About piribedila piperazine derivative,dopamine agonist, antiparkinsonism, antidyskinetic.mechanism of action of piribedilthe exact mechanism of action is not known. a lesion in the nigra striatum may be responsible for parkinson`s disease which results in a reduction in dopamine concentrations. this in turn causes a relative imbalance between dopaminergic and cholinergic neurological pathways. piribedil crosses the blood brain barrier and it act on the cerebral dopaminergic pathways. it stimulates dopaminergic receptors (d2 & d3) and restores effective neurotransmission.indications for piribedil1.parkinson`s disease 2.symptoms and signs of cerebral ageing 3.memory and vigilance disorders 4.disorders of intellectual function typical dosage for piribedilparkinson`s disease monotherapy: 50 - 250 mg /day in divided doses with meals. dose is depending on patient`s response, adjuvant therapy: 80 - 140 mg daily. cerebral ageing: 150 mg / day with principle meal