Dopamine agonists causing drowsiness

[spephspeph]

I'll soon be starting on Bromocriptine, Cabergoline or Quinagolide because of a Prolactinoma (yay me 8( ).

After reading a bit about them (like I like to do whenever a doctor gives me something), I found out that dopamine agonists tend to cause drowsiness as a side effect.

Can anyone explain how and why this is?

I had always assumed that things that working on the dopaminergic system were more activating than sedating?

 

[Kel44]

Hey, I just wanted to say I'm sorry for your diagnosis.

May I ask if you are male or female? I'm curious as to what symptoms led you to the doctor.

Wiki has some good info on this type of tumor.

I would think these meds may cause some drowsiness, but your doctor can probably work with you on what would be the best choice if you are trying to avoid that.

Good luck!

 

[spephspeph]

Hey, thanks, but don't be sorry, apparently it's completely treatable and the -oma suffix makes it sound a lot scarier than it is.
To answer your questions...I'm male, I lost my sex drive, I put on weight in different places and I got a lot of headaches/sight problems.

But my question was about the medication - why would a dopamine agonist make you sleepy?
I had thought this would happen from an antagonist rather than an agonist?

 

[Memantine]

It is because dopamine agonists have a vasodilatory effect peripherally, therefore causing hypotension.

Other than that dopamine agonists like Bromocriptine, Cabergoline or Quinagolide have greater affinity to the presynaptic dopamine autoreceptor rather than the post synaptic receptor. This causes a decrease in dopamine release and an increased function of the dopamine transporter DAT.