This is a working overview of creatine, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-05-11. Anything still debated is marked as such rather than presented as settled.
Quality assessment of creatine monohydrate typically uses high-performance liquid chromatography to separate creatine from creatinine and other impurities. Other methods include nuclear magnetic resonance spectroscopy, titration, and infrared spectroscopy for identity confirmation. Purity is often reported as a percentage of the labeled compound on a dry basis, while moisture content is measured separately. Because different analytical methods have different selectivity, comparing purity values across sources requires attention to the method and sample preparation.
In dry solid form, creatine monohydrate is relatively stable when protected from moisture and heat. The crystal lattice includes water, and exposure to high humidity can cause caking or gradual changes in powder flow. Elevated temperatures may accelerate decomposition, particularly if moisture is present. Studies generally report that sealed, dry material retains acceptable purity for extended periods, although exact shelf life depends on packaging and storage conditions. Light exposure is not usually considered a major factor for this compound.
In aqueous solution, creatine monohydrate undergoes a slow conversion to creatinine, a cyclized degradation product. This reaction is pH- and temperature-dependent, and it proceeds faster in warm or alkaline conditions. Because the conversion is gradual, analytical measurements of creatine in solution must account for time and storage history. The equilibrium favors creatinine more strongly at higher temperatures, which is relevant to sample handling in laboratories and to beverage formulations. Refrigeration slows but does not entirely stop this process.
In animals, creatine is synthesized mainly in liver, kidney, and pancreas from arginine, glycine, and methionine. The first committed step transfers a guanidino group from arginine to glycine, forming guanidinoacetate. Subsequent methylation by S-adenosylmethionine yields creatine. Dietary sources include meat and fish; endogenous synthesis supplies part of the body pool. Most creatine is stored in skeletal muscle, where it is converted to phosphocreatine and participates in rapid regeneration of adenosine triphosphate during short, intense activity.
Commercial creatine products appear in several forms, including monohydrate, hydrochloride, citrate, nitrate, and ethyl ester. Creatine monohydrate is the most studied form and serves as a reference material in comparative research. Different forms vary in solubility, pH, and water content, but they share creatine as the active moiety after dissolution. Claims that one form is uniformly superior remain debated, and study designs often differ in population, exercise protocol, and outcome measures. Purity and hydration state are central to interpreting product labels.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 15–25 °C | Cool, dry, sealed container; avoid heat |
| Relative humidity | Low; keep below about 60% | Moisture promotes caking and degradation |
| Primary degradation product | Creatinine | Forms by cyclization, especially in solution |
| Common assay method | HPLC with UV or RI detection | Separates creatine from creatinine and related impurities |
| Moisture content | Typically reported as percentage | Measured by Karl Fischer titration or loss on drying |
Quality control of creatine monohydrate relies on a combination of identity, purity, and moisture tests. High-performance liquid chromatography with ultraviolet detection is widely used to separate creatine from creatinine and other related nitrogenous compounds. Spectroscopic methods such as infrared and nuclear magnetic resonance provide structural confirmation. Because the material is a hydrate, water content is measured separately, often by Karl Fischer titration. These tests together establish whether a lot meets a defined specification.
Manufacturing processes can leave trace amounts of dicyandiamide, creatinine, or residual solvents, depending on the synthetic route and purification steps. Heavy metals, arsenic, and microbial contamination are also monitored for food or pharmaceutical grades. Particle size distribution can affect dissolution behavior and blending uniformity, so it may be specified for certain applications. Analytical results are reported on a dry basis or as-is basis, and the difference matters when comparing certificates of analysis. Open questions remain about how minor impurities influence long-term stability under varied storage conditions.
Stability studies examine how creatine monohydrate changes under controlled temperature and humidity. The solid is generally stable when kept dry, but moisture can promote hydrolysis to creatinine, especially in solution or at elevated temperatures. Color, odor, and assay values are monitored over time to detect degradation. Because degradation pathways depend on storage conditions, shelf-life claims should specify the tested packaging, temperature, and humidity. Open questions remain about the long-term behavior of different crystal habits and particle sizes.
Regulatory treatment of creatine monohydrate varies by country and intended use. In some jurisdictions it is sold as a dietary supplement, while in others it may be treated as a food ingredient or a pharmaceutical raw material. Pharmacopeial monographs, where available, define identification, assay limits, and impurity thresholds. Manufacturers often follow these monographs or internal specifications to ensure batch-to-batch consistency. Analytical method validation is important because different methods can yield different apparent purity values if sample preparation or detection conditions are not controlled.
Quality control for creatine monohydrate begins with identity confirmation and assay determination. Laboratories commonly use high-performance liquid chromatography with ultraviolet detection, often after derivatization or using a suitable column, to quantify creatine. Karl Fischer titration measures water content, which helps verify the monohydrate stoichiometry. Additional tests screen for heavy metals, residual solvents, and microbial contamination depending on the intended use. These tests establish composition and purity rather than biological effect.
== External links == A primer on "Immunotherapy to Treat Cancer", NIH Immunotherapy – Using the Immune System to Treat Cancer. Archived 4 April 2017 at the Wayback Machine Cancer Research Institute – What is Cancer Immunotherapy. Archived 26 January 2017 at the Wayback Machine Association for Immunotherapy of Cancer Society for Immunotherapy of Cancer "And Then There Were Five". Economist. "Discover the Science of Immuno-Oncology". Bristol-Myers Squibb. Archived from the original on 10 October 2014. Retrieved 13 March 2014. Eggermont A, Finn O (September 2012). "Advances in immuno-oncology. Foreword". Annals of Oncology. 23 (Suppl 8): viii5. doi:10.1093/annonc/mds255. PMID 22918929. "Cancer Immunotherapy in Gujarat"
==== Minds ==== By contrast to drones, Minds are orders of magnitude more powerful and intelligent than the Culture's other biological and artificial citizens. Typically they inhabit and act as the controllers of large-scale Culture hardware such as ships or space-based habitats. Unsurprisingly, given their duties, Minds are tremendously powerful: capable of running all of the functions of a ship or habitat, while holding potentially billions of simultaneous conversations with the citizens that live aboard them. To allow them to perform at such a high degree, they exist partially in hyperspace to get around hindrances to computing power such as the speed of light. Some inhabited planets and all orbitals have their own Minds: sapient, hyperintelligent machines originally built by biological species, which have evolved, redesigned themselves, and become many times more intelligent than their original creators. According to Consider Phlebas, a Mind is an ellipsoid object roughly the size of a bus and weighing around 15,000 tons. A Mind is in fact a 4-D entity, meaning that the ellipsoid is only the protrusion of the larger four dimensional device into our 3D 'real space'. In the Culture universe, Minds have become an indispensable part of the prevailing society, enabling much of its post-scarcity amenities by planning and automating societal functions, and by handling day-to-day administration with mere fractions of their mental power.
==== Oil solutions ==== Oil solutions are solutions of a compound with oil, for instance sesame oil or castor oil. When free steroids like estradiol are administered in oil solution by intramuscular injection, they are rapidly absorbed and the duration is relatively short. A single 1 to 2 mg dose of estradiol in oil solution by intramuscular injection has a duration of about 1 or 2 days. Little prolongation of duration is achieved with the use of larger doses. Nonetheless, the duration of estradiol in oil solution by intramuscular injection is significantly longer than an intravenous injection of estradiol or estradiol valerate, which show a duration of only a few hours. Conversely, intramuscular injections of estradiol esters in oil solution have durations of days to months, depending on the ester administered. Following a single 4 or 5 mg intramuscular injection in oil solution, peak estradiol levels are about 950 pg/mL with estradiol benzoate after 2 days, 400 to 650 pg/mL with estradiol valerate after 2 days, and 250 to 350 pg/mL with estradiol cypionate after 4 days. The durations with a 5 mg dose are 4 or 5 days with estradiol benzoate, 7 or 8 days with estradiol valerate, and 11 to 14 days with estradiol cypionate. The differences in estradiol levels and the different durations with estradiol levels are due to their different rates of release from the oily depot at the injection site. The longer and hence more lipophilic the fatty acid ester, the slower the release from the depot, the lower the peak estradiol levels, and the longer the duration.
== Function == Androgens that bind to and activate the androgen receptor have numerous physiological functions which can broadly divided into androgenic (male sexual development) and anabolic (building muscle and bone). The anabolic effects are important in both males and females, although females have lower circulating levels of androgens. The physiologically most important androgens are testosterone (T) and dihydrotestosterone (DHT), which are considered classical androgens because their role in human health was discovered in 1930s. However, much later, in 2010s, the role in human health of 11-oxygenated androgens was established, namely, of 11-ketotestosterone (11KT) and 11-ketodihydrotestosterone (11KDHT), that both bind and activate the human androgen receptor with affinities, potencies, and efficacies that are similar to that of testosterone (T) and DHT, respectively, although 11-oxygenated androgens were long known to be principal androgens in teleost fishes. The main biochemical route to T and DHT is the canonical (classical) pathway that proceeds from pregnenolone (P5). Alternatively, DHT but not T can be produced through a backdoor pathway that proceeds from 17α-hydroxyprogesterone (17OHP) or progesterone (P4). The function of androgen backdoor pathways is to produce physiologically significant androgens in normal conditions where the conventional pathway is insufficient, such as in male early sexual differentiation. Sexual differentiation is a process by which hormones determine anatomic phenotype, mainly the development of the reproductive organs.
Sources: en.wikipedia.org
=== 1983 === January: Soviet spy Dieter Gerhardt is arrested in New York. March 8: In speech to the National Association of Evangelicals, Reagan labels the Soviet Union an "evil empire". March 23: Ronald Reagan proposes the Strategic Defense Initiative (SDI, or "Star Wars"). June 5: The Second Sudanese Civil War begins. July 7: Ten-year-old American child Samantha Smith accepts the invitation of Soviet leader Yuri Andropov and visits the Soviet Union with her parents. Smith had written to Andropov to ask if he would "vote to have a war or not?". Smith's letter, published in the Soviet newspaper Pravda, prompted Andropov to reply and invite the girl to the USSR. The widely publicized event leads to other Soviet–American cultural exchanges. July 22: Martial law in Poland is lifted. July 23: The Sri Lankan Civil War begins between the LTTE and the Sri Lankan government. July 30: Sri Lankan government bans all its major communist parties claiming they were involved in ethnic riots, Soviet Union intervenes to unban the parties. August 4: Thomas Sankara overthrows Jean-Baptiste Ouédraogo and becomes president. He also renamed the country of Upper Volta to Burkina Faso a year later. August 19: During a two-hour meeting with 9 democratic senators Soviet Leader Yuri Andropov proposes that the Soviet Union and the United States agree to a complete ban on antisatellite weapons, and he pledged that the Soviet Union would not place any such weapons in space as long as other countries refrain from doing so. August 21: Former senator Benigno "Ninoy" S.
=== Alpha cell dysfunction === Onset of autoimmune diabetes is accompanied by impaired ability to regulate the hormone glucagon, which acts in antagonism with insulin to regulate blood sugar and metabolism. Progressive beta cell destruction leads to dysfunction in the neighboring alpha cells, which secrete glucagon, exacerbating excursions away from euglycemia in both directions; overproduction of glucagon after meals causes sharper hyperglycemia, and failure to stimulate glucagon upon hypoglycemia prevents a glucagon-mediated rescue of glucose levels.
These adenylyl cyclases are toxins secreted by pathogenic bacteria such as Bacillus anthracis, Bordetella pertussis, Pseudomonas aeruginosa, and Vibrio vulnificus during infections. These bacteria also secrete proteins that enable the AC-II to enter host cells, where the exogenous AC activity undermines normal cellular processes. The genes for Class II ACs are known as cyaA, one of which is anthrax toxin. Several crystal structures are known for AC-II enzymes.
Sources: en.wikipedia.org
===== Mice ===== Researchers at the Department of Pharmacology and Medical Chemistry used serotonergic drugs on male mice to study the effects of selected drugs on their behavior. Mice in isolation exhibit increased levels of agonistic behavior towards one another. Results found that serotonergic drugs reduce aggression in isolated mice while simultaneously increasing social interaction. Each of the treatments use a different mechanism for targeting aggression, but ultimately all have the same outcome. While the study shows that serotonergic drugs successfully target serotonin receptors, it does not show specifics of the mechanisms that affect behavior, as all types of drugs tended to reduce aggression in isolated male mice. Aggressive mice kept out of isolation may respond differently to changes in serotonin reuptake.
=== 1970s === Recombinant DNA technology emerged in the 1970s, fundamentally transforming biomedical research. In 1972 and 1973, Paul Berg, Herbert Boyer, and Stanley Cohen developed techniques to cut and splice DNA molecules from different organisms, establishing the foundation of modern biotechnology. In 1975, Georges Kohler and Cesar Milstein developed hybridoma technology to produce monoclonal antibodies, creating highly specific tools for diagnostic assays and targeted therapies. The late 1970s also witnessed major public health milestones, including the global eradication of smallpox, certified by the World Health Organization in 1979, and the introduction of Fred Sanger's DNA sequencing method in 1977.
== Biology == Linker DNA, the part of a genomic DNA strand that connects two nucleosomes Polylinker or multiple cloning site, a short segment of DNA with many restriction sites Signal transducing adaptor protein, proteins that provide mechanisms by which receptors can amplify and regulate downstream effector proteins Linker of activated T cells, a protein in the biochemical signaling path transferring signals from T cell antigen receptors B-cell linker, a human gene that encodes a linker protein related to B cells Linker peptide, a flexible part of a peptide between relatively rigid structural domains.
=== Tutorials and educational websites === "An Introduction to Proteins" from HOPES (Huntington's Disease Outreach Project for Education at Stanford) Proteins: Biogenesis to Degradation – The Virtual Library of Biochemistry and Cell Biology
Sources: en.wikipedia.org
Dry, sealed creatine monohydrate can remain stable for years, but storage conditions affect its shelf life. Moisture, heat, and repeated opening of containers can reduce quality over time.
Creatine can lose a water molecule and cyclize into creatinine, especially in aqueous solution and at elevated temperatures. This is a chemical degradation process rather than microbial spoilage.
High-performance liquid chromatography is commonly used to quantify creatine and detect creatinine. Identity can be confirmed with spectroscopy or other instrumental methods.
Creatine is the base compound, while creatine monohydrate includes one water molecule per creatine molecule in its crystal structure. The monohydrate form is common in supplements and analytical standards. The body uses creatine itself after the water is removed or dissociated.