[DuskStar]

Carfentanil, maybe?

[quickthrowman]

Opiate overdoses are easily reversible with naloxone. I suppose it’s possible that carfentanyl is strong enough that it would take an unreasonable amount of naloxone to reverse.

[michaelmrose]

Why not both carfentanyl plus insert fast but awful poison and hope nobody gives your spy naloxone in time.