Everything below concerns certificate of analysis. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-11-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L cells after food intake. The molecule is a 31-amino-acid backbone modified at three positions to resist cleavage by dipeptidyl peptidase-4, the enzyme that degrades native GLP-1 within minutes. A lysine residue at position 26 carries a linker and a C18 fatty diacid, which promotes binding to serum albumin and slows renal clearance. These changes extend the circulating half-life from roughly two minutes to about one week in humans.
The sequence incorporates alpha-aminoisobutyric acid at position 8, replacing the alanine found in the natural hormone. This substitution blocks the primary DPP-4 recognition site and contributes most of the enzymatic stability. Albumin binding further protects the peptide and reduces the frequency of administration required to maintain active plasma levels. Because the fatty acid chain increases lipophilicity, the compound is formulated as a solution rather than a simple aqueous buffer. Researchers describe the design as an incremental optimization of earlier GLP-1 analogs rather than a wholly new scaffold.
Reported molecular weight is approximately 4113.6 daltons for the free base, and the peptide is supplied as a lyophilized powder or in buffered liquid form depending on the intended use. It is freely soluble in water when formulated with appropriate excipients, though the unconjugated peptide shows limited stability at neutral pH over long periods. Analytical characterization typically relies on reversed-phase high-performance liquid chromatography and mass spectrometry. Purity specifications for research-grade material commonly exceed ninety-five percent by area. Isotopic and impurity profiles differ between suppliers.
Quality control for research material typically involves reversed-phase HPLC for purity and identity, mass spectrometry for molecular weight confirmation, and Karl Fischer titration for residual water content. Peptide content is often reported as the mass of actual peptide rather than total powder mass, since counterions and water contribute to the latter. A certificate of analysis should list the method used for each specification. Limits and acceptance criteria vary by supplier and by intended application.
Handling practices center on minimizing contamination and adsorption. Lyophilized peptide tends to accumulate static charge, so weighing is done with antistatic measures and calibrated balances. Reconstitution with appropriate solvent should be gentle, avoiding vigorous vortexing that generates foam and shear. Solutions are typically aliquoted before freezing to reduce repeated temperature cycling. Personal protective equipment and a fume hood are standard for powder handling.
Reconstituted solutions are less stable than the dry powder, and stability depends on concentration, pH, buffer composition, and container material. Low-protein-binding tubes reduce loss of peptide to plastic surfaces. Some researchers add a carrier protein to limit adsorption at low concentrations. The exact shelf life of a given solution is best determined empirically through a stability study rather than assumed from general guidance, because published data cover only a limited set of conditions.
| Property | Value | Notes |
|---|---|---|
| Molecular formula (free base) | C187H291N45O59 | Approximate; salt and hydrate forms differ |
| Molecular weight | ~4113.6 Da | Varies with counterion and hydration |
| Appearance | White to off-white powder | Lyophilized research material |
| Solubility class | Freely soluble in water | As formulated; native peptide less stable near neutral pH |
| Typical storage | 2 to 8 degrees Celsius | Protect from light; avoid repeated freeze-thaw |
Storage at minus 20 degrees Celsius or lower in a desiccated container preserves the peptide for extended periods, while working solutions are commonly held at two to eight degrees Celsius for short intervals. Light exposure and repeated freeze-thaw cycles accelerate degradation, so dividing material into single-use aliquots is generally recommended. Adsorption to glass and plastic surfaces can lower the measured concentration of dilute solutions, particularly below one milligram per millilitre. The degradation routes most often reported for GLP-1 analogues are deamidation, methionine oxidation, and backbone hydrolysis. Relative rates under specific conditions are frequently described only for individual formulations.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 or 280 nanometres is widely used to assess purity and to resolve related impurities. Liquid chromatography coupled to mass spectrometry confirms identity through the protonated molecular ion and fragment ions formed in tandem experiments. Capillary electrophoresis and peptide mapping after enzymatic digestion supply complementary information on charge variants and modification sites. Circular dichroism and nuclear magnetic resonance can report on secondary structure in solution. Absolute quantification usually depends on an external standard, and reported purity depends on the detection wavelength and integration parameters chosen.
Lyophilised material appears as a white to off-white cake or powder that is hygroscopic, and containers are usually equilibrated to room temperature before opening to limit condensation. Dissolution is performed in water, phosphate-buffered saline, or a mildly alkaline buffer, since solubility rises above neutral pH. Gentle inversion or low-speed mixing is preferred, because vigorous vortexing can promote surface denaturation and aggregation. Complete dissolution may require several minutes, and brief sonication is sometimes applied. Passing the solution through a 0.22 micrometre membrane removes particulates but does not by itself sterilise the liquid.
Development began in the early 2010s with the goal of extending GLP-1 activity beyond the brief window achieved by native peptide infusion. The earliest approved formulation was a subcutaneous injection given once weekly. A later oral tablet pairs the peptide with an absorption enhancer, sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, usually shortened to SNAC. That carrier lowers local pH and helps the peptide cross gastric tissue. Both routes deliver the same active molecule.
Semaglutide is a synthetic peptide analog of human glucagon-like peptide-1, a gut hormone released after meals. Its backbone retains the GLP-1 sequence but incorporates two substitutions that slow enzymatic breakdown by dipeptidyl peptidase-4. A short polyethylene glycol linker and a C18 fatty diacid are attached to the peptide chain, allowing the molecule to bind serum albumin and remain in circulation far longer than the native hormone. The result is a circulating half-life measured in days rather than the minutes typical of endogenous GLP-1.
Receptor activation occurs at GLP-1 receptors distributed across pancreatic islets, the hypothalamus, and the gastrointestinal tract. Binding triggers G protein signaling that raises cyclic AMP and enhances glucose-dependent insulin release. Because the effect depends on prevailing glucose levels, insulin secretion does not rise when blood sugar is already low. Signaling in the brain and gut also influences appetite and gastric emptying, which is why the compound appears in both metabolic and weight-related research literature.
Identity and purity are usually assessed by reverse-phase high-performance liquid chromatography coupled to mass spectrometry. Retention time and observed mass are compared against a reference standard run under identical conditions. Impurity profiles reveal deamidation products, oxidized methionine variants, and truncated fragments that arise during synthesis or storage. Peptide mapping through enzymatic digestion confirms the primary sequence, while amino acid analysis offers an independent check on overall composition.
Stability studies examine how temperature, pH, and moisture influence degradation rates over time. In aqueous solution, hydrolysis and deamidation accelerate as pH moves away from mildly acidic conditions. Light exposure and residual metal ions can also trigger oxidation of susceptible residues. Accelerated aging at elevated temperature is used to estimate shelf life, though extrapolation to room temperature carries uncertainty because individual degradation pathways do not always scale predictably.
=== Confirmation === In December 2015, the Joint Working Party of international scientific bodies International Union of Pure and Applied Chemistry (IUPAC) and International Union of Pure and Applied Physics (IUPAP) recognized the element's discovery and assigned the priority of the discovery to the Dubna–Livermore collaboration. This was on account of two 2009 and 2010 confirmations of the properties of the granddaughter of 294Og, 286Fl, at the Lawrence Berkeley National Laboratory, as well as the observation of another consistent decay chain of 294Og by the Dubna group in 2012. The goal of that experiment had been the synthesis of 294Ts via the reaction 249Bk(48Ca,3n), but the short half-life of 249Bk resulted in a significant quantity of the target having decayed to 249Cf, resulting in the synthesis of oganesson instead of tennessine. From 1 October 2015 to 6 April 2016, the Dubna team performed a similar experiment with 48Ca projectiles aimed at a mixed-isotope californium target containing 249Cf, 250Cf, and 251Cf, with the aim of producing the heavier oganesson isotopes 295Og and 296Og. Two beam energies at 252 MeV and 258 MeV were used. Only one atom was seen at the lower beam energy, whose decay chain fitted the previously known one of 294Og (terminating with spontaneous fission of 286Fl), and none were seen at the higher beam energy. The experiment was then halted, as the glue from the sector frames covered the target and blocked evaporation residues from escaping to the detectors.
In the second half of the century the ideas of population genetics began to be applied in the new discipline of the genetics of behavior, sociobiology, and, especially in humans, evolutionary psychology. In the 1960s W.D. Hamilton and others developed game theory approaches to explain altruism from an evolutionary perspective through kin selection. The possible origin of higher organisms through endosymbiosis, and contrasting approaches to molecular evolution in the gene-centered view (which held selection as the predominant cause of evolution) and the neutral theory (which made genetic drift a key factor) spawned perennial debates over the proper balance of adaptationism and contingency in evolutionary theory. In the 1970s Stephen Jay Gould and Niles Eldredge proposed the theory of punctuated equilibrium which holds that stasis is the most prominent feature of the fossil record, and that most evolutionary changes occur rapidly over relatively short periods of time. In 1980 Luis Alvarez and Walter Alvarez proposed the hypothesis that an impact event was responsible for the Cretaceous–Paleogene extinction event. Also in the early 1980s, statistical analysis of the fossil record of marine organisms published by Jack Sepkoski and David M. Raup led to a better appreciation of the importance of mass extinction events to the history of life on earth.
=== Gene expression === PLP has been implicated in increasing or decreasing the expression of certain genes. Increased intracellular levels of the vitamin lead to a decrease in the transcription of glucocorticoids. Vitamin B6 deficiency leads to the increased gene expression of albumin mRNA. Also, PLP influences expression of glycoprotein IIb by interacting with various transcription factors; the result is inhibition of platelet aggregation.
Sources: en.wikipedia.org
===== North America ===== Canada - DMT is classified as a Schedule III drug under the Controlled Drugs and Substances Act, but is legal for religious groups to use. In 2017 the Santo Daime Church Céu do Montréal received religious exemption to use ayahuasca as a sacrament in their rituals. United States - DMT is classified in the United States as a Schedule I drug under the Controlled Substances Act of 1970. In 2019, it was decriminalized, along with other naturally derived psychedelics, in the city of Oakland after a campaign by Decriminalize Nature.
=== 2000 === 13 March The Secret Life of the Crash Test Dummy, about the biomechanics of car crashes; a typical crash test dummy cost around £100,000, with about three hundred individual parts, that had to be included by safety law, and new cars could not be sold until the dummy had tested it sufficiently; the Volvo 300 1980s television advert; Lt-Col Wayne Mattson of the USAF and a strange crash in New Mexico, one hundred miles north of the Trinity (nuclear test), and near White Sands Missile Range, where German V-2 missiles were being tested, which were conveniently blamed by the USAF on anthropomorphic dummies; John Melvin (engineer) and the legacy of USAF biophysicist and doctor Colonel John Stapp, who mostly invented aviation safety testing; John Stapp conducted gruesome horrific deceleration tests on himself; Alderson had made artificial limbs for injured USAF World War II pilots, so made a full artificial proto-human; John Stapp tested his dummies in vehicles; Clarence Ditlow and the Center for Auto Safety; in 1966 it became legal in the US for new cars to have been tested by dummies; mathematical models of injury were needed, to translate the acquired crash data into possible effects on the human body, worked out by mechanical engineer Walter Pilkey of the University of Virginia; Scottish orthopaedic surgeon Angus Wallace and impact speed on bone tensile strength; in 1976 the Hybrid III dummy was designed, the automotive industry standard design; David Abbott, advertising executive; the data for designing the crash test dummy, Hybrid III, was mostly derived from data procured for human male occupants - and typical (fiftieth percentile) males, not female, and females had much different bodies; child dummies were essentially smaller adult male dummies, which was not biologically true; new dummies were developed at the National Transportation Biomechanics Research Center. Narrated by Andrew Lincoln, produced by Cathy Rogers, directed by Peter Webber, made by RDF Television. Shown on Wednesday 17 January 2001 on The Nature of Things in Canada 20 March Rise and Fall of GM Food, about genetically modified food; Belgian geneticist Marc Van Montagu, of the University of Ghent, visits Havana in Cuba, where a new research centre opened with Carlos Borroto; protests by topless women; GM was largely first developed by Mexican geneticist Herrera Estrella, of the Centre of Investigation and Advanced Studies; Rob Fraley of Monsanto; US farmers spend $8bn dollars on herbicides and pesticides; Roger N. Beachy had a breakthrough in 1986 at the Washington University in St. Louis, now at the Donald Danforth Plant and Science Center; Monsanto made the first insecticide-resistant plant in 1987; many African farmers cannot afford insecticides; Cyrus Ndiritu of the Kenya Agriculture Research Institute; much food harvested in Africa does not last before it reaches the consumer; in 1990 Don Grierson of the Plant Science Division of the University of Nottingham found genes of ripening; Channapatna Prakash of Tuskegee University in Alabama; aluminium toxicity of soils in tropical countries affected yield; Julian Borger of The Guardian; biologist Mae-Wan Ho of the Open University; biologist John Gatehouse of the University of Durham, and the Pusztai affair at The Rowett Institute; Helen Browning, Chairman of the Soil Association; former Vice-Chancellor of UEA, Derek Burke; former Independent environment correspondent Richard D. North, who had grown out of love with the hard-line environmental movement; European farmers grew five times more produce than they did in the 1960s, and there were twice as many trees in the UK than in the 1920s; Renée Elliott of Planet Organic; around 100m children in Third World countries suffered from Vitamin A deficiency. Directed by Martin Durkin, made by his company Kugelblitz 27 March Simply Complex, about the physicist Murray Gell-Mann; by an accident, he devised strangeness of sub-atomic particles, in his mid-20s; he predicts an omega minus particle, which was found in 1962; he predicts that the proton and neutron were made of three triplet particles, which he called quarks from Finnegans Wake and his Eightfold way (physics), also predicted by George Zweig; he worked closely with Richard Feynman at Caltech in the 1960s; on 30 October 1969 he is told that he had won the Nobel Prize for Physics; his friendship with MIT mechanical engineer Seth Lloyd; British physicist Geoffrey West; the documentary is in a biographic informal style that Horizon has since often followed. Produced by Barbara Altounyan, directed by Celia Lowenstein, made by Diverse Productions 3 April Meningitis - Search for a Cure, 3,000 people in the UK had meningitis in 1999; microbiologist Martin C. J. Maiden; one in five died from meningococcal disease; damage is caused by the endotoxin (lipopolysaccharide); a healthy survey is carried out at Burford School; Mike Levin (paediatrician) at Imperial College, and how meningitis A is a huge danger in Africa; 60% of cases in the UK are meningitis B, and many such cases are treated at St Mary's Hospital, London; Brett Giroir of the Children's Medical Center Dallas; 17-year-old Amy Mansell from Whitstable was in a coma for five weeks. Narrated by Paul Brightwell, produced by David Dugan, directed by Jeremy Llewellyn-Jones, made by Windfall Films with Nova and WGBH Boston. It was shown on Nova as Killer Disease on Campus, episode 9 of season 29, shown on 3 September 2002, and shown under the original programme title as a half-hour programme on 6 November 2003 on Catalyst on ABC in Australia 10 April The Box, about flight recorders, with ValuJet Airlines Flight 592 which crashed on 11 May 1996; voice recorders have been compulsory since the late 1960s; Dukane Seacom make emergency underwater locator beacons (ULBs); the Boeing 737, which had around 21,000 take-offs per day, was believed to have unreliable rudder control since the 1980s, as shown in the United Airlines Flight 585 crash on 3 March 1991, having had two rudder incidents in the previous two weeks, with the aircraft flipping 35 seconds after take-off and crashing all in seven seconds; the electrohydraulic servo valve in the Boeing 737 rudder control unit was thought to be sometimes temperamental; Boeing claimed that the March 1991 crash was due to a rotor or lee wave, caused by nearby mountains; the USAir Flight 427 crash on 8 September 1994, where the aircraft flipped at 6,000 ft, in 28 seconds crashing; British Airways did not rely on their Penny & Giles quick access recorders, and would consolidate this data where anomalies were checked, so the NTSB needed BA's data for their 737 aircraft; this safer BA method was introduced by the previous British European Airways (BEA) when it had to prove to the CAA that its autoland system for the Trident was safe, in the Civil Aircraft Airworthiness Data Recording Programme which since 1990 has been collected by the British Airways Safety Information System (BASIS); the 1991 crash investigation concluded after 8 years in 1999, with Boeing ordered to redesign the servo valve. 9 October Full Throttle, about the technology and psychology of motor racing; Brazilian driver Christian Fittipaldi; the Eurofighter, controlled by computers, and due to enter RAF service in 2002; Archie Neill, BAE test pilot; Stephen Olvey, motor racing medical officer; driver Mark Blundell; the Long Beach Grand Prix in Los Angeles; Steve Clark, engineer for Mercedes; Brian Lisles and Peter Gibbons of Newman Haas Racing; the edge of performance envelope; Mario Andretti, former driver: Edward Winter of Sheffield Hallam University and predicting outcomes in sport, by intuition; John Rothwell of the Institute of Neurology in London, testing reflexes, by an MRI scanner, and how the brain stores instructions; psychologist Mike Land of the University of Sussex, and the psychology of prediction, and feedforward; life expectancy of racing drivers in the 1970s was short; racing drivers had risk positive personalities, and became accustomed to risk; psychologist Tim Wheeler; Jimmy Vasser of Chip Ganassi Racing; a female violinist plays La fille aux cheveux de lin; sports psychologist Brian Hemmings; Austrian driver Alexander Wurz of Benetton Formula; RAF SEPECAT Jaguar XZ103 of 41 Squadron; engineer Pat Symonds of Benetton Racing; Simon Taylor (journalist) of Motor Sport; Graham Rood of DERA Air Systems in north Hampshire. Narrated by Stephen Rashbrook, produced by Patrick Uden, directed by Andy Robbins, made by Uden Associates 16 October Lethal Seas: the Maelstrom, about ocean whirlpools; the Gulf of Corryvreckan in Scotland, Lofoten and Saltstraumen in Norway; with Prof Tsukasa Nishimura of Tokyo University of Science and Prof Walter Munk of the Scripps Institution of Oceanography; the Firth of Lorn in west Scotland has one of the world's most dangerous whirlpools, the Royal Navy avoids it; atmospheric physicist Peter Read; mathematician David Dritschel, and the Great Red Spot vortice; the dangerous Arran Rapids on the Cordero Channel in western Canada; Burkard Baschek of the Institute of Ocean Sciences, who dropped a CTD (instrument) into the torrential river currents; Tremble Island in the notorious Slingsby Channel, where a geophone was placed; the novel A Descent into the Maelström; Bjørn Gjevik, a fluid dynamicist in the Department of Mathematics, at the University of Oslo; strong tidal currents in the Naruto Strait in Japan, and the Naruto whirlpools. Narrated by Stephen Rashbrook, produced by Robert Sproul-Cran, directed by Kim Flitcroft, made by Northlight Productions with the Discovery Channel 23 October Einstein's Biggest Blunder, about calculations of the expansion of the universe; the documentary opens with a pastiche of the Star Wars opening credits; two physicists met in 1996, with a new radical proposal for explaining the many anomalies in the expansion of the universe - Andreas Albrecht (cosmologist) of the University of California, Davis and João Magueijo of Portugal; Dave Wark of the University of Sussex, visits Bern in Switzerland; Ruth Durrer of the University of Geneva; John E. Baldwin of the University of Cambridge, and the 1887 Michelson–Morley experiment, which found that the Earth's rotational speed did not affect the speed of light in any way, alongside the Venus movement of The Planets; to account for this, Einstein made his field equations, and lambda - the cosmological constant was added by Einstein to account for how space-time would need to expand; Einstein's equations inferred that the expansion of the universe rested on inherently unstable conditions; due to the Doppler effect, background radiation from the Big Bang is now perceived as microwave radiation; Richard Ellis (astronomer) of Caltech; Einstein didn't believe in the Big Bang until a meeting with Hubble in 1932 in California; with the new theory of an expanding universe, the cosmological constant was now required, but the precise trajectory of the expansion of the universe could not be directly predicted, which led to the flatness problem; the theory of inflation was put forward by Alan Guth in the 1970s; when at St John's College, Cambridge, João Magueijo had the radical proposal that if the speed of light was higher, in the early universe, a cosmological horizon of sufficient distance would be possible, to explain the predicted conditions of the expansion of the early universe, and the cosmological constant problem; the Royal Society gave him a research fellowship to work at Imperial College; as further exploratory work was clocked up, with calculations inclya variable speed of light, the team of physicists looked at other applications for their controversial proposals, such as the flatness problem, and what happened before the Big Bang; in 1998 astrophysicist John Webb, at the University of Cambridge, worked on the theory of a variable speed of light, through investigating quasars, the most distant objects that can be seen; and by looking at supernovae, it was largely expected that any recorded data would show indications of a deceleration in the rate of expansion of the universe, but the data instead showed that the rate of expansion was - increasing, which led to the lambda-CDM model. Narrated by Scottish actor Matthew Zajac, directed by David Sington, made by Dox Productions 30 October The Science of Stress, with 42-year-old actor Angus Kennedy; endocrinologist Stafford Lightman of the University of Bristol; Vivette Glover, a perinatal psychobiological at Imperial College; Sir Cary Cooper, psychologist at the former UMIST; Carolyn M. Mazure, psychiatrist at Yale School of Medicine; Charles Nemeroff, psychiatrist at Emory University School of Medicine. Narrated by Geoffrey Palmer, directed by Michael Samuels, produced by Bridget Sneyd, made by Lion Television and the Discovery Health Channel 7 December Science of Crime - Psychopath, with psychologists Robert D. Hare and Adrian Raine, about the psychopathic traits of insincere superficial charm, on the Psychopathy Checklist. Narrated by Neil Pearson, directed by John Purdie, produced by Rosalind Arden, made by Union Pictures 14 December Science of Crime - Criminal Evidence, about the forensic psychologist 49-year-old Kathy Reichs. Produced by Geoff Deehan, directed by Roger Pyke, made by Yap Films 21 December Science of Crime - Cybercops, the Hackers on Planet Earth conference; Cult of the Dead Cow, founded by Swamp Rat, and its Back Orifice software for accessing Windows 98; the Happy99 virus; wardialing; part of the High Technology Theft Apprehension and Prosecution Program in California. Narrated by Steven Mackintosh, written by Callum Macrae, directed by Witold Starecki
Pardaxin is a peptide produced by the Red Sea sole (P4, P5) and the Pacific Peacock sole (P1, P2, P3) that is used as a shark repellent. It causes lysis of mammalian and bacterial cells, similar to melittin.
Flupentixol (INN), also known as flupenthixol (former BAN), marketed under brand names such as Depixol and Fluanxol is a typical antipsychotic drug of the thioxanthene class. It was introduced in 1965 by Lundbeck. In addition to single drug preparations, it is also available as flupentixol/melitracen—a combination product containing both melitracen (a tricyclic antidepressant) and flupentixol (marketed as Deanxit). It is approved for use in the UK, Australia, Canada, Russian Federation, South Africa, New Zealand, Philippines, Iran, Germany, among others. Flupentixol is not approved for use in the United States.
Sources: en.wikipedia.org
Other methods of weight loss include use of anti-obesity drugs that decrease appetite, block fat absorption, or reduce stomach volume. Obesity has been resistant to drug-based therapies, with a 2021 review stating that existing medications are "often delivering insufficient efficacy and dubious safety". Semaglutide has also become popular recently as an aid in weight loss. It is particularly beneficial for those with type 2 diabetes and obesity.
== Awards and honors == Member of the National Academy of Sciences (1976) Fellow of the American Academy of Arts and Sciences (1975) Gairdner Foundation International Award (1975) Member of the Institute of Medicine (2004) Beutler was a president of both the American Society of Hematology and the Western Association of Physicians. He also received a Doctor Philosophiae Honoris Causa, Tel Aviv University. He was also elected to the United States National Academy of Sciences and was presented with the inaugural Award for Lifetime Achievement from The American Society of Hematology. He was a recipient of the American Society of Hematology's E. Donnall Thomas Prize in 2003.
Ada Esther Yonath (Hebrew: עדה יונת, pronounced [ˈada joˈnat]; née Lifshitz; 22 June 1939 – 31 August 2026) was an Israeli crystallographer and Nobel laureate in chemistry, best known for her pioneering work on the structure of ribosomes. She was the director of the Helen and Milton A. Kimmelman Center for Biomolecular Structure and Assembly of the Weizmann Institute of Science. In 2009, Yonath received the Nobel Prize in Chemistry along with Venkatraman Ramakrishnan and Thomas A. Steitz for her studies on the structure and function of the ribosome, becoming the first Israeli woman to win the Nobel Prize.
== RF value, solutes, and solvents == The retardation factor (RF) may be defined as the ratio of the distance travelled by the solute to the distance travelled by the solvent. It is used in chromatography to quantify the amount of retardation of a sample in a stationary phase relative to a mobile phase. RF values are usually expressed as a fraction of two decimal places.
Drugs administered through topical application can act locally or systemically. However, the drug molecules must first be retained in and penetrate the surface layer of the skin. Absorption of the drug through the skin surface is a passive process of diffusion. Skin penetration of the drug can take place by passive diffusion directly through the epidermis (via transcellular or intercellular routes), or absorption through shunt routes (diffusion through hair follicles and sweat glands). Initially, drug absorption may take place via the transfolliar route. After the drug reaches a steady state, transepidermal absorption may replace transfolliar absorption as the main pathway for absorption. Drug absorption through the skin varies depending on the concentration gradient between the surface of the skin and the body, with a higher rate of absorption resulting from a greater concentration gradient. The rate of drug absorption can be maintained at a constant level by ensuring that the drug concentration at the surface of the skin remains consistently and substantially greater than that in the body. The rate of penetration of the drug across the skin barrier depends on the physiological factors, physicochemical properties of the drug, and gel characteristics. Physiological factors include skin properties, size of application area, frequency and force of application. Physicochemical properties of the drug include drug solubility, affinity for the skin, and metabolism. Gel characteristics include stability, thermodynamic activity, and occlusive properties.
Sources: en.wikipedia.org
It is a modified version of the natural hormone, with three amino acid changes and a fatty acid side chain added. These edits extend its half-life from minutes to about one week. The core receptor activity is retained.
Both deliver the same active peptide and act on the same receptor. The tablet includes an absorption enhancer because peptides are poorly taken up intact from the gut. Bioavailability of the oral route is substantially lower, so the two are not dose-equivalent.
No, it is entirely synthetic and does not occur in nature. Native GLP-1 is produced in the gut and pancreas, but the analog is manufactured by chemical synthesis or recombinant methods. Traces of the analog are not expected in people who never received it.
Sealed, protected from light, and refrigerated at two to eight degrees Celsius for most research material. Desiccated storage limits moisture uptake. Allow the vial to reach room temperature before opening to prevent condensation.