QT-Interval Prolongation Associated with Supratherapeutic Guanfacine Concentration: A Case Report.
J Med Toxicol
; 20(2): 218-221, 2024 Apr.
Article
in En
| MEDLINE
| ID: mdl-38231419
ABSTRACT
INTRODUCTION:
Guanfacine, an alpha-2 adrenergic agonist, is used to treat attention deficit hyperactivity disorder (ADHD). Although cardiovascular effects including hypotension and bradycardia are common adverse effects of guanfacine, the effect of guanfacine on QT intervals remains unclear. The association between the serum concentration of guanfacine and its toxicity has also not been fully investigated. CASE REPORT This is a case of a 21-year-old woman with ADHD who developed repeated presyncope 1 day before admission. She was taking 3 mg of extended-release guanfacine and 50 mg of sertraline. On admission, she had bradycardia and hypotension. An electrocardiogram (ECG) showed a QT interval of 0.68 s and a QTcF interval of 0.648 s. The QT intervals were manually measured and corrected by the Fridericia formula (QTcF = QT/RR1/3). Although she denied taking an overdose of guanfacine and other drugs, we suspected guanfacine toxicity. The serum guanfacine concentration was 13.0 ng/mL on admission and decreased to 3.2 ng/mL on day 1 and 0.4 ng/mL on day 2. Changes in QTcF intervals and her vital signs correlated with serum guanfacine concentrations.CONCLUSION:
Supratherapeutic serum guanfacine concentrations may induce QT prolongation.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Attention Deficit Disorder with Hyperactivity
/
Hypotension
Type of study:
Risk_factors_studies
Limits:
Adult
/
Female
/
Humans
Language:
En
Journal:
J Med Toxicol
Journal subject:
TOXICOLOGIA
Year:
2024
Document type:
Article
Affiliation country:
Japan
Country of publication:
United States