**Core Concept**
Methadone is a synthetic opioid analgesic with a unique pharmacological profile that distinguishes it from other opioids like morphine. Its pharmacokinetics and pharmacodynamics differ significantly, affecting its efficacy, potency, and side effect profile.

**Why the Correct Answer is Right**
Methadone has a longer half-life (15-59 hours) and a higher volume of distribution compared to morphine. This results in a longer duration of action and increased accumulation with repeated dosing, making it suitable for chronic pain management and opioid substitution therapy. Methadone also exhibits a higher affinity for the opioid receptor and a slower dissociation rate, contributing to its longer-lasting effects.

**Why Each Wrong Option is Incorrect**

**Option A:** Methadone has a lower potency compared to morphine.
* This is incorrect because methadone is actually more potent than morphine on a milligram-for-milligram basis.

**Option B:** Methadone has a faster onset of action compared to morphine.
* This is incorrect because methadone has a slower onset of action compared to morphine due to its slower absorption and higher volume of distribution.

**Option C:** Methadone is less likely to cause respiratory depression compared to morphine.
* This is incorrect because methadone can cause significant respiratory depression, similar to morphine, especially at higher doses.

**Clinical Pearl / High-Yield Fact**
Methadone's unique pharmacological profile makes it a valuable option for chronic pain management and opioid substitution therapy, but its use requires careful dosing and monitoring due to its potential for accumulation and toxicity.

**Correct Answer: C. Methadone is more likely to cause QT interval prolongation compared to morphine.**