Drug interactions mnemonic

Common inducers of cytochrome P450 enzymes

The mnemonic

PC BRAGS

What each word stands for

  • PPhenytoin
  • CCarbamazepine
  • BBarbiturates
  • RRifampicin
  • AAlcohol (chronic use)
  • GGriseofulvin
  • SSulfonylureas (listed in some versions)

Why it matters clinically

Inducers lower levels of co-administered drugs such as warfarin and oral contraceptives, risking therapeutic failure.

Where it stops being reliable

Inclusion of sulfonylureas varies by source, and St John's wort is a clinically important inducer that the mnemonic omits. Acute alcohol use inhibits rather than induces.

Teaching aid, still awaiting independent review. Confirm facts in a standard source.

More mnemonics

Common questions

What is the Drug interactions mnemonic?

PC BRAGS. It helps you recall: Common inducers of cytochrome P450 enzymes.

What does "P" stand for?

Phenytoin

What does "C" stand for?

Carbamazepine

What does "B" stand for?

Barbiturates

What are all the parts of the PC BRAGS mnemonic?

P: Phenytoin; C: Carbamazepine; B: Barbiturates; R: Rifampicin; A: Alcohol (chronic use); G: Griseofulvin; S: Sulfonylureas (listed in some versions).

Which topic does this mnemonic belong to?

It belongs to Drug interactions in Pharmacology.

Where does this mnemonic stop being reliable?

Inclusion of sulfonylureas varies by source, and St John's wort is a clinically important inducer that the mnemonic omits. Acute alcohol use inhibits rather than induces.

How is this useful clinically?

Inducers lower levels of co-administered drugs such as warfarin and oral contraceptives, risking therapeutic failure.

How do I make this mnemonic stick?

Say it aloud, write it from memory tomorrow, then again in a week. Then test yourself on a Pharmacology question about Drug interactions.

Is this a standard mnemonic?

It is a teaching aid written or adapted by our team. Some resemble ones students share informally. Check any fact that matters in a standard source.