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CARDIOVASCULAR SYSTEM › CARDIAC THERAPY › ANTIARRHYTHMICS, CLASS I AND III › Antiarrhythmics, class Ia
quinidine, combinations with psycholeptics
C01BA71
Forms & Strengths
- Tablets: 200mg quinidine sulfate with 25mg chlorpromazine
- Tablets: 200mg quinidine sulfate with 50mg promethazine
- Injectable: 200mg quinidine sulfate with 25mg chlorpromazine per 2mL
- Injectable: 200mg quinidine sulfate with 50mg promethazine per 2mL
Adult Dosing
- Oral: 200-400mg quinidine sulfate with 25-50mg psycholeptic every 6-8 hours
- IV: 200mg quinidine sulfate with 25mg psycholeptic diluted in 10mL saline, administered over 1 minute
- Maximum daily dose: 1200mg quinidine sulfate with 300mg psycholeptic
Pediatric Dosing
- Not recommended for children under 12 years
- 12-16 years: start with low dose (100mg quinidine sulfate with 12.5mg psycholeptic) and titrate
- Pediatric patients require close monitoring due to increased risk of toxicity
Indications
- Life-threatening ventricular arrhythmias
- Supraventricular arrhythmias when other treatments have failed
- Atrial fibrillation with rapid ventricular response
Mechanism of Action
- Class I antiarrhythmic: blocks sodium channels, reducing automaticity and prolonging refractory period
- Anticholinergic effects: may contribute to antiarrhythmic efficacy
- Psychotropic effects of psycholeptic component may enhance patient compliance
Contraindications
- Known hypersensitivity to quinidine, psycholeptics, or related compounds
- Myasthenia gravis
- Digitalis toxicity
- Concurrent use of drugs that prolong QT interval
Adverse Reactions
- Gastrointestinal: nausea, vomiting, diarrhea
- Cardiovascular: hypotension, worsening arrhythmia, QT prolongation
- Neurological: dizziness, headache, psychosis
- Hematological: thrombocytopenia, agranulocytosis
Drug Interactions
- Digitalis: increased risk of digitalis toxicity
- Anticholinergics: increased anticholinergic effects
- Antiarrhythmics: increased risk of arrhythmias and QT prolongation
- MAOIs: increased risk of hypertensive crisis
Curated Content: Needs Vetting Before Put to Clinical Use