GABAA receptor positive allosteric modulator
In pharmacology, GABAA receptor positive allosteric modulators are positive allosteric modulator molecules that increase the activity of the GABAA receptor protein in the vertebrate central nervous system. GABA is a major inhibitory neurotransmitter in the central nervous system. Upon binding, it triggers the GABAA receptor to open its chloride channel to allow chloride ions into the neuron, making the cell hyperpolarized and less to fire. GABAA PAMs increase the effect of GABA by making the channel open more or for longer periods. However, they have no effect if another agonist is not present. Unlike GABAA receptor agonists, GABAA PAMs do not bind at the same active site as the γ-Aminobutyric acid neurotransmitter molecule: they affect the receptor by binding at a different site on the protein; this is called allosteric modulation. In psychopharmacology, GABAA receptor PAMs used as drugs have sedative and anxiolytic effects. Examples of GABAA PAMs include alcohol, benzodiazepines such as diazepam and alprazolam, Z-drugs such as zolpidem and the barbiturate drugs.
The GABAA receptors have been a target of drug treatment research. The earliest compounds were ions, such as bromide. In 1903, the first psychoactive derivative of barbituric acid was synthesized and marketed for headaches. Within 30 years, many other barbiturates were developed and found use as sedatives, sleep aids and general anesthetics. Although barbiturates fell out of favor, they continue to serve as a short-acting anesthetic and anti-epileptic drugs. Benzodiazepines were discovered in 1948 and replaced the barbiturates because of their larger therapeutic index. At first benzodiazepines were considered to be safe and efficient minor tranquilizers but were criticized for their dependence producing effects. Several efficient benzodiazepines offer choices about dosage form, length of action, metabolic interaction and safety. Benzodiazepines function by binding to the benzodiazepine site on most, but not all, GABAA receptors. GABAA modulation by benzodiazepine site agonists is self-limiting.
The channel conductance is not higher in the presence of benzodiazepine and GABA than the conductance with the presence of only high GABA concentrations. Additionally, in the absence of GABA the presence of benzodiazepines alone does not open the chloride channel. Certain metabolites of progesterone and deoxycorticosterone are potent and selective positive allosteric modulators of the γ-aminobutyric acid type A receptor. Hans Selye demonstrated in the 1940 that certain pregnane steroids could cause both anesthesia and sedation but 40 years the molecular mechanism emerged to explain their depressant effect. In a rat brain slice preparation, the synthetic steroidal anesthetic alphaxalone enhanced both stimulus-evoked inhibition and the effects of exogenously applied muscimol, a GABAA selective agonist; the GABAA receptors are made up of subunits. Humans have 19 receptor subunits and are classified into α, β, γ, δ, ε, π, θ, ρ; the function of the receptor is different according to. The most common complex that includes around 40% of the GABAA receptors is the α1β2γ2 combination.
The expression of the subunits can be different depending on brain region. The combination of the subunits influences. For example, if the α1 and β2 subunits are expressed together they have high sensitivity to GABA, but low channel conductance, but if the γ2 is expressed with α1 and β2 the sensitivity is low and channel conductance is high. Γ2 subunit has to be present for high affinity binding of benzodiazepine. Little is known about where different complexes are located in the brain, complicating drug discovery. For example, the binding site of neurosteroids in the GABAA receptor is not known and barbiturates bind at a beta subunit, distinct from the benzodiazepine binding site. Alcohols Barbiturates Benzodiazepines Nonbenzodiazepines Barbiturates' precise action sites have not yet been defined; the second and third transmembrane domains of the β subunit appear to be critical. Barbiturates were introduced as hypnotics for patients with schizophrenia, it induced a state of prolonged sleep. But this was not used for long because of adverse side effects.
Phenobarbital was the first effective drug against epilepsy. It was discovered by accident; the positive side effects were anticonvulsant properties that reduced seizure intensity. Pentobarbital is used as a hypnotic. It´s used in CT imaging when sedation is needed, it is efficient and the recovery time is short. In 2013 the barbiturates phenobarbital and butabarbital are still used as sedatives in certain cases as well as to antagonize the effects of drugs as ephedrine and theophylline. Phenobarbital is used in cases of drug withdrawal syndromes, it is used as normal and emergency treatment in some cases of epilepsy. Synaptic action of benzodiazepines: GABAA receptors located at synapses are activated when they are exposed to high concentration of GABA. Benzodiazepines enhance the receptor affinity for GABA by decreasing the decay of spontaneous miniature inhibitory postsynaptic currents. Sedative actions of benzodiazepines limit their usefulness as analgesic agents and they are therefore not considered to be appropriate.
This limitation can be bypassed by intrathecal administration. GABAA receptors in the periaqueductal gray are pro-nociceptive at
The Jmol applet, among other abilities, offers an alternative to the Chime plug-in, no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, the Sculpt mode. Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS 9. Jmol operates on a wide variety of platforms. For example, Jmol is functional in Mozilla Firefox, Internet Explorer, Google Chrome, Safari. Chemistry Development Kit Comparison of software for molecular mechanics modeling Jmol extension for MediaWiki List of molecular graphics systems Molecular graphics Molecule editor Proteopedia PyMOL SAMSON Official website Wiki with listings of websites and moodles Willighagen, Egon. "Fast and Scriptable Molecular Graphics in Web Browsers without Java3D". Doi:10.1038/npre.2007.50.1
In chemistry, an alcohol is any organic compound in which the hydroxyl functional group is bound to a carbon. The term alcohol referred to the primary alcohol ethanol, used as a drug and is the main alcohol present in alcoholic beverages. An important class of alcohols, of which methanol and ethanol are the simplest members, includes all compounds for which the general formula is CnH2n+1OH, it is these simple monoalcohols. The suffix -ol appears in the IUPAC chemical name of all substances where the hydroxyl group is the functional group with the highest priority; when a higher priority group is present in the compound, the prefix hydroxy- is used in its IUPAC name. The suffix -ol in non-IUPAC names typically indicates that the substance is an alcohol. However, many substances that contain hydroxyl functional groups have names which include neither the suffix -ol, nor the prefix hydroxy-. Alcohol distillation originated in India. During 2000 BCE, people of India used. Alcohol distillation was known to Islamic chemists as early as the eighth century.
The Arab chemist, al-Kindi, unambiguously described the distillation of wine in a treatise titled as "The Book of the chemistry of Perfume and Distillations". The Persian physician, alchemist and philosopher Rhazes is credited with the discovery of ethanol; the word "alcohol" is from a powder used as an eyeliner. Al- is the Arabic definite article, equivalent to the in English. Alcohol was used for the fine powder produced by the sublimation of the natural mineral stibnite to form antimony trisulfide Sb2S3, it was considered to be the essence or "spirit" of this mineral. It was used as an antiseptic and cosmetic; the meaning of alcohol was extended to distilled substances in general, narrowed to ethanol, when "spirits" was a synonym for hard liquor. Bartholomew Traheron, in his 1543 translation of John of Vigo, introduces the word as a term used by "barbarous" authors for "fine powder." Vigo wrote: "the barbarous auctours use alcohol, or alcofoll, for moost fine poudre."The 1657 Lexicon Chymicum, by William Johnson glosses the word as "antimonium sive stibium."
By extension, the word came to refer to any fluid obtained by distillation, including "alcohol of wine," the distilled essence of wine. Libavius in Alchymia refers to "vini alcohol vel vinum alcalisatum". Johnson glosses alcohol vini as "quando omnis superfluitas vini a vino separatur, ita ut accensum ardeat donec totum consumatur, nihilque fæcum aut phlegmatis in fundo remaneat." The word's meaning became restricted to "spirit of wine" in the 18th century and was extended to the class of substances so-called as "alcohols" in modern chemistry after 1850. The term ethanol was invented 1892, combining the word ethane with the "-ol" ending of "alcohol". IUPAC nomenclature is used in scientific publications and where precise identification of the substance is important in cases where the relative complexity of the molecule does not make such a systematic name unwieldy. In naming simple alcohols, the name of the alkane chain loses the terminal e and adds the suffix -ol, e.g. as in "ethanol" from the alkane chain name "ethane".
When necessary, the position of the hydroxyl group is indicated by a number between the alkane name and the -ol: propan-1-ol for CH3CH2CH2OH, propan-2-ol for CH3CHCH3. If a higher priority group is present the prefix hydroxy-is used, e.g. as in 1-hydroxy-2-propanone. In cases where the OH functional group is bonded to an sp2 carbon on an aromatic ring the molecule is known as a phenol, is named using the IUPAC rules for naming phenols. In other less formal contexts, an alcohol is called with the name of the corresponding alkyl group followed by the word "alcohol", e.g. methyl alcohol, ethyl alcohol. Propyl alcohol may be n-propyl alcohol or isopropyl alcohol, depending on whether the hydroxyl group is bonded to the end or middle carbon on the straight propane chain; as described under systematic naming, if another group on the molecule takes priority, the alcohol moiety is indicated using the "hydroxy-" prefix. Alcohols are classified into primary and tertiary, based upon the number of carbon atoms connected to the carbon atom that bears the hydroxyl functional group.
The primary alcohols have general formulas RCH2OH. The simplest primary alcohol is methanol, for which R=H, the next is ethanol, for which R=CH3, the methyl group. Secondary alcohols are those of the form RR'CHOH, the simplest of, 2-propanol. For the tertiary alcohols the general form is RR'R"COH; the simplest example is tert-butanol, for which each of R, R', R" is CH3. In these shorthands, R, R', R" represent substituents, alkyl or other attached organic groups. In archaic nomenclature, alcohols can be named as derivatives of methanol using "-carbinol" as the ending. For instance, 3COH can be named trimethylcarbinol. Alcohols have a long history of myriad uses. For simple mono-alcohols, the focus on this article, the following are most important industrial alcohols: methanol for the production of formaldehyde and as a fuel additive ethanol for alcoholic beverages, fuel additive, solvent 1-propanol, 1-butanol, isobutyl alcohol for use as a solvent a
European Chemicals Agency
The European Chemicals Agency is an agency of the European Union which manages the technical and administrative aspects of the implementation of the European Union regulation called Registration, Evaluation and Restriction of Chemicals. ECHA is the driving force among regulatory authorities in implementing the EU's chemicals legislation. ECHA helps companies to comply with the legislation, advances the safe use of chemicals, provides information on chemicals and addresses chemicals of concern, it is located in Finland. The agency headed by Executive Director Bjorn Hansen, started working on 1 June 2007; the REACH Regulation requires companies to provide information on the hazards and safe use of chemical substances that they manufacture or import. Companies register this information with ECHA and it is freely available on their website. So far, thousands of the most hazardous and the most used substances have been registered; the information is technical but gives detail on the impact of each chemical on people and the environment.
This gives European consumers the right to ask retailers whether the goods they buy contain dangerous substances. The Classification and Packaging Regulation introduces a globally harmonised system for classifying and labelling chemicals into the EU; this worldwide system makes it easier for workers and consumers to know the effects of chemicals and how to use products safely because the labels on products are now the same throughout the world. Companies need to notify ECHA of the labelling of their chemicals. So far, ECHA has received over 5 million notifications for more than 100 000 substances; the information is available on their website. Consumers can check chemicals in the products. Biocidal products include, for example, insect disinfectants used in hospitals; the Biocidal Products Regulation ensures that there is enough information about these products so that consumers can use them safely. ECHA is responsible for implementing the regulation; the law on Prior Informed Consent sets guidelines for the import of hazardous chemicals.
Through this mechanism, countries due to receive hazardous chemicals are informed in advance and have the possibility of rejecting their import. Substances that may have serious effects on human health and the environment are identified as Substances of Very High Concern 1; these are substances which cause cancer, mutation or are toxic to reproduction as well as substances which persist in the body or the environment and do not break down. Other substances considered. Companies manufacturing or importing articles containing these substances in a concentration above 0,1% weight of the article, have legal obligations, they are required to inform users about the presence of the substance and therefore how to use it safely. Consumers have the right to ask the retailer whether these substances are present in the products they buy. Once a substance has been identified in the EU as being of high concern, it will be added to a list; this list is available on ECHA's website and shows consumers and industry which chemicals are identified as SVHCs.
Substances placed on the Candidate List can move to another list. This means that, after a given date, companies will not be allowed to place the substance on the market or to use it, unless they have been given prior authorisation to do so by ECHA. One of the main aims of this listing process is to phase out SVHCs where possible. In its 2018 substance evaluation progress report, ECHA said chemical companies failed to provide “important safety information” in nearly three quarters of cases checked that year. "The numbers show a similar picture to previous years" the report said. The agency noted that member states need to develop risk management measures to control unsafe commercial use of chemicals in 71% of the substances checked. Executive Director Bjorn Hansen called non-compliance with REACH a "worry". Industry group CEFIC acknowledged the problem; the European Environmental Bureau called for faster enforcement to minimise chemical exposure. European Chemicals Bureau Official website
Tert-Butyl alcohol called tert-butanol or t-butanol, is the simplest tertiary alcohol, with a formula of 3COH. It is one of the four isomers of butanol. Tert-Butyl alcohol is a colorless solid, which melts near room temperature and has a camphor-like odor, it is miscible with water and diethyl ether. Tert-Butyl alcohol has been identified in beer and chickpeas, it is found in cassava, used as a fermentation ingredient in certain alcoholic beverages. Tert-Butyl alcohol is derived commercially from isobutane as a coproduct of propylene oxide production, it can be produced by the catalytic hydration of isobutylene, or by a Grignard reaction between acetone and methylmagnesium chloride. Purification cannot be performed by simple distillation due to formation of an azeotrope with water, although initial drying of the solvent containing large amounts of water is performed by adding benzene to form a tertiary azeotrope and distilling off the water. Smaller amounts of water are removed by drying with calcium oxide, potassium carbonate, calcium sulfate, or magnesium sulfate, followed by fractional distillation.
Anhydrous tert-butyl alcohol is obtained by further refluxing and distilling from magnesium activated with iodine, or alkali metals such as sodium or potassium. Other methods include the use of 4 Å molecular sieves, aluminium tert-butylate, calcium hydride, or fractional crystallization under inert atmosphere. Tert-Butyl alcohol is used as a solvent, ethanol denaturant, paint remover ingredient, gasoline octane booster and oxygenate, it is a chemical intermediate used to produce methyl tert-butyl ether and ethyl tert-butyl ether by reaction with methanol and ethanol and tert-butyl hydroperoxide by reaction with hydrogen peroxide. As a tertiary alcohol, tert-butyl alcohol is more resistant to oxidation and less reactive than the other isomers of butanol; when tert-butyl alcohol is deprotonated with a strong base, the product is an alkoxide anion. In this case, it is tert-butoxide. For example, the used organic reagent potassium tert-butoxide is prepared by refluxing dry tert-butanol with potassium metal.
K + t-BuOH → t-BuO−K+ + 1/2 H2The tert-butoxide is a strong, non-nucleophilic base in organic chemistry. It abstracts acidic protons from substrates, but its steric bulk inhibits the group from participating in nucleophilic substitution, such as in a Williamson ether synthesis or an SN2 reaction. Tert-Butyl alcohol reacts with hydrogen chloride to form tert-butyl chloride, it reacts with sodium in liquid ammonia. There is limited data on the pharmacology and toxicology of tert-butanol in humans and other animals. Human exposure may occur due to fuel oxygenate metabolism. Tert-butanol is poorly absorbed through skin but absorbed if inhaled or ingested. Tert-butanol is irritating to skin or eyes. Toxicity of single doses is low but high doses can produce a sedative or anesthetic effect. International Chemical Safety Card 0114 NIOSH Pocket Guide to Chemical Hazards. "#0078". National Institute for Occupational Safety and Health. IPCS Environmental Health Criteria 65: Butanols: four isomers IPCS Health and Safety Guide 7: tert-Butanol
Hypnotic or soporific drugs known as sleeping pills, are a class of psychoactive drugs whose primary function is to induce sleep and to be used in the treatment of insomnia, or for surgical anesthesia. This group is related to sedatives. Whereas the term sedative describes drugs that serve to calm or relieve anxiety, the term hypnotic describes drugs whose main purpose is to initiate, sustain, or lengthen sleep; because these two functions overlap, because drugs in this class produce dose-dependent effects they are referred to collectively as sedative-hypnotic drugs. Hypnotic drugs are prescribed for insomnia and other sleep disorders, with over 95% of insomnia patients being prescribed hypnotics in some countries. Many hypnotic drugs are habit-forming and, due to a large number of factors known to disturb the human sleep pattern, a physician may instead recommend changes in the environment before and during sleep, better sleep hygiene, the avoidance of caffeine or other stimulating substances, or behavioral interventions such as cognitive behavioral therapy for insomnia before prescribing medication for sleep.
When prescribed, hypnotic medication should be used for the shortest period of time necessary. Among individuals with sleep disorders, 13.7% are taking or prescribed nonbenzodiazepines, while 10.8% are taking benzodiazepines, as of 2010. Early classes of drugs, such as barbiturates, have fallen out of use in most practices but are still prescribed for some patients. In children, prescribing hypnotics is not yet acceptable unless used to treat night terrors or somnambulism. Elderly people are more sensitive to potential side effects of daytime fatigue and cognitive impairments, a meta-analysis found that the risks outweigh any marginal benefits of hypnotics in the elderly. A review of the literature regarding benzodiazepine hypnotics and Z-drugs concluded that these drugs can have adverse effects, such as dependence and accidents, that optimal treatment uses the lowest effective dose for the shortest therapeutic time period, with gradual discontinuation in order to improve health without worsening of sleep.
Falling outside the above-mentioned categories, the neuro-hormone melatonin has a hypnotic function. Hypnotica was a class of somniferous drugs and substances tested in medicine of the 1890s and including: Urethan, Methylal, paraldehyde, Hypnon and Ohloralamid or Chloralimid. Research about using medications to treat insomnia evolved throughout the last half of the 20th century. Treatment for insomnia in psychiatry dates back to 1869 when chloral hydrate was first used as a soporific. Barbiturates emerged as the first class of drugs that emerged in the early 1900s, after which chemical substitution allowed derivative compounds. Although the best drug family at the time they were dangerous in overdose and tended to cause physical and psychological dependence. During the 1970s, quinazolinones and benzodiazepines were introduced as safer alternatives to replace barbiturates. Benzodiazepines are not without their drawbacks. Questions have been raised as to. Nonbenzodiazepines are the most recent development.
Although it's clear that they are less toxic than their predecessors, comparative efficacy over benzodiazepines have not been established. Without longitudinal studies, it is hard to determine. Other sleep remedies that may be considered "sedative-hypnotics" exist. Examples of these include mirtazapine, clonidine and the over-the-counter sleep aid diphenhydramine. Off-label sleep remedies are useful when first-line treatment is unsuccessful or deemed unsafe. Barbiturates are drugs that act as central nervous system depressants, can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia, they are effective as anxiolytics and anticonvulsalgesic effects. They have dependence liability, both psychological. Barbiturates have now been replaced by benzodiazepines in routine medical practice – for example, in the treatment of anxiety and insomnia – because benzodiazepines are less dangerous in overdose. However, barbiturates are still used in general anesthesia, for epilepsy, assisted suicide.
Barbiturates are derivatives of barbituric acid. The principal mechanism of action of barbiturates is believed to be positive allosteric modulation of GABAA receptors. Examples include amobarbital, phenobarbital and sodium thiopental. Quinazolinones are a class of drugs which function as hypnotic/sedatives that contain a 4-quinazolinone core, their use has been proposed in the treatment of cancer. Examples of quinazolinones include cloroqualone, etaqualone, mebroqualone and methaqualone. Benzodiaz
Regulation of therapeutic goods
The regulation of therapeutic goods, drugs and therapeutic devices, varies by jurisdiction. In some countries, such as the United States, they are regulated at the national level by a single agency. In other jurisdictions they are regulated at the state level, or at both state and national levels by various bodies, as is the case in Australia; the role of therapeutic goods regulation is designed to protect the health and safety of the population. Regulation is aimed at ensuring the safety and efficacy of the therapeutic goods which are covered under the scope of the regulation. In most jurisdictions, therapeutic goods must be registered. There is some degree of restriction of the availability of certain therapeutic goods depending on their risk to consumers. Modern drug regulation has historical roots in the response to the proliferation of universal antidotes which appeared in the wake of Mithridates' death. Mithridates had brought together physicians and shamans to concoct a potion that would make him immune to poisons.
Following his death, the Romans became keen on further developing the Mithridates potion's recipe. Mithridatium re-entered western society through multiple means; the first was through the Leechbook of the Bald, written somewhere between 900 and 950, which contained a formula for various remedies, including for a theriac. Additionally, theriac became a commercial good traded throughout Europe based on the works of Greek and Roman physicians; the resulting proliferation of various recipes needed to be curtailed in order to ensure that people were not passing off fake antidotes, which led to the development of government involvement and regulation. Additionally, the creation of these concoctions took on ritualistic form and were created in public and the process was observed and recorded, it was believed that if the concoction proved unsuccessful, it was due to the apothecaries’ process of making them and they could be held accountable because of the public nature of the creation. In the 9th century, many Muslim countries established an office of the hisba, which in addition to regulating compliance to Islamic principles and values took on the role of regulating other aspects of social and economic life, including the regulation of medicines.
Inspectors were appointed to employ oversight on those who were involved in the process of medicine creation and were given a lot of leigh weigh to ensure compliance and punishments were stringent. The first official'act', the'Apothecary Wares and Stuffs' Act was passed in 1540 by Henry VIII and set the foundation for others. Through this act, he encouraged physicians in his College of Physicians to appoint four people dedicated to inspecting what was being sold in apothecary shops. In conjunction with this first piece of legislation, there was an emergence of standard formulas for the creation of certain ‘drugs’ and ‘antidotes’ through Pharmacopoeias which first appeared in the form of a decree from Frederick II of Sicily in 1240 to use consistent and standard formulas; the first modern pharmacopoeias were the Florence Pharmacopoeia published in 1498, the Spanish Pharmacopoeia published in 1581 and the London Pharmacopoeia published in 1618. In the United States, regulation of drugs was a state right, as opposed to federal right.
But with the increase in fraudulent practices due to private incentives to maximize profits and poor enforcement of state laws, increased the need for stronger federal regulation. President Roosevelt signed the Federal Food and Drug Act in 1906 which established stricter standards. A 1911 Supreme Court decision, United States vs. Johnson, established that misleading statements were not covered under the FFDA; this directly led to Congress passing the Sherley Amendment which established a clearer definition of ‘misbranded’. Another key catalyst for advances in drug regulation were certain catastrophes that served as calls to the government to step in and impose regulations that would prevent repeats of those instances. One such instance occurred in 1937 when more than a hundred people died from using sulfanilamide elixir which had not gone through any safety testing; this directly led to the passing of the Federal, Food and Cosmetic Act in 1938. One other major catastrophe occurred in the late 1950s when Thalidomide, sold in Germany and sold around the world, led to 100,000 babies being born with various deformities.
The UK's Chief Medical Officer had established a group to look into safety of drugs on the market in 1959 prior to the crisis and was moving in the direction of address the problem of unregulated drugs entering the market. The crisis created a greater sense of emergency to establish safety and efficacy standards around the world; the UK started a temporary Committee on Safety of Drugs while they attempted to pass more comprehensive legislation. Though compliance and submission of drugs to the Committee on Safety of Drugs was not mandatory after, the pharmaceutical industry larger complied due to the thalidomide situation; the European Economic Commission passed a directive in 1965 in order to impose greater efficacy standards before marketing a drug. The United States congress passed the Drug Amendments Act of 1962 The Drug Amendments Act required the FDA to ensure that new drugs being introduced to the market had passed certain tests and standards. Both the EU and US acts introduced the requirements to ensure efficacy.
Of note, increased regulations and standards for testing led to greater innovation in pharm