Editing Tricyclic antidepressant (section)

== Interactions ==

The TCAs are highly metabolised by the [[Cytochrome P450 oxidase|cytochrome P450]] (CYP) hepatic enzymes. Drugs that inhibit [[Cytochrome P450 oxidase|cytochrome P450]] (for example [[cimetidine]], [[methylphenidate]], [[fluoxetine]], [[antipsychotic]]s, and [[calcium channel blocker]]s) may produce decreases in the TCAs' metabolism, leading to increases in their blood concentrations and accompanying toxicity.<ref>{{cite book | last=Preskorn | first=Sheldon H. | date=1996 | chapter=Why Are CYP Enzymes Important When Considering SSRIs? | chapter-url=http://www.preskorn.com/books/ssri_s7.html | title=Clinical pharmacology of serotonin selective reuptake inhibitors | publication-place=Caddo, Oklahoma | publisher=Professional Communications | isbn=978-1-884735-08-0 | oclc=41113507 | url=https://www.preskorn.com/books/ssri_open.html}}</ref> Drugs that prolong the [[QT interval]] including antiarrhythmics such as [[quinidine]], the antihistamines [[astemizole]] and [[terfenadine]], and some [[antipsychotic]]s may increase the chance of ventricular dysrhythmias. TCAs may enhance the response to [[alcohol (drug)|alcohol]] and the effects of [[barbiturate]]s and other CNS depressants. Side effects may also be enhanced by other drugs that have antimuscarinic properties.