Sign-in to Ask A Doctor - 24x7
OR
Sign in with Google
Suggest Ways To Wean Off Fluoxetine
Question: I am taking reglan for gastroparesis/nauseau and fluoxetine for depression. My G.I. wants me to switch from Reglan to Domperidone but I think there could be an interaction between domperidone and fluoxetine. (Do you know?) If I switched from fluoxetine to effexor (my phychiatrist is suggesting a switch back to effexor due to its efficacy) is there an interaction between effexor and domperidone? I see my phychiatrist later this week but I would like a second opinion on how to wean from fluoxetine (currently 40mg, once daily) while adding effexor (last time I was on effexor I was taking 75mg daily). Thank you.
Brief Answer:
Domperidone shouldn't be used wth both
Detailed Answer:
Hi, thanks for writing through HCM. I have read your query and understood your concerns.
You are right there is interaction between fluoxetine and domperidone. Fluoxetine is a enzyme inhibitor, so the enzymes metabolizing domperidone will be inhibited so you may have unexpected high level of domperidone in your plasma which may be harmful. Taking domperidone in minor dosage will be wise.
Some scientific explanation: Domperidone is metabolized by cyp3a4, so potent inhibitors of cyp3a4 will increase the level of domperidone to dangerous level, but fluoxetine is not a potent inhibiotor of cyp3a4, it is a mild inhibitor, so taking domperidone with fluoxetine won't cause much problem unless you take higher doses of both together.
Effexor does not interact with cyp450 isoenzymes, so it does not affect plasma level of domperidone. You can safely take both the drugs together. Most common side effect of effexor is nausea. By taking it with domperidone, you won't experience that one. That will be the extra benefit.
Weaning off from fluoxetine is easy because fluoxetine has higher half life of 4 to 7 days, so it won't cause severe discontinuation symptoms as compared to effexor. Decreasing the dose of fluoxetine from 40 to 20 mg initially and after 15 days take 20 mg on alternate days and then stop within next 15 days.
When you start decreasing the dose of fluoxetine at the same time start effexor 75 mg in a day. After 10 days increase it to 150 and gradually reach the level of 225 mg in a month.
This is my personal opinion, you should follow your doctor's advice before making any changes in drugs or dosages. His opinion may differ from mine.
Hope I have answered your query. If you have further query then I will be happy to help.
Wish you good health.
Domperidone shouldn't be used wth both
Detailed Answer:
Hi, thanks for writing through HCM. I have read your query and understood your concerns.
You are right there is interaction between fluoxetine and domperidone. Fluoxetine is a enzyme inhibitor, so the enzymes metabolizing domperidone will be inhibited so you may have unexpected high level of domperidone in your plasma which may be harmful. Taking domperidone in minor dosage will be wise.
Some scientific explanation: Domperidone is metabolized by cyp3a4, so potent inhibitors of cyp3a4 will increase the level of domperidone to dangerous level, but fluoxetine is not a potent inhibiotor of cyp3a4, it is a mild inhibitor, so taking domperidone with fluoxetine won't cause much problem unless you take higher doses of both together.
Effexor does not interact with cyp450 isoenzymes, so it does not affect plasma level of domperidone. You can safely take both the drugs together. Most common side effect of effexor is nausea. By taking it with domperidone, you won't experience that one. That will be the extra benefit.
Weaning off from fluoxetine is easy because fluoxetine has higher half life of 4 to 7 days, so it won't cause severe discontinuation symptoms as compared to effexor. Decreasing the dose of fluoxetine from 40 to 20 mg initially and after 15 days take 20 mg on alternate days and then stop within next 15 days.
When you start decreasing the dose of fluoxetine at the same time start effexor 75 mg in a day. After 10 days increase it to 150 and gradually reach the level of 225 mg in a month.
This is my personal opinion, you should follow your doctor's advice before making any changes in drugs or dosages. His opinion may differ from mine.
Hope I have answered your query. If you have further query then I will be happy to help.
Wish you good health.
Note: For more detailed guidance, please consult an Internal Medicine Specialist, with your latest reports. Click here..
Above answer was peer-reviewed by :
Dr. Vinay Bhardwaj
Answered by
Get personalised answers from verified doctor in minutes across 80+ specialties
