Salbutamol / β-Agonist Toxicity

Sources: • Therapeutic excess (high-dose nebulised salbutamol in severe asthma). • Iatrogenic IV salbutamol. • Intentional overdose (oral tablets / inhaler abuse). • Pre-term labour tocolysis. Features (β2-mediated): • Cardiac: sinus tachycardia (often >150), palpitations, occasional hypotension, rarely arrhythmia. • Tremor (β2 in skeletal muscle). • Hypokalaemia (K shifts intracellularly) — can be severe (<3.0). • Hyperglycaemia (β2-mediated glycogenolysis + ↓ insulin). • Lactic acidosis (high-flux glycolysis + adrenergic). • Anxiety, insomnia, headache. • Hypoxia paradox in nebuliser-treated asthmatic — pulmonary vasodilation worsens V/Q mismatch.