Quinidine, Procainamide, Disopyramide (The Queen proclaims Diso's pyramid)

- ↑ AP duration, ↑ effective refractory period (ERP), ↑ QT interval, some potassium channel blocking effects.

Clinical use: Atrial and ventricular arrhythmias, especially re-entrant and ectopic SVT and VT.

Adverse effects:- Cinchonism (headache, tinnitus with quinidine)- Reversible SLE-like syndrome (procainamide)- HF (disopyramide)- Thrombocytopenia- Torsades de pointes due to ↑ QT interval