Phenacetin (or acetophenetidin) is a pain-relieving and fever-reducing drug, which was widely used between its introduction in 1887 and the 1983 ban imposed by the U.S. Food and Drug Administration.

Pharmacologic action

Phenacetin's analgesic effects are due to its actions on the sensory tracts of the spinal cord. In addition, phenacetin has a depressant action on the heart, where it acts as a negative inotrope. It is an antipyretic, acting on the brain to decrease the temperature set point. It is also used to treat rheumatoid arthritis (subacute type) and intercostal neuralgia.
It is metabolized in the body to paracetamol (acetaminophen), which is also a clinically relevant analgesic.

Uses

In the United States, the Food and Drug Administration ordered the withdrawal of drugs containing phenacetin in November 1983, due to its carcinogenic and kidney-damaging properties.It was also banned in India.As a result, some branded, and previously phenacetin-based, preparations continued to be sold, but with the phenacetin replaced by safer alternatives. A popular brand of phenacetin was Roche's Saridon, which was reformulated in 1983 to contain propyphenazone, paracetamol and caffeine. Coricidin was also reformulated without phenacetin. Paracetamol is a metabolite of phenacetin with similar analgesic and antipyretic effects, but the new formulation has not been found to have phenacetin's carcinogenicity.

Phenacetin has been used as a cutting agent to adulterate cocaine in the UK and Canada, due to the similar physical properties.
Due to its low cost, phenacetin is used for research into the physical and refractive properties of crystals. It is an ideal compound for this type of research.