17-year-old ingested 189 mg ER guanfacine and 340 mg of olanzapine. Transferred from another facility (timing not described), presented with bradycardia, hypotension, somnolence, and orientation only to self over the first 24 hours. On day 4, became fully alert and oriented with bradycardia resolving. Between days 4 and 6 experienced sinus pause with forcefully drinking fluid, which resolved.
17-year-old presented 2 hours following 80 mg ingestion of ER guanfacine. Home dose was prescribed as 2 mg per day. Presented sleepy but arousable with sinus bradycardia. Respiratory distress developed necessitating intubation and heart failure with reduced EF of 30%. Extubated on day 5.
12-year-old presented 18 hours following 12 mg ingestion of ER guanfacine. Home dose was prescribed as 4 mg per day. Presented with sedation and unable to stand without assistance. HR 45, BP 140/80. BP peaked at 170/116 and IV nicardipine started for 3 hours. 36 hours after ingestion, symptomatic hypotension developed 70/26 mmHg with up to 85 hours postingestion.
16-year-old with ingestion of 25 mg of IR guanfacine. Prescribed dose was 1 mg per day. Reported to parents 8 hours postingestion, BP at that time 160/120 and taken to ED. ED discharged 2 hours later with BP and HR stable. At home had a syncopal episode (BP 97/57) and returned to ED where BP was 67/30 standing, QTc 593 msec. Vital signs normalized and symptoms of orthostasis ceased by 60 hours after ingestion.
2-year-old presented 1.5 hours after 4 mg guanfacine exposure. Initial BP was 100/60 mmHg and HR 83 bpm. Somnolence and diaphoresis noted. 18 hours postexposure SBP and HR decreased as low as 58 mmHg and 66 bpm, respectively. Discharged without intervention, 24 hours after admission.
8-year-old received an accidental second dose of 3 mg ER guanfacine at school. Somnolence, hypotension, and bradycardia were noted 3 hours after. Improvements by 18 hours postexposure with monitoring needed until 45 hours after exposure.
2-year-old presented approximately 12 hours postingestion of nearly 24 mg guanfacine. Somnolence, bradycardia, mild hypertension, and miosis reported. Monitored in the PICU for approximately 24 hours and discharged next day.
Most guanfacine ingestions () were patients aged 13-18 (53%) as a single substance ingestion (58%). 95% were admitted and 32% with at least 1 day in the ICU. Intravenous fluids were the primary intervention required. No deaths were directly attributed to guanfacine.
Review of a nation poison control center database (2000-2016)
10,927 of pediatric guanfacine exposure cases identified in the National Poison Data System. Common signs and symptoms included: drowsiness (39%), bradycardia (15.5%), and hypotension (10.3%). Duration of effects between 8 and 24 hours occurred in 44.2% of cases. Of all symptomatic cases, 80% had resolution within 24 hours. One death reported. 50.3% of cases were asymptomatic. The authors recommend evaluation at a healthcare facility for children 0–12 years old exposed to guanfacine, or any age if the ingestion is twice prescribed dose, and for all pediatric patients with intentional ingestion. Symptomatic patients should be monitored for at least 24 hours postexposure and via telephone follow-up for asymptomatic cases.
Review of a nation poison control center database (1993-1999)
870 cases were reviewed with most being years of age (54.9%). 62.8% of exposures resulted in no symptoms. Most common symptoms were drowsiness (76.8%), bradycardia (30%), and hypotension (25.8%). 19.9% of cases had ICU admissions and no deaths. Delay or duration of symptoms was not discussed. The authors concluded, pediatric patients with sedation should be observed for up to 24 hours due to the risk of developing delayed toxicities such as coma, bradycardia, and hypotension.
Review of ingestion cases and cost analysis related to commonly used medication for ADHD. Data of all medications pooled, so unable to specifically describe outcomes with guanfacine individually. In two separate cohorts, guanfacine accounted for 5.3% of cases (2000-2002) and 8.7% of cases (2009-2010).
Review of guanfacine exposures in children less than 6 years of age, noting an increase in this population. There were 28 cases in this age group 11/2014–12/2019. Mean exposure was 2.5 mg of which 39.3% had prescriptions for guanfacine. 53.6% of cases were asymptomatic. Most reported symptom was lethargy (84.6%). The authors disagree with Winograd that all pediatric exposures 0-12 years of age require referral to a healthcare facility. Recommend individual cases should be assessed by the poison center and referred based on patient specific factors.
Review of a nation poison control center database (2000-2011)
The authors reviewed alpha-2 agonist exposures as a class. Guanfacine accounted for 22% of the 27,825 exposures. Most common symptoms in guanfacine exposures were drowsiness (28.7%), bradycardia (8.1%), and hypotension (5.8%). 12 patients developed coma. There were no deaths. Timing was not discussed.
