If you know someone who takes drugs to treat high blood pressure or heart failure, the chances are high that they are taking a drug from the drug ACE-inhibitor class (Angiotensin Converting Enzyme inhibitors). These are the most famous example of the successful use of snake venom (indeed, any venom of animal origin) in medicine. In 1975, three scientists from the US found a component in the venom of the south-American lancehead (Bothrops jararaca), that caused a drop in blood pressure.

The mode of action was new and revolutionary. As the name implies, this substance inhibits the enzyme ACE, an enzyme that plays a crucial role in the regulation of blood pressure. ACE converts oligopeptide angiotensin-I into angiotensin-II. The latter is a vasoconstrictor — it leads to narrowing of blood vessels — resulting in lower arterial pressure and a higher venous capacity, which results in a lower blood pressure. ACE-inhibitors also help in the excretion of sodium in the urine, which also leads to a lower blood pressure. At present, ACE-inhibitors are being prescribed for the treatment of:

* High blood pressure
* Heart failure
* Cardiac arrest
* Renal insufficiency

Meanwhile, this class of medicines has become a true billion dollar industry, as ACE-inhibitors are used and prescribed worldwide. In 2002, their turn-over was around US&7.8 billion. However, these products also have a number of disadvantages. One of these is their short half-life. Therefore patients often have to take their drug three times a day. Maybe once a new and better ACE inhibitor will be found in the venom of other animals.