ropinirol

Ropinirole is a non-ergoline dopamine agonist used to treat Parkinson's disease and restless legs syndrome. It acts by directly stimulating dopamine D2-like receptors, particularly D2 and D3, in the brain to help improve motor control and reduce symptoms. It is available in immediate-release and extended-release formulations and is sold under brand names such as Requip in several markets.

Medical uses

In Parkinson's disease, ropinirole may be used as monotherapy in mild to moderate cases or as an adjunct to levodopa in advanced disease. It can also be prescribed for restless legs syndrome (RLS), particularly when symptoms are uncomfortable or disruptive to sleep. Dosing is tailored to the individual and may change over time based on response and tolerability.

Pharmacology and pharmacokinetics

Ropinirole is administered by mouth and is absorbed with variable bioavailability. It is mainly metabolized by the liver enzyme CYP1A2 and eliminated via urine and feces. The elimination half-life is in the range of several hours, with extended-release formulations designed for once-daily dosing. The drug’s effect lasts long enough to allow regular dosing schedules coordinated with meals and daily activities.

Dosing and administration

Immediate-release ropinirole is typically started at a low dose and gradually titrated to a maintenance dose, which may range up to around 24 mg per day in Parkinson's disease, given in divided doses. For restless legs syndrome, lower nightly doses are used, commonly in the range of 0.5 to 4 mg at bedtime, adjusted based on response and tolerability.

Side effects and precautions

Common adverse effects include dizziness, nausea, somnolence, headache, orthostatic hypotension, edema, and fatigue. Ropinirole can cause dyskinesias, hallucinations, and impulse control disorders, including compulsive gambling or shopping. It may interact with other dopaminergic medications and agents influencing blood pressure or CYP1A2 activity. Caution is advised in patients with psychotic disorders or those with significant orthostatic symptoms or sleep disorders.