What’s in the pharmaceutical pipeline for Parkinson’s disease (PD)?
Many of my patients ask me at every visit about new treatments for PD. Naturally, what they REALLY want is The Cure, as do I. Failing that, we would all like to have newer, better treatments with fewer side-effects. ….not to mention less expensive!
New drug studies are now looking beyond symptom management. Drugs are being tested for more than symptom management to include their disease modifying ability, that is, the ability to positively affect future disease changes. An additional area of research growth is the number of potential drugs or supplements being tested whose cellular action is different than the dopaminergic activity that is standard of therapy today.
The process of getting new drugs on the market is a slow one, largely due to the testing that must be done insure the efficacy and safety of each new medication. Click here for more information on clinical research trials.
Fortunately, the current pipeline for Parkinson’s drugs has increased from a trickle to a relatively healthy flow in recent years. Quite a few new drugs are in the clinical trials phase, meaning that, after years of laboratory study, they are currently being tested in actual patients.
When the study is completed and analyzed, the data will be used to determine if the drug works better than a placebo or sugar-pill and what, if any, side-effects come to light that were not previously noted. If the drug shows benefit without serious side-effects, the pharmaceutical company then applies to the FDA to be allowed to market the drug.
A vital factor in speeding up this process is the number of patients who participate in these trials. The more patients who sign up, the quicker we will to have access to new medications.
Here are some of the medications currently in clinical trials. You can find out more about them by going to www.PDTrials.org or www.clinicaltrials.gov
Potential disease-modifying agents.
Co-Enzyme Q-10 This ‘neutraceutical’ is being studied in early PD to see if it has any beneficial impact on the slowing of PD progression. There should be some data on this in the next year or so.
Isradipine This blood pressure medication is also being studied in early PD to see if it slows the rate of decline. Early laboratory studies had some promising results.
Creatine This is another neutraceutical agent that is being studied in a five-year trial of patients with mild, treated PD to see if it can delay the progression of disability in PD. It will be several years before the results are revealed.
Inosine: Some studies have found an association between elevated levels of uric acid in the blood and a lower likelihood of having PD, implying a possible disease-modifying effect. In order to determine whether a large study could be done, inosine is being studied to see whether it could safely be used to increase the blood levels of uric acid
Agents that may treat motor symptoms in PD patients:
Safinamide: An MAO Inhibitor which may improve motor function. It is being studied in patients who are on dopamine agonists or on levodopa. There is also a study of safinamide and dyskinesia.
IPX066: A new formulation of carbidopa/levodopa designed to prolong improvement in motor function. It is being studied in patients who are just starting on levodopa and patients who are having wearing off of effect.
Carbidopa/levodopa Intestinal Gel: This new formulation of carbidopa/levodopa is being tested to see whether it is helpful in patients with severe motor fluctuations when administered via a tube placed into the upper intestine.
Novartis AFQ056: This medication is being studied to see whether it will improve motor fluctuations and dyskinesias, the involuntary movements that may occur as a side-effect of PD treatment.
CERE-120: This is a treatment consisting of a gene attached to a virus which is placed in the brain surgically to see if it can promote production of factors that help to support dopamine cells. Studies in animals were promising, as was an open-label study in humans. The first placebo-controlled study yielded some mixed results, but another trial in fairly advanced patients is underway.
Agents that may treat non-motor symptoms in PD:
Droxidopa: This agent is being tested to see if it helps treat orthostatic hypotension, which is a significant drop in blood-pressure experienced by some patients with PD and other types of parkinsonism.
Naltrexone: This medication has been used for years to reverse the effects of narcotics. It is being studied to see with it could be used to treat impulse control behaviors which occur with some PD treatments.
SAM-e: This is a health-food supplement that is being studied to see if it helps depression, another common non-motor feature of PD
PD drugs already on the market that are being tested to see whether they have additional benefits:
Rivastigmine patch: The oral form of this drug is already approved for use in PD dementia. The patch form is now being studied in a similar group of patients.
Rasagiline mesylate: This agent is approved to treat motor symptoms in patients with early PD or as add-on therapy with levodopa. There is now study to see whether rasagiline could restore the sense of smell in PD patients, who often lose this. Another current rasagiline study involves patients who are currently taking a dopamine agonist such as pramipexole or ropinirole, but not levodopa. Rasagiline is also being studied in Multiple Systems Atrophy (MSA), a condition related to PD.
Other interesting studies:
The Chinese Parkinson’s Study Group (CPSG) has found mild symptomatic benefits and possibly disease-modifying effects of Green Tea Polyphenols at some doses. The CPSG is also evaluating Língzhi or Ganoderma lucidum, a medicinal mushroom, for treating some non-motor features of PD.
In summary, there are probably more agents under study for PD treatment than at any time in history. Hopefully, some of these medications will prove promising in our treatment of PD.
Author: Melanie M. Brandabur, MD, Clinic Director, The Parkinson’s Institute,