U01.05.040 Drug reactions—multiorgan

This guide focuses on specific drug reactions involving multiple organ systems, the associated causal agents, and keynotes to aid in memorization and clinical application.

Key Drug Reactions and Their Agents

1. Antimuscarinic Toxicity

Causal Agents:

Atropine
Tricyclic Antidepressants (TCAs)
H1-blockers
Antipsychotics

Features:
Antimuscarinic toxicity commonly presents with dry mouth, blurred vision, urinary retention, constipation, and confusion (especially in the elderly).

2. Disulfiram-like Reaction

Causal Agents:

1st-generation Sulfonylureas
Procarbazine
Certain Cephalosporins
Griseofulvin
Metronidazole

Mnemonic:
“Sorry Pals, Can’t Go Mingle”

Mechanism:
These drugs inhibit acetaldehyde dehydrogenase, leading to acetaldehyde accumulation. Patients experience flushing, hypotension, and nausea upon alcohol consumption.

3. Nephrotoxicity and Ototoxicity

Causal Agents:

Loop diuretics
Aminoglycosides
Cisplatin
Vancomycin
Amphotericin B

Mnemonic:
“Listen And Pee Very TERriBly”

Notes:

Cisplatin toxicity may respond to amifostine, a cytoprotective agent.
Monitor renal function and hearing in patients receiving these drugs.

Summary Table

Reaction	Causal Agents	Notes
Antimuscarinic	Atropine, TCAs, H1-blockers, antipsychotics	Commonly causes dry mouth, confusion, blurred vision, and urinary retention.
Disulfiram-like	1st-gen Sulfonylureas, Procarbazine, Cephalosporins, Griseofulvin, Metronidazole	Avoid alcohol; presents with flushing and nausea. Mnemonic: “Sorry Pals, Can’t Go Mingle.”
Nephrotoxicity/Ototoxicity	Loop diuretics, Aminoglycosides, Cisplatin, Vancomycin, Amphotericin B	Use amifostine for cisplatin toxicity. Mnemonic: “Listen And Pee Very TERriBly.”

Points to Remember

Recognize Patterns: Certain drug classes often have predictable toxicities, e.g., aminoglycosides causing ototoxicity.
Use Mnemonics: Helps retain information (e.g., “Sorry Pals, Can’t Go Mingle” for Disulfiram-like reactions).
Monitor and Prevent: Regular lab tests (renal function, audiometry) can prevent severe adverse outcomes.
Avoid Risk Factors: Caution in elderly patients or those with pre-existing renal or hepatic dysfunction.

References

First Aid for the USMLE Step 1
Basic and Clinical Pharmacology by Bertram G. Katzung

USMLE Step 1 Review Series

Curriculum

U01.05.040 Drug reactions—multiorgan

Key Drug Reactions and Their Agents

1. Antimuscarinic Toxicity

2. Disulfiram-like Reaction

3. Nephrotoxicity and Ototoxicity

Summary Table

Points to Remember

References

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