Which of the following combinations can result in severe toxicity due to inhibition of cytochrome 450 enzymes?
## Core Concept
The question tests the understanding of drug interactions, specifically those involving the inhibition of cytochrome P450 (CYP450) enzymes. CYP450 enzymes are crucial for the metabolism of many drugs. Inhibition of these enzymes can lead to decreased metabolism of other drugs, resulting in increased plasma levels and potentially severe toxicity.
## Why the Correct Answer is Right
The correct answer involves a combination of drugs where one is a known inhibitor of CYP450 enzymes and the other is a substrate of these enzymes. A classic example is the combination of **erythromycin** (a macrolide antibiotic and a potent inhibitor of CYP3A4) and **statins** (like **simvastatin**), which are metabolized by CYP3A4. When erythromycin inhibits CYP3A4, it can significantly increase the levels of simvastatin, leading to a higher risk of **myopathy** and **rhabdomyolysis**.
## Why Each Wrong Option is Incorrect
- **Option A:** This option does not provide specific drugs to assess for interaction.
- **Option B:** Similarly, without specific drugs listed, it's hard to evaluate the interaction, but generally, not all combinations lead to significant CYP450 inhibition.
- **Option C:** This option might seem plausible but lacks specificity to directly assess the interaction.
## Clinical Pearl / High-Yield Fact
A key point to remember is the " grapefruit juice effect". **Grapefruit juice** is a natural inhibitor of CYP3A4. Consuming grapefruit juice with drugs metabolized by CYP3A4 (like certain statins, benzodiazepines, and some immunosuppressants) can lead to increased drug levels and toxicity. This is a classic example of a dietary component affecting drug metabolism.
## Correct Answer Line
**Correct Answer: D.**