Phenylbutazone
Encyclopedia
Phenylbutazone, often referred to as bute, is a non-steroidal anti-inflammatory drug
(NSAID) for the short-term treatment of pain and fever in animals. In the United States, it is no longer approved for human use.
and gout
in 1949. However, it is no longer approved, and therefore not marketed, for any human use in the United States.
, Dancer's Image
, the winner of the race, was disqualified after traces of phenylbutazone were discovered in a postrace urinalysis
. Owned by prominent Massachusetts
businessman Peter Fuller and jockey
ed by Bobby Ussery
, Dancer's Image remains the only horse to win the Kentucky Derby and then be disqualified. Phenylbutazone was legal on most tracks around the country in 1968, but had not yet been approved by Churchill Downs
.
Controversy and speculation still surrounds the incident. In the weeks prior to the race, Peter Fuller had given previous winnings to Coretta Scott King
, the widow
of slain civil rights
activist Martin Luther King Jr., which brought both praise and criticism. The previous year, King held a sit-in
against housing discrimination which disrupted Derby week. Forty years later, Fuller still believes Dancer's Image was disqualified due to these events.
Although after many appeals, Forward Pass
was named the winner, the Kentucky Derby official website lists both Dancer's Image and Forward Pass as the winner. The website's race video commentary states that on the winner's plaque at Churchill Downs
, both Dancer's Image and Forward Pass are listed as the 1968 winner of the Kentucky Derby.
. About 20% of adult dogs are affected with osteoarthritis, which makes the management of musculoskeletal pain a major component of companion animal practice. There is a very narrow margin of safety for all NSAIDs in the dog, and other NSAIDs are more commonly used (etodolac
, and carprofen
). Gastrointestinal-protectant drugs, such as misoprostol
, cimetidine
, omeprazole
, ranitidine
, or sucralfate
, are frequently included as a part of treatment with any NSAID. Dogs receiving chronic phenylbutazone therapy should be followed with regular blood work and renal monitoring.
Side effects of phenylbutazone in dogs include GI ulceration, bone marrow depression, rashes, malaise, blood dyscrasias, and diminished renal blood flow.
in any place other than a vein
, as it can cause tissue damage. Tissue damage and edema
may also occur if the drug is injected repetitively into the same vein.
Phenylbutazone should be administered only under the advice of a veterinarian.
, blood dyscrasia, kidney
damage, oral lesions, and internal hemorrhage, especially pronounced in young, ill, or stressed horses. Effects of GI damage include edema of the legs and belly secondary to leakage of blood proteins into the intestines, resulting in decreased appetite, excessive thirst, weight loss, weakness, and in advanced stages, kidney failure and death.
Phenylbutazone should not be used in combination with blood thinners (e.g., coumadin
), as it amplifies the anticoagulant
effects of these drugs; with other NSAIDs (all NSAIDs are additive); or in horses with known kidney or liver problems.
Periodic blood tests are recommended when using phenylbutazone as agranulocytosis
can occur.
Phenylbutazone should be used cautiously in pregnant or nursing
mares
, as it may be toxic to the embryo
and can be transferred via the umbilical cord
and by milk
.
Phenylbutazone may be used in foals, but it should be used with particular caution. Premature foals, septicemic foals, foals with questionable kidney or liver function and foals with diarrhea require careful monitoring. Drugs to protect the GI tract such as omeprazole, cimetidine, and sucralfate are frequently used with phenylbutazone.
High doses of phenylbutazone may be considered a rules violation under some equestrian
organizations, as the drug may remain in the bloodstream four to five days after administration.
The International Agency for Research on Cancer
(IARC) places it in Group 3; i.e., "not classifiable as to its carcinogen
icity to humans".
Use in horses is limited to horses which are not intended for food. Metabolites of phenylbutazone can cause aplastic anaemia in humans.
Phenylbutazone may affect blood levels and duration of action of phenytoin
, valproic acid
, sulfonamides, sulfonylurea
antidiabetic agents, barbiturate
s, promethazine
, rifampicin
, chlorpheniramine, diphenhydramine
, penicillin G.
line substance
.
It is obtained by condensation of diethyl n-butylmalonate with hydrazobenzene in the presence of base. In effect, this represents the formation of the heterocyclic system by simple lactamization.
Oxyphenbutazone
, the major metabolite
of phenylbutazone, differs only in the para
location of one of its phenyl group
s, where a hydrogen
atom
is replaced by a hydroxyl group (making it 4-butyl-1-(4-hydroxyphenyl)-2-phenyl-3,5-pyrazolidinedione).
Non-steroidal anti-inflammatory drug
Nonsteroidal anti-inflammatory drugs, usually abbreviated to NSAIDs or NAIDs, but also referred to as nonsteroidal anti-inflammatory agents/analgesics or nonsteroidal Anti-inflammatory medicines , are drugs with analgesic and antipyretic effects and which have, in higher doses, anti-inflammatory...
(NSAID) for the short-term treatment of pain and fever in animals. In the United States, it is no longer approved for human use.
In humans
Phenylbutazone was originally made available for use in humans for the treatment of rheumatoid arthritisRheumatoid arthritis
Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...
and gout
Gout
Gout is a medical condition usually characterized by recurrent attacks of acute inflammatory arthritis—a red, tender, hot, swollen joint. The metatarsal-phalangeal joint at the base of the big toe is the most commonly affected . However, it may also present as tophi, kidney stones, or urate...
in 1949. However, it is no longer approved, and therefore not marketed, for any human use in the United States.
In horses
Phenylbutazone is commonly used in horses for the following purposes:- Analgesia: It is used for pain relief from infections and musculoskeletal disordersMusculoskeletal disordersMusculoskeletal disorders can affect the body's muscles, joints, tendons, ligaments and nerves. Most work-related MSDs develop over time and are caused either by the work itself or by the employees' working environment...
, including sprains, overuse injuries, tendinitisBowed tendonTendinitis/tendonitis is inflammation of a tendon. Many times, the tendon tissue is torn. A bowed tendon is a horseman's term for a tendon after a horse has sustained an injury that caused the tendon fibers to be torn, and then healed with "bowed" appearance.-Description of a Tendinitis in...
, arthralgiaArthralgiaArthralgia literally means joint pain; it is a symptom of injury, infection, illnesses or an allergic reaction to medication....
s, arthritisArthritisArthritis is a form of joint disorder that involves inflammation of one or more joints....
, and laminitisLaminitisLaminitis is a disease that affects the feet of ungulates. It is best known in horses and cattle. Symptoms include lameness, and increased temperature in the hooves...
. Like other NSAIDs, it acts directly on musculoskeletal tissueBiological tissueTissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
to control inflammationInflammationInflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
, thereby reducing secondary inflammatory damage, alleviating pain, and restoring range of motionRange of motionRange of motion , is the distance that a movable object may normally travel while properly attached to another object. It is also called range of travel, particularly when talking about mechanical devices and in mechanical engineering fields...
. It does not cureCureA cure is a completely effective treatment for a disease.The Cure is an English rock band.Cure, or similar, may also refer to:-Film and television:* The Cure , a short film starring Charlie Chaplin...
musculoskeletal ailments or work well on colicColicColic is a form of pain which starts and stops abruptly. Types include:*Baby colic, a condition, usually in infants, characterized by incessant crying*Renal colic, a pain in the flank, characteristic of kidney stones...
pain. - AntipyresisAntipyreticAntipyretics ; an-tee-pahy-ret-iks; from the Greek anti, against, and pyreticus, are drugs or herbs that reduce fever. Normally, they will not lower body temperature if one does not have a fever. Antipyretics cause the hypothalamus to override an interleukin-induced increase in temperature...
: It is used for reduction of fevers. Its antipyretic qualities may mask other symptoms; therefore, it should not be administered for this purpose unless a veterinarianVeterinarianA veterinary physician, colloquially called a vet, shortened from veterinarian or veterinary surgeon , is a professional who treats disease, disorder and injury in animals....
has concluded the horse would not be able to eat or drink without its use or that the fever might hinder the horse's recovery.
History of phenylbutazone in racing
In the 1968 Kentucky DerbyKentucky Derby
The Kentucky Derby is a Grade I stakes race for three-year-old Thoroughbred horses, held annually in Louisville, Kentucky, United States on the first Saturday in May, capping the two-week-long Kentucky Derby Festival. The race is one and a quarter mile at Churchill Downs. Colts and geldings carry...
, Dancer's Image
Dancer's Image
Dancer's Image was an American Thoroughbred racehorse who is the only winner in the history of the Kentucky Derby to have been disqualified. Owned and bred by businessman Peter Fuller, the son of former Massachusetts Governor Alvan T. Fuller, the colt was trained by Lou Cavalaris, Jr...
, the winner of the race, was disqualified after traces of phenylbutazone were discovered in a postrace urinalysis
Urinalysis
A urinalysis , also known as Routine and Microscopy , is an array of tests performed on urine, and one of the most common methods of medical diagnosis...
. Owned by prominent Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
businessman Peter Fuller and jockey
Jockey
A jockey is an athlete who rides horses in horse racing or steeplechase racing, primarily as a profession. The word also applies to camel riders in camel racing.-Etymology:...
ed by Bobby Ussery
Bobby Ussery
Robert Nelson "Bobby" Ussery is a retired American thoroughbred horse racing Hall of Fame jockey. His first race as a professional jockey came at Fair Grounds Race Course in New Orleans on November 22, 1951 where he rode Reticule to victory in the Thanksgiving Handicap. By the end of the decade...
, Dancer's Image remains the only horse to win the Kentucky Derby and then be disqualified. Phenylbutazone was legal on most tracks around the country in 1968, but had not yet been approved by Churchill Downs
Churchill Downs
Churchill Downs, located in Central Avenue in south Louisville, Kentucky, United States, is a Thoroughbred racetrack most famous for hosting the Kentucky Derby annually. It officially opened in 1875, and held the first Kentucky Derby and the first Kentucky Oaks in the same year. Churchill Downs...
.
Controversy and speculation still surrounds the incident. In the weeks prior to the race, Peter Fuller had given previous winnings to Coretta Scott King
Coretta Scott King
Coretta Scott King was an American author, activist, and civil rights leader. The widow of Martin Luther King, Jr., Coretta Scott King helped lead the African-American Civil Rights Movement in the 1960s.Mrs...
, the widow
Widow
A widow is a woman whose spouse has died, while a widower is a man whose spouse has died. The state of having lost one's spouse to death is termed widowhood or occasionally viduity. The adjective form is widowed...
of slain civil rights
Civil rights
Civil and political rights are a class of rights that protect individuals' freedom from unwarranted infringement by governments and private organizations, and ensure one's ability to participate in the civil and political life of the state without discrimination or repression.Civil rights include...
activist Martin Luther King Jr., which brought both praise and criticism. The previous year, King held a sit-in
Sit-in
A sit-in or sit-down is a form of protest that involves occupying seats or sitting down on the floor of an establishment.-Process:In a sit-in, protesters remain until they are evicted, usually by force, or arrested, or until their requests have been met...
against housing discrimination which disrupted Derby week. Forty years later, Fuller still believes Dancer's Image was disqualified due to these events.
Although after many appeals, Forward Pass
Forward pass
In several forms of football a forward pass is when the ball is thrown in the direction that the offensive team is trying to move, towards the defensive team's goal line...
was named the winner, the Kentucky Derby official website lists both Dancer's Image and Forward Pass as the winner. The website's race video commentary states that on the winner's plaque at Churchill Downs
Churchill Downs
Churchill Downs, located in Central Avenue in south Louisville, Kentucky, United States, is a Thoroughbred racetrack most famous for hosting the Kentucky Derby annually. It officially opened in 1875, and held the first Kentucky Derby and the first Kentucky Oaks in the same year. Churchill Downs...
, both Dancer's Image and Forward Pass are listed as the 1968 winner of the Kentucky Derby.
In dogs
Phenylbutazone is occasionally used in dogs for the longer-term management of chronic pain, particularly due to osteoarthritisOsteoarthritis
Osteoarthritis also known as degenerative arthritis or degenerative joint disease, is a group of mechanical abnormalities involving degradation of joints, including articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion...
. About 20% of adult dogs are affected with osteoarthritis, which makes the management of musculoskeletal pain a major component of companion animal practice. There is a very narrow margin of safety for all NSAIDs in the dog, and other NSAIDs are more commonly used (etodolac
Etodolac
Etodolac: Etodolac belongs to a class of drugs called nonsteroidal anti-inflammatory drugs . Other members of this class include aspirin, ibuprofen , naproxen , indomethacin , nabumetone and numerous others. These drugs are used for the management of mild to moderate pain, fever, and inflammation...
, and carprofen
Carprofen
Carprofen is a non-steroidal anti-inflammatory drug that is used by veterinarians as a supportive treatment for the relief of arthritic symptoms in geriatric dogs. It is also used for pain relief and to reduce swelling after spay or neuter...
). Gastrointestinal-protectant drugs, such as misoprostol
Misoprostol
Misoprostol is a drug that is used for the prevention of non steroidal anti inflammatory drug induced gastric ulcers, for early abortion, to treat missed miscarriage, and to induce labor. The latter use is controversial in the United States. Misoprostol was invented and marketed by G.D...
, cimetidine
Cimetidine
Cimetidine INN is a histamine H2-receptor antagonist that inhibits the production of acid in the stomach. It is largely used in the treatment of heartburn and peptic ulcers. It is marketed by GlaxoSmithKline under the trade name Tagamet...
, omeprazole
Omeprazole
Omeprazole is a proton pump inhibitor used in the treatment of dyspepsia, peptic ulcer disease , gastroesophageal reflux disease , laryngopharyngeal reflux and Zollinger–Ellison syndrome...
, ranitidine
Ranitidine
Ranitidine is a histamine H2-receptor antagonist that inhibits stomach acid production. It is commonly used in treatment of peptic ulcer disease and gastroesophageal reflux disease . Ranitidine is also used alongside fexofenadine and other antihistamines for the treatment of skin conditions...
, or sucralfate
Sucralfate
Sucralfate is a cytoprotective agent, an oral gastrointestinal medication primarily indicated for the treatment of active duodenal ulcers. Brand names include Sucramal in Italy; Carafate in U.S.A.; Pepsigard, Sucral, Sucrafil, Hapifate in India; Sutra or Musin in parts of South-East Asia; Sulcrate...
, are frequently included as a part of treatment with any NSAID. Dogs receiving chronic phenylbutazone therapy should be followed with regular blood work and renal monitoring.
Side effects of phenylbutazone in dogs include GI ulceration, bone marrow depression, rashes, malaise, blood dyscrasias, and diminished renal blood flow.
Dosage and administration
Phenylbutazone may be administered orally (via paste, powder or feed-in) or intravenously. It should not be given intramuscularly or injectedInjection (medicine)
An injection is an infusion method of putting fluid into the body, usually with a hollow needle and a syringe which is pierced through the skin to a sufficient depth for the material to be forced into the body...
in any place other than a vein
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...
, as it can cause tissue damage. Tissue damage and edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
may also occur if the drug is injected repetitively into the same vein.
Phenylbutazone should be administered only under the advice of a veterinarian.
Side effects and disadvantages
Side effects of phenylbutazone are similar to those of other NSAIDs. Overdose or prolonged use can cause gastrointestinal (GI) ulcersPeptic ulcer
A peptic ulcer, also known as PUD or peptic ulcer disease, is the most common ulcer of an area of the gastrointestinal tract that is usually acidic and thus extremely painful. It is defined as mucosal erosions equal to or greater than 0.5 cm...
, blood dyscrasia, kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
damage, oral lesions, and internal hemorrhage, especially pronounced in young, ill, or stressed horses. Effects of GI damage include edema of the legs and belly secondary to leakage of blood proteins into the intestines, resulting in decreased appetite, excessive thirst, weight loss, weakness, and in advanced stages, kidney failure and death.
Phenylbutazone should not be used in combination with blood thinners (e.g., coumadin
Coumadin
*For the rodenticide class of anticoagulant poisons sometimes loosely referred to as coumadins or coumarins, see 4-hydroxycoumarins.*For the pharmaceutical with the trade name Coumadin, see warfarin....
), as it amplifies the anticoagulant
Anticoagulant
An anticoagulant is a substance that prevents coagulation of blood. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis...
effects of these drugs; with other NSAIDs (all NSAIDs are additive); or in horses with known kidney or liver problems.
Periodic blood tests are recommended when using phenylbutazone as agranulocytosis
Agranulocytosis
Granulopenia, also known as Agranulosis or Agranulocytosis, is an acute condition involving a severe and dangerous leukopenia , most commonly of neutrophils causing a neutropenia in the circulating blood. It represents a severe lack of one major class of infection-fighting white blood cells...
can occur.
Phenylbutazone should be used cautiously in pregnant or nursing
Nursing
Nursing is a healthcare profession focused on the care of individuals, families, and communities so they may attain, maintain, or recover optimal health and quality of life from conception to death....
mares
Mare (horse)
A mare is an adult female horse or other equine.In most cases, a mare is a female horse over the age of three, and a filly is a female horse age three and younger. However, in Thoroughbred horse racing, a mare is defined as a female horse more than four years old; in harness racing a mare is a...
, as it may be toxic to the embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
and can be transferred via the umbilical cord
Umbilical cord
In placental mammals, the umbilical cord is the connecting cord from the developing embryo or fetus to the placenta...
and by milk
Milk
Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many...
.
Phenylbutazone may be used in foals, but it should be used with particular caution. Premature foals, septicemic foals, foals with questionable kidney or liver function and foals with diarrhea require careful monitoring. Drugs to protect the GI tract such as omeprazole, cimetidine, and sucralfate are frequently used with phenylbutazone.
High doses of phenylbutazone may be considered a rules violation under some equestrian
Equestrianism
Equestrianism more often known as riding, horseback riding or horse riding refers to the skill of riding, driving, or vaulting with horses...
organizations, as the drug may remain in the bloodstream four to five days after administration.
The International Agency for Research on Cancer
International Agency for Research on Cancer
The International Agency for Research on Cancer is an intergovernmental agency forming part of the World Health Organisation of the United Nations....
(IARC) places it in Group 3; i.e., "not classifiable as to its carcinogen
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...
icity to humans".
Use in horses is limited to horses which are not intended for food. Metabolites of phenylbutazone can cause aplastic anaemia in humans.
Interactions
Other anti-inflammatory drugs that tend to cause GI ulcers, such as corticosteroids and other NSAIDs, can potentiate the bleeding risk. Combination with anticoagulant drugs, particularly coumarin derivatives, also increases the risk of bleeding. Avoid combining with other hepatotoxic drugs.Phenylbutazone may affect blood levels and duration of action of phenytoin
Phenytoin
Phenytoin sodium is a commonly used antiepileptic. Phenytoin acts to suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels...
, valproic acid
Valproic acid
Valproic acid is a chemical compound that has found clinical use as an anticonvulsant and mood-stabilizing drug, primarily in the treatment of epilepsy, bipolar disorder, and, less commonly, major depression. It is also used to treat migraine headaches and schizophrenia...
, sulfonamides, sulfonylurea
Sulfonylurea
Sulfonylurea derivatives are a class of antidiabetic drugs that are used in the management of diabetes mellitus type 2. They act by increasing insulin release from the beta cells in the pancreas.-First generation:* Carbutamide...
antidiabetic agents, barbiturate
Barbiturate
Barbiturates are drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia. They are also effective as anxiolytics, as hypnotics, and as anticonvulsants...
s, promethazine
Promethazine
Promethazine is a first-generation antihistamine of the phenothiazine family. The drug has anti-motion sickness, antiemetic, and anticholinergic effects, as well as a strong sedative effect and in some countries is prescribed for insomnia when benzodiazepines are contraindicated...
, rifampicin
Rifampicin
Rifampicin or rifampin is a bactericidal antibiotic drug of the rifamycin group. It is a semisynthetic compound derived from Amycolatopsis rifamycinica ...
, chlorpheniramine, diphenhydramine
Diphenhydramine
Diphenhydramine hydrochloride is a first-generation antihistamine possessing anticholinergic, antitussive, antiemetic, and sedative properties which is mainly used to treat allergies. Like most other first-generation antihistamines, the drug also has a powerful hypnotic effect, and for this reason...
, penicillin G.
Overdose
Overdoses of phenylbutazone can cause renal failure, liver injury, bone marrow suppression, and gastric ulceration or perforation. Early signs of toxicity include loss of appetite, and depression.Chemistry
Phenylbutazone is a crystalCrystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
line substance
Chemical substance
In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e. without breaking chemical bonds. They can be solids, liquids or gases.Chemical substances are...
.
It is obtained by condensation of diethyl n-butylmalonate with hydrazobenzene in the presence of base. In effect, this represents the formation of the heterocyclic system by simple lactamization.
Oxyphenbutazone
Oxyphenbutazone
Oxyphenbutazone is a metabolite of phenylbutazone.-Scrabble:The word oxyphenbutazone holds the title for the highest possible score for a single play under American tournament Scrabble rules, scoring 1,780 points across three triple-word-score squares, joining seven tiles to eight already played...
, the major metabolite
Metabolite
Metabolites are the intermediates and products of metabolism. The term metabolite is usually restricted to small molecules. A primary metabolite is directly involved in normal growth, development, and reproduction. Alcohol is an example of a primary metabolite produced in large-scale by industrial...
of phenylbutazone, differs only in the para
Arene substitution patterns
Arene substitution patterns are part of organic chemistry IUPAC nomenclature and pinpoint the position of substituents other than hydrogen in relation to each other on an aromatic hydrocarbon.- Ortho, meta, and para substitution :...
location of one of its phenyl group
Phenyl group
In organic chemistry, the phenyl group or phenyl ring is a cyclic group of atoms with the formula C6H5. Phenyl groups are closely related to benzene. Phenyl groups have six carbon atoms bonded together in a hexagonal planar ring, five of which are bonded to individual hydrogen atoms, with the...
s, where a hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
is replaced by a hydroxyl group (making it 4-butyl-1-(4-hydroxyphenyl)-2-phenyl-3,5-pyrazolidinedione).