Curare

TL0; $50/dose. LC1.
Curare is extracted from the sap of a poisonous vine (Strychnos toxifera) - it's the active element in the vine and is used to make poisoned blowgun darts (TL0). It’s a follow-up agent with a one-minute delay and a HT-6 roll to resist, repeated at 30-minute intervals for four cycles. It causes 2d toxic damage per roll regardless of the result, but any failure indicates paralysis, while critical failure indicates choking which may lead to death by suffocation. Note that Curare does not cause unconsciousness. Holdout rolls are at +6; Sleight of Hand rolls are at +4.

A combination of atropine and neostigmine is an antidote for curare, but will not take effect until 30 minutes have elapsed.

Source: GURPS 4th - Low-Tech, page 131 and GURPS 4th - Mysteries, page 36