A practical reference on creatine kinase: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-03-23 and is reviewed periodically as new material appears.
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.
The term creatine monohydrate is often shortened to creatine in casual usage, though other creatine forms exist, including citrate, nitrate, and hydrochloride salts. These alternative forms differ in solubility, pH behavior, and the amount of creatine delivered per unit mass. Regulatory categories vary by country: some jurisdictions treat it as a food ingredient, while others place it under supplement or drug frameworks depending on claims and presentation. Standard reference texts list it as a naturally occurring nitrogenous organic acid rather than a vitamin or mineral.
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.
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.
| 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 stable under dry, cool conditions but can degrade when exposed to moisture and heat. In solution, it undergoes hydrolysis to creatinine, a cyclic derivative with little role in phosphagen energy transfer. The rate of conversion increases with temperature, storage time, and acidic or alkaline pH. Solid material kept in a sealed container at room temperature generally retains its composition for extended periods. Moisture uptake is a primary concern because it can accelerate breakdown and caking.
Analytical laboratories commonly use high-performance liquid chromatography to separate creatine from creatinine and related impurities. Ion chromatography, nuclear magnetic resonance, and titration assays can also quantify the compound. Water content is measured by Karl Fischer titration or loss on drying, because the monohydrate has a defined theoretical water fraction. Particle size, bulk density, and flowability are physical properties that affect blending and capsule filling. These measurements support quality control and help verify that a lot matches its specification.
In the body, creatine is synthesized from the amino acids arginine, glycine, and methionine, primarily in the liver and kidneys. It is transported to muscle and other tissues, where it is phosphorylated to phosphocreatine by creatine kinase. This phosphagen system provides a rapid source of adenosine triphosphate during short, intense contractions. Dietary creatine comes mainly from meat and fish, and the body's total pool is influenced by both synthesis and intake.
As a supplement, creatine monohydrate is studied for its effects on muscle performance and recovery. The compound is often described as an ergogenic aid, meaning it may support physical work capacity. Research typically compares it with placebo or other forms, such as citrate or nitrate, under controlled conditions. Questions remain about the optimal dose and long-term effects in different populations, and findings are not uniform across all studies. The monohydrate form remains the most extensively tested.
Natural opiates: alkaloids contained in the resin of the opium poppy, primarily morphine, codeine, and thebaine, but not papaverine and noscapine which have a different mechanism of action Esters of morphine opiates: slightly chemically altered but more natural than the semi-synthetics, as most are morphine prodrugs, diacetylmorphine (morphine diacetate; heroin), nicomorphine (morphine dinicotinate), dipropanoylmorphine (morphine dipropionate), acetylpropionylmorphine, dibenzoylmorphine, diacetyldihydromorphine; Semi-synthetic opioids: created from either the natural opiates or morphine esters, such as hydromorphone, hydrocodone, oxycodone, oxymorphone, ethylmorphine, buprenorphine and desomorphine; Fully synthetic opioids: such as fentanyl, pethidine, levorphanol, methadone, tramadol, tapentadol, and dextropropoxyphene; Endogenous opioid peptides, produced naturally in the body, such as endorphins, enkephalins, dynorphins, and endomorphins. Endogenous opioids, non-peptide: Morphine, and some other opioids, which are produced in small amounts in the body, are included in this category. Natural opioids, non-animal, non-opiate: the leaves from Mitragyna speciosa (kratom) contain a few naturally occurring opioids, active via Mu- and Delta receptors. Salvinorin A, found naturally in the Salvia divinorum plant, is a kappa-opioid receptor agonist. Tramadol and tapentadol, which act as monoamine uptake inhibitors also act as mild and potent agonists (respectively) of the μ-opioid receptor. Both drugs produce analgesia even when naloxone, an opioid antagonist, is administered.
=== Plasma cortisol concentration === Resting plasma cortisol may be slightly elevated in affected horses, but is commonly within normal limits or below normal. Additionally, elevations may occur secondary to stress, concurrent disease, and due to individual variation. Therefore, resting cortisol levels alone are not adequate to diagnose or rule out the presence of PPID.
In contrast, the accidental forms of S are its non-essential properties—properties that S can lose or gain without changing into a different kind of substance: the chick can lose its feathers (due to, e.g., parasites or the like) without ceasing to be an individual chicken.
Sources: en.wikipedia.org
=== Royalty litigation === In March 2003, Cambridge Antibody Technology (CAT) stated its wish to "initiate discussions regarding the applicability of the royalty offset provisions for Humira" with Abbott Laboratories in the High Court of London. In November 2004, the trial began, and in December 2004, Justice Hugh Laddie ruled for CAT. A short version of the full statement of the proceedings was released. In it Justice Laddie remarked, "Abbott was in error when it made its first royalty payment to CAT calculated on the basis that only 2% of the Net Sales was due. It should have calculated on the basis of the full royalty of just over 5% and should have paid and continued to pay CAT accordingly." Justice Laddie went on to observe "...that the construction advanced by Abbott does violence to the language of the agreements, renders them obscure and makes little or no commercial sense. For this reason CAT wins the action." Abbott was required to pay CAT US$255 million, some of which was to be passed to its partners in development. Of this sum, the Medical Research Council received US$191 million, and in addition, Abbott was asked to pay the MRC a further US$7.5 million over five years from 2006, providing that Humira remains on the market. The MRC also is to receive a further £5.1 million (sterling) in respect of past royalties.
== Properties == PAW contains reactive oxygen and nitrogen species, with a pH lower than untreated water along with higher electrical conductivity. PAW has disinfective properties: the oxidative stress that it causes on the cell membranes of the bacterial cells results in disruption of the cell membrane, followed by further damage that leads to cell death.
== Products and services == Access Control Systems Industrial and Commercial Fire Safety Consumer and Residential Fire Safety Hazard Sensing and Combustion Control Electronic Security Commercial Refrigeration Transport Refrigeration Heating, Ventilating, Air Conditioning Monitoring and Response Physical Security Cash in Transit Security Personnel Intrusion sensors Digital Video
Sources: en.wikipedia.org
=== European Union === Use of zinc pyrithione is prohibited within cosmetic products in the European Union since December 2021. The substance was considered safe for use in rinse-off and leave-in products of different tested concentrations, but due to potential environmental toxicity consideration of the use of zinc pyrithione was made against potential alternative substance ingredients. Due to no industry submission to the regulators supporting the continued use of zinc pyrithione and/or an absence of indications that there were no suitable alternatives to the substance: the use of zinc pyrithione became automatically prohibited within cosmetic products as an intended ingredient. This was as a consequence of zinc pyrithione addition to the Cosmetic Product Regulation (EC) No 1223/2009 Annex II list.
Taking a break from training to allow time for recovery. Reducing volume and/or intensity of training. Suitable periodization of training. Splitting the training program so that different sets of muscles are worked on different days. Increase sleep time. Deep-tissue or sports massage of the affected muscles. Self-massage or rub down of the affected muscles. Short sprints with long resting time once the athlete is able to continue with light training.
1993/2685) Walsgrave Hospitals National Health Service Trust (Transfer of Trust Property) Order 1993 (S.I. 1993/2686) Industrial Tribunals (Constitution and Rules of Procedure) Regulations 1993 (S.I. 1993/2687) Industrial Tribunals (Constitution and Rules of Procedure) (Scotland) Regulations 1993 (S.I. 1993/2688) Disclosure of Interests in Shares (Amendment) (No. 2) Regulations 1993 (S.I. 1993/2689) Prior Rights of Surviving Spouse (Scotland) S.I. 1993/2690) Central Manchester National Health Service Trust (Transfer of Trust Property) Order 1993 (S.I. 1993/2691) Lancaster Acute Hospitals National Health Service Trust (Transfer of Trust Property) Order 1993 (S.I. 1993/2692) Lancaster Priority Services National Health Service Trust (Transfer of Trust Property) Order 1993 (S.I. 1993/2693) Lifecare National Health Service Trust (Transfer of Trust Property) Order 1993 (S.I. 1993/2694) Lifespan Health Care Cambridge National Health Service Trust (Transfer of Trust Property) Order 1993 (S.I. 1993/2695) Lincolnshire Ambulance and Health Transport Service National Health Service Trust (Transfer of Trust Property) Order 1993 (S.I. 1993/2696) Mayday Healthcare National Health Service Trust (Transfer of Trust Property) Order 1993 (S.I. 1993/2697) Weights and Measures Act 1985 Commencement (Revocation) Order 1993 (S.I. 1993/2698)
== Structure == NFE2L2 and other genes, such as NFE2, NFE2L1 and NFE2L3, encode basic leucine zipper (bZIP) transcription factors. They share highly conserved regions that are distinct from other bZIP families, such as JUN and FOS, although remaining regions have diverged considerably from each other. NRF2 is a basic leucine zipper (bZip) transcription factor with a Cap "n" Collar (CNC) structure. NRF2 possesses seven highly conserved domains called NRF2-ECH homology (Neh) domains. From the N-terminus to the C-terminus, they are:
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.
Karl Fischer titration is a standard method for measuring water content in solid and liquid samples. The result helps confirm the expected monohydrate stoichiometry. Loss-on-drying can also indicate moisture but may not distinguish water from other volatile substances.