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How did curare become useful in medicine?

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Map of South America and the Caribbean showing the distribution of Aboriginal cultural groups, with regions color-coded by cultural type including Andean, Central American, tropical forest, and various nomadic cultures such as aquatic nomads, forest hunters and gatherers, and shellfish gatherers. Major group names are labeled across the continent and surrounding islands. — South American forest Indian Distribution of aboriginal South American and circum-Caribbean cultural groups.

Curare, a term derived from Indigenous languages of South America, refers to a group of plant-based poisons traditionally used on arrow tips to hunt game. Its transition into modern medicine began with the scientific study of its potent ability to induce skeletal muscle relaxation.12

The pharmacological potential of curare was realized through the isolation of its active alkaloids. In 1897, the principal alkaloid, tubocurarine, was first isolated, and it was successfully obtained in crystalline form by 1935. By 1942, tubocurarine chloride—derived from the vine Chondrodendron tomentosum—was introduced into clinical practice as a muscle relaxant for use during general anesthesia.1

In medicine, curare and its derivatives function as neuromuscular blocking agents. They compete with the neurotransmitter acetylcholine at the neuromuscular junction, effectively preventing nerve impulses from triggering muscle contractions. This property is invaluable for:1

Facilitating endotracheal intubation by relaxing airway muscles.1
Providing muscle relaxation during complex abdominal or chest surgeries, which allows for lower doses of general anesthesia and faster patient recovery.1
Managing severe muscle contractions and convulsions, such as those seen in tetanus.1