The History of Acetaminophen (Tylenol)

Acetaminophen or paracetamol, as it is known in Europe, is a popular analgesic that is used for the relief of fever, headaches and other minor aches and pains. It is also a major ingredient in many over the counter cold and flu medications and can also be found in many prescription medicines. It is very common in many households today. Prior to the development of acetaminophen, the only antipyretic, or fever reducer, available was cinchona bark. This treatment for fever reduction had been employed since the early 17th century.

The bark of the tree was ground into a fine powder and then given as a beverage. However, in the 1880’s this tree was becoming scarce and scientists began to look for alternatives. Two new fever reducers were soon developed; acetanilide in 1886 and phenacetin in 1887. Harmon Northrop Morse synthesized acetaminophen before the development of these two drugs in 1873. However, its uses as an antipyretic were not found until 1893. Prior to its discovery as a fever reducer, acetaminophen was found in the urine of patients who had taken phenacetin.

It was also found to be a urinary metabolite of acetanilide.

These discoveries failed to attract much attention at the time and were largely ignored. In 1946, the Institute for the Study of Analgesic and Sedative Drugs assigned Bernard Brodie and Julius Axelrod to investigate problems associated with analgesic agents such as phenacetin and acetanilide. Their major concern was why these non-aspirin agents were associated with a non-lethal blood condition called, methemoglobinemia. In 1948, they concluded that acetanilide was the cause of the disorder.

They also noted that analgesic effect of acetanilide was due to its active metabolite, acetaminophen.

They promoted the use of acetaminophen as an analgesic since it does not have the toxic effects of acetanilide. Interest in acetaminophen was stimulated by the findings of Brodie and Axelrod. The product went on sale in the United States in 1955 as Tylenol. In 1956, Panadol, Tylenol’s European counterpart, was released in the United Kingdom. It was originally available only by prescription in the United Kingdom. Today, a wide variety of generic forms exist in the United States, however, certain Tylenol preparations are still protected by patent until 2007.