Azapropazone Chemical formula
Synonyms: AHR-3018; Apazone (USAN); Atsapropatsoni; Azapropazon; Azapropazona; Azapropazonum; Mi85; NSC-102824. 5-Dimethylamino-9-methyl-2-propylpyrazolo[1,2a][1,2,4]benzotriazine1,3(2H)-dione.
Cyrillic synonym: Азапропазон.

💊 Chemical information

Chemical formula: C16H20N4O2 = 300.4.
CAS — 13539-59-8.
ATC — M01AX04.
ATC Vet — QM01AX04.


Br. includes the dihydrate.

BP 2008

(Azapropazone). The dihydrate is a white to pale yellow crystalline powder. Very slightly soluble in water and in chloroform; soluble in alcohol; dissolves in solutions of alkali hydroxides.

💊 Profile

Azapropazone is an NSAID, structurally related to phenylbutazone. It also has uricosuric properties. Because azapropazone appears to be associated with a higher incidence of adverse effects than with some other NSAIDs, its use has been restricted to the treatment of rheumatoid arthritis, ankylosing spondylitis, and acute gout in patients for whom other NSAIDs have been ineffective. Azapropazone is used as the dihydrate and doses are expressed in terms of this hydrated form. For the treatment of rheumatoid arthritis or ankylosing spondylitis the usual oral dose was up to 1.2 g daily in 2 divided doses. Patients over 60 years of age have been given 300 mg twice daily. Reduced doses were also recommended in patients with renal impairment, see below.

Administration in renal impairment.

In the treatment of rheumatoid arthritis or ankylosing spondylitis in patients with reduced renal function the usual dose was reduced according to creatinine clearance (CC) as follows:
CC 50 to 75 mL/minute: reduce usual dose (see above) by one-third to one-half
CC less than 50 mL/minute: reduce usual dose by one-half to two-thirds

Breast feeding.

Small quantities of azapropazone are excreted into breast milk.1 However, the American Academy of Pediatrics2 states that there have been no reports of any clinical effect on the infant associated with the use of azapropazone by breast-feeding mothers, and that therefore it may be considered to be usually compatible with breast feeding.
1. Bald R, et al. Excretion of azapropazone in human breast milk. Eur J Clin Pharmacol 1990; 39: 271–3
2. 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 01/11/07)

Effects on the blood.

Auto-immune haemolytic anaemia, occasionally fatal, often with pulmonary infiltration, allergic alveolitis, pulmonary fibrosis, or fibrosing alveolitis, has been reported in patients receiving azapropazone.1-3
1. Chan-Lam D, et al. Red cell antibodies and autoimmune haemolysis after treatment with azapropazone. BMJ 1986; 293: 1474.
2. Albazzaz MK, et al. Alveolitis and haemolytic anaemia induced by azapropazone. BMJ 1986; 293: 1537–8
3. Montgomery RD, Babb RG. Alveolitis and haemolytic anaemia induced by azapropazone. BMJ 1987; 294: 375.

Effects on the gast

rointestinal tract. In a review1 of the relative safety of 7 oral NSAIDs, the UK CSM commented that azapropazone was associated with the highest risk of gastrointestinal reactions in both epidemiological studies and an analysis of spontaneous reporting of adverse reactions. Although it appeared that some patients over 60 years of age had received doses exceeding those recommended for this age group, it was considered that even when this was taken into account a marked difference remained between gastrointestinal reactions for azapropazone compared with other NSAIDs. The CSM recommended that azapropazone should be restricted to use in rheumatoid arthritis, ankylosing spondylitis, and acute gout and only when other NSAIDs have been ineffective. Its use in patients with a history of peptic ulceration was contra-indicated. It was also recommended that when used in patients over 60 years of age for rheumatoid arthritis or ankylosing spondylitis the dose should be restricted to a maximum of 600 mg daily. Azapropazone has been withdrawn in many countries including the UK.
1. CSM/MCA. Relative safety of oral non-aspirin NSAIDs. Current Problems 1994; 20: 9–11. Also available at: http:// FILE&dDocName=CON2015615&RevisionSelectionMethod= LatestReleased (accessed 01/11/07)

Effects on the skin.

Of 917 reports of adverse reactions associated with azapropazone forwarded to the WHO Collaborating Centre for International Drug Monitoring1 before September 1984, 190 (21%) were of photosensitivity. Of 154 reports of photosensitivity evaluated a causal relationship to use of azapropazone was considered certain in 6, probable in 138, and possible in 10. In May 1994 the UK CSM stated2 that since 1976 they had received 464 reports of photosensitivity reactions associated with azapropazone and commented that, when corrected for prescription volume, reporting of this reaction was 50 times greater than with other commonly prescribed NSAIDs. They recommended that patients should be advised to avoid direct exposure to sunlight or to use sunblock preparations.
1. Olsson S, et al. Photosensitivity during treatment with azapropazone. BMJ 1985; 291: 939
2. CSM/MCA. Photosensitivity associated with azapropazone (Rheumox). Current Problems 1994; 20: 6. Also available at: FILE&dDocName=CON2015616&RevisionSelectionMethod= LatestReleased (accessed 01/11/07)


Azapropazone is considered to be unsafe in patients with porphyria because it has been shown to be porphyrinogenic in animals.

💊 Preparations

BP 2008: Azapropazone Capsules; Azapropazone Tablets.

Proprietary Preparations

Arg.: Debelex†; Austria: Prolixan†; Gr.: Prolixan†; Hung.: Prolixan†; Irl.: Rheumox†; Port.: Prolixan†; S.Afr.: Rheumox; Turk.: Prodisan; UK: Rheumox†.
Published November 14, 2018.