Parkinson disease (PD) diagnosis goes back to 1817. Even though there is documentation of possible PD earlier than that—dating back to approximately 1000 BC—James Parkinson, was the first to define the disease clearly and medically. In the mid 1800s, Jean-Martin Charcot helped distinguish PD from other neurological disorders, such as multiple sclerosis and other disorders characterized by tremor or Parkinsonism-like symptoms.

The most complete pathologic analysis of Parkinson's disease and the clear delineation of the brain stem lesions was performed in 1953 by Greenfield and Bosanquet.¹ As far as statistics go, PD is the second most common neurodegenerative disease after Alzheimer disease. The population prevalence of PD increases from about 1% at age 60 to 4% by age 80.²

We have approximately 1 million individuals living with PD in the United States in 2020 and approximately 60,000 Americans are diagnosed with the disease each year. This number increases to approximately 10 million people worldwide who are living with the disease. Men are 1.5 times more likely to have PD than women.

The estimated cost of the disease is approximately $52 billion per year in the United States along, with medications costing approximately $2500 per year and therapeutic surgery costing approximately $100,000 per person. Symptoms for these patients may include tremor, weakness, spasticity, visual disturbances, bradykinesia, loss of automatic movements, speech and writing changes.

In PD, certain nerve cells in the brain start to break down gradually and die due to a lack of dopamine. The causes of this disease are unknown, but genomics may play a role, such as having a family member affected by it. Triggers may include exposure to certain toxins or environmental factors.

Researchers also believe the presence of Lewy bodies in the brain cells hold an important clue to the cause of PD. Connected to causes, risk factors therefore include age, heredity, gender, and exposure to toxins.

Treatment options for PD are very important, since the disease may cause many complications and disabilities if left untreated. Some of these complications may include thinking difficulties, depression, emotional changes, swallowing problems, chewing, eating problems, sleep problems, bladder issues, fatigue, pain, and sexual dysfunction.

Medication options for PD have been around for many years. The most common option for these patients includes levodopa, developed in 1960s, a central nervous system agent that is converted to dopamine in the brain. Dopamine agonists are another class of medications that help with PD, which include pramipexole (Mirapex, Mirapex EX), ropinirole (Requip, Requip XL), apomorphine (Apokyn), rotigotine transdermal system (Neupro).

Amantadine (Symmetrel, Gocovri, Osmolex ER) was initially developed as an antiviral medication to treat influenza in the 1960s. Later, researchers discovered that it can be used as a treatment for PD. Adenosine A2a antagonists are another class of medications that can help with the “off” time for these patients by 30 to 60 minutes per day.

An example of this class of drugs include istradefylline (Nourianz). A catechol-O-methyltransferase inhibitors, including Entacapone (Comtan, Tolcapone (Tasmar) are 2 examples of this class. There is also a combination of entacapone with levodopa/carbidopa approved by FDA in the market, called Stalevo.

The third and most recent option of this class of medications, is called opicapone (Ongentys). Opicapone was approved in April 2020, indicated as an adjunctive treatment to levodopa/carbidopa in patients with PD experiencing “off” episodes.³      

Another class of medications used for PD is anticholinergics, such as benztropine (Cogentin) and trihexyphenidyl (Artane), which are helpful in treating tremor and may ease dystonia associated with wearing-off or peak-dose effects. MAO-B inhibitors, such as selegiline (Eldepryl, Zelapar), rasagiline (Azilect) and safinamide (Xadago) are also available for these patients by increasing dopamine levels in the brain.         
                                                       
Finally, apomorphine hydrochloride (Kynmobi), a new novel sublingual film and a non-ergoline dopamine agonist, was approved for treatment of OFF episodes in patients with PD on May 21, 2020. This medication comes in 10 mg to 30 mg per doses, administered sublingually. Apomorphine hydrochloride has high in vitro binding affinity for the dopamine D4 receptor and moderate affinity for the dopamine D2, D3, and D5, and adrenergic α1D, α2B, α2C receptors.⁴         
                                
Patients with PD have more options these days for treatment, on top of surgical interventions. This is fortunate news, especially with new medications recently approved in the market.

Although these medications carry adverse effects—such as dyskinesia, insomnia, hallucinations, and dizziness—they still offer new treatment solutions and hopes of better clinical outcomes for patients suffering from PD and its debilitating daily symptoms.

Works Cited
  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3234454/
  2. https://www.cdc.gov/genomics/hugenet/casestudy/parkinson/parkcoffee_view.htm
  3. https://www.parkinson.org/Understanding-Parkinsons/Treatment/Prescription-Medications/COMT-Inhibitors
  4. https://www.kynmobi.com/Kynmobi-Prescribing-Information.pdf