Antiarrhythmic drugs - kau



Antiarrhythmic drugs

Antiarrhythmic drugs can be classified according to their effects on the electrical behavior of myocardial cells during activity into:

(The Vaughan Williams classification)

Class IA, B, C: Sodium channel blockers (membrane stabilizing drugs).

Class II: beta-blockers.

Class III: potassium-channel blockers.

Class IV: calcium-channel blockers.

Class IA: Na cannel blockers

|Drugs |Quinidine |*Procainamide |Disopyramide |

| |(Kinidin Durules®) |(Pronestyl®) |(Norpace ®) |

|MOA |Decreases myocardial conduction velocity and excitability.|Primarily increases the effective refractory period of atrial and |As quinidine. |

| |Depresses myocardial contractility. Suppresses |ventricular sodium-dependent tissue. | |

| |automatically in His-Purkinje system. |As quinidine. | |

| |Sodium channel blocker with moderate anticholinergic | | |

| |properties. |Sodium channel blocker with weak anticholinergic properties. | |

| | | | |

| | | |Sodium channel blocker with strong anticholinergic properties. |

|Uses |•Atrial flutter or fibrillation |As quinidine. |As quinidine. |

| |•Ventricular tachycardia | | |

| |•Paroxysmal supraventricular tachycardia | | |

|Pregnancy risk factor |C |C |C |

|Pharmaco- |Metabolism: extensively hepatic. |Metabolism: hepatic via acetylation to produce N-acetyl |Duration:1.5-8.5 h |

|kinetics | |procainamide (NAPA) (active metabolite). |Metabolism: hepatic |

| |Half-life elimination: |Half-life elimination: | |

| |Adults: 6-8 hr |Adults: 2.5-4.7 h (relatively short half-life) | |

| | |Excretion: urine (25% as NAPA) |Half-life elimination:4 -10 h |

| |Excretion: urine. | | |

| | | |Excretion: urine. |

|Dosing |Adults: PO: 100-600 mg/dose q4-6h; begin at 200 mg/dose & |Adults: PO: 250-500mg/dose q3-6 h or 500mg to 1g q6h extended |Adults: |

| |titrate to desired effect (maximum 3-4g/d). |release; usual dose 50mg /kg/d; max: 4g/d. |50 kg: 150 mg q6h or 300-mg extended-release (CR) capsule |

| | |over 25-30 min or 100-200 mg /dose repeated q5 minas needed to a |q12h. |

| | |total dose of 1g; maintenance dose: 1-4 mg/min by continues |If no response ↑ to 200 mg q6h. |

| | |infusion. |max. dose required for patient with sever refractory |

| | | |ventricular tachycardia is 400 mg q6h. |

|Adjustment of dosage |• Kidney disease: |• Kidney disease: |• Kidney disease: |

| |Creatinine clearance ................
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