Pain relief: from coal tar to paracetamol
Analgesics, ie pain-relieving drugs, fall into two categories: those that also reduce body temperature in fevers (antipyretics), and those that act mainly on the brain - typically morphine and diamorphine/heroin. Here we consider members of the first group, particularly those once designated 'coal tar analgesics'. Paracetamol, our most popular over-the-counter pain killer, is one of these.
Towards the middle of the 19th century, a person suffering from mild to moderate pain, eg headache, toothache, or arthritis, had little choice of remedies. Narcotics, typically laudanum, an ethanolic extract of crude opium, were available but were unpopular because they had side effects - ie sleepiness, constipation and the risk of addiction. Salicylic acid, at this time only available as derivatives from willow bark, became freely and cheaply available after the synthesis of the free acid by Hermann Kolbe in 1859, but was toxic. Its further development into the well-tolerated and still widely used acetyl derivative, aspirin, did not occur until the late 1890s.1 So, in the second half of the 19th century there was a need for more acceptable analgesics for everyday use.
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