Which feature best distinguishes succinylcholine from rocuronium when used during rapid sequence induction in a 32-year-old patient with acute appendicitis requiring emergency surgery?

## Pharmacokinetic Comparison: Succinylcholine vs Rocuronium **Key Point:** The critical discriminator between succinylcholine and rocuronium is the combination of onset time AND duration of action. Succinylcholine is a depolarizing agent with rapid onset (30–60 seconds) but short duration (5–10 minutes clinically, ~20–30 minutes at the neuromuscular junction), while rocuronium is a non-depolarizing agent with slightly slower onset (60–90 seconds) but prolonged duration (30–40 minutes). ### Mechanism Basis | Feature | Succinylcholine | Rocuronium | |---------|-----------------|------------| | **Class** | Depolarizing | Non-depolarizing (aminosteroid) | | **Onset** | 30–60 seconds | 60–90 seconds | | **Duration** | 5–10 min (clinical); 20–30 min (NMJ recovery) | 30–40 minutes | | **Metabolism** | Plasma pseudocholinesterase | Hepatic (minimal renal) | | **Intubating dose** | 1–1.5 mg/kg IV | 1.2 mg/kg IV | **High-Yield:** In RSI, succinylcholine remains the gold standard for its **rapid onset and short duration**, allowing quick airway control with minimal prolonged paralysis. Rocuronium is preferred when succinylcholine is contraindicated (malignant hyperthermia risk, pseudocholinesterase deficiency, severe burns, crush injury, hyperkalemia risk). **Clinical Pearl:** Rocuronium can be rapidly reversed with sugammadex (encapsulation mechanism), whereas succinylcholine relies on enzymatic hydrolysis by plasma pseudocholinesterase — no reversal agent exists. **Mnemonic:** **SUCC-FAST, ROCU-SLOW** — Succinylcholine: Fast onset, Short duration; Rocuronium: Slower onset, Longer duration.