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Date of last update: 9/5/2017.

Forum Name: Pharmacy & Drug Topics

Question: P-450 pathway question


 AilingBlackLab - Fri Sep 04, 2009 4:16 pm

If a person takes 50mg of Primidone at bed time ,would it's glutathione induction deplete the glutathione stores in the liver over night, so that when you woke it would be unsafe to take acetaminophen?, also would enough 3A4 remain to increase metabolisim of Acetaminophen , hence creating a surplus of NAPQI in excess of the available amount of glutatthione to neutralize the NAPQI?
 Kathleen Plamondon - Thu Oct 08, 2009 9:35 pm

Hello,
Primidone is strongly metabolized by several enzymes in the liver: CYP1A2, CYP2B6, CYP2C8, CYP2C9 and CYP3A4. And since it is a prodrug, Primidone is metabolized into its active ingredient phenobarbital.

Acetaminophen is weakly metabolized by some the same enzymes. It also inhibits CYP3A4 so theoretically would decrease levels of phenobarbital in the system.

In practice, acetaminophen and Primidone are reported to have no adverse interactions and are considered safe to use together.

Take care.

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