Parkinson's disease (PD) is a progressive neurodegenerative condition primarily characterised by the loss of dopaminergic neurons in the substantia nigra pars compacta, resulting in reduced dopamine availability in the striatum. This dopaminergic deficit underlies the cardinal motor features: bradykinesia (slowness of movement), resting tremor, rigidity, and postural instability. The condition also produces a broad range of non-motor symptoms — autonomic dysfunction, cognitive impairment (Parkinson's dementia in later stages), mood changes, sleep disorders, and pain — which significantly affect quality of life.
Pharmacological treatment of Parkinson's disease addresses the dopaminergic deficit directly or indirectly through several complementary mechanisms. No currently approved pharmacotherapy is proven to slow, stop, or reverse the underlying neurodegeneration — treatment is symptomatic. The neurological management of Parkinson's disease is specialist territory: optimising therapy requires balancing motor symptom control against the complex motor and psychiatric complications that emerge with disease progression and long-term pharmacotherapy (dyskinesias, motor fluctuations, impulse control disorders, hallucinations). All Parkinson's medications listed below are prescription-only and should be managed by or in consultation with a movement disorder neurologist.
Principal drug classes for Parkinson's disease include:
- Levodopa / Carbidopa (Sinemet): The most effective symptomatic therapy. Levodopa is the dopamine precursor, combined with carbidopa (a peripheral decarboxylase inhibitor) to allow more levodopa to cross the blood-brain barrier while reducing peripheral side effects. Remains the gold standard for motor symptom control in all stages of PD. Long-term use leads to motor complications (wearing-off, dyskinesias) in most patients.
- Dopamine Agonists (Requip / Ropinirole; Pramipexole / Mirapex; Rotigotine / Neupro patch): Directly stimulate dopamine receptors (D2/D3) in the striatum — they mimic dopamine without needing conversion. Used as monotherapy in early PD (particularly in younger patients to delay levodopa and its associated motor complications) or as adjuncts to levodopa in more advanced disease. Risk of impulse control disorders (ICDs) in all dopamine agonists — compulsive gambling, hypersexuality, binge eating, compulsive shopping.
- MAO-B Inhibitors (Selegiline, Rasagiline / Azilect): Inhibit monoamine oxidase type B, the enzyme responsible for dopamine breakdown in the brain, thereby prolonging the action of endogenous and exogenous dopamine. Used as monotherapy in early mild disease or as adjuncts. Generally well tolerated with fewer side effects than full dopamine agonists. Selegiline is metabolised to amphetamine derivatives; rasagiline has a cleaner metabolite profile.
- Anticholinergics (Trihexyphenidyl / Artane): Older drug class; primarily useful for tremor in younger patients. Significant cognitive and anticholinergic side effect burden limits use in older patients.
- COMT Inhibitors (Entacapone / Comtan): Reduce peripheral conversion of levodopa, extending its effective duration. Used as adjuncts to levodopa/carbidopa to address wearing-off.
Lucas Clinic provides detailed information about the dopamine agonist class available in our inventory for Parkinson's disease management: