Question 14

Compare and contrast the clinical features and management of a patient following beta blocker overdose with those of a patient following calcium-channel blocker overdose.

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College Answer

	Beta-blockers	Ca channel blockers
General	Clinical features depend on type of drug and amount ingested. Most symptoms within 4 hrs of ingestion	Varying CVS effects
CVS	Hypotension, bradycardia, AV block,	Hypotension, bradycardia

	CCF
Other systems	Bronchospasm, hypoglycemia, hyperkalemia, stupor, coma, seizures	Hyperglycemia, nausea and vomiting reported. Seizures uncommon.
Treatment	Charcoal, fluids, Beta agonists, vasopressors, atropine, pacing, glucagon.	Charcoal, IV fluids, IV CaCl2, glucagon, hyperinsulinemai- euglycemia therapy, pacing, charcoal hemoperfusion in the case of verapamil

Discussion

Though satisfactory, the college answer lacks qualities which help the studying candidate generate some memory of the differences between these drugs. The table below builds on the college answer by highlighting in bold the key differences between these overdoses.

	Calcium channel blocker overdose	Beta-blocker overdose
Clinical features	Bradycardia Hypotension Heart block Hyperglycaemia Constipation/ileus	Bradycardia Hypotension Heart block HYPOglycaemia Bronchospasm
Management:
Antidote	Ionised calcium (eg. calcium chloride) Glucagon Insulin-dextrose Inotropes and vasopressors	Glucagon Insulin-dextrose Inotropes and vasopressors
Decontamination	Activated charcoal	Activated charcoal
Enhancement of clearance	Hemoperfusion for verapimil	Hemoperfusion for metoprolol

References

DeWitt, Christopher R., and Javier C. Waksman. "Pharmacology, pathophysiology and management of calcium channel blocker and β-blocker toxicity." Toxicological reviews 23.4 (2004): 223-238.

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