Phenylbutazone Chemical formula
Synonyms: Butadione; Fenilbutazon; Fenilbutazona; Fenilbutazonas; Fenylbutazon; Fenylobutazon; Fenyylibutatsoni; Phénylbutazone; Phenylbutazonum. 4-Butyl-1,2-diphenylpyrazolidine-3,5-dione.
Cyrillic synonym: Фенилбутазон.

💊 Chemical information

Chemical formula: C19H20N2O2 = 308.4.
CAS — 50-33-9 (phenylbutazone); 129-18-0 (phenylbutazone sodium); 4985-25-5 (phenylbutazone piperazine).
ATC — M01AA01; M02AA01.
ATC Vet — QM01AA01; QM02AA01.


In Eur., Jpn, and US.

Ph. Eur. 6.2

(Phenylbutazone). A white or almost white, crystalline powder. Practically insoluble in water; sparingly soluble in alcohol; it dissolves in alkaline solutions. Protect from light.

USP 31

(Phenylbutazone). A white to off-white, odourless, crystalline powder. Very slightly soluble in water; soluble in alcohol; freely soluble in acetone and in ether. Store in airtight containers.

💊 Profile

Phenylbutazone, a pyrazolone derivative, is an NSAID. However, because of its toxicity and in particular its adverse haematological reactions (see Effects on the Blood, below), it is not used as a general analgesic or antipyretic. Although phenylbutazone is effective in almost all musculoskeletal and joint disorders including ankylosing spondylitis, acute gout, osteoarthritis, and rheumatoid arthritis, it should only be used in acute conditions where less toxic drugs have failed. Initial oral doses of up to 600 mg daily in divided doses have been used in the treatment of rheumatic disorders although up to 800 mg daily may be required in acute gout. After 1 to 3 days, the dose should be reduced to the minimum effective amount, which may be as little as 200 mg daily; treatment should be given for the shortest period possible, up to a usual maximum of 1 week. Reduced doses are recommended in elderly patients. In some countries phenylbutazone has also been given as a rectal suppository and applied topically for musculoskeletal pain and in soft-tissue injury. It has also been given intramuscularly as the sodium salt. Other salts of phenylbutazone that have been used in musculoskeletal, joint, and soft-tissue disorders include the calcium, megallate, and piperazine salts.

Breast feeding.

No adverse effects have been seen in breastfed infants whose mothers were given phenylbutazone, and the American Academy of Pediatrics considers1 that it is therefore usually compatible with breast feeding. However, when phenylbutazone had been available in the UK the BNF had advised that phenylbutazone should be avoided during breast feeding as small amounts are distributed into breast milk.
1. American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 2001; 108: 776–89. Correction. ibid.; 1029. Also available at: pediatrics%3b108/3/776 (accessed 08/11/07)

Effects on the blood.

Both phenylbutazone1-3 and oxyphenbutazone1,3 are well known for their adverse effects on the blood and especially for fatal agranulocytosis and aplastic anaemia. Leucopenia, pancytopenia, haemolytic anaemia, and thrombocytopenia may also occur. The UK CSM4 noted that between July 1963 and January 1993 it had received 74 reports of agranulocytosis (39 fatal) associated with phenylbutazone and 40 reports of neutropenia (4 fatal). Up-to-date figures were not provided on oxyphenbutazone, but it is considered to be more toxic to the bone marrow than phenylbutazone.1
1. Anonymous. Phenylbutazone and oxyphenbutazone: time to call a halt. Drug Ther Bull 1984; 22: 5–6
2. Böttiger LE, Westerholm B. Drug-induced blood dyscrasias in Sweden. BMJ 1973; 3: 339–43
3. The International Agranulocytosis and Aplastic Anemia Study. Risks of agranulocytosis and aplastic anemia: a first report of their relation to drug use with special reference to analgesics. JAMA 1986; 256: 1749–57
4. CSM/MCA. Drug-induced neutropenia and agranulocytosis. Current Problems 1993; 19: 10–11. Also available at: http:// FILE&dDocName=CON2024456&RevisionSelectionMethod= LatestReleased (accessed 27/04/07)


Phenylbutazone has been associated with acute attacks of porphyria and is considered unsafe in porphyric patients.

💊 Preparations

Proprietary Preparations

Belg.: Butazolidin; Braz.: Butazolidina; Butazolon†; Butazona; Butazonil†; Neo Butazol; Peralgin†; Fr.: Butazolidine†; Ger.: Ambene; exrheudon OPT; Indon.: Akrofen; Berlizon; Irgapan; Ital.: Kadol; Mex.: Astrofen; Bloken; Bresal; Butalen; Butazolidina; Delbulasa†; Fezona†; Lorfenil†; Meprosona-F; Rudesol†; Neth.: Butazolidin; Pol.: Butapirazol; Port.: Basireuma†; Rus.: Butadion (Бутадион); S.Afr.: Inflazone; Spain: Butazolidina; Switz.: Butadion; Thai.: Buta†; Neo-Pyrazol; Venez.: Promifen†; Ticinil. Multi-ingredient: Austria: Ambene; Ambene N; Braz.: Butazil†; Dorend†; Mioflex; Reumat†; Reumix†; Chile: Balsamo Analgesico con Fenilbutazona; Fr.: Dextrarine Phenylbutazone; Ger.: Ambene Comp†; Hung.: Rheosolon; Indon.: Butamidon; Cetapyrin; Enkapyrin; New Skelan; Mex.: Butayonacol; Butisel; Dexadutil; Dibutasona; Vengesic†; Zolidime†; Rus.: Ambene (Амбене); Spain: Artrodesmol Extra; Doctofril Antiinflamat; Switz.: Butaparin; Hepabuzone; Thai.: Alaxan; Asialax; Buta Pee Dee†; Butarion; Myophen; Trabit†.
Published February 27, 2019.