Ehrlich coins 'chemotherapy' Science

In search of the magic bullet

In this week's An eye for an i, we will see how Paul Ehrlich (left) succeeded in turning his idea into a working mechanism.   | Photo Credit: Wikimedia Commons

Diseases and disasters have been two causes through history that have led to drastic loss of human lives. While disasters, be it the eruption of Mount Vesuvius in 79 AD or the earthquakes in Nepal earlier this year, are beyond human control, diseases offer a different alternative. Studying the causes of diseases has enabled us to control and cure a number of them.

We’ll be looking at Paul Ehrlich today, the 1908 Nobel Prize winner in Physiology or Medicine for his work on immunity, who is also credited with coining the term chemotherapy. Though he used it to express what we know today as pharmacotherapy — treatment of disease with drugs — it has now come to correspond to treatment of cancer using chemical substances.

"Life as a Dream"

Even as a child, Ehrlich’s interest in medicine was evident. A story from his school days suggests that when asked by a teacher to write an essay on the topic “Life as a Dream,” Ehrlich’s approach was completely different.

Ehrlich corresponded to life as being dependent on normal oxidation processes. He used nerve activity as an example of one such process and therefore equated a dream as a form of oxidation resulting in the phosphorescence of the brain.

Throughout his research career, which began in the 1870s, Ehrlich believed that chemicals could kill infectious microbes without affecting their human hosts. “We must search for magic bullets,” he once said to describe these type of drugs. “We must strike the parasites, and the parasites only, if possible, and to do this, we must learn to aim with chemical substances!” It was with regard to this belief that he coined the term chemotherapy.

Atoxyl holds the key

Ehrlich’s search for magic bullets made him revisit small molecules. He started studying atoxyl, an arsenic compound, that was known to kill syphilis but was too toxic for humans. Along with his army of assistants, Ehrlich began preparing variations of atoxyl with the desired properties.

Along with his Japanese student Sahachiro Hata, Ehrlich produced their 606th preparation, an arsenobenzene compound in 1907. Two years later, on August 31, 1909, Hata injected it into a rabbit with syphilitic ulcers and the ulcers were completely gone in three weeks time.

Salvarsan and its side effects

After the drug was tested on mice, guinea pigs and more rabbits, it was brought to the market as Salvarsan by the chemical firm Hoechst. As it went on to be widely used with tremendous success, side effects were also reported more frequently.

Ehrlich suffered humiliating accusations owing to these side effects, and he was also deeply affected by the outbreak of the First World War. Undeterred, Ehrlich supervised the chemical modification of Salvarsan. Over three hundred iterations later, compound 914 (neosalvarsan), proved to be both safe and effective for syphilis treatment.

The translation of his research, which was done along with the innumerable top chemists at his disposal, into a drug was possible owing to public-private partnerships. Even though giving birth to the idea of chemotherapy is considered Ehrlich’s main achievement, his contributions to the medical field are many more, some of which have proved to be enough for generations that followed to build up on.

Write to A.S.Ganesh at

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Printable version | Jul 31, 2021 2:13:46 AM |

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