From the Guidelines
Quinine toxicity features that do not include hypotension, ventricular bradycardia, supraventricular arrhythmia, hypoglycemia, and prolonged QRS complex are cinchonism, which encompasses symptoms such as tinnitus, hearing loss, vertigo, blurred vision, and nausea.
Key Features of Quinine Toxicity
- Cinchonism: a condition characterized by tinnitus, hearing loss, vertigo, blurred vision, and nausea 1
- Quinine can cause QT prolongation and Torsades de Pointes, a life-threatening arrhythmia 1
- The risk of quinine-induced Torsades de Pointes is estimated to be around 8% 1
- Quinine can also cause hypoglycemia, particularly in patients with diabetes or those taking oral hypoglycemic agents
- Hypotension and ventricular bradycardia are not typically associated with quinine toxicity, but can occur in severe cases
- Supraventricular arrhythmia is not a common feature of quinine toxicity
- Prolonged QRS complex is not typically associated with quinine toxicity, but can occur in cases of severe quinine overdose
Management of Quinine Toxicity
- Removal of the offending agent is indicated in patients with quinine-induced Torsades de Pointes or QT prolongation 1
- Intravenous magnesium can suppress episodes of Torsades de Pointes without necessarily shortening QT, even when serum magnesium is normal 1
- Temporary pacing is highly effective in managing Torsades de Pointes that is recurrent after potassium repletion and magnesium supplementation 1
From the FDA Drug Label
The cardiotoxicity of quinine is due to its negative inotropic action, and to its effect on cardiac conduction, resulting in decreased rates of depolarization and conduction, and increased action potential and effective refractory period ECG changes observed with quinine overdose include sinus tachycardia, PR prolongation, T wave inversion, bundle branch block, an increased QT interval, and a widening of the QRS complex. Quinine's alpha-blocking properties may result in hypotension and further exacerbate myocardial depression by decreasing coronary perfusion Quinine overdose has been also associated with hypotension, cardiogenic shock, and circulatory collapse, ventricular arrhythmias, including ventricular tachycardia, ventricular fibrillation, idioventricular rhythm, and torsades de pointes, as well as bradycardia, and atrioventricular block
The features of Quinine toxicity that do not include hypotension, ventricular bradycardia, supraventricular arrhythmia, hypoglycemia, and prolonged QRS complex are:
- Sinus tachycardia
- PR prolongation
- T wave inversion
- Bundle branch block
- Increased QT interval
- Ventricular arrhythmias (including ventricular tachycardia, ventricular fibrillation, idioventricular rhythm, and torsades de pointes)
- Atrioventricular block
- Cardiogenic shock
- Circulatory collapse 2
From the Research
Features of Quinine Toxicity
The features of quinine toxicity that do not include hypotension, ventricular bradycardia, supraventricular arrhythmia, hypoglycemia, and prolonged QRS complex are:
- Ventricular tachycardia 3
- Status epilepticus 3
- Hypothermia 3
- Coma 3
- Reactive mydriasis 3
- Bilateral retinal edema 3
- Transitory bilateral blindness 3
- Nausea, vomiting, and diaphoresis 4
- Atrioventricular dissociation with escape His bundle or fascicular rhythm 4
- QT prolongation 5, 6
- Torsades de pointes (TdP) 5, 6
- Sinus bradycardia 4
- Bundle-branch block 4, 7
- Cardiac index and left ventricular ejection fraction abnormalities 7
- Right ventricular effective refractory period increase 7
Cardiovascular Side-Effects
Quinine poisoning can cause various cardiovascular side-effects, including:
- Hypotension 3, 4, 7, 6
- Abnormal myocardial conduction 3
- Ventricular arrhythmias 3, 4, 7
- Supraventricular arrhythmias 4, 7
- Prolonged QRS complex 3, 4, 7
- QT interval prolongation 5, 6
Treatment and Management
Quinine toxicity can be managed with various treatments, including: