China
Africa
Explore chapters and articles related to this topic
Magnetic Nanoparticles: Challenges and Opportunities in Drug Delivery
Published in Jeffrey N. Anker, O. Thompson Mefford, Biomedical Applications of Magnetic Particles, 2020
Allan E. David, Mahaveer S. Bhojani, Adam J. Cole
In many cases, MNPs rely on the circulatory system (i.e. blood flow) in order to reach the target tissue. Nanoparticles, and indeed any other substance introduced into the body, have several possible fates; they may: (1) enter the blood circulation, (2) distribute into body tissues, (3) be degraded, or (4) be excreted from the body. This is often termed ADME, for absorption, distribution, metabolism, and excretion. The rate and extent to which each of these processes occurs determines the pharmacokinetics of the particle. Pharmacokinetics, a quantitative description of how a substance travels through the body, how the body acts upon it, and how it is eliminated from the body, are therefore an important consideration for design of MNP-based drug delivery systems. Surface properties and size of the MNP have the greatest impact on the particle’s pharmacokinetics (Yoo, Chambers, and Mitragotri 2010). These properties determine the extent of MNP interaction with the mononuclear phagocyte system (MPS), which is a part of the immune system comprised of a group of cells whose primary function is to eliminate foreign particles from the body. Note that in some texts, the MPS is referred to as the “reticuloendothelial system (RES),” but this is an older term that is no longer in favor as it gives incorrect prominence to endothelial cells, which do not play a major role in this process.
An Introduction to Risk Assessment with a Nod to History
Published in Ted W. Simon, Environmental Risk Assessment, 2019
Mathematical modeling of the distribution of chemicals in the body is also known as physiologically based toxicokinetic modeling. It is also known as ADME modeling, where ADME stands for Absorption, Distribution, Metabolism, and Excretion. Simply, PBPK modeling is a way of dividing up the body into functional compartments into which chemicals may accumulate or be metabolized and excreted. One of the best-known PBPK models is the Widmark model—this simple one-equation model is used for retrograde extrapolation of measured blood or breath alcohol levels in forensic evaluation of potential drunk driving cases. The Widmark model assumes the body is a single compartment and that elimination of alcohol occurs by a zero-order kinetic process. What this means is that a constant amount of alcohol is metabolized and excreted per time unit.
Assessment of Quercetin Isolated from Enicostemma Littorale Against Few Cancer Targets: An in Silico Approach
Published in A. K. Haghi, Ana Cristina Faria Ribeiro, Lionello Pogliani, Devrim Balköse, Francisco Torrens, Omari V. Mukbaniani, Applied Chemistry and Chemical Engineering, 2017
ADME-Tox refers to absorption, distribution, metabolism, excretion, and toxicity properties of failures for candidate molecules in drug design. The early evaluation of these properties during drug design could save time and money because certain properties make a drug different from other compounds. An appropriate concentration of the drug must circulate in the body for a reasonable length of time to achieve a desired beneficial effect with minimum adverse effects. For this process, oral drugs have to dissolve or suspend in the gastrointestinal tract and be absorbed through the gut wall to reach the blood stream though the liver. From there, the drug will be distributed to various tissues and organs and finally binds to its molecular target and exert its desired action. The drug is then subjected to hepatic metabolism followed by its elimination as bile or via the kidneys. Several pharmacokinetics properties are involved in this mechanism.
Plant pharmacology: Insights into in-planta kinetic and dynamic processes of xenobiotics
Published in Critical Reviews in Environmental Science and Technology, 2022
Tomer Malchi, Sara Eyal, Henryk Czosnek, Moshe Shenker, Benny Chefetz
Exposure to, or administration, of multiple drugs may result in pharmacokinetic or pharmacodynamic drug–drug interactions. Pharmacokinetic mechanisms of drug–drug interactions include alterations in the ADME process. Absorption is changed due to pH-altering drugs or drugs that act as chelators or adsorbents. Distribution is modified due to displacement from binding sites or modulation of transporter functions at blood–tissue barriers. Metabolism is altered due to activation or inhibition of specific enzymes, which is well documented for antiepileptic drugs (Ashraf & Lionel, 2012; Perucca, 2006). Pharmacodynamic interactions involve additive, antagonistic or synergistic effects at the receptor level. Additive interactions are when the effect of two drugs is the sum of the effect of the two chemicals taken individually. Antagonistic interactions are when one drug reduces or eliminates the effect of the other drug. Synergistic interactions are when the combined effect of two drugs is greater than the sum of the effects of each drug given alone (Jonker et al., 2005; Zheng, 2020). Nonspecific pharmacodynamic drug interactions can occur when two drugs react with different receptors of the sample complex or as a result of alterations in electrolyte balance and electrochemical potential (Buxton & Benet, 2013; Corrie & Hardman, 2014). Due to a lack of knowledge and data, pharmacodynamic drug–drug interactions are not well understood and are more difficult to predict than pharmacokinetic interactions.
Inhibitory effects of protopanaxatriol type ginsenoside fraction (Rgx365) on particulate matter-induced pulmonary injury
Published in Journal of Toxicology and Environmental Health, Part A, 2019
Wonhwa Lee, Sae-Kwang Ku, Ji-Eun Kim, Soo-Hyun Cho, Gyu-Yong Song, Jong-Sup Bae
Our findings demonstrated that prior to challenge with PM2.5, Rgx365 was administered po for 10 days to mice and noted to produce beneficial effects. If Rgx365 was given via iv route, two Rgx365 treatments were sufficient to show similar beneficial effects against PM2.5-induced vascular disruptive responses (data not shown). Four physiological factors absorption, distribution, metabolism, and excretion (ADME) need to be considered with respect to the disposition of a pharmaceutical compound within an organism and the effectiveness of the compound. These physiologic/pharmacokinetic factors all influence the Rgx365 levels and hence influence the performance and pharmacological activity of Rgx365. Therefore, for Rgx365 to reach a vascular tissue, it usually needs to be taken into the bloodstream prior and transported to target cells. Factors such as Rgx365 solubility, gastric emptying time, intestinal transit time, chemical instability in the stomach, and inability to permeate the intestinal wall might all reduce the extent to which Rgx365 is absorbed after oral administration. Absorption is a key factor in determining Rgx365‘s bioavailability. Subsequently, Rgx365 needs to be transported to its effector site, most often via the bloodstream. From there, Rgx365 may distribute into tissues and organs, usually to differing extent. After entry into the systemic circulation, Rgx365 is subjected to numerous distribution processes that tend to lower its plasma concentration. Finally, Rgx365 is catabolized and excreted. This may account for differences between po versus iv effects that were reported.