U01.05.036 Drug reactions—musculoskeletal/skin/connective tissue

Understanding drug reactions related to the musculoskeletal, skin, and connective tissue systems is crucial for USMLE Step 1 preparation. Below is an organized guide to help you learn these reactions effectively.

Common Drug Reactions and Causal Agents

Table: Drug Reactions, Agents, and Mnemonics

Reaction	Causal Agents	Mnemonic
Drug-induced lupus	Methyldopa, Minocycline, Hydralazine, Isoniazid, Phenytoin, Sulfa drugs, Etanercept, Procainamide	Lupus Makes My HIPS Extremely Painful
Fat redistribution	Protease inhibitors, Glucocorticoids	Fat PiG
Gingival hyperplasia	Cyclosporine, Ca²⁺ channel blockers, Phenytoin	Can Cause Puffy gums
Hyperuricemia (gout)	Pyrazinamide, Thiazides, Furosemide, Niacin, Cyclosporine	Painful Tophi and Feet Need Care
Myopathy	Statins, Fibrates, Niacin, Colchicine, Daptomycin, Hydroxychloroquine, Interferon-α, Penicillamine, Glucocorticoids	–
Osteoporosis	Corticosteroids, Depot medroxyprogesterone acetate, GnRH agonists, Aromatase inhibitors, Anticonvulsants, Heparin, PPIs	–
Photosensitivity	Sulfonamides, Amiodarone, Tetracyclines, 5-FU	SAT For Photo
Rash (Stevens-Johnson syndrome)	Anti-epileptic drugs (especially lamotrigine), Allopurinol, Sulfa drugs, Penicillin	Steven Johnson has epileptic allergy to sulfa drugs and penicillin
Teeth discoloration	Tetracyclines	Teethracyclines
Tendon/cartilage damage	Fluoroquinolones	–

Detailed Notes on Reactions

Drug-Induced Lupus
- Clinical Significance: Presents with lupus-like symptoms such as fever, rash, and arthritis.
- Mnemonic: Lupus Makes My HIPS Extremely Painful.
Fat Redistribution
- Mechanism: Central obesity with peripheral wasting.
- Mnemonic: Fat PiG (Protease inhibitors, Glucocorticoids).
Gingival Hyperplasia
- Description: Excessive growth of gingival tissue leading to discomfort.
- Mnemonic: Can Cause Puffy gums.
Hyperuricemia (Gout)
- Implications: Gout symptoms such as joint pain due to urate crystal deposition.
- Mnemonic: Painful Tophi and Feet Need Care.
Myopathy
- Symptoms: Muscle pain or weakness, elevated creatine kinase levels.
- Causal Agents: Includes statins and fibrates.
Osteoporosis
- Concern: Increased risk of fractures due to reduced bone density.
Photosensitivity
- Manifestations: Sunburn-like rash on exposure to sunlight.
- Mnemonic: SAT For Photo (Sulfonamides, Amiodarone, Tetracyclines, 5-FU).
Rash (Stevens-Johnson Syndrome)
- Symptoms: Severe mucocutaneous reactions with bullous lesions.
- Mnemonic: Steven Johnson has epileptic allergy to sulfa drugs and penicillin.
Teeth Discoloration
- Agent: Tetracyclines.
- Mnemonic: Teethracyclines.
Tendon/Cartilage Damage
- Associated with: Fluoroquinolones, known to cause tendinitis and Achilles tendon rupture.

Points to Remember

Always link drugs to their adverse effects using mnemonics to enhance memory retention.
Focus on differentiating reactions with overlapping drugs, e.g., Photosensitivity and Rash (Stevens-Johnson syndrome) both involve sulfa drugs.
Be mindful of clinical presentations during patient care and pharmacological interventions.

Bibliography

First Aid for the USMLE Step 1, 2024.
Katzung’s Basic & Clinical Pharmacology, 16th Edition.
UpToDate: Drug-Induced Skin Reactions.

USMLE Step 1 Review Series

Curriculum