Top 10 Pharmacology Mnemonics for USMLE Step 1

Pharmacology on USMLE Step 1 is a volume problem. There are hundreds of drugs, each with mechanisms, side effects, interactions, and contraindications. Raw memorization hits a ceiling fast. Mnemonics provide the scaffolding that makes this volume manageable — provided they encode the right information.

These ten mnemonics are selected for yield and durability. Each encodes information that appears on virtually every Step 1 exam form.

1. Cytochrome P450 Inducers: "Queen Barb Takes Phen-Phen and Refuses Greasy Carbs Chronically"

• Quinidine (minor)
• Barbiturates
• Tobacco
• Phenytoin
• Phenobarbital
• Rifampin
• Griseofulvin
• Carbamazepine
• Chronic alcohol use

Clinical implication: Inducers speed drug metabolism → decreased drug levels of co-administered medications (e.g., rifampin decreases oral contraceptive efficacy — a classic USMLE question).

2. Cytochrome P450 Inhibitors: "SICKFACES.COM"

• Sodium valproate
• Isoniazid
• Cimetidine
• Ketoconazole
• Fluconazole
• Acute alcohol use
• Chloramphenicol
• Erythromycin
• Sulfonamides
• Ciprofloxacin
• Omeprazole
• Metronidazole

Clinical implication: Inhibitors slow drug metabolism → increased drug levels → toxicity risk (e.g., erythromycin + statin → rhabdomyolysis).

3. Drugs Causing Disulfiram-Like Reactions: "Some Crazy Medicines Provoke Terrible Gastric Symptoms"

Sulfonylureas (1st gen), Cephalosporins (with methyltetrazole ring), Metronidazole, Procarbazine, Tinidazole, Griseofulvin

These drugs block aldehyde dehydrogenase. Combined with alcohol → acetaldehyde accumulation → flushing, nausea, vomiting, headache.

4. Sulfa Drug Allergies: "STDP" (Sulfa Things to Definitely Pause)

Before prescribing these to a patient with a sulfa allergy: Sulfasalazine, Thiazides, Dapsone, Probenecid, plus sulfonylureas, acetazolamide, and loop diuretics (furosemide, bumetanide). Celecoxib contains a sulfonamide group.

5. Aminoglycoside Toxicity: "A Mean Old Nephrotoxic Ototoxic Group"

Aminoglycosides (gentamicin, tobramycin, amikacin) cause nephrotoxicity (ATN) and ototoxicity (CN VIII — both vestibular and cochlear). Monitor trough levels. Potentiated by loop diuretics.

6. Zero-Order Elimination: "PEA"

• Phenytoin
• Ethanol
• Aspirin (at high doses)

Zero-order = constant amount eliminated per unit time (saturation kinetics). Small dose increases can cause disproportionate toxicity. This is why phenytoin has a narrow therapeutic index.

7. Drug-Induced Lupus: "HIP"

• Hydralazine
• Isoniazid
• Procainamide

Also: minocycline, methyldopa, quinidine, chlorpromazine. Presents with anti-histone antibodies (unlike SLE, which has anti-dsDNA). Resolves when the drug is discontinued.

8. Drugs Causing Megaloblastic Anemia: "MTP" (Messing up The Pathways)

Methotrexate (inhibits dihydrofolate reductase), Trimethoprim (same mechanism), Phenytoin (impairs folate absorption). Also: 5-FU, hydroxyurea. Treat with leucovorin (folinic acid) for methotrexate toxicity.

9. Drugs Safe in Pregnancy — The "BAM" Rule

When in doubt about pregnancy safety, remember the classes that are generally safe:

• Beta-lactams (penicillins, cephalosporins)
• Acetaminophen
• Metformin (in gestational diabetes), Methyldopa (for HTN in pregnancy)

Category X drugs to absolutely avoid: isotretinoin, statins, warfarin, methotrexate, thalidomide, ACE inhibitors/ARBs (2nd and 3rd trimester).

10. Anti-Epileptics and Teratogenicity: "VCP" (Valproate Creates Problems)

Valproate → neural tube defects (highest risk of all AEDs). Carbamazepine → neural tube defects (lower risk than valproate). Phenytoin → fetal hydantoin syndrome (nail/digit hypoplasia, facial features, growth restriction).

Lamotrigine is the preferred anti-epileptic in pregnancy.

Making Mnemonics Stick

A mnemonic is only useful if you can retrieve it under exam pressure. The solution: active practice. USMLAI's pharmacology module presents drug interaction and side effect questions that force you to deploy these mnemonics in clinical context — transforming recall aids into applied knowledge.