Final answer:
The options provided do not include the reversal agent for barbiturates; barbiturates do not have a specific reversal agent. Instead, treatment for a barbiturate overdose consists of supportive care. Physostigmine can sometimes be used with caution to reverse the effects of barbiturate overdose.
Step-by-step explanation:
The reversal agent for barbiturates such as Thiopental is not included directly in the options provided. Flumazenil is an antagonist for benzodiazepine receptors and would not reverse the effects of barbiturates. Naloxone is an opioid antagonist and is not effective against barbiturates. Protamine sulfate is used to reverse the effects of heparin, an anticoagulant, and thus is not the correct choice. Physostigmine can sometimes reverse the central nervous system effects of barbiturate overdose through its action as a cholinesterase inhibitor, but it is not the primary reversal agent used for barbiturates and should be used with caution.
Since barbiturates do not have a specific reversal agent like benzodiazepines do, the treatment for an overdose typically involves supportive care to maintain breathing and circulation, and minimize the effects until the substance can be metabolized and cleared from the body. The absence of a direct antagonist means that critical attention must be paid to the symptoms and supportive measures taken to prevent serious complications or death.