This is a working overview of Pentapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-03-14 and is reviewed periodically as new material appears.
Ipamorelin is a synthetic pentapeptide that belongs to the growth hormone secretagogue class of compounds. Researchers at a pharmaceutical company first described it in the 1990s while screening small peptides for growth hormone releasing activity. Its chain contains five amino acid residues, two of which are non-natural building blocks, including 2-aminoisobutyric acid and a naphthylalanine derivative. The molecule was designed to act at the ghrelin receptor while avoiding several effects observed with earlier secretagogues.
At the cellular level, ipamorelin binds the growth hormone secretagogue receptor, also called the ghrelin receptor. Activation of this receptor on pituitary somatotroph cells triggers a signaling cascade that leads to release of growth hormone into circulation. Because release follows a pulsatile pattern, studies often report peak concentration and total area under the curve rather than a single time point. Selectivity for this receptor is the property most frequently discussed in comparative work.
Compared with older secretagogues such as hexarelin or GHRP-6, ipamorelin shows weaker stimulation of cortisol, prolactin, and appetite in the animal models used for early characterization. Whether that selectivity is preserved across longer human exposures remains an open question, because published clinical data are limited in size and duration. Reported effects on food intake are generally described as modest. The compound is therefore treated in the literature as a relatively selective research tool rather than a fully characterized therapeutic agent.
Lyophilized material is generally stored cold and dry, with desiccant, and protected from light. In solution the peptide is more vulnerable: the histidine side chain can oxidize, and repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. A mildly acidic aqueous buffer is often used for short-term handling because it limits several degradation routes. Accurate prediction of long-term stability under a given set of conditions is difficult, and published stability data remain sparse.
Published discussion of this compound is uneven. Some references describe it as a tool for probing growth hormone regulation, while others focus on analytical characterization or on comparisons with related secretagogues. Statements about selectivity, half-life and potency often trace back to a small number of original reports that later authors cite secondhand. Readers evaluating a claim should therefore check whether a figure reflects a direct measurement or a repeated citation, and whether the underlying study was conducted in animals, in isolated cells or in human volunteers.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic pentapeptide | Growth hormone secretagogue family |
| Sequence | Aib-His-D-2-Nal-D-Phe-Lys-NH2 | Contains two non-natural residues |
| Molecular formula | C38H49N9O5 | Free base form |
| Molecular weight | 711.85 g/mol | Calculated from formula |
| Primary target | GHS-R1a ghrelin receptor | Agonist activity |
对 ipamorelin 的常规表征以反相高效液相色谱测定纯度，检测波长多设为 214 nm，因为肽键在该波长有较强吸收。身份确认通常借助电喷雾电离质谱或串联质谱，将实测分子量与理论值逐项比对。序列层面可用肽图分析或氨基酸分析进一步验证。这些手段组合起来，可以分别覆盖纯度、身份与序列三个不同层次的信息。
杂质谱一般包含缺失序列片段、差向异构体、氧化产物以及残留溶剂或反离子，其中组氨酸与芳香残基的氧化常被重点关注。反相色谱中这类杂质往往紧邻主峰洗脱，因此方法需要足够的分离度并经过系统适用性验证。纯度百分比的解读依赖于检测波长与梯度条件，不同实验室公布的数字不宜直接横向比较。参考标准品有助于跨批次对照，但其自身赋值同样需要可追溯来源。
冻干状态下的肽通常比溶液状态更稳定，常规做法是维持 -20 °C 或更低温度、保持干燥并避开强光。复溶后的降解主要来自水解、氧化与脱酰胺，速率受 pH、缓冲液种类、离子强度与温度共同影响，碱性条件一般会加快这些反应。反复冻融会造成聚集与容器吸附损失，分装保存能降低该风险。容器材质与金属离子也可能参与氧化过程，需与操作条件一并考虑。
Lyophilized ipamorelin is generally held at minus twenty degrees Celsius or colder, protected from light and moisture. In solution the peptide is less stable, and degradation proceeds through hydrolysis of the amide backbone, oxidation of the histidine residue, and aggregation. Repeated freeze-thaw cycles accelerate these processes, so dividing material into single-use aliquots before freezing is common practice in research settings. Buffered formulations near neutral pH tend to show the slowest degradation, while strongly acidic or basic conditions raise hydrolysis rates. Stability data specific to ipamorelin are sparse, and much guidance is extrapolated from other short peptides.
Quality control for research-grade ipamorelin is not governed by a single harmonized pharmacopeial monograph, so certificates of analysis vary between suppliers. Common tests include appearance, solubility, water content, peptide content by quantitative amino acid analysis, and residual counterion measurement. Independent verification by an outside laboratory is often used to confirm identity and purity claims. Salt form, counterion content, and residual solvent levels are frequently unspecified, which complicates direct comparison between lots and leaves reproducibility partly unresolved.
Identity and purity assessment of ipamorelin relies mainly on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometers, a wavelength where the peptide backbone absorbs. Mass confirmation is typically obtained by electrospray ionization mass spectrometry or by liquid chromatography coupled to mass spectrometry, comparing the observed mass with the calculated value. Amino acid analysis and peptide mapping after enzymatic digestion can confirm the sequence. Impurity profiles include deletion peptides, truncated fragments, and oxidation products, reported as relative area percentages.
Selectivity is the property most often attached to this peptide. Published animal and early human studies record increases in growth hormone release after administration, with adrenocorticotropic hormone and cortisol responses remaining small by comparison. Effects on appetite-related pathways also appear weaker than those reported for several earlier secretagogues. Reviews that compare members of the growth hormone secretagogue family cite these findings frequently, though the receptor-level explanation for the selectivity continues to be debated rather than settled.
Ipamorelin is a synthetic pentapeptide classified as a growth hormone secretagogue. Its sequence, Aib-His-D-2-Nal-D-Phe-Lys-NH2, combines three non-proteinogenic residues with a C-terminal amide. The N-terminal aminoisobutyric acid unit and the two aromatic D-amino acids distinguish it from peptides assembled only from standard L-amino acids. Its formula is C38H49N9O5, corresponding to an average mass near 711.9 Da. At neutral pH the molecule carries a net positive charge, a property that shapes its behaviour in chromatographic and electrophoretic systems.
The compound was developed at Novo Nordisk during the 1990s as part of a programme seeking secretagogues with improved selectivity. It was described in the peer-reviewed literature in 1998 alongside related pentapeptides from the same series. Investigators advanced it because it raised growth hormone output in animal models while leaving other pituitary hormones comparatively unaffected. The development code NNC 26-0161 appears in earlier reports, and ipamorelin later became the common designation in published work.
At the next performance on 25 October, his fellow actors realised that Thomas was very ill: "He was desperately ill…we didn't think that he would be able to do the last performance because he was so ill…Dylan literally couldn't speak he was so ill…still my greatest memory of it is that he had no voice." On the evening of 27 October, Thomas attended his 39th birthday party but felt unwell and returned to his hotel after an hour. The next day, he took part in Poetry and the Film, a recorded symposium at Cinema 16. A turning point came on 2 November. Air pollution in New York had risen significantly and exacerbated chest illnesses such as Thomas's. By the end of the month, over 200 New Yorkers had died from the smog. On 3 November, Thomas spent most of the day in his room, entertaining various friends. He went out in the evening to keep two drink appointments. After returning to the hotel, he went out again for a drink at 2 am. After drinking at the White Horse, Thomas returned to the Hotel Chelsea, declaring, "I've had 18 straight whiskies. I think that's the record!" The barman and the owner of the pub who served him later commented that Thomas could not have drunk more than half that amount. Thomas had an appointment at a clam house in New Jersey with Ruthven Todd on 4 November. When Todd telephoned the Chelsea that morning, Thomas said he was feeling ill and postponed the engagement. Todd thought he sounded "terrible". The poet, Harvey Breit, was another to phone that morning. He thought that Thomas sounded "bad". Thomas's voice, recalled Breit, was "low and hoarse".
=== Planned/unfinished designs === Focke-Wulf Fw 42 – twin-engined medium bomber project developed from the F 19, 1933. Focke-Wulf Ta 183 Huckebein – design for a jet-engined fighter, 1942. Focke-Wulf Fw 206 – planned commercial aircraft, 1940. Focke-Wulf Fw 238 – long-range bomber project (RLM airframe number 8-238 already used by Blohm und Voss) Focke-Wulf Fw 249 – large transport aircraft project; officially designated as Project 195. Focke-Wulf Fw 250 – twin-engine jet fighter project Focke-Wulf Fw 252 – single engine jet fighter Focke-Wulf Ta 254 – proposed version of the Ta 154 fighter. Focke-Wulf Fw 259 Frontjäger (concept) Focke-Wulf Fw 260 – 1960s VTOL airliner proposal Focke-Wulf Fw 261 – four-engine bomber/reconnaissance/U-boat support aircraft project Focke-Wulf Ta 283 – interceptor fighter project Focke-Wulf Fw 300 – proposed long-range version of Fw 200, 1941-1942. Focke-Wulf Ta 400 – Amerikabomber design competitor, never built, 1943. Focke-Wulf Fw P.03.10206 – series of long-range strategic bomber projects, 1944. Focke-Wulf Fw P.03.10221-15 – large capacity strategic transport, 1941. Focke-Wulf Fw P.03.10025 – A 1944 design with a swept wing, a forward-swept V-tail, and two pusher propellers at the rear. Focke-Wulf Fw 03.10251 – series of jet-engined night and bad weather fighters Focke-Wulf Fighter Project w/BMW803 – A 1941 design with a connected twin-boom tail, slightly swept-back wings, and two pusher propellers at the rear.
=== Imaging === After determination using biomarkers, a variety of imaging studies may be used to differentiate between intrahepatic or extrahepatic cholestasis. Ultrasound is often used to identify the location of the obstruction but, is often insufficient in determining the level of biliary obstruction or its cause because it can pick up bowel gas that may interfere with readings. CT scans are not impacted by bowel gas and may also be more suitable for overweight patients. Typically, the cause of cholestasis and magnitude of obstruction is better diagnosed with CT compared to ultrasound. MRI scans provide similar information to CT scans but are more prone to interference from breathing or other bodily functions. Although CT, ultrasound, and MRI may help differentiate intrahepatic and extrahepatic cholestasis, the cause and extent of obstruction is best determined by cholangiography. Potential causes of extrahepatic cholestasis include obstructions outside the wall of the lumen, those outside the duct, and obstructions found in the duct lumen. Endoscopic retrograde cholangiography may be useful to visualize the extrahepatic biliary ducts. In case of anatomical anomalies, or if endoscopic retrograde cholangiography is unsuccessful, percutaneous transhepatic cholangiography may be used. CT or MRI-based cholangiography may also be useful, particularly in cases where additional interventions are not anticipated.
English: Moscow German: Moskau French: Moscou Portuguese: Moscou, Moscovo Spanish: Moscú Moscow has acquired epithets, such as the "Third Rome". It was one of 12 honorary Hero Cities in the Soviet Union. The demonym for a Moscow resident is rendered as Muscovite in English.
Sources: en.wikipedia.org
== History == The idea that the effect of a drug in the human body is mediated by specific interactions of the drug molecule with biological macromolecules, (proteins or nucleic acids in most cases) led scientists to the conclusion that individual chemicals are required for the biological activity of the drug. This made for the beginning of the modern era in pharmacology, as pure chemicals, instead of crude extracts of medicinal plants, became the standard drugs. Examples of drug compounds isolated from crude preparations are morphine, the active agent in opium, and digoxin, a heart stimulant originating from Digitalis lanata. Organic chemistry also led to the synthesis of many of the natural products isolated from biological sources. Historically, substances, whether crude extracts or purified chemicals, were screened for biological activity without knowledge of the biological target. Only after an active substance was identified was an effort made to identify the target. This approach is known as classical pharmacology, forward pharmacology, or phenotypic drug discovery. Later, small molecules were synthesized to specifically target a known physiological/pathological pathway, avoiding the mass screening of banks of stored compounds. This led to great success, such as the work of Gertrude Elion and George H. Hitchings on purine metabolism, the work of James Black on beta blockers and cimetidine, and the discovery of statins by Akira Endo.
=== Helium charged sniffer test === In this case the part is pressurized with helium. The mass spectrometer is fitted with a special device, a sniffer probe usually mounted near the location of expected leak points, that allows the sniffer probe to sample air (and tracer gas when confronted with a leak) at atmospheric pressure and to bring it into the mass spectrometer. This mode of operation is frequently used to locate a leak that has been detected by other methods, in order to allow for parts repair at the detected leak points. Modern machines can digitally remove the helium 20 times below the background level and thus it is now possible detect leaks as small as 5·10−10 Pa·m3·s−1 in sniffing mode.
=== Pharmacokinetics === Cyproheptadine is well-absorbed following oral ingestion, with peak levels occurring after 1 to 4 hours. Its elimination half-life when taken orally is approximately 8.6 hours.
Sources: en.wikipedia.org
It is a synthetic pentapeptide in the growth hormone secretagogue family. The chain contains five residues, two of which are non-natural amino acids.
It acts as an agonist at the growth hormone secretagogue receptor, also known as the ghrelin receptor. Binding at pituitary somatotroph cells promotes growth hormone release.
Early studies report weaker effects on cortisol, prolactin, and appetite than compounds such as GHRP-6. The size of that difference in humans is not firmly established.
Reversed-phase liquid chromatography is standard for purity, and mass spectrometry is standard for identity. Amino acid analysis is used when quantitative composition matters. No single technique answers every question, so laboratories usually combine two or three.