Tubocurarine (also known as d-tubocurarine or DTC) is a toxic alkaloid historically known for its use as an arrow poison. In the mid-1900s, it was used in conjunction with an anesthetic to provide skeletal muscle relaxation during surgery or mechanical ventilation. It is now rarely used as an adjunct for clinical anesthesia because safer alternatives, such as cisatracurium and rocuronium, are available.