The exact mechanism of action of pramipexole as a treatment for Parkinson's disease is unknown at this time. It is thought, however, that the ability of pramipexole to cause stimulation of the dopamine receptors in the striatum of the brain, a region that receives a vast array of neurological input and is responsible for a wide variety of functions, may be involved. Studies performed in animals show that pramipexole influences striatal neuronal transmission rates following activation of dopamine receptors. Pramipexole is considered a non-ergot dopamine agonist that shows specificity and strong activity at the D2 subfamily of dopamine receptors in vitro, binding selectively and dopamine D2 receptors and showing a preference for the dopamine D3 receptor subtype rather than other subtypes. The clinical significance of this binding specificity is unknown.

Pramipexole is indicated for the treatment of-

• Parkinson's disease used alone or as an adjunct to levodopa with dopa-decarboxylase inhibitor
• Moderate to severe restless legs syndrome

The recommended dose of Pramipexole is as follows-

Parkinson's disease:

• Initial dose: 88 micrograms 3 times daily, dose doubled every 5-7 days if tolerated to 350 micrograms 3 times daily; further increased if necessary by 180 micrograms 3 times daily at weekly intervals
• Maximum dose: 3.3 mg daily in 3 divided doses. During pramipexole dose titration and maintenance Levodopa dose should be reduced.

Restless legs syndrome:

• Initial dose: 88 micrograms once daily 2-3 hours before bedtime, dose doubled every 4-7 days if necessary to 350 micrograms daily.
• Maximum dose: 540 micrograms daily.

Use in children: Pramipexole is not recommended for children below 18 years of age.

Pramipexole is contraindicated in patients with known Hypersensitivity to the active substance or to any of the excipients.

The common side effects are dizziness, dyskinesia, nausea, hypotension, abnormal dreams, confusion, constipation, delusion, hallucinations, headache, hyperkinesia, increased eating (binge eating, hyperphagia), insomnia, libido disorders, nausea, peripheral oedema, paranoia, pathological gambling, hypersexuality and other abnormal behaviour, somnolence, weight increase, sudden onset of sleep, pruritus and rash and other hypersensitivity.

Overdose Effects

There is no clinical experience with massive overdose. Symptoms of overdose are nausea, vomiting, hyperkinesia, hallucinations, agitation and hypotension. There is no established antidote. If signs of central nervous system stimulation are present, a neuroleptic agent may be indicated. Management of the overdose may require general supportive measures, along with gastric lavage, intravenous fluids, administration of activated charcoal and electrocardiogram monitoring.

Caution should be taken in patients with psychotic disorder, ophthalmologic monitoring is recommended at regular intervals, severe cardiovascular disease and renal impairment.

Pregnancy & Lactation

The effect of pramipexole on pregnancy and lactation has not been investigated in humans so it should be used during pregnancy only if the potential benefit justifies the potential risk to the foetus. Pramipexole inhibits secretion of prolactin in humans. The excretion of pramipexole into breast milk has not been studied in women so it should not be used during breast-feeding. However, if its use is unavoidable then breast-feeding should be discontinued.