Harold King (1887–1956)
Extracts of curare were long used as arrow poisons for hunting by the indigenous people of the upper Amazon and Orinoco river basins of South America. Curare’s profound effects captured the interest of scientists who sought to better understand the mechanisms underlying nerve-muscle interactions, as well as physicians who saw its clinical potential for muscle relaxation and the treatment of seizure disorders.
Preparation of curare extracts—along with the plant and animal ingredients and the magical, religious rituals that accompanied their fabrication—were a carefully guarded secret. Researchers collected samples of curare and classified and identified them based on the three types of containers in which they were stored and transported from South America. The contents of each container type came from a common region and were more homogeneous. However, the variable nature and composition of the extracts impeded clinical trials until 1935, when Harold King, a chemist at London’s National Institute for Medical Research, isolated curare’s active alkaloid from materials transported in bamboo tubes (hence, the name tubocurarine).
In 1942, tubocurarine was first used to relax the voluntary muscles of the abdominal and thoracic walls. When administered with surgical anesthetics and pain-relieving drugs, lower (and safer) doses of these anesthetics were needed to render the patient unconscious, oblivious to pain, and relaxed, thus reducing the stress of the operative procedure for both the patient and the surgeon. The use of such a drug combination is referred to as balanced anesthesia. Tubocurarine was also used to control spastic disorders involving voluntary muscles, such as tetanus.
Tubocurarine causes a number of undesirable side effects and acts for an inordinately long time (one to two hours), which delays the ability of the patient to breathe unassisted after the conclusion of the operation. Safer drugs that act for more abbreviated periods, such as atracurium (Tracrium) and succinylcholine (Anectine), have since replaced it.
SEE ALSO Alkaloids (1806), Curare (1850), Succinylcholine (1951).
This Amazonian woman’s blowgun or blowpipe, propelling a curare-coated dart, is particularly effective for hunting such arboreal animals as monkeys and birds.