If you are a rapid metabolizer and you get interdose withdrawal daily, is pristiq (desvenlafaxine) the ideal antidepressant, since it bypasses the liver?

Not necessarily: About 45% of Pristiq (desvenlafaxine) is excreted unmetabolized by 72 hours post dose. The rest is metabolized by CYP3A4 which is a liver enzyme. It does avoid CYP2D6 which is the most common enzyme which metabolizes psychiatric medications. I assume you mean that you are a rapid metabolizer of the 2D6 enzyme. In that case, Pristiq (desvenlafaxine) may be a reasonable choice.