Drug General Information (ID: DDIHQ284JU)
Drug Name			Fentanyl		Drug Info		Guanfacine		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Narcotic Analgesics				Antiadrenergic Agents
Structure

Mechanism of Fentanyl-Guanfacine Interaction (Severity Level: Moderate)
Increased risk of bradycardia Click to Show/Hide Mechanism Graph
Drug Name		Fentanyl				Guanfacine
Mechanism		Bradycardia				Bradycardia
Key Mechanism Factor 1
		Factor Name		Bradycardia
		Factor Description		Bradycardia is a slow heart rate in which the heart beats less than 60 times per minute. If the heart rate is very slow and the heart is not pumping enough oxygen-rich blood to the body, and you may feel dizzy, very tired or weak, and short of breath.
Mechanism Description		Increased risk of bradycardia by the combination of Fentanyl and Guanfacine

Recommended Action
Management		While some centrally acting alpha-antagonists, like guanfacine, are used preoperatively, it is recommended that the clinician monitor for bradycardia and be prepared for its consequences.

References
1	Product Information. Duragesic Transdermal System (fentanyl). Janssen Pharmaceutica, Titusville, NJ.
2	Kharasch ED, Whittington D, Hoffer C "Influence of Hepatic and Intestinal Cytochrome P4503A Activity on the Acute Disposition and Effects of Oral Transmucosal Fentanyl Citrate." Anesthesiology 101 (2004): 729-737
3	Burney RG "Bradycardia during epidural anesthesia in a patient receiving guanfacine." Anesthesiology 77 (1992): 1228-9