If you have been reading about lactam bridge and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-04-06. Where a claim depends on a specific study, the study is described rather than over-claimed.
PT-141 is the original development code for bremelanotide, a synthetic peptide first studied as a potential tanning and sexual-response agent in the 1990s. Researchers at a small American biotechnology firm designed it as a shortened analogue of melanotan II, which itself came from work on alpha-melanocyte-stimulating hormone. Early screening focused on pigmentation, but behavioural observations in animal models redirected attention toward sexual motivation. That shift made PT-141 one of the first melanocortin compounds investigated specifically for effects on desire rather than on skin colour.
Clinical development proceeded through two routes of administration. An intranasal formulation advanced first, but variable absorption and tolerability problems led to a switch to subcutaneous injection. The United States Food and Drug Administration approved the subcutaneous product in 2019 for hypoactive sexual desire disorder in premenopausal women. Marketing rights subsequently changed hands, and commercial availability has fluctuated since approval. Use in men, in postmenopausal women, and in combination with other agents remains outside the approved label.
Outside the approved product, bremelanotide circulates as a research chemical sold by peptide vendors, often labelled PT-141. Such material is not manufactured under pharmaceutical quality standards, and independent testing has repeatedly found content that differs from the label. Analytical certificates supplied with a purchase are not strong evidence of purity because they are usually generated by the seller. Online discussion tends to blur the distinction between the approved drug and unregulated powder, which complicates interpretation of reported experiences.
Early research on PT-141 grew out of work on melanotan II, a related cyclic peptide studied for pigmentation. Investigators observed that centrally acting melanocortin agonists also influenced sexual behaviour in animal models, and the programme shifted toward that endpoint. A nasal formulation was evaluated in clinical trials but showed inconsistent absorption, and later studies used subcutaneous administration instead. Regulatory approval in the United States followed in 2019 for a defined population of premenopausal women with acquired, generalised hypoactive sexual desire disorder. That approval was specific to that group rather than a broad indication.
Bremelanotide acts as a non-selective agonist at melanocortin receptors, with reported activity at MC1R, MC3R, MC4R and MC5R. The proposed basis for its central effects is activation of MC4R populations in the hypothalamus, a region associated with appetite and reproductive signalling. Because the peptide carries a net positive charge and polar side chains, it does not cross biological membranes freely, which is one reason oral administration is not the standard route. Effects generally appear within an hour of parenteral administration and are described as centrally mediated rather than peripheral.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H68N14O10 | Free base; the drug product is formulated as an acetate salt |
| Molar mass | About 1025 g/mol | Calculated for the free base |
| Appearance | White to off-white lyophilized powder | Typical form of research-grade material |
| CAS Registry Number | 189691-06-3 | Common listing for the free base |
| Typical storage | -20 °C, desiccated, protected from light | Repeated freeze-thaw cycles are best avoided |
From a pharmacokinetic standpoint, the peptide is usually delivered by injection because oral bioavailability is very low; proteases in the digestive tract degrade it rapidly. After subcutaneous administration, plasma concentrations reach a peak within roughly one hour. Its elimination half-life is relatively short, with most reports placing it in the range of a few hours. Nasal formulations have also been examined, though absorption varies widely between individuals. Metabolism proceeds mainly through peptidase cleavage, and the resulting products are excreted by the kidneys.
PT-141 initiates cellular signaling by binding to specific subtypes within the melanocortin receptor family. These receptors belong to the G protein-coupled receptor superfamily, and activation raises intracellular cyclic adenosine monophosphate levels. This cascade ultimately influences neuronal circuits in the central nervous system that are associated with sexual desire and arousal. Research indicates the compound's action concentrates in hypothalamic regions rather than peripheral tissues, which helps explain some observed pharmacological features. The selectivity of receptor binding underlies its functional differences.
Compared with the related compound melanotan II, PT-141 shows markedly weaker activation of receptors tied to pigmentation. This difference stems from subtle structural variations that alter affinity distribution across receptor subtypes. Investigators propose that such selectivity produces a different side effect profile in specific applications. However, downstream consequences of prolonged receptor activation remain uncertain in the literature. Published studies do not fully agree on the duration of signaling pathway activity and the mechanisms of desensitization.
After subcutaneous dosing, peak plasma concentrations appear within roughly one hour, and elimination is fast, with a half-life on the order of a few hours. Degradation is mainly proteolytic, and at least one circulating fragment retains receptor activity, so parent-drug levels alone do not describe total exposure. Clearance does not depend heavily on hepatic cytochrome enzymes, which lowers the likelihood of common metabolic interaction routes. Data in renal or hepatic impairment are limited. Repeated dosing does not appear to produce marked accumulation given the short half-life.
Reported pharmacodynamic effects include transient rises in blood pressure and heart rate, flushing, nausea and headache, appearing soon after dosing and resolving within hours. These responses were dose-related in early studies and shaped the label's cardiovascular cautions and blood pressure monitoring advice. Gastrointestinal upset is the most frequent reason cited for discontinuation in trials. Whether the vascular signal attenuates with repeated use is not settled. Central effects on desire are described as emerging over weeks rather than immediately, which points to a cumulative rather than acute process.
Melanocortin receptors form a family of five G-protein-coupled receptors designated MC1 through MC5. Bremelanotide binds most strongly at MC4R and MC1R, with weaker activity reported at MC3R and MC5R. MC4R is expressed in hypothalamic nuclei that coordinate energy balance and aspects of sexual behaviour. The prevailing interpretation is that central MC4R activation, rather than peripheral vascular effects alone, drives the reported changes in desire. This account remains partly inferential, since direct receptor-level measurement in living humans is not practical.
After subcutaneous administration, plasma concentrations rise within roughly thirty minutes and the elimination half-life is short, on the order of two to three hours. Reported physiological responses include transient increases in blood pressure and nausea, which tended to diminish with repeated dosing in trial settings. Because the peptide clears quickly, effects are not expected to persist long after a dose. Absorption from non-injected routes is poorly characterised, and nasal delivery produced variable plasma levels in older work.
But I realised that wasn't the truth." Upon Ceaușescu's return from Iran on the evening of 20 December, the situation became even more tense, and he gave a televised speech from the TV studio inside the Central Committee Building (CC Building) in which he spoke about the events at Timișoara in terms of an "interference of foreign forces in Romania's internal affairs" and an "external aggression on Romania's sovereignty." The country, which had no information about the Timișoara events from the national media, heard about the Timișoara revolt from Western radio stations like Voice of America and Radio Free Europe, and by word of mouth. A mass meeting was staged for the next day, 21 December, which, according to the official media, was presented as a "spontaneous movement of support for Ceaușescu," emulating the 1968 meeting in which Ceaușescu had spoken against the invasion of Czechoslovakia by Warsaw Pact forces.
=== Taxonomy === Rhodiola rosea was first described by Pedanius Dioscorides in De Materia Medica. Many North American plants formerly included in R. rosea are now treated separately as Rhodiola integrifolia and Rhodiola rhodantha.
=== Mayo Quadratic formula === Another estimation tool to calculate GFR is the Mayo Quadratic formula. This formula was developed by Rule et al., in an attempt to better estimate GFR in patients with preserved kidney function. It is well recognized that the MDRD formula tends to underestimate GFR in patients with preserved kidney function. Studies in 2008 found that the Mayo Clinic Quadratic Equation compared moderately well with radionuclide GFR, but had inferior bias and accuracy than the MDRD equation in a clinical setting. The equation is:
=== Under British Raj (1858–1947) === During the 1861-65 American Civil War, American Union blockades of Southern cotton led to the Indian press speculating about the opportunity for India to export more of its cotton. The impact on the British economy also drove the construction of the Indian Railways forward, as faster transport assisted in exporting Indian cotton. In the United States, as Northerners fretted about the ultimate status of African American slaves, The New York Times argued in the weeks leading up to President Abraham Lincoln's Emancipation Proclamation that African Americans could never rise in American society above the "condition which the inferior castes of India have always occupied." India's inability to defend itself from British conquests was also referenced; Lincoln and his Secretary of State William H. Seward agreed on the need to maintain American unity in part to avoid a similar fate as that of British India, and throughout the previous decade, Southerners who sought to expand the institution of slavery to new territories referred to the rapid white conquest of places like India to justify colonizing nonwhite territories south of the United States (see also: Knights of the Golden Circle). The 1869 opening of the Suez Canal was celebrated by famous American poet Walt Whitman, who saw it as a way to connect West and East and tie into the last stage of global consolidation through American expansion.
Sources: en.wikipedia.org
On 3 February 2014, Altria Group, Inc. acquired popular e-cigarette brand Green Smoke for $110 million. The deal was finalized in April 2014 for $110 million with $20 million in incentive payments. Altria also markets its own e-cigarette, the MarkTen, while Reynolds American has entered the sector with its Vuse product. Philip Morris, the world's largest tobacco company, purchased UK's Nicocigs in June 2014. On 30 April 2015, Japan Tobacco bought the US Logic e-cigarette brand. Japan Tobacco also bought the UK E-Lites brand in June 2014. On 15 July 2014, Lorillard sold blu to Imperial Tobacco as part of a deal for $7.1 billion. Following these changes, the main players in the e-cigarette market (at least in the US) were as follows (as of end 2015):
==== Jamaica ==== "Cow cod soup" is a traditional, rustic dish in Jamaican cuisine that is considered an aphrodisiac and made with bull penis ("cod"). It is traditionally cooked with bananas and Scotch bonnet peppers in a white rum-based broth.
After harnessing fire, humans discovered other forms of energy. The earliest known use of wind power is the sailing ship; the earliest record of a ship under sail is that of a Nile boat dating to around 7,000 BCE. From prehistoric times, Egyptians likely used the power of the annual flooding of the Nile to irrigate their lands, gradually learning to regulate much of it through purposely built irrigation channels and "catch" basins. The ancient Sumerians in Mesopotamia used a complex system of canals and levees to divert water from the Tigris and Euphrates rivers for irrigation. Archaeologists estimate that the wheel was invented independently and concurrently in Mesopotamia (in present-day Iraq), the Northern Caucasus (Maykop culture), and Central Europe. Time estimates range from 5,500 to 3,000 BCE, with most experts putting it closer to 4,000 BCE. The oldest artifacts with drawings depicting wheeled carts date from about 3,500 BCE. More recently, the oldest-known wooden wheel in the world as of 2024 was found in the Ljubljana Marsh of Slovenia; Austrian experts have established that the wheel is between 5,100 and 5,350 years old. The invention of the wheel revolutionized trade and war. It did not take long to discover that wheeled wagons could be used to carry heavy loads. The ancient Sumerians used a potter's wheel and may have invented it. A stone pottery wheel found in the city-state of Ur dates to around 3,429 BCE, and even older fragments of wheel-thrown pottery have been found in the same area.
For example, the Jumblatt family sponsored the building of the Maronite Church of Our Lady of Durra in Mukhtara, and the Arslan family supported construction of the Saint Michael the Archangel Orthodox Church in Choueifat. Educated generations of Maronite commoners took up positions as scribes, clerks, physicians, and household agents in the service of notables, including both Maronite and Druze feudal families, such as the Jumblatt family.
Responsible drug use advocates that users should not take drugs at the same time as activities such as driving, swimming, operating machinery, or other activities that are unsafe without a sober state. Responsible drug use is emphasized as a primary prevention technique in harm-reduction drug policies. Harm-reduction policies were popularized in the late 1980s, although they began in the 1970s counter-culture, through cartoons explaining responsible drug use and the consequences of irresponsible drug use to users. Another issue is that the illegality of drugs causes social and economic consequences for users—the drugs may be "cut" with adulterants and the purity varies wildly, making overdoses more likely—and legalization of drug production and distribution could reduce these and other dangers of illegal drug use.
Sources: en.wikipedia.org
=== Organisms === Polystyrene is generally considered to be non-biodegradable. However, certain organisms are able to degrade it, albeit very slowly. In 2015, researchers discovered that mealworms, the larvae form of the darkling beetle Tenebrio molitor, could digest and subsist healthily on a diet of EPS. About 100 mealworms could consume between 34 milligrams (0.52 gr) and 39 milligrams (0.60 gr) of this white foam in a day. The droppings of mealworm were found to be safe for use as soil for crops. In 2016, it was also reported that superworms (Zophobas morio) may eat expanded polystyrene (EPS). A group of high school students in Ateneo de Manila University found that compared to Tenebrio molitor larvae, Zophobas morio larvae may consume greater amounts of EPS over longer periods of time. In 2022 scientists identified several bacterial genera, including Pseudomonas, Rhodococcus and Corynebacterium, in the gut of superworms that contain encoded enzymes associated with the degradation of polystyrene and the breakdown product styrene. The bacterium Pseudomonas putida is capable of converting styrene oil into the biodegradable plastic PHA. This may someday be of use in the effective disposing of polystyrene foam. It is worthy to note the polystyrene must undergo pyrolysis to turn into styrene oil.
Bromazepam has a similar misuse risk as other benzodiazepines such as diazepam. In France car accidents involving psychotropic drugs in combination with alcohol (itself a major contributor) found benzodiazepines, mainly diazepam, nordiazepam, and bromazepam, to be the most common drug present in the blood stream, almost twice that of the next-most-common drug cannabis. Bromazepam has also been used in serious criminal offences including robbery, homicide, and sexual assault.
=== Simple AAS, PDCAAS === PDCAAS considers digestibility and AAS separately. It has a single "reference protein" profile, in which the amounts in milligrams of each essential amino acid (EAA) in each gram of the reference protein is listed. To find the AAS given the amino acid profile of the test protein Ti and the amino acid profile of the reference protein Ri:
The DSM-5 discourages using the term drug addiction because of its "uncertain definition and its potentially negative connotation" and prefers the term substance use disorder to describe the wide range of the disorder, from a mild form to a severe state of chronically relapsing, compulsive pattern of drug taking. Substance use disorder is one of the substance-related disorders. It is a long-term, relapsing condition in which a person continues seeking and taking a substance despite the harm it causes. Repeated use alters the brain circuits that handle reward, stress and self-control, which is why cutting down becomes harder over time. The substances most often involved are alcohol, nicotine, cannabis, opioids, cocaine and amphetamines. Use may begin socially, or follow from a prescribed medication. No single theory accounts for substance use disorder on its own. Phenomenological, operant and classical conditioning, cognitive, and cue reactivity models each explain part of it.
Sources: en.wikipedia.org
PT-141 is a research code for bremelanotide, a cyclic peptide that activates melanocortin receptors. It was developed for sexual dysfunction and later approved under a brand name as a subcutaneous injection. The same code is widely used by suppliers selling non-pharmaceutical material.
Both are synthetic melanocortin agonists and share a similar peptide backbone, but they are distinct molecules with different receptor profiles. Melanotan II was never approved as a medicine, whereas bremelanotide was. Findings about one compound should not be transferred to the other without direct evidence.
It is typically distributed as a lyophilized powder in sealed vials, sometimes with a separate solvent. Purity statements usually originate from the supplier rather than an independent laboratory. Storage recommendations vary between vendors, which makes comparison across sources difficult.
PT-141 was the development code used for bremelanotide during its preclinical and early clinical programme. The peptide is now generally referred to by its international nonproprietary name.