This is a working overview of guanidinoacetate, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-12. Anything still debated is marked as such rather than presented as settled.
Creatine monohydrate is a crystalline organic compound formed from creatine and water in a one-to-one ratio. It belongs to the guanidino family and contains a methylated guanidine group attached to an acetate-like chain. The solid is commonly described as a white, odorless powder with a mildly bitter taste. Its molecular formula is C4H11N3O3·H2O, and the hydrated form is the most widely traded grade. The compound occurs naturally in vertebrate muscle and brain tissue, where it participates in rapid energy buffering.
In aqueous solution, creatine monohydrate exists mainly as a zwitterion, carrying both a positive guanidinium charge and a negative carboxylate charge. This charge separation raises water solubility relative to many neutral organic solids and helps explain its behavior in analytical separations. The monohydrate can lose its water of crystallization under sustained heat or low humidity, converting toward anhydrous creatine. Such transitions matter for mass balance calculations because the hydrate contributes water mass that is not part of the active creatine molecule.
In solid form, creatine monohydrate is relatively stable when kept dry and away from heat. Moisture and elevated temperatures promote cyclization into creatinine, a related compound with no role in the phosphagen system. Degradation accelerates in aqueous solution, where the conversion can occur within hours to days depending on pH and temperature. Manufacturers typically recommend storage in sealed containers at room temperature, with relative humidity below 50 percent. Long-term stability data for opened containers are limited.
Analytical methods for creatine monohydrate focus on identity, purity, and degradation products. High-performance liquid chromatography with ultraviolet detection is common, often at a wavelength near 210 nanometers. Titration and nuclear magnetic resonance spectroscopy can also quantify the parent compound. Pharmacopeial monographs specify tests for appearance, solubility, water content, and related substances, including creatinine. Purity values above 99 percent are typical for pharmaceutical-grade material, though supplement-grade products vary. Independent verification can detect label discrepancies.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C4H11N3O3·H2O | Hydrated form includes one water molecule per creatine unit. |
| Molar mass | 149.15 g/mol | Calculated for the monohydrate form. |
| Appearance | White crystalline powder | Common commercial grade is odorless or nearly odorless. |
| Solubility in water | Moderately soluble | Solubility increases with temperature and depends on pH. |
| Common synonyms | Creatine hydrate; N-methylguanidinoacetic acid | Monohydrate distinguishes it from anhydrous creatine. |
Creatine monohydrate is the hydrated form of creatine, a nitrogen-containing organic acid involved in cellular energy transfer. Its molecular formula is C4H11N3O3, and it consists of creatine plus one water molecule in the crystal lattice. The anhydrous base, creatine, has the formula C4H9N3O2. The compound appears as a white, odorless, crystalline powder and is classified as a guanidine derivative. It is distinct from creatinine, a breakdown product measured in clinical chemistry.
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.
Creatine monohydrate is a crystalline compound formed from creatine and one molecule of water. Creatine itself is a nitrogen-containing organic acid that occurs in vertebrate muscle and other tissues. The monohydrate designation refers to the water included in the crystal lattice, not to water added during manufacturing. Its chemical formula is commonly written as C4H9N3O2·H2O. The solid is typically a white, odorless powder with low solubility in water at room temperature. It is one of several creatine forms described in scientific and commercial literature.
The compound was identified in the nineteenth century after chemists isolated a nitrogenous substance from meat extracts. Later work established its role in muscle energy metabolism and its conversion to phosphocreatine. Chemical synthesis of creatine followed, and industrial production made the monohydrate widely available as a purified powder. Interest expanded in the late twentieth century when researchers began studying creatine supplementation and muscle physiology. Historical accounts sometimes differ on exact dates and attributions, but the broad sequence from tissue extracts to synthetic production is well documented.
The hepatocyte is a complex and multifunctional differentiated cell whose cell response will be influenced by the zone in hepatic lobule, because concentrations of oxygen and toxic substances present in the hepatic sinusoids change from periportal zone to centrilobular zone10. The hepatocytes of the intermediate zone have the appropriate morphological and functional features since they have the environment with average concentrations of oxygen and other substances. This specialized cell is capable of:
Arrestins (abbreviated Arr) are a small family of proteins important for regulating signal transduction at G protein-coupled receptors. Arrestins were first discovered in the late '80s as a part of a conserved two-step mechanism for regulating the activity of G protein-coupled receptors (GPCRs) in the visual rhodopsin system by Hermann Kühn, Scott Hall, and Ursula Wilden and in the β-adrenergic system by Martin J. Lohse and co-workers.
While AM could be an important biomarker for bacterial infections like sepsis, AM has diminished value in its utility for cardiovascular diseases (CVD), attributable to its minimal increase in these conditions and reduced half-life. AM is associated with controlling vascular integrity, blood pressure, and general cardiovascular function. Since AM has been noted for its exacerbated levels in intense diseases with an elevated concern for mortality, AM could still have some value as a predictive biomarker of harmful clinical consequences for an array of cardiovascular illnesses. AM has conservatory effects against arteriosclerosis and vascular harm. Extended AM administration or hyper-expression of its target gene in rodent model organisms diminishes vascular hyperplasia, fatty streak construction, and intimal expansion. AM also has angiogenic characteristics, leading to organ and tissue maintenance by reducing the risk of ischemic diseases. AM binds to particular receptors like calcitonin gene-related peptide (CGRP) receptors, which affects the cardiovascular system by contributing to vasodilation as well as elevated heart rate and blood pressure.
Sources: en.wikipedia.org
The cell-mediated response to the virus and to vectors is poorly characterised, and has been largely ignored in the literature as recently as 2005. Clinical trials using an AAV2-based vector to treat haemophilia B seem to indicate that targeted destruction of transduced cells may be occurring. Combined with data that shows that CD8+ T-cells can recognise elements of the AAV capsid in vitro, it appears that there may be a cytotoxic T lymphocyte response to AAV vectors. Cytotoxic responses would imply the involvement of CD4+ T helper cells in the response to AAV and in vitro data from human studies suggests that the virus may indeed induce such responses, including both Th1 and Th2 memory responses. A number of candidate T cell stimulating epitopes have been identified within the AAV capsid protein VP1, which may be attractive targets for modification of the capsid if the virus is to be used as a vector for gene therapy. There are several steps in the AAV infection cycle, from infecting a cell to producing new infectious particles:
AOAC International's technical contributions center on the creation, validation, and global publication of reliable analytical test methods. Their areas of focus include, but are not limited to, safety of foods, beverages, dietary supplements, fertilizers, animal feeds, soil and water, and veterinary drugs. The aim of the test methods is to evaluate the purity of materials used in the production of foodstuffs, and their ingredients. The development of these analytical methods in achieved as part of a range of programs operated by AOAC. The Official Methods of Analysis (OMA) program is AOAC's premier program for developing food testing analytical science methods that are recognized and legally defensible worldwide. AOAC Research Institute (AOAC RI) Performance Tested Methods program develops, improves, and validates proprietary kit-based food safety testing methods. Proficiency Testing (PT) program helps labs compete in the global marketplace by demonstrating that through participation they meet the highest international standards for accuracy, reliability, and compliance.
failure mode and effects analysis (FMEA) manual statistical process control (SPC) manual measurement systems analysis (MSA) manual production part approval process (PPAP) manual APQP serves as a guide in the development process and also a standard way to share results between suppliers and automotive companies. APQP specifies three phases: Development, Industrialization, and Product Launch. Through these phases, 23 main topics will be monitored. These topics must be completed before the production is started. They include the following aspects: design robustness, design testing, and specification compliance, production process design, quality inspection standards, process capability, production capacity, product packaging, product testing, and operator training plan. These activities are sometimes carried out by third-party inspection and quality control companies such as SGS, Bureau Veritas, or QCADvisor, which provide on-site inspections, audits, and testing services to support APQP compliance. APQP focuses on:
Sources: en.wikipedia.org
In common usage, yes, but technically creatine monohydrate is one specific hydrated salt form. Other creatine forms exist and differ in composition and properties. The monohydrate is the most studied and most widely available grade.
Yes. Each creatine molecule in the crystal is associated with one water molecule. That water contributes to the total mass but is not part of the creatine molecule itself. Heating or drying can remove some or all of this water.
It occurs naturally in meat and fish, and the human body also makes and stores creatine. Food sources provide varying amounts depending on the type and preparation. The compound is not considered an essential dietary nutrient for adults because the body can synthesize it.
Yes, especially when exposed to moisture or heat, where it converts to creatinine. In dry, sealed containers at room temperature, degradation is slow and the product may remain within specification for two to three years.