What is Mirapex?


Pramipexole
Systematic (IUPAC) name
(6S)-N⁶-propyl-4,5,6,7-tetrahydro-1,3-benzothiazole-2,6-diamine
Identifiers
CAS number	104632-26-0
ATC code	N04BC05
PubChem	59868
DrugBank	APRD00156
Chemical data
Formula	C₁₀H₁₇N₃S
Mol. mass	211.324 g/mol
Pharmacokinetic data
Bioavailability	>90%
Protein binding	15%
Metabolism	Minimal
Half life	8 hours
Excretion	Renal (90%) and fecal (2%)
Therapeutic considerations
Licence data	EU, US
Pregnancy cat.	B3(AU) C(US)
Legal status	℞ Prescription only
Routes	Oral

Pramipexole (INN, trade names Mirapexin, Mirapex and Sifrol) is a medication indicated for treating Parkinson’s disease and restless legs syndrome (RLS). It is also sometimes used off-label as a treatment for cluster headache or to counteract the problems with low libido experienced by some users of SSRI antidepressant drugs. Pramipexole has shown robust effects on pilot studies in a placebo-controlled proof of concept study in bipolar disorder^[1]. Pramipexole is classified as a non-ergoline dopamine agonist.

1 Mechanism of action
2 Adverse effects
3 References
- 3.1 Notes
- 3.2 Sources
4 External links

Mechanism of action

Basal ganglia connectivity diagram showing glutamatergic pathways as red, dopaminergic as magenta and GABA pathways as blue.

The basal ganglia is a region of the human brain involved in the regulation of body movement; hence, when components of the basal ganglia are damaged, disorders of body movement may occur.

Parkinson’s disease is a neurodegenerative disease affecting the substantia nigra, a component of the basal ganglia. The substantia nigra has a high quantity of dopaminergic neurons, which are neurons that release the neurotransmitter known as dopamine. When dopamine is released, it may activate dopamine receptors in the striatum, which is another component of the basal ganglia. When neurons of the substantia nigra deteriorate in Parkinson’s disease, the striatum no longer receives dopamine signals. As a result, the basal ganglia can no longer regulate body movement effectively and motor function becomes impaired.

By acting as an agonist to the dopamine receptors, pramipexole may directly stimulate dopamine receptors in the striatum, thereby restoring the dopamine signals needed for proper functioning of the basal ganglia. Any depressant effects are most likely the result of pramipexole binding to the D₂ receptor subtype, which exhibits inhibitory behavior.

Pramipexole binds to dopamine receptors, with particularly high affinity for the D₃ receptor subtype.^[2]

Adverse effects

Some of the more common side effects of pramipexole include:^[3]

Dizziness, lightheadedness, or fainting, especially when standing up (orthostatic hypotension)
Drowsiness
Hallucinations (seeing, hearing, or feeling things that are not there)
Weight gain
Weight loss
Nausea
Trouble in sleeping
Twitching, twisting, or other unusual body movements
Unusual tiredness or weakness

Several unusual adverse effects of this medication may include compulsive gambling, hypersexuality, and overeating. These side effects may be linked to the D₃ receptor agonist activity of pramipexole. D₃ receptors are located in brain regions involved in mood, behavior, and rewards.^[4]

References

Notes

^ Biol Psychiatry. 2004 Jul 1;56(1):54-60. Pramipexole for bipolar II depression: a placebo-controlled proof of concept study.Zarate CA Jr, Payne JL, Singh J, Quiroz JA, Luckenbaugh DA, Denicoff KD, Charney DS, Manji HK.PMID: 15219473
^ Mierau J, Schneider F, Ensinger H, Chio C, Lajiness M, Huff R (1995). “Pramipexole binding and activation of cloned and expressed dopamine D2, D3 and D4 receptors.”. Eur J Pharmacol 290 (1): 29–36. doi:10.1016/0922-4106(95)90013-6. PMID 7664822.
^ “MedlinePlus Drug Information: Pramipexole (Systemic)“. United States National Library of Medicine. Retrieved on 2006-09-27.
^ Mayo Clinic Staff; M. Leann Dodd (July 15, 2005). “Parkinson’s drug can cause compulsive gambling“. Mayo Clinic. Retrieved on 2006-09-27.