Clonipress Overdosage

Symptoms: In a patient who ingested clonidine 100 mg, plasma levels were 60 ng/mL (1 hr), 100 ng/mL (1.5 hrs), 370 ng/mL (2 hrs) and 120 ng/mL (5.5 and 6.5 hrs). The patient developed hypertension followed by hypotension, bradycardia, apnea, hallucinations, semicoma and premature ventricular contractions. The patient fully recovered after intensive treatment.
Other symptoms of clonidine overdosage are bradycardia, hypotension, CNS depression, respiratory depression, apnea, hypothermia, miosis, coma, seizures, lethargy, agitation, irritability, vomiting, hypoventilation, reversible cardiac conduction defects, arrhythmias, transient hypotension, profound hypotension, weakness, somnolence and diminished or absent reflexes.
Treatment: Naloxone may be a useful adjunct for the management of clonidine-induced respiratory depression.
Induction of emesis is usually not recommended because of rapid onset of CNS depression. Establish respiration if necessary, perform gastric lavage and administer activated charcoal. A saline cathartic (magnesium sulfate) will increase the rate of transport through the gastrointestinal tract. Routine hemodialysis is of limited benefit because a maximum of 5% of circulating clonidine is removed.
Supportive care may include atropine sulfate for the treatment of persistent bradycardia, and dopamine infusion and IV fluids for hypotension.
Hypertension can be treated with IV furosemide or diazoxide or α-blocking agents eg, phentolamine. Tolazoline, an α-blocker, in IV doses of 10 mg at 30-min intervals may reverse clonidine's effects if other efforts fail. Naloxone may be a useful adjunct for the management of clonidine-induced respiratory depression, hypotension or coma.