Drug General Information (ID: DDI4M20JYB)
Drug Name			Cimetidine		Drug Info		Paroxetine		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antiulcer Agents				Antidepressants
Structure

Mechanism of Cimetidine-Paroxetine Interaction (Severity Level: Moderate)
Decreased metabolism (Unspecific) Click to Show/Hide Mechanism Graph
Drug Name		Cimetidine				Paroxetine
Mechanism		Inhibition of hepatic first-pass metabolism of paroxetine				Paroxetine
Key Mechanism Factor 1
		Factor Name		Pharmacokinetics
		Factor Description		Alters the metabolism of the drug, leading to changes in the plasma concentration of the drug and affecting the pharmacological effects.
Mechanism Description		Decreased metabolism of Paroxetine caused by Cimetidine

Recommended Action
Management		During concomitant administration with cimetidine, the possibility of prolonged and/or increased pharmacologic effects of paroxetine should be considered, particularly in susceptible patients such as the elderly or debilitated. Pharmacologic response to paroxetine should be monitored more closely whenever cimetidine is added to or withdrawn from therapy in patients stabilized on their paroxetine regimen, and the dosage adjusted as necessary. alternatively, other H2-receptor antagonists such as famotidine, nizatidine, and ranitidine may be considered, since they are unlikely to interact with paroxetine.

References
1	Bannister SJ, Houser VP, Hulse JD, Kisicki JC, Rasmussen JG "Evaluation of the potential for interactions of paroxetine with diazepam, cimetidine, warfarin, and digoxin." Acta Psychiatr Scand Suppl 350 (1989): 102-6. [PMID: 2530759]
2	Boyer WF, Blumhardt CL "The safety profile of paroxetine." J Clin Psychiatry 53 Suppl (1992): 61-6. [PMID: 1531828]
3	Greb WH, Buscher G, Dierdorf HD, Koster FE, Wolf D, Mellows G "The effect of liver enzyme inhibition by cimetidine and enzyme induction by phenobarbitone on the pharmacokinetics of paroxetine." Acta Psychiatr Scand 80 Suppl (1989): 95-8. [PMID: 2530801]