True statements regarding halothane are all of the following except: March 2007
**Core Concept**
Halothane is a potent inhalational anesthetic agent that was widely used in the past. It has a high lipid solubility, which allows it to rapidly induce anesthesia. However, halothane is also known to cause severe hepatotoxicity, a condition known as halothane hepatitis.
**Why the Correct Answer is Right**
Halothane hepatitis is thought to be an immune-mediated response to the halogenated metabolites of halothane. These metabolites are produced through the action of cytochrome P450 enzymes in the liver. The liver is exposed to these toxic metabolites, leading to an immune response that causes liver cell damage and inflammation. This condition is often referred to as "halothane hepatitis" and can be fatal.
**Why Each Wrong Option is Incorrect**
**Option A:** This statement is true. Halothane is indeed a potent inhalational anesthetic agent with a high lipid solubility, making it suitable for rapid induction of anesthesia.
**Option B:** This statement is true. Halothane is metabolized by cytochrome P450 enzymes in the liver, producing toxic halogenated metabolites that can cause liver damage.
**Option C:** This statement is true. Halothane hepatitis is an immune-mediated response to the toxic metabolites of halothane, leading to liver cell damage and inflammation.
**Clinical Pearl / High-Yield Fact**
To remember the key points about halothane, use the mnemonic "H.A.L.O.T.H.A.N.E." where each letter represents a key concept: H - Hepatotoxicity, A - Anesthetic potency, L - Lipid solubility, O - Oxidative metabolism, T - Toxic metabolites, H - Hepatitis, A - Anaphylaxis, N - Necrosis, E - Enzyme-mediated response.
**Correct Answer: D**