Tuesday, June 25, 2013

Antiarrhytmics Na+ Channel Blockers (Class I)

The image corresponds the ventricular action potential curve. The academic figure shows a black normal ventricular action potential Na+ (type I) antiarrhytmic effects or "BACman" in comparisson with the normal black curve: B of Before (blue curve), A of After (red curve), and C of Cara (face in Spanish) of our hero BACman (see mindmap below).

Correlating the figure above with our minmap:
  • Ventricular potential curve description:
    • Four phases starting with 0
    • Phase 2 called "Plateau" influx Ca+ and efflux K+, atrial potential curve does not have it.
  • The BACman face silhouette is the normal curve. See the phase 3 of the curve to apply the mnemonic:
    • IB antiarrhytmics show the line Before the (normal) face.
    • IA antiarrhytmics show the line After the (normal) face.
    • IC antiarrhytmics show the line Cara (spanish world of face), because is the same as normal in phase 3.
  • Antiarrhytmic type I Meds menmonic (3 words each one):
    • Before you started eating healthy (salads): Lettuce + Tomatoes + Mayo
    • Current you eat so so (fries): More + Fries + Please
    • After you will eat so fat: Double + Quarter + Pounder

REMEMBER:  Drug induced lupus causes: quinidine, hydralazine, chlorpromazine, isoniazide, methyldopa, minocycline, terbinafine, phenytoin, and sulfasalazine.


  1. Procainamide also causes drug induced lupus. Also, anti-histone antodies are prevalent in Lupus.

  2. Q: Via what mechanism do class IA antiarrhytmic exert their antiarrhytmic effects?

    A: Prolongs depolarization via Na+ channel blocked.

  3. Q: A 56 yeras-old woman presents persistent fever, malaise, facial rash, photo sensitivity, and numerous oral ulcers. She is taking an antiarrhytmic medication. Labs shows antinuclear antibodies presence. What antiarrhytmic is the patient taking, and what is the mechanism of the drug?

    A: Quinidine - Stabilization of cardiac membranes and depression of cardiac potential phase 0.

  4. Spelling: Should be 'word' not 'world'.