Does liver failure effect efficacy of plavix and eliquis ?

Yes. dosage of medications are adjusted accordingly if there is Liver dysfunction as most things ingested pass thru it

Outright liver failure would be a concern in particular for someone taking Eliquis - not for the efficacy but for safety reasons, as healthy liver function is necessary to ensure that drug levels of Eliquis do not get too high. Determining whether a person should continue taking Eliquis depends on the degree of continued liver function.