Isoniazid and rifampin vs Pyrazinamide and ethambutol
How to tell Isoniazid and rifampin and Pyrazinamide and ethambutol apart when a board question makes them look alike.
INH equals B6 neuropathy; rifampin equals orange/CYP; pyrazinamide equals uric acid; ethambutol equals eyes.
Side by side
Isoniazid needs pyridoxine for neuropathy prevention; rifampin causes orange body fluids and strong enzyme induction.
Pyrazinamide causes hyperuricemia/hepatotoxicity; ethambutol causes optic neuritis with red-green color difficulty.
Isoniazid inhibits mycolic acid synthesis; rifampin inhibits DNA-dependent RNA polymerase.
Pyrazinamide disrupts mycobacterial membrane/energy function in acidic environments; ethambutol inhibits arabinosyl transferase in cell-wall synthesis.
Peripheral neuropathy prevented by B6 points isoniazid; orange secretions and drug interactions point rifampin.
Gout-like hyperuricemia points pyrazinamide; visual acuity or red-green color loss points ethambutol.
The trap
Hepatotoxicity is shared across first-line TB therapy, so it is not the best separator by itself.
The repair move
Attach one organ toxicity to each TB drug before trying to memorize the whole regimen.
Try a free question
CoreA patient starts tuberculosis therapy and is given pyridoxine to prevent peripheral neuropathy. The drug inhibits mycolic acid synthesis and can cause hepatitis. Which drug is this?
Show answer and explanation
Answer: A. Isoniazid. Isoniazid inhibits mycolic acid synthesis; pyridoxine prevents neuropathy, and hepatitis is monitored.
Why the other choices are tempting
- B. Rifampin inhibits DNA-dependent RNA polymerase and causes orange body fluids plus CYP induction.
- C. Pyrazinamide is remembered for hepatotoxicity and hyperuricemia.
- D. Ethambutol is remembered for optic neuritis and red-green color problems.
- E. Streptomycin is an aminoglycoside with oto-nephrotoxicity.
Flashcards
Tap a card to flip it.
What is the fastest separator for Isoniazid and rifampin vs Pyrazinamide and ethambutol?
INH equals B6 neuropathy; rifampin equals orange/CYP; pyrazinamide equals uric acid; ethambutol equals eyes.
What clue should make you choose Isoniazid and rifampin?
Isoniazid needs pyridoxine for neuropathy prevention; rifampin causes orange body fluids and strong enzyme induction.
Quick answers
What is the fastest way to tell Isoniazid and rifampin from Pyrazinamide and ethambutol?
INH equals B6 neuropathy; rifampin equals orange/CYP; pyrazinamide equals uric acid; ethambutol equals eyes.
What is the key clue for Isoniazid and rifampin?
Isoniazid needs pyridoxine for neuropathy prevention; rifampin causes orange body fluids and strong enzyme induction.
What is the key clue for Pyrazinamide and ethambutol?
Pyrazinamide causes hyperuricemia/hepatotoxicity; ethambutol causes optic neuritis with red-green color difficulty.
What is the common trap with Isoniazid and rifampin vs Pyrazinamide and ethambutol?
Hepatotoxicity is shared across first-line TB therapy, so it is not the best separator by itself.