Phenacetin (acetophenetidin, N-(4-ethoxyphenyl)acetamide) is a pain-relieving and fever-reducing drug, which was widely used following its introduction in 1887.
It was withdrawn from medicinal use as dangerous from the 1970s (e.g., withdrawn in Canada in 1973, and by the U.S. Food and Drug Administration in 1983).
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.
Phenacetin has been used as a cutting agent to adulterate cocaine in the UK and Canada, due to the similar physical properties.
Since being withdrawn phenacetin has become a common adulterant of illicit substances. In a 9-year longitudinal study of cocaine powders in the Netherlands, the percentage of samples containing phenacetin increased from 1.6 to 40.6 with a peak of 48% in 2006. Additionally, phenacetin was the most frequently identified adulterant in the samples.