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Liver Enzymes Cytochrome P450 Drug Interaction Tables

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Altostrata

Psychiatric drugs are often metabolized by liver enzymes. Multiple drugs may utilize the same enzyme, causing drug interactions, or normal variability in these enzymes may affect ability to metabolize specific drugs.

 

This go-to reference indicates potential drug interactions resulting from competition for, or effects on the human cytochrome P450 system, a way to identify the liver enzymes.

 

Flockhart DA. Drug Interactions: Cytochrome P450 Drug Interaction Table. Indiana University School of Medicine (2007). http://medicine.iupui.edu/clinpharm/ddis/table.aspx. Accessed 17 Nov 2011.

 

Full text pdf available at http://medicine.iupui.edu/clinpharm/ddis/

 

An online interactive table is here.

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Altostrata

Another good source of P450 cytochrome information for specific drugs is http://www.drugbank.ca/.

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westcoast

What an amazing amount of data. Might explain a lot. Venlafaxine/Effexor interactions could fill a phone book. Seroquel/quetiapine too. Bupropion/Wellbutrin not so much. (Alto's second post, above.)

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Lilu

This explains, I think, why my dental injection for a routine filling lasted almost 6 hours instead of 2. Lexapro/escitalompram is an inhibitor and the anesthetic Lidocaine is a substrate. So Lexapro inhibits the metabolism of Lidocaine.

  •  
  • Substrates: drugs that are metabolized as substrates by the enzyme
  • Inhibitors: drugs that prevent the enzyme from metabolizing the substrates
  • Activators: drugs that increase the enzyme's ability to metabolize the substrates

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Lilu

Here's the link for Enzyme mediated interactions for Escitalopram (Lexapro)

 

https://www.drugbank.ca/drugs/DB01175/biointeractions#enzyme-tab

 

I also found this study which is relevant to anyone who routinely takes Antacid (PPI) medications such as Prilosec and Nexium. 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4297217/

Conclusions:

The effect of comedication with PPIs on the serum concentration of SSRIs is more pronounced for omeprazole and esomeprazole than for lansoprazole and pantoprazole, and escitalopram is affected to a greater extent than are citalopram and sertraline. When omeprazole or esomeprazole are used in combination with escitalopram, a 50% dose reduction of the latter should be considered.

Key Words: citalopram, escitalopram, sertraline, proton pump inhibitor, drug interactions

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Altostrata

Yes, it's important for us to be aware of these resources regarding drug-drug conflicts. Physicians and pharmacists are supposed to be alert to that type of risk, but in the US, they often skip that research.

 

The results from the Drug Interactions Checker are partially based on drug-drug interactions, but the report won't give you that level of detail.

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