Seroquel - Mirapex Interaction Details
In our latest question and answer, our pharmacist discusses the interaction between Mirapex and Seroquel in regard to treating RLS (restless legs syndrome).
I am a 75-year-old male and have Restless Legs Syndrome (RLS). I take 0.5mg of Mirapex twice daily and 300mg of Gabapentin once daily. Recently, I was prescribed Quetiapine Fumarate, 50mg at bedtime for insomnia. My RLS symptoms improved immediately, and I stopped taking Gabapentin. I continue to get good sleep and have few RLS symptoms. However, I am concerned about taking both drugs together and taking Quetiapine long-term. What do you advise?
Answered by Dr. Brian Staiger, PharmD
Medical Content Reviewed By HelloPharmacist Staff
Last updated Mar 13, 2023
- Miralax (pramipexole) and Seroquel (quetiapine) have conflicting mechanisms of action related to dopamine, and their use together could lead to reduced efficacy or adverse effects in the treatment of restless legs syndrome (RLS).
- While there haven't been many studies on the long-term use of Miralax and Seroquel together, extended use of Miralax has been well tolerated, and Seroquel should be tapered slowly if being discontinued to avoid withdrawal symptoms.
Miralax (pramipexole) and Seroquel (quetiapine) have conflicting mechanisms of action, and it's possible the overall effects of both drugs may be reduced when combined.
Thanks so much for reaching out to us! This is a great question and I'll do my best to provide some context to what I have in the 'quick answer' section regarding a conflict in how these drugs work.
I do want to state at the outset that restless legs syndrome (RLS) isn't very well understood, and it's not completely known exactly how the drugs used to treat it (such as gabapentin and Mirapex) work.
What I'm going to go over is what we understand about the conflict between Seroquel and Mirapex purely in the terms of how they work as their overall mechanism of action.
If the combination of Mirapex and Seroquel is working for you, great! There aren't really any concerns with the combination outside of their conflicting mechanisms, and there could be a reason the combination is effective for your particular medical situation.
How Seroquel And Mirapex Work
Seroquel (quetiapine fumarate) is an atypical antipsychotic and is used for a number of different indications. It can help treat bipolar disorder, bipolar depression, and schizophrenia, to name a few. It is also very commonly used 'off-label' at low dosages to treat insomnia (trouble sleeping).
It has a very complex mechanism of action and affects several different neurotransmitters, including histamine, dopamine, and serotonin. It also acts as an antagonist at certain alpha receptors.
In regard to dopamine, it acts as an antagonist primarily at the D2 receptor (there are several different dopamine receptors in the body, and the D2 receptor is involved in a variety of functions, including movement control, mood regulation, and reward and pleasure sensations).
Mirapex (pramipexole), on the other hand, is a dopamine agonist (the opposite of an antagonist). Studies show it acts as an agonist on several different dopamine receptors, including D2 and D3.
So, right there, we can see a conflict, with Seroquel antagonizing dopamine at the D2 receptor and Miralax agonizing it.
The other issue is that you are treating restless legs syndrome, which is a condition that has been reported to be made worse by Seroquel in some individuals.
Seroquel Is Associated With Causing RLS (Restless Legs)
Restless legs syndrome (RLS) and what causes it is not fully understood.
There is thought to be at least some relationship between it and the dopaminergic system in the body since RLS symptoms show improvement with dopaminergic therapy. Additionally, drugs that antagonize dopamine are often associated with causing movement disorders.
Antipsychotics are notorious for causing movement disorders as a side effect, although atypical antipsychotics, like Seroquel, are far safer in this regard when compared to older-generation antipsychotics, like haloperidol.
Among atypical antipsychotics, Seroquel is actually considered to be one of the least likely to cause these movement side effects, although it still is reported (as shown in the image below, which is an excerpt from the prescribing information for Seroquel):
Safe To Use Mirapex & Seroquel Together?
So, as described, there certainly is a theoretical conflict between Mirapex and Seroquel simply based on how they work (again, Mirapex agonizes dopamine and Seroquel antagonizes it).
Their use together could lead to reduced efficacy or adverse effects in the treatment of RLS.
However, in your question, you mention two very important points:
- You are taking Seroquel to help sleep at night
- You have found your RLS symptoms to be better since starting Mirapex and Seroquel
There could be a few things going on here.
For one, Seroquel is extremely commonly prescribed 'off-label' to help people sleep. This is because Seroquel has relatively strong antihistamine effects and blocks alpha receptors. Both of these contribute Seroquel to being quite sedating, generally among the most sedating of the atypical antipsychotics.
When used for insomnia, Seroquel is generally used at low doses, typically around 25-100mg at night. At this dose, it's very possible you are experiencing the sedative effects of the drug, but the dose isn't high enough for you to realize the dopaminergic effects of the drug.
Adding Mirapex to a low dose of Seroquel may just have been what was needed for you to find a good balance (although there will always be a reported 'interaction' between the two drugs based on what I described).
There haven't been too many studies evaluating the effects of the long-term combined use of Mirapex and Seroquel.
There have been studies showing that extended use of Miralax (up to 9 months) has been well tolerated and effective.
Seroquel, with its complex mechanism of action, can be used long-term, but it is important to note that it generally needs to be slowly discontinued over a period of at least a few weeks to avoid withdrawal symptoms. You can almost view it as an antidepressant in this regard, where it has been associated with a withdrawal syndrome and it should be tapered slowly to reduce the effects of that should it occur.
Overall, it seems like you have had positive effects from taking Mirapex and Seroquel together. Like any combination of drugs, it's a question of risk over benefit, and it's something you should be sure to talk to your doctor about as everyone's medical situation is different.
Thanks for much for reaching out to us and please do so again anytime!
I didn't touch on gabapentin as you said you stopped taking it, but if you have questions about that, let us know!
- Seroquel Prescribing Information, AccessFDA
- Controlled withdrawal of pramipexole after 6 months of open-label treatment in patients with restless legs syndrome, PubMed
- Movement disorders associated with atypical antipsychotic drugs, PubMed
- Antipsychotic-Induced Movement Disorders, PubMed
- Mirapex Prescribing Information, AccessFDA
- Dr. Brian Staiger, PharmD
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