The Dose-response relationship describes the change in effect on an organism caused by differing levels of exposure (or doses) to a stressor (usually a chemical). In chemistry a stressor is something that either speeds up a Reaction rate or keeps the reaction rate the same A chemical substance is a Material with a definite chemical composition. This may apply to individuals (eg: a small amount has no observable effect, a large amount is fatal), or to populations (eg: how many people are affected at different levels of exposure). In Biology a population is the collection of inter-breeding organisms of a particular Species; in Sociology
Studying dose response, and developing dose response models, is central to determining "safe" and "hazardous" levels and dosages for drugs, potential pollutants, and other substances that humans are exposed to. A drug, broadly speaking is any chemical substance that when absorbed into the body Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus These conclusions are often the basis for public policy.
When the agent is radiation instead of a drug, this is called the exposure-response relationship. Radiation, as in Physics, is Energy in the form of waves or moving Subatomic particles emitted by an atom or other body as it changes from a higher energy
Dose-response curve
A dose-response curve is a simple X-Y graph relating the magnitude of a stressor (e. In Mathematics, the Cartesian coordinate system (also called rectangular coordinate system) is used to determine each point uniquely in a plane g. concentration of a pollutant, amount of a drug, temperature, intensity of radiation) to the response of the receptor (e. g. organism under study). The response is usually death (mortality), but other effects (or endpoints) can be studied.
The measured dose (usually in milligrams, micrograms, or grams per kilogram of body-weight) is generally plotted on the X axis and the response is plotted on the Y axis. For other uses of the words gram or gramme see Gram (disambiguation. Commonly, it is the logarithm of the dose that is plotted on the X axis, and in such cases the curve is typically sigmoidal, with the steepest portion in the middle. In Mathematics, the logarithm of a number to a given base is the power or Exponent to which the base must be raised in order to produce A sigmoid function is a Mathematical function that produces a sigmoid curve &mdash a curve having an "S" shape
The first point along the graph where a response above zero is reached is usually referred to as a threshold-dose. For most beneficial or recreational drugs, the desired effects are found at doses slightly greater than the threshold dose. At higher doses still, undesired side effects appear and grow stronger as the dose increases. The stronger a particular substance is, the steeper this curve will be. In quantitative situations, the Y-axis usually is designated by percentages, which refer to the percentage of users registering a standard response (which is often death, when the 50% mark refers to LD50). In Toxicology, the median lethal dose, LD50 (abbreviation for “Lethal Dose 50%” or LCt50 (Lethal Concentration & Time of a Such a curve is referred to as a quantal dose response curve, destinguishing it from a graded dose response curve, where response is continuous.
Problems exist regarding non-linear relationships between dose and response, thresholds reached and 'all-or-nothing' responses. These inconsistencies can challenge the validity of judging causality solely by the strength or presence of a dose-response relationship.
See also
- Pharmacodynamics
- Spatial epidemiology
- EC50
- IC50
- Certain safety factor
- Schild regression
- hormesis
- Arndt-Schulz rule
External links
Pharmacodynamics is the study of the Biochemical and Physiological effects of drugs on the body or on microorganisms or parasites within or on the body and the mechanisms Spatial Epidemiology is the study of the Spatial distribution of Disease. The term half maximal effective concentration ( EC50) refers to the concentration of a drug or antibody which induces a response halfway between the baseline and maximum The IC50 is a measure of the effectiveness of a compound in inhibiting biological or biochemical function The Certain Safety Factor is the ratio of the Lethal dose to 1% of population to the Effective dose to 99% of the population (LD1/ED99 Schild regression analysis, named for Heinz Otto Schild, is a useful tool for studying the effects of Agonists and antagonists on the cellular response caused by the Hormesis (from Hellenistic Greek hórmēsis "rapid motion eagerness" from ancient Greek hormáein "to set in motion impel urge on" is Arndt-Schulz rule or Schulz' law is a claimed law concerning the Effects of Pharmaca or Poisons in various concentrationsDapyx Software network: MP3 Explorer | Ebook Manager | Zenithic