Drug General Information (ID: DDIOUVAZ65)
Drug Name			Haloperidol		Drug Info		Guanethidine		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antipsychotic Agents				Antihypertensive Agents
Structure

Mechanism of Haloperidol-Guanethidine Interaction (Severity Level: Moderate)
Antagonize the effect of antihypertensive agents Click to Show/Hide Mechanism Graph
Drug Name		Haloperidol				Guanethidine
Mechanism		Decrease the antihypertensive effect of some peripherally acting antiadrenergic agents				Antiadrenergic agent
Key Mechanism Factor 1
		Factor Name		Antihypertensive agents
		Factor Description		The hypotensive effect of antihypertensive agents may be reduced, leading to higher blood pressure, increased blood pressure fluctuations, and possible cardiovascular damage.
Mechanism Description		Antagonize the effect of Haloperidol when combined with Guanethidine

Recommended Action
Management		Blood pressure monitoring is recommended during concurrent use and after discontinuation of haloperidol. An alternative antihypertensive or antipsychotic agent may be considered if evidence of an interaction is observed.

References
1	Markowitz JS, Wells BG, Carson WH "Interactions between antipsychotic and antihypertensive drugs." Ann Pharmacother 29 (1995): 603-9. [PMID: 7663034]
2	Warrington SJ, Ankier SI, Turner P "Evaluation of possible interactions between ethanol and trazodone or amitriptyline." Neuropsychobiology 15 (1986): 31-7. [PMID: 3725002]
3	Janowsky DS, El-Yousef MK, Davis JM, Fann WE "Antagonism of guanethidine by chlorpromazine." Am J Psychiatry 130 (1973): 808-12