Snake venom can kill, yet some of the most widely used blood-pressure medicines began with a substance found in it. The story starts in Brazil with a pit viper called the jararaca. A bite from this snake makes a person's blood pressure fall sharply, and in the 1960s the Brazilian scientist Sérgio Ferreira wanted to know why.
Ferreira found that the venom contains peptides, which are short chains of the same building blocks that make up proteins. He took the venom to a laboratory in London, where researchers discovered what one of these peptides does. It blocks an enzyme that the body uses to raise blood pressure. With the enzyme blocked, the pressure stays low.
This discovery suggested a new kind of treatment for patients whose blood pressure is dangerously high. There was an obstacle, however. The venom peptide does not work when it is swallowed, so it could be given only by injection, which is impractical for a medicine that people need every day. Two scientists at an American drug company therefore studied how the peptide fits the enzyme and designed a much smaller molecule that does the same job and can be swallowed. Their drug, captopril, was approved in 1981. It was the first of a family of medicines that have since been taken as a simple pill by millions of people.
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