Aminophenazone

Aminophenazone is a non-narcotic analgesic substance. It is a pyrazolone and a derivative of phenazone, which also has anti-inflammatory and antipyretic properties. While inexpensive and effective, especially in the treatment of rheumatism, the drug carries a serious risk of severe and sometimes fatal side-effects, including agranulocytosis. While its production and use have been banned in many countries, including France, Thailand, India, Japan and USA, it is still sometimes used in the developing world.
A breath test with ¹³C-labeled aminopyrine has been used as a non-invasive measure of cytochrome P-450 metabolic activity in liver-function tests. It is also used in measuring the total body water in the human body system.

History

Aminophenazone was first synthesized by Friedrich Stolz and Ludwig Knorr in the late nineteenth century, and sold as an anti-fever medicine known as Pyramidon by Hoechst AG from 1897 until its eventual replacement n the late 1970s by the safer propyphenazone molecule.

Symptoms

Symptoms of exposure to this compound include:

allergic reactions
strong spasmolytic effect on smooth muscle of peripheral blood vessels
irritability
palsy
copious sweating
dilated pupils
sharp drop then rise in body temperature
dysuria
dyspnea
anxiety
rectal tenesmus
urinary frequency
intermittent fever
fatty infiltration of the liver
heart muscle degeneration
death due to circulatory failure following cardiovascular collapse

Agranulocytosis often occurs. Ingestion may cause central nervous system stimulation, vomiting, convulsions, cyanosis, tinnitus, leukopenia, kidney damage and coma. Ingestion may also lead to nausea, mental disturbances, methemoglobinemia, chocolate-colored blood, dizziness, epigastric pain, difficulty in hearing, thready pulse and liver damage.
Other symptoms reported via ingestion include hemolytic anemia, porphyria and severe gastrointestinal bleeding. Bone marrow depression also occurs. Rare eye effects include acute transient myopia.
Chronic symptoms include:

anorexia
edema
oliguria
urticaria
hypersensitivity
aplastic anemia
sore throat
fever
pharyngeal membrane
jaundice enlargement of the liver and spleen
exfoliative dermatitis
gastric or duodenal erosion with perforation or bleeding
adrenal necrosis
thrombocytopenic purpura
acute leukemia

When heated to decomposition this compound emits toxic fumes of nitrogen oxides.

Metabolism

Amidopyrine is metabolized by demethylation and acetylation. Amidopirina metabolites are 4-aminoantipyrine, metilaminoantipirin, rubazonovaya and metilrubazonovaya acid. These acids have a reddish color. At high amidopirine doses, urine can have a reddish brown coloration, due to the presence in the urine of these acid markers.

Drug Interactions

When aminophenazone is combined with other medications, severe side effects, including fatal ones, may occur. Aminophenazone may reduce the effect of other tablet medications
aminophenazone may interact with a wide range of tablet medications. Among them, the following stand out in the table below.

Drug	Side effect
Abrocitinib	The metabolism of Abrocitinib can be decreased when combined with Aminophenazone.
Acamprosate	The excretion of Acamprosate can be decreased when combined with Aminophenazone.
Acebutolol	Aminophenazone may decrease the antihypertensive activities of Acebutolol.
Aceclofenac	The risk or severity of adverse effects can be increased when Aminophenazone is combined with Aceclofenac.

In popular culture

Hospital Universitario Ramón y Cajal in Madrid, Spain was built as a center for specialized surgery, a panacea for the ills of the health system in Madrid.
Locals hence nicknamed it el piramidón.