A patient on propranolol (non-selective beta-blocker) receives 4 carpules of local anesthetic with epinephrine. Blood pressure rises to 200/100 mmHg. What is the MOST likely cause?

Correct answer: C. Unopposed alpha-adrenergic stimulation from epinephrine due to beta-2 blockade by propranolol

• A. Incorrect. Anxiety-induced BP elevation does not typically reach 200/100 and is not specifically caused by the carpule count + drug combination.
• B. Incorrect. Allergic reactions manifest as urticaria, bronchospasm, anaphylaxis — not sudden severe hypertension.
• C. Correct. Propranolol blocks both beta-1 (cardiac) and beta-2 (vasodilatory) receptors. When epinephrine is given, its ALPHA-1 vasoconstrictive effects are UNOPPOSED (beta-2 vasodilation is blocked), causing a pronounced hypertensive crisis. Classic non-selective beta-blocker + epinephrine interaction.
• D. Incorrect. Intravascular injection causes tachycardia AND hypertension simultaneously with more CNS symptoms.