THERAPEUTICS

Brands

• Symmetrel, Symadine

Generic?

• Yes

Class

• Antiparkinson agent

Commonly Prescribed for

(FDA approved in bold)

• Parkinson's disease (PD)

• Drug-induced extrapyramidal reactions

• Influenza-A prophylaxis/treatment

• Post-encephalitic parkinsonism

• Vascular parkinsonism

• Fatigue in multiple sclerosis (MS)

• Accelerate recovery after traumatic brain injury

• Attention deficit hyperactivity disorder

• SSRI-related sexual dysfunction

• Tardive dyskinesia

How the Drug Works

• The mechanism of action in PD is poorly understood but animal studies suggest either that it induces release or decreases reuptake of dopamine. Also is a weak NMDA receptor antagonist that in animals decreases release of acetylcholine from the striatum. Treats and prevents influenza-A by preventing the release of viral nucleic acid into the host cell by interfering with the function of a viral M2 protein. It may also prevent virus assembly during replication

How Long Until It Works

• PD: 48 hours or less

If It Works

• PD: most patients require dose adjustment over time and will need to take other agents, such as levodopa

If It Doesn't Work

• PD: motor symptoms, such as bradykinesia, gait, and tremor should improve. Reduces extrapyramidal reactions, such as dyskinesias, and can allow reduction of carbidopa-levodopa doses. Non-motor symptoms, including autonomic symptoms such as postural hypotension, depression, and bladder dysfunction, do not improve. If the patient has significantly impaired functioning, add levodopa or a dopamine agonist

• Fatigue: MS-related fatigue may respond to stimulants or modafinil

Best Augmenting Combos for Partial Response or Treatment-Resistance

• For suboptimal effectiveness add carbidopalevodopa with or without a catechol-Omethyltransferase (COMT) inhibitor or dopamine agonist depending on disease severity. Monoamine oxidase (MAO)-B inhibitors may also be beneficial

• For younger patients with bothersome tremor anticholinergics may help

• For severe motor fluctuations and/or dyskinesias with good “on” time, functional neurosurgery is an option