allometric in many scaling drugdevelopment was used to translate failures and,the data along obtained with it, billionsfrom the of preclinical dollars in losses. phase Traditionally,in drug development, allometric which scaling includes was used in tovitro translate and in the vivo data studies, obtained to fromfirst- thein-human preclinical studies. phase However, in drug development, this approach which does includes not addresin vitros theand interin vivo-speciesstudies, differences to first-in-human that are studies.critical to However, consider thisto accurately approach predict does not drug address pharmacokinetics the inter-species, including differences transporters that are and critical drug to- considermetabolizing to accurately enzymes predict [2]. Over drug the pharmacokinetics, past few decades, including there transportershas been an and evolution drug-metabolizing from non- enzymescompartm [2ental]. Over modeling the past fewto decades,complex therephysiologically has been an- evolutionbased pharmacokinetic from non-compartmental (PBPK) models modeling to toensure complex that physiologically-basedthe experimental drug pharmacokinetic will demonstrate (PBPK) safety modelsand clinical to ensure efficacy. that theThey experimental offer many drugapplications will demonstrate in pharmaceutical safety and research clinical throughout efficacy. They the omanyffer many phases applications of drug dev in pharmaceuticalelopment, from researchdiscovery throughout to phase III the clinical many trials. phases of drug development, from discovery to phase III clinical trials. FigureFigure 1.1. Drug pharmacokinetic profilesprofiles for the fasted and fed states. In the cases of no food effect, effect, changeschanges inin the the pharmacokinetic pharmacokinetic profile profile are minorare minor and within and within the normal the variationsnormal variation observeds followingobserved oralfollowing administration. oral administration. Positive food Positive effects food are associated effects are with associated increases with in systemic increases drug in systemic exposure drug and negativeexposure food and enegativeffects are food associated effects with are associated decreases inwith drug decreases exposure. in Adapted drug exposure. from reference Adapted [3 ].from reference [3]. PBPK models aim to mimic human anatomy and physiology through a series of interconnected compartments,PBPK models representative aim to mimic of physiologicalhuman
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