Which one of the following is the shoest acting intravenous analgesic:
**Core Concept**
The question is testing knowledge of intravenous analgesics and their durations of action. Intravenous analgesics are a class of medications used for rapid pain relief, and their choice depends on the type and severity of pain, as well as the duration of action required.
**Why the Correct Answer is Right**
The correct answer is **C. Alfentanil**. Alfentanil is a potent, short-acting synthetic opioid analgesic that is commonly used for anesthesia induction and for providing analgesia during surgical procedures. Its short duration of action (approximately 10-15 minutes) is due to its rapid redistribution and metabolism by the liver. This makes alfentanil an ideal choice for procedures requiring brief periods of analgesia.
**Why Each Wrong Option is Incorrect**
**Option A:** **Fentanyl** is a synthetic opioid analgesic with a longer duration of action (approximately 1-2 hours) compared to alfentanil, making it less suitable for short procedures.
**Option B:** **Remifentanil** is another short-acting opioid analgesic, but its duration of action is slightly longer (approximately 3-5 minutes) compared to alfentanil. However, its pharmacokinetic profile is more complex due to its rapid metabolism by esterases.
**Clinical Pearl / High-Yield Fact**
When choosing an intravenous analgesic, consider the procedure's duration and the patient's pain profile. Short-acting opioids like alfentanil are ideal for brief procedures, while longer-acting opioids like fentanyl may be more suitable for longer procedures or for providing postoperative pain relief.
**Correct Answer: C. Alfentanil**