This is a working overview of creatinine, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-03-07. Anything still debated is marked as such rather than presented as settled.
Recommended storage usually involves a sealed container kept at room temperature, away from direct sunlight and moisture. High humidity can cause caking, which changes flow properties and may complicate accurate weighing. Repeated opening of containers exposes the powder to air and moisture, so smaller aliquots can reduce handling effects. Storage temperature ranges are not absolute requirements; they reflect conditions that slow degradation and preserve consistent physical characteristics. Clean, dry tools help prevent contamination during sampling.
Identity and purity are commonly assessed by high-performance liquid chromatography, often with ultraviolet detection, and by spectroscopic techniques such as infrared or nuclear magnetic resonance. These methods can distinguish creatine from creatinine and detect related impurities. Moisture content may be measured by Karl Fischer titration or loss on drying. Particle size, bulk density, and heavy metal limits are additional quality parameters. Not every product is tested by every method, so specifications depend on the intended use and regulatory framework.
Solid creatine monohydrate is generally stable when kept dry and protected from extremes of heat and humidity. In the presence of moisture, it can gradually convert to creatinine, a cyclic dehydration product that has little value for phosphocreatine synthesis. Elevated temperatures and acidic conditions accelerate this conversion in solution. Because the reaction is slow in cool, dry storage, typical shelf lives are measured in years rather than weeks. Packaging that limits moisture and oxygen exposure helps maintain purity.
Creatine monohydrate is sold as a dietary ingredient in some countries and as a food supplement in others. Regulatory frameworks vary, so purity limits, labeling rules, and permitted claims are not globally uniform. In the United States, it falls under dietary supplement rules, whereas the European Union treats it as a food supplement ingredient. Pharmacopeial monographs, where they exist, can provide public quality standards, but not every product is required to meet them. Questions about long-term effects and patterns of use remain areas of active study rather than settled regulatory findings.
Solid creatine monohydrate is generally stable when kept cool and dry, but it can hydrolyze to creatinine over time. Moisture, heat, and acidic conditions accelerate this conversion, which reduces assay values and changes the material's properties. Creatinine is a cyclic dehydration product that is also a normal human metabolite, so its presence in a sample is not necessarily a health concern by itself. In quality testing, creatinine is monitored as a marker of degradation and purity.
Identity and purity are assessed with several complementary methods. High-performance liquid chromatography can separate creatine from creatinine and related impurities, often with ultraviolet detection. Nuclear magnetic resonance and infrared spectroscopy provide structural confirmation, while Karl Fischer titration measures water content. Elemental analysis and mass spectrometry may be used for additional confirmation, especially in research or forensic settings. No single method captures every quality attribute, so laboratories typically combine results and compare them against a specification.
| Property | Value | Notes |
|---|---|---|
| Typical storage temperature | 15–25 °C | Cool, dry, sealed conditions slow conversion to creatinine. |
| Moisture sensitivity | Moderate | Absorbs water from humid air, which can cause caking. |
| Primary purity method | HPLC-UV | Separates creatine from creatinine and related impurities. |
| Moisture method | Karl Fischer titration | Measures water content; loss on drying is an alternative. |
| Degradation product | Creatinine | Forms by dehydration, especially in solution or humid heat. |
Commercial creatine monohydrate is typically a white to off-white powder with low odor. It is commonly sold as a fine powder, micronized powder, or larger crystals, but these are physical forms of the same chemical. Purity grades vary, and products may contain small amounts of related substances such as creatinine, dicyandiamide, or moisture. The monohydrate is often selected for supplements and research because its production is well established and its behavior in water is predictable. Analytical certificates usually report assay, loss on drying, and heavy metals.
Creatine monohydrate is a crystalline compound formed from creatine and one water molecule in its solid lattice. Creatine itself is a nitrogen-containing organic acid involved in energy transfer in muscle and other tissues. The monohydrate form is the most common solid form used in research and commercial products because it is stable and easy to handle. The term "monohydrate" refers to the fixed one-to-one ratio of water to creatine in the crystal, not to moisture content. This distinction matters when comparing labels or calculating creatine content.
In 1910, Hahn was appointed professor by the Prussian Minister of Culture and Education, August von Trott zu Solz. Two years later, Hahn became head of the Radioactivity Department of the newly founded Kaiser Wilhelm Institute for Chemistry (KWIC) in Berlin-Dahlem (in what is today the Hahn-Meitner-Building of the Free University of Berlin). This came with an annual salary of 5,000 marks (equivalent to €29,000 in 2021). In addition, he received 66,000 marks in 1914 (equivalent to €369,000 in 2021) from Knöfler for the mesothorium process, of which he gave 10 per cent to Meitner. The new institute was inaugurated on 23 October 1912 in a ceremony presided over by Kaiser Wilhelm II. The Kaiser was shown glowing radioactive substances in a dark room. The move to new accommodation was fortuitous, as the wood shop had become heavily contaminated by radioactive liquids that had been spilt, and radioactive gases that had vented and then decayed and settled as radioactive dust, making sensitive measurements impossible. To ensure that their clean new laboratories stayed that way, Hahn and Meitner instituted strict procedures. Chemical and physical measurements were conducted in different rooms, people handling radioactive substances had to follow protocols that included not shaking hands, and rolls of toilet paper were hung next to every telephone and door handle. Strongly radioactive substances were stored in the old wood shop, and later in a purpose-built radium house on the institute grounds.
=== General === The breasts of female humans vary from most other mammals that tend to have less conspicuous mammary glands. The number and positioning of mammary glands varies widely in different mammals. The protruding teats and accompanying glands can be located anywhere along the two milk lines. In general most mammals develop mammary glands in pairs along these lines, with a number approximating the number of young typically birthed at a time. The number of teats varies from 2 (in most primates) to 18 (in pigs). The Virginia opossum has 13, one of the few mammals with an odd number. The following table lists the number and position of teats and glands found in a range of mammals:
The coastal taipan is the second-longest venomous snake in Australia after the king brown snake (Pseudechis australis). Adult specimens of this species typically attain sexual maturity around 1.2 m (3.9 ft) in total length (including tail). More mature specimens can grow to between 1.5 and 2.0 m (4.9 and 6.6 ft). Other taipans, including the inland taipan, attain broadly similar sizes, although they tend to be slightly smaller in average size. A specimen of an average 2.0 m (6.6 ft) total length weighs around 3.0 kg (6.6 lb). According to the Queensland Museum, the longest recorded total length for the coastal taipan was a specimen that was 2.9 m (9.5 ft) and weighed 6.5 kg (14 lb). Though exceptionally rare, much larger specimens are widely believed to exist, including specimens of as much as 3.3 m (11 ft). O. scutellatus has a long and narrow head with an angular brow and is lighter-coloured on the face. The body is slender and colouration can vary. It is often uniformly light olive or reddish-brown in colour, but some specimens may be dark gray to black. The colouration is lighter on the sides of the body, and the ventral side (the belly) is usually a creamy-white to a pale light yellow in colour, and is often marked with orange or pink flecks. Individuals undergo a seasonal change in colour, becoming darker in winter and fading in summer. The eyes are large, round, and are light brown or even hazel in colour with large pupils. As a large, brownish snake, the coastal taipan resembles the eastern brown snake (Pseudonaja textilis), northern brown snake (P.
Biography at the Biographical Directory of the United States Congress Financial information (federal office) at the Federal Election Commission Legislation sponsored at the Library of Congress Profile at Vote Smart
== Identification == S. haemolyticus can be identified on the species level using a variety of manual and automated methods. The most frequently employed are: the reference method (based on growth tests), API ID 32 Staph (bioMe´rieux), Staph-Zym (Rosco), UZA (a rapid 4-h method), and polymerase chain reaction and electrophoretic analysis of the 16S rRNA, hsp60, or sodA gene sequence. Preference towards a particular method usually depends on convenience, economics, and required specificity (some species have identical 16S rRNA). The most closely related species of S. haemolyticus is Staphylococcus borealis.
Sources: en.wikipedia.org
==== Dopamine ==== In certain brain regions, amphetamine increases the concentration of dopamine in the synaptic cleft by modulating DAT through several overlapping processes. Amphetamine can enter the presynaptic neuron either through DAT or, to a lesser extent, by diffusing across the neuronal membrane directly. As a consequence of DAT uptake, amphetamine produces competitive reuptake inhibition at the transporter. Upon entering the presynaptic neuron, amphetamine provokes the release of Ca2+ from endoplasmic reticulum stores, an effect that raises intracellular calcium to levels sufficient for downstream kinase-dependent signalling. In parallel, amphetamine also increases intracellular cAMPTooltip cyclic adenosine monophosphate, which activates protein kinase A (PKA) and protein kinase C (PKC), whilst elevated intracellular Ca2+ activates PKC alone. Phosphorylation of DAT by either kinase induces transporter internalization (non-competitive reuptake inhibition), but PKC-mediated phosphorylation alone induces the reversal of dopamine transport through DAT (i.e., dopamine efflux). TAAR1 has been identified as a biomolecular target of amphetamine that initiates some of amphetamine's kinase-dependent signaling cascades. When TAAR1 signals via Gs-coupled receptors, intracellular cAMP increases through adenylyl cyclase activation and activates PKA and PKC, in turn phosphorylating DAT.
=== α/β === α/β proteins are a class of structural domains in which the secondary structure is composed of alternating α-helices and β-strands along the backbone. The β-strands are therefore mostly parallel. Common examples include the flavodoxin fold, the TIM barrel and leucine-rich-repeat (LRR) proteins such as ribonuclease inhibitor.
Cochlin is a protein that in humans is encoded by the COCH gene. It is an extracellular matrix (ECM) protein highly abundant in the cochlea and vestibule of the inner ear, constituting the major non-collagen component of the ECM of the inner ear. The protein is highly conserved in human, mouse, and chicken, showing 94% and 79% amino acid identity of human to mouse and chicken sequences, respectively.
== Domain == The C1q domain is a conserved protein domain. C1q is a subunit of the C1 enzyme complex that activates the serum complement system. C1q comprises 6 A, 6 B and 6 C chains. These share the same topology, each possessing a small, globular C-terminal domain, a collagen-like Gly/Pro-rich central region, and a conserved C-terminal region, the C1q domain. The C1q protein is produced in collagen-producing cells and shows sequence and structural similarity to collagens VIII and X.
=== Toxicology === Mitragynine toxicity in humans is largely unknown, as animal studies show significant species-specific differences in mitragynine tolerance. Mitragynine toxicity in humans is rarely reported although specific examples of seizures and liver toxicity in kratom consumers have been reported. Due to cytochrome P450 enzyme inhibition, the combination of mitragynine with other drugs poses concern for adverse reactions to mitragynine. Fatalities involving mitragynine tend to include its use in combination with opioids and some cough suppressants. Post-mortem toxicology screens indicate a wide range of mitragynine blood concentrations ranging from 10 μg/L to 4800 μg/L, making it difficult to calculate what constitutes a toxic dose in humans. These variations are suggested to result from differences in the toxicology assays used, and how long after death the assays were conducted.
Sources: en.wikipedia.org
==== CYP3A4 inhibition ==== Although initially developed as an antiviral, ritonavir is now primarily utilized as a pharmacokinetic enhancer (or "booster") because it is a highly potent inhibitor of the cytochrome P450 3A4 (CYP3A4) enzyme. By inhibiting CYP3A4, ritonavir prevents the metabolic breakdown of co-administered drugs (such as nirmatrelvir or lopinavir), thereby increasing their plasma concentrations and extending their therapeutic efficacy. The structural key to this inhibition is the unsubstituted P2' 5-thiazolyl group of ritonavir; the unhindered nitrogen atom on this specific thiazole ring binds directly to the heme iron inside the CYP3A4 active site. Researchers have proposed four primary mechanisms by which ritonavir achieves its quasi-irreversible inactivation of CYP3A4:
This list of former players includes those who received international caps while playing for the team, made significant contributions to the team in terms of appearances or goals while playing for the team, or who made significant contributions to the sport either before they played for the team, or after they left. It is not complete or all inclusive, and additions and refinements will continue to be made over time.
Many other species worldwide within the family Muricidae, for example Plicopurpura pansa, from the tropical eastern Pacific, and Plicopurpura patula from the Caribbean zone of the western Atlantic, can also produce a similar substance (which turns into an enduring purple dye when exposed to sunlight) and this ability has sometimes also been historically exploited by local inhabitants in the areas where these snails occur. (Some other predatory gastropods, such as some wentletraps in the family Epitoniidae, seem to also produce a similar substance, although this has not been studied or exploited commercially.) The dog whelk Nucella lapillus, from the North Atlantic, can also be used to produce red-purple and violet dyes.
Growth hormone therapy refers to the use of growth hormone (GH) as a prescription medication—it is one form of hormone therapy. Growth hormone is a peptide hormone secreted by the pituitary gland that stimulates growth and cell reproduction. In the past, growth hormone was extracted from human pituitary glands. Growth hormone is now produced by recombinant DNA technology and is prescribed for a variety of reasons. GH therapy has been a focus of social and ethical controversies for 50 years. This article describes the history of GH treatment and the current uses and risks arising from GH use. Other articles describe GH physiology, diseases of GH excess (acromegaly and pituitary gigantism), deficiency, the recent phenomenon of HGH controversies, growth hormone in sports, and growth hormone for cows.
Sources: en.wikipedia.org
Solid product can remain within specification for years when stored dry and sealed, but expiration dates reflect manufacturer testing and regulatory conventions. Moisture and heat increase conversion to creatinine, so storage conditions matter more than the printed date alone. Degradation is gradual and can be monitored by purity testing.
Purity is typically evaluated by chromatographic separation with ultraviolet detection, sometimes supported by spectroscopic identity tests. Moisture and creatinine content are common quality parameters. Results depend on the analytical method, sample preparation, and specification limits.
Clumping occurs when powder absorbs moisture, causing particles to stick together. Humidity, temperature changes, and repeated container opening promote this effect. Clumps do not necessarily indicate chemical degradation, but they can affect weighing and mixing.
A sealed container kept at room temperature and away from moisture is typical. Heat and humidity promote conversion to creatinine and can reduce assay values. Long-term storage under dry conditions helps maintain the original crystalline form.