Home
Disease Vault Drug Index & Alternatives Drug Interactions Pregnancy Drug Safety Drug Recalls & Alerts OTC Navigator
Medical Bot Med Lab Clinical Cases Nutrition & Macro Calculator
Questo Insights Global Opportunities Paper Helper Citation Generator Scholarships & Travel Visa & Mobility Navigator English Assessment Test
Med Jobs Med Lounge Pharma Swap Pharmacies Directory Medical Case Donations Opportunity Crowdfunding
Courses Academy Quiz Arena Memory Palace STEM Academy Toolkits
About Us Contact Us Privacy Policy Terms of Service
Back to Memory Palace
Pharmacology Drug Metabolism & Pharmacokinetics Intermediate
2,325 views

Cytochrome P450 Enzyme Inducers

CRAP
GPS
Classic mnemonic for agents that induce hepatic microsomal enzymes, accelerating metabolism of co-administered drugs.

Enzyme inducers upregulate transcriptional synthesis of CYP enzymes (primarily via PXR and CAR nuclear receptors). This accelerates drug clearance, leading to subtherapeutic plasma levels and clinical failure of oral contraceptives, warfarin, and immunosuppressants.

Systematic Breakdown

C

Carbamazepine

Powerful inducer of CYP3A4; also notable for auto-induction (induces its own metabolism over time).

R

Rifampin (Rifampicin)

The most potent CYP3A4/2C9 inducer known. Rapidly renders oral contraceptives and warfarin ineffective.

A

Alcohol (Chronic Use)

Chronic alcoholism induces CYP2E1, causing increased acetaminophen conversion to toxic NAPQI.

P

Phenytoin

Anticonvulsant that induces CYP3A4, 2C9, and 2C19.

G

Griseofulvin

Oral antifungal used for tinea capitis; induces hepatic cytochrome P450 system.

P

Phenobarbital

Barbiturate that powerfully upregulates transcription of multiple CYP isoenzymes.

S

St. John's Wort / Smoking

Herbal supplement that induces CYP3A4 and P-glycoprotein; aromatic hydrocarbons in cigarette smoke induce CYP1A2.

High-Yield Clinical Pearls & Exam Tips
  • Classic Board Scenario: A woman on oral contraceptive pills is started on Rifampin for latent TB (or St. John's Wort for depression) and becomes pregnant.
  • Organ Transplant Scenario: A patient on Cyclosporine or Tacrolimus starts St. John's Wort, experiences sharp drop in drug level, and suffers acute organ rejection.
Related Pharmaceuticals
Rifampin Carbamazepine Phenytoin Phenobarbital St. John's Wort
Related Clinical Conditions
Unintended Pregnancy Graft Rejection Subtherapeutic Anticoagulation
Authoritative Sources: Katzung Basic & Clinical Pharmacology 15e · First Aid USMLE Step 1

More Pharmacology Mnemonics

Pharmacology Beginner
NOT

Aminoglycoside Major Toxicities

N O T

The three classical adverse effect categories of aminoglycoside antibiotics (Gentamicin, Tobramycin, Amikacin).

Sanford Guide to Antimicrobial Therapy 695
Pharmacology Intermediate
LEAD LINES

Lead Poisoning Manifestations: LEAD

LEAD LINES

Clinical signs of environmental lead toxicity in pediatric and occupational populations.

Goldfrank's Toxicologic Emergencies 11e 2,117
Pharmacology Intermediate
TERATO

Teratogenic Drugs High-Yield List

T E R A T O

The highest-yield universally tested medications that cause severe fetal structural malformations when taken during pregnancy.

Briggs Drugs in Pregnancy and Lactation 12e 1,641

System Notice

Confirm Action