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Absorption (pharmacokinetics)
Absorption is the journey of a drug travelling from the site of administration to the site of action. The drug travels by some route of administration ( oral, topical-dermal, etc.) in a chosen dosage form (e.g., tablets, capsules, or in solution). Absorption by some other routes, such as intravenous therapy, intramuscular injection, enteral nutrition, is even more straightforward and there is less variability in absorption and bioavailability is often near 100%. Intravascular administration does not involve absorption, and there is no loss of drug. The fastest route of absorption is inhalation. Absorption is a primary focus in drug development and medicinal chemistry, since a drug must be absorbed before any medicinal effects can take place. Moreover, the drug's pharmacokinetic profile can be easily and significantly changed by adjusting factors that affect absorption. Dissolution Oral ingestion is the most common route of administration of pharmaceuticals. Passin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Route Of Administration
In pharmacology and toxicology, a route of administration is the way by which a medication, drug, fluid, poison, or other substance is taken into the body. Routes of administration are generally classified by the location at which the substance is applied. Common examples include oral administration, oral and intravenous therapy, intravenous administration. Routes can also be classified based on where the target of action is. Action may be topical medication, topical (local), enteral administration, enteral (system-wide effect, but delivered through the gastrointestinal tract), or #Parenteral, parenteral (systemic action, but is delivered by routes other than the GI tract). Route of administration and dosage form are aspects of drug delivery. Classification Routes of administration are usually classified by application location (or exposition). The route or course the active substance takes from application location to the location where it has its target effect is usually rat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GI Tract
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus, stomach, and intestines. Food taken in through the mouth is digested to extract nutrients and absorb energy, and the waste expelled at the anus as feces. ''Gastrointestinal'' is an adjective meaning of or pertaining to the stomach and intestines. Most animals have a "through-gut" or complete digestive tract. Exceptions are more primitive ones: sponges have small pores ( ostia) throughout their body for digestion and a larger dorsal pore ( osculum) for excretion, comb jellies have both a ventral mouth and dorsal anal pores, while cnidarians and acoels have a single pore for both digestion and excretion. The human gast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stearic Acid
Stearic acid ( , ) is a saturated fatty acid with an 18-carbon chain. The IUPAC name is octadecanoic acid. It is a soft waxy solid with the formula . The triglyceride derived from three molecules of stearic acid is called stearin. Stearic acid is a prevalent fatty-acid in nature, found in many animal and vegetable fats, but is usually higher in animal fat than vegetable fat. It has a melting point of °C and a pKa of 4.50. Its name comes from the Greek word στέαρ "''stéar''", which means tallow. The salts and esters of stearic acid are called stearates. As its ester, stearic acid is one of the most common saturated fatty acids found in nature and in the food supply, following palmitic acid.Gunstone, F. D., John L. Harwood, and Albert J. Dijkstra "The Lipid Handbook with Cd-Rom. 3rd ed. Boca Raton: CRC Press, 2007. , Dietary sources of stearic acid include meat, poultry, fish, eggs, dairy products, and foods prepared with fats; beef tallow, lard, butterfat, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Esterification
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods. Esters can be formed from oxoacids (e.g. esters of acetic acid, carbonic acid, sulfu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymorphism (materials Science)
In crystallography, polymorphism is the phenomenon where a compound or element can crystallize into more than one crystal structure. The preceding definition has evolved over many years and is still under discussion today. Discussion of the defining characteristics of polymorphism involves distinguishing among types of transitions and structural changes occurring in polymorphism versus those in other phenomena. Overview Phase transitions (phase changes) that help describe polymorphism include polymorphic transitions as well as melting and vaporization transitions. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure." Additionally, Walter McCrone described the phases in polymorphic matter as "different in crystal structure but identical in the liquid or vapor states." McCrone also def ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Specific Surface Area
Specific surface area (SSA) is a property of solids defined as the total surface area (SA) of a material per unit mass, (with units of m2/kg or m2/g). Alternatively, it may be defined as SA per solid or bulk volume (units of m2/m3 or m−1). It is a physical value that can be used to determine the type and properties of a material (e.g. soil or snow). It has a particular importance for adsorption, heterogeneous catalysis, and reactions on surfaces. Measurement Values obtained for specific surface area depend on the method of measurement. In adsorption based methods, the size of the adsorbate molecule (the probe molecule), the exposed crystallographic planes at the surface and measurement temperature all affect the obtained specific surface area. For this reason, in addition to the most commonly used Brunauer–Emmett–Teller (N2-BET) adsorption method, several techniques have been developed to measure the specific surface area of particulate materials at ambient tempera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micronization
Micronization is the process of reducing the average diameter of a solid material's particles. Traditional techniques for micronization focus on mechanical means, such as milling and grinding. Modern techniques make use of the properties of supercritical fluids and manipulate the principles of solubility. The term micronization usually refers to the reduction of average particle diameters to the micrometer range, but can also describe further reduction to the nanometer scale. Common applications include the production of active chemical ingredients, foodstuff ingredients, and pharmaceuticals. These chemicals need to be micronized to increase efficacy. Traditional techniques Traditional micronization techniques are based on friction to reduce particle size. Such methods include milling, bashing and grinding. A typical industrial mill is composed of a cylindrical metallic drum that usually contains steel spheres. As the drum rotates the spheres inside collide with the particles of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffusion Layer
In electrochemistry, the diffusion layer, according to IUPAC, is defined as the "region in the vicinity of an electrode where the concentrations are different from their value in the bulk solution. The definition of the thickness of the diffusion layer is arbitrary because the concentration approaches asymptotically the value in the bulk solution". The diffusion layer thus depends on the diffusion coefficient () of the analyte and, for voltammetric measurements, on the scan rate (V/s). It is usually considered to be some multiple of \sqrt (where \tfrac 1 t = scan rate). The value is physically relevant since the concentration of solute varies according to the expression derived from Fick's laws: \frac=\operatorname\left(\frac\right) where is the error function In mathematics, the error function (also called the Gauss error function), often denoted by , is a function \mathrm: \mathbb \to \mathbb defined as: \operatorname z = \frac\int_0^z e^\,\mathrm dt. The integral he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coefficient
In mathematics, a coefficient is a Factor (arithmetic), multiplicative factor involved in some Summand, term of a polynomial, a series (mathematics), series, or any other type of expression (mathematics), expression. It may be a Dimensionless quantity, number without units, in which case it is known as a numerical factor. It may also be a constant (mathematics), constant with units of measurement, in which it is known as a constant multiplier. In general, coefficients may be any mathematical expression, expression (including Variable (mathematics), variables such as , and ). When the combination of variables and constants is not necessarily involved in a product (mathematics), product, it may be called a ''parameter''. For example, the polynomial 2x^2-x+3 has coefficients 2, −1, and 3, and the powers of the variable x in the polynomial ax^2+bx+c have coefficient parameters a, b, and c. A , also known as constant term or simply constant, is a quantity either implicitly attach ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffusion
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical potential. It is possible to diffuse "uphill" from a region of lower concentration to a region of higher concentration, as in spinodal decomposition. Diffusion is a stochastic process due to the inherent randomness of the diffusing entity and can be used to model many real-life stochastic scenarios. Therefore, diffusion and the corresponding mathematical models are used in several fields beyond physics, such as statistics, probability theory, information theory, neural networks, finance, and marketing. The concept of diffusion is widely used in many fields, including physics (Molecular diffusion, particle diffusion), chemistry, biology, sociology, economics, statistics, data science, and finance (diffusion of people, ideas, data and price v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Area
The surface area (symbol ''A'') of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of arc length of one-dimensional curves, or of the surface area for polyhedra (i.e., objects with flat polygonal faces), for which the surface area is the sum of the areas of its faces. Smooth surfaces, such as a sphere, are assigned surface area using their representation as parametric surfaces. This definition of surface area is based on methods of infinitesimal calculus and involves partial derivatives and double integration. A general definition of surface area was sought by Henri Lebesgue and Hermann Minkowski at the turn of the twentieth century. Their work led to the development of geometric measure theory, which studies various notions of surface area for irregular objects of any dimension. An important example is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noyes–Whitney Equation
Arthur Amos Noyes (September 13, 1866 – June 3, 1936) was an American chemist, inventor and educator, born in Newburyport, Massachusetts, son of Amos and Anna Page Noyes, née Andrews. He received a PhD in 1890 from Leipzig University under the guidance of Wilhelm Ostwald. He served as the acting president of MIT between 1907 and 1909 and as professor of chemistry at the California Institute of Technology from 1919 to 1936. "Although he Noyeslaboratory at MIT was like an institute in its intramural funding (from Carnegie Institute of Washington and Noyes's patent royalties), Noyes recruited many of his disciples as undergraduates and took a deep interest in undergraduate engineering education, both at MIT and later at Caltech. Roscoe Gilkey Dickinson was one of his famous students. Noyes was a major influence both on the educational philosophy of the core curriculum of Caltech as well as in the negotiations leading to the creation of the National Research Council along ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
