A new hope for patients of Parkinson’s disease

For Mark Reyes, walking is a difficult task. Most of the time, his lower limbs would lock while in mid-stride. His body would then stop as if he is an actor following the director’s "freeze" command. The only way he could unfreeze his body is by stepping backward.

Mark (the name of the patient has been changed) suffers from a degenerative neurological disease known as Parkinson’s disease (PD). Chinese leader Deng Xiaoping was suffering from the late stage of the disease before he died at the age of 92. American evangelist Billy Graham, boxing great Muhammad Ali, and Hollywood star Michael J. Fox are still fighting the devastating symptoms of the disease.

In the United States, there are 1.5 million people suffering from PD, a slowly progressive disease of the nervous system, affecting mainly the substantia nigra, the region of the brain which controls movement. It causes motor or muscle complications such as tremors, muscle rigidity, slowed motion, shuffling gait and a loss of facial expression.

Although a lot has been written about PD, there are still many unanswered questions in the treatment of the condition. In the recently concluded Philippine Neurological Association’s mid-year convention at Subic in Zambales, Dr. Mayvelyn Gose, a neurologist at the Philippine General Hospital and chairwoman of the Movement Disorder Council, discussed these unanswered questions in her lecture "Toward a New Paradigm in the Management of Parkinson’s Disease."

According to Gose, the "gold standard" for PD therapy is levodopa being the first line of treatment for the disease. First approved in 1970, levodopa is an effective drug in the treatment of PD, she said.

Gose, however, cautioned that chronic levodopa intake is associated with a series of motor complications such as dyskinesia. Between 60 and 90 percent of PD patients treated with levodopa experience motor complications within five to 10 years.

Dyskinesia, also known as tardive dyskinesia, is a side-effect of neuroleptic drugs such as levodopa. It is characterized by repetitive, involuntary and purposeless movements such as grimacing, tongue protrusion, lip smacking, puckering and pursing and rapid eye blinking.

"Recent studies have shown that dopamine agonists like pramipexole can delay the onset of motor complications compared to levodopa," Gose said. She added that there is also lesser neuron degeneration with pramipexole as demonstrated in neuron imaging studies.

Dopamine agonists are a group of drugs that stimulate or mimic the action of dopamine, the substance which helps transmit the signal from one brain or nerve cell to another. Numerous clinical and laboratory data conducted in the United States and Europe are suggesting that dopamine agonists like pramipexole should be the drug of choice to be used for symptomatic relief, instead of levodopa. Pramipexole also reduces the risk of developing motor complications or fluctuations associated with levodopa.

A multicenter, randomized, double-blind trial conducted by researchers from St. Luke’s Medical Center in Illinois found out that pramipexole is safe and effective in the treatment of early PD. The 32-week study showed that pramipexole significantly reduced the severity of PD symptoms compared to placebo measured through UPDRS (Unified Parkinson’s Disease Rating Scale) and the ADL (Activities of Daily Living).

Another study made by the Parkinson’s Study Group showed that as an initial therapy in patients with early Parkinson’s disease, pramipexole reduced risk of developing certain dopaminergic motor complications compared to initiation with levodopa therapy. The study was a double-blind, multi-center, parallel-group, randomized trial conducted at 22 sites in the US and Canada and enrolled 301 patients with early PD.

The Parkinson’s Study Group report noted a 23-percent absolute risk reduction on motor complications seen with pramipexole therapy over levodopa. The study also showed that both pramipexole and levodopa improved Parkinsonian seizures.