U01.05.032 Drug reactions—cardiovascular

Understanding cardiovascular drug reactions is crucial for USMLE Step 1 preparation. Below is an organized overview to help students remember key agents and their associated reactions.

1. Drug Reactions and Their Causal Agents

A. Coronary Vasospasm

Causal Agents:
- Cocaine
- Amphetamines
- Sumatriptan
- Ergot alkaloids
Mnemonic: CASE

B. Cutaneous Flushing

Causal Agents:
- Vancomycin
- Adenosine
- Niacin
- Ca²⁺ Channel Blockers
- Echinocandins
- Nitrates
Mnemonic: Flushed from VANCEN (dancing)

Red Man Syndrome

Definition: A rate-dependent infusion reaction to vancomycin.
Presentation: Widespread pruritic erythema caused by histamine release.
Management:
1. Administer diphenhydramine.
2. Slow the infusion rate of vancomycin.

C. Dilated Cardiomyopathy

Causal Agents:
- Anthracyclines (e.g., Doxorubicin, Daunorubicin)
Prevention: Use Dexrazoxane (a cardioprotective agent).

D. Torsades de Pointes

Causal Agents: Drugs that prolong the QT interval:
- AntiArrhythmics (Class IA, III)
- AntiBiotics (e.g., macrolides)
- Anti“C”ychotics (e.g., ziprasidone)
- AntiDepressants (e.g., TCAs)
- AntiEmetics (e.g., ondansetron)
Mnemonic: ABCDE

2. Summary Table

Drug Reaction	Causal Agents	Mnemonic	Management
Coronary vasospasm	Cocaine, Amphetamines, Sumatriptan, Ergot alkaloids	CASE	Avoid triggers
Cutaneous flushing	Vancomycin, Adenosine, Niacin, Ca²⁺ Channel Blockers, Echinocandins, Nitrates	VANCEN (dancing)	Diphenhydramine for Red Man Syndrome
Dilated cardiomyopathy	Anthracyclines (e.g., Doxorubicin, Daunorubicin)	—	Prevent with Dexrazoxane
Torsades de pointes	AntiArrhythmics (IA, III), AntiBiotics (macrolides), Anti“C”ychotics (ziprasidone), AntiDepressants (TCAs), AntiEmetics (ondansetron)	ABCDE	Stop offending drugs, magnesium sulfate

3. Points to Remember

Always link specific drug reactions to their causal agents with mnemonics for easy recall.
Remember preventive measures, such as Dexrazoxane for anthracycline-induced cardiotoxicity.
Management strategies like slowing infusion rates or administering antihistamines can mitigate reactions such as Red Man Syndrome.
Be cautious of drugs that prolong the QT interval; they can precipitate Torsades de Pointes.

Bibliography

First Aid for the USMLE Step 1 (Latest Edition)
Clinical Pharmacology and Therapeutics Textbooks