During laryngoscopy and endotracheal intubation, a patient receives atracurium 0.5 mg/kg. Shortly after, the anaesthetist notes facial flushing and a drop in blood pressure. What is the mechanism of this side effect of atracurium?

• A Direct myocardial depression
• B Activation of nicotinic receptors at autonomic ganglia
• C Vagal stimulation causing bradycardia
• D Histamine release from mast cells ✓

Explanation

Atracurium can cause dose-dependent histamine release from mast cells, leading to flushing, hypotension, and occasionally bronchospasm. This is a known side effect of the benzylisoquinolinium class. The flush is typically transient and self-limiting. Vecuronium and rocuronium (aminosteroids) do not cause histamine release. Pancuronium, by contrast, causes tachycardia through vagolysis rather than histamine release.

Reference: Pharmacology and Physiology for Anaesthesia, 2nd ed.

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