Acute intermittent porphyria is precipitated by which of the following drug/s?
**Core Concept**
Acute intermittent porphyria (AIP) is a genetic disorder characterized by a deficiency of the enzyme porphobilinogen deaminase (PBGD), leading to the accumulation of porphyrin precursors. The condition is often precipitated by factors that induce the cytochrome P450 system, resulting in increased demand for heme synthesis.
**Why the Correct Answer is Right**
The cytochrome P450 system, specifically the CYP1A2 and CYP3A4 enzymes, plays a crucial role in the metabolism of various drugs. In AIP, the increased demand for heme synthesis due to drug-induced stimulation of these enzymes leads to the accumulation of toxic porphyrin precursors. Certain drugs, particularly those that induce the cytochrome P450 system, can exacerbate this condition. For example, barbiturates, which are potent inducers of CYP2C9 and CYP2C19, can precipitate AIP by increasing the demand for heme synthesis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the drug mentioned does not have a well-established association with AIP precipitation.
**Option B:** While this drug may have some effect on the cytochrome P450 system, it is not a known precipitant of AIP.
**Option C:** This option is incorrect because, although the drug may have some metabolic interactions with the cytochrome P450 system, it is not a known precipitant of AIP.
**Clinical Pearl / High-Yield Fact**
It is essential to note that AIP can be precipitated by various factors, including hormonal changes, infection, and certain medications. A history of abdominal pain, neurological symptoms, and psychiatric disturbances should prompt consideration of AIP in the differential diagnosis.
**Correct Answer:** B. Barbiturates