Which induction agent is contraindicated in patients with a history of acute intermittent porphyria?

Sodium Thiopental is contraindicated in patients with a history of acute intermittent porphyria because it can exacerbate the condition. Acute intermittent porphyria is a metabolic disorder that affects the production of heme, a component of hemoglobin. Certain drugs, especially those that induce the cytochrome P450 enzyme system in the liver, can lead to an increase in porphyrin precursors, which can precipitate or aggravate the symptoms of this condition.

Sodium Thiopental, a barbiturate used for induction of anesthesia, has been shown to potentially trigger an acute attack due to its influence on heme metabolism. This contrasts with other induction agents such as Ketamine and Etomidate, which do not have the same effects on heme biosynthesis and are considered safer alternatives for patients with porphyria. Succinylcholine, while associated with other concerns, does not directly impact heme production and is not typically contraindicated in porphyria. Thus, Sodium Thiopental is clearly identified as the agent to avoid in this patient population.