U01.05.039 Drug reactions—respiratory

Respiratory drug reactions are significant side effects that medical students must be familiar with for USMLE Step 1. Understanding these adverse effects, their causal agents, and associated mnemonics aids in retention and quick recall during clinical practice and exams.

Common Respiratory Drug Reactions

1. Dry Cough

Causal Agent: Angiotensin-converting enzyme (ACE) inhibitors.
Mechanism: ACE inhibitors increase bradykinin levels, leading to irritation in the respiratory tract.

2. Pulmonary Fibrosis

Causal Agents:
- Methotrexate
- Nitrofurantoin
- Carmustine
- Bleomycin
- Busulfan
- Amiodarone
Mnemonic: “My Nose Cannot Breathe Bad Air”
- M: Methotrexate
- N: Nitrofurantoin
- C: Carmustine
- B: Bleomycin
- B: Busulfan
- A: Amiodarone

Summary Table

Reaction	Causal Agents	Mnemonic/Notes
Dry Cough	ACE inhibitors	Elevated bradykinin levels
Pulmonary Fibrosis	Methotrexate, Nitrofurantoin, Carmustine, Bleomycin, Busulfan, Amiodarone	“My Nose Cannot Breathe Bad Air”

Points to Remember

ACE inhibitors commonly cause dry cough, and switching to an angiotensin receptor blocker (ARB) may help.
Pulmonary fibrosis is a severe adverse effect of several drugs; the mnemonic helps recall their names.
Regular monitoring, including pulmonary function tests, is crucial for patients on drugs with a high risk of pulmonary toxicity.

Bibliography

First Aid for the USMLE Step 1 2024 Edition.
Katzung, B. G., & Trevor, A. J. (2021). Basic and Clinical Pharmacology.

USMLE Step 1 Review Series

Curriculum