Pramipexole

Pramipexole is a non-ergot dopamine agonist used to treat Parkinson's disease and restless legs syndrome. It acts on dopamine receptors, with relatively high affinity for D3 receptors, to mimic dopamine activity in motor circuits.

In Parkinson's disease, it may be used as initial therapy or as an adjunct to levodopa to improve motor symptoms and reduce off time. In restless legs syndrome, it reduces urge to move and improves sleep.

Dosing and administration: Pramipexole is taken by mouth as immediate-release tablets and, in some settings, an extended-release form. For Parkinson's disease, starting dose is commonly 0.125 mg three times daily, titrating gradually to about 1.5–4.5 mg per day (roughly 0.5–1.5 mg three times daily). For restless legs syndrome, starting at 0.125 mg once nightly at bedtime, with weekly increases of 0.125 mg to reach a typical maintenance range of 0.5–0.75 mg per day.

Safety: Common adverse effects are nausea, dizziness, somnolence, and constipation. Orthostatic hypotension, edema, confusion, and dyskinesias can occur, especially in older patients. Dopamine agonists carry a risk of impulse control disorders, sleep attacks, and hallucinations; use requires monitoring for psychiatric symptoms.

Pharmacokinetics: Oral pramipexole is well absorbed; peak levels occur within 1–3 hours. The elimination half-life is about 8 hours; most of the drug is excreted unchanged in urine, so dose adjustment is needed in renal impairment.

Pramipexole was developed as a non-ergot dopamine agonist and is marketed for Parkinson's disease and restless legs syndrome by Boehringer Ingelheim and other companies. It is not disease-modifying.