Phenacetin

Phenacetin, or N-(4-ethoxyphenol)acetamide, or acetophenetidin
para-acetamino-phenetol
Empiric Formula	CH3CONHC6H4OC2H5
Molecular Weight	179.22

Phenacetin, introduced in 1887, is used principly as a analgesic. Typical doses of 300mg to 500mg a day result in an analgesic effect. Its analgesic effects are due to its actions on the sensory tracts of the spinal cord. In addition, phenacetin has a depressant action of the heart, where it acts as a negative inotrope. It also is an antipyretic, acting on the brain to decrease the temperature set point. It is also used to treat rheumatoid arthritis (subacute type), intercostal neuralgia , and some forms of ataxia.

In 1983, phenacetin was removed from the market because of its link to analgesic-induced nephropathy.

Phenacetin, and products containing phenacetin have been shown in an animal model to be carcinogenic. In humans, many case reports have implicated products containing phenacetin in renal pelvic cancer. In one prospective series, phenacetin was associated with an increased risk of death due to urologic or renal diseases, death due to cancers, and death due to cardiovascular diseases¹.

Acetaminophen, as a metabolite of phenacetin, has similar analgesic and antipyretic effects but does not share phenacetin's carcinogenic side-effects.

References

• Dubach UC et al. An epidemiologic study of abuse of analgesic drugs: effects of phenacetin and salicylate on mortality and cardiovascular morbidity (1968 to 1987) N Engl J Med 1991 Jan 17; 324:155-160 (Medline abstract)
• Carcinogen report from the NIH