What are the features of Quinine (Chloroquine) toxicity, except hypotension, ventricular bradycardia, supraventricular arrhythmia, hypoglycemia, and prolonged QRS interval?

From the Guidelines

Quinine toxicity, except for hypotension, ventricular bradycardia, supraventricular arrhythmia, hypoglycemia, and prolonged QRS interval, is characterized by cinchonism, which includes symptoms such as tinnitus, vertigo, headache, and acute hearing loss 1.

Features of Quinine Toxicity

• Cinchonism: a condition caused by an overdose of quinine, characterized by symptoms such as tinnitus, vertigo, headache, and acute hearing loss 1
• Electrocardiographic changes: such as prolongation of the QT-interval, which may be an accurate indicator of both plasma concentration and incipient cardiotoxicity 1
• Cardiotoxicity: quinine can cause cardiotoxicity, particularly at high plasma concentrations, and patients requiring parenteral quinidine should be treated in intensive-care facilities with close monitoring of their electrocardiogram and hemodynamic status 1

Management of Quinine Toxicity

• Monitoring: close attention to the patient's hydration, blood glucose, and electrocardiogram is required 1
• Dose adjustment: plasma quinidine levels greater than 6 mg/mL, QT interval greater than 0.6 sec, or QRS widening beyond 25% of baseline are indications for slowing infusion rates 1
• Treatment of hypoglycemia: persons with hypoglycemia should be treated with intravenous dextrose 1

From the FDA Drug Label

Quinine overdose can be associated with serious complications, including visual impairment, hypoglycemia, cardiac arrhythmias, and death. Visual impairment can range from blurred vision and defective color perception, to visual field constriction and permanent blindness. Cinchonism occurs in virtually all patients with quinine overdose Symptoms range from headache, nausea, vomiting, abdominal pain, diarrhea, tinnitus, vertigo, hearing impairment, sweating, flushing, and blurred vision, to deafness, blindness, serious cardiac arrhythmias, hypotension, and circulatory collapse Central nervous system toxicity (drowsiness, disturbances of consciousness, ataxia, convulsions, respiratory depression, and coma) has also been reported with quinine overdose, as well as pulmonary edema and adult respiratory distress syndrome 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, except hypotension, ventricular bradycardia, supraventricular arrhythmia, hypoglycemia, and prolonged QRS interval, include:

• Visual impairment: blurred vision, defective color perception, visual field constriction, permanent blindness
• Cinchonism: headache, nausea, vomiting, abdominal pain, diarrhea, tinnitus, vertigo, hearing impairment, sweating, flushing
• Central nervous system toxicity: drowsiness, disturbances of consciousness, ataxia, convulsions, respiratory depression, coma
• Pulmonary edema and adult respiratory distress syndrome
• Sinus tachycardia
• PR prolongation
• T wave inversion
• Bundle branch block
• Increased QT interval
• Cardiogenic shock and circulatory collapse
• Ventricular arrhythmias: ventricular tachycardia, ventricular fibrillation, idioventricular rhythm, torsades de pointes
• Atrioventricular block 2 2

From the Research

Features of Quinine (Chloroquine) Toxicity

The features of quinine (chloroquine) toxicity, excluding hypotension, ventricular bradycardia, supraventricular arrhythmia, hypoglycemia, and prolonged QRS interval, are:

• Obnubilation, coma, convulsions, and respiratory depression 3
• Blindness, which is a frequent complication in quinine overdose 3
• Hypokalaemia, which is consistently present in severe chloroquine poisoning and is a good index of severity 3
• Cardiogenic shock and circulatory arrest 3
• Conduction disturbances and ventricular arrhythmias 3
• Methaemoglobinaemia, which is the main feature of primaquine overdose, but not directly related to quinine or chloroquine toxicity 3
• Nausea, vomiting, confusion, convulsion, and acute psychosis, which can occur in overdose with quinacrine, an acridine derivative 3
• Transiently hypotensive plasma concentrations can occur when doses of 5 mg base/kg or more are given by intramuscular or subcutaneous injection 4
• Bilateral retinal edema 5
• Transitory bilateral blindness 5