In overdose, which beta-blocker has an under-recognised risk of toxicity?

In overdose, which beta-blocker has an under-recognised risk of toxicity?

• A. Metoprolol
• B. Propranolol hydrochloride
• C. Atenolol
• D. Bisoprolol

Answer: (B)

The important idea is how a beta-blocker’s properties influence overdose toxicity. Propranolol hydrochloride is non-selective and highly lipophilic, so it readily crosses the blood–brain barrier. In overdose, this means it can produce significant central nervous system effects—confusion, coma, seizures—in addition to the usual cardiovascular effects like severe bradycardia and hypotension. Those CNS and metabolic toxicities can be under-recognised because clinicians often focus on heart-rate and blood pressure, not on brain function or glucose issues. This makes propranolol toxicities more dramatic and potentially overlooked compared with the other listed beta-blockers. Metoprolol, atenolol, and bisoprolol are generally more hydrophilic and/or more cardioselective, so their overdose effects tend to be dominated by cardiac depression with less pronounced CNS involvement. Therefore, propranolol presents a higher and more often under-appreciated risk of toxicity in overdose.

The important idea is how a beta-blocker’s properties influence overdose toxicity. Propranolol hydrochloride is non-selective and highly lipophilic, so it readily crosses the blood–brain barrier. In overdose, this means it can produce significant central nervous system effects—confusion, coma, seizures—in addition to the usual cardiovascular effects like severe bradycardia and hypotension. Those CNS and metabolic toxicities can be under-recognised because clinicians often focus on heart-rate and blood pressure, not on brain function or glucose issues.

This makes propranolol toxicities more dramatic and potentially overlooked compared with the other listed beta-blockers. Metoprolol, atenolol, and bisoprolol are generally more hydrophilic and/or more cardioselective, so their overdose effects tend to be dominated by cardiac depression with less pronounced CNS involvement. Therefore, propranolol presents a higher and more often under-appreciated risk of toxicity in overdose.