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Updated: Jul 5, 2025
09:45
Modification and Functionalization of the Guanidine Group by Tailor-made Precursors
Published on: April 27, 2017
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QT-Interval Prolongation Associated with Supratherapeutic Guanfacine Concentration: A Case Report
Fumiya Inoue1, Yuji Okazaki2, Kenichiro Kashiwa1
1Department of Emergency Medicine, Hiroshima City Hiroshima Citizens Hospital, 7-33 Motomachi, Naka-Ku, Hiroshima City, 730-8518, Japan.
Summary
High guanfacine levels in a patient with ADHD were linked to dangerous heart rhythm changes, specifically QT prolongation. This suggests that excessive guanfacine concentrations can cause significant cardiovascular toxicity.
Area of Science:
- Cardiology
- Pharmacology
- Psychiatry
Background:
- Guanfacine, an alpha-2 adrenergic agonist, is prescribed for ADHD.
- Common side effects include hypotension and bradycardia, but its effect on QT intervals is not well-established.
- The relationship between guanfacine serum concentration and toxicity requires further investigation.
Observation:
- A case report details a 21-year-old woman with ADHD experiencing presyncope.
- She presented with bradycardia, hypotension, and significantly prolonged QT intervals (QTcF 0.648 s) on ECG.
- Serum guanfacine concentration was markedly elevated at 13.0 ng/mL.
Findings:
- QT prolongation and vital sign abnormalities correlated with serum guanfacine levels.
- The patient's QT intervals normalized as guanfacine levels decreased.
- This suggests a direct link between supratherapeutic guanfacine concentrations and QT prolongation.
Implications:
- Elevated guanfacine levels may induce QT prolongation, a potentially life-threatening cardiac arrhythmia.
- This case highlights the importance of monitoring serum guanfacine concentrations in patients experiencing cardiovascular adverse events.
- Further research is warranted to establish safe therapeutic ranges and understand the mechanisms of guanfacine-induced cardiotoxicity.
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