“Life is 10 percent what you make it, and 90 percent how you take it.” Irving Berlin
“My attitude is that if you push me towards something that you think is a weakness, then I will turn that perceived weakness into a strength.” Michael Jordan
Pharmacological treatment of Parkinson’s [Please note that these views and opinions expressed here are my own. Content presented here is not meant as medical advice. Definitely consult with your physician before taking any type of drug.]: The management of Parkinson’s is broadly divided up into motor and non-motor therapy. A brief description of the therapy for motor dysfunction will be presented here. Please see the drawing below for an overview. Within the framework of treating someone with Parkinson’s you must consider managing their symptoms with the hope that some compound might possess either neuroprotective or neurorestorative actions. To date, we do not have a cure for Parkinson’s but the study described below suggests an existing compound may be neuroprotective when used for a long time.
“Things turn out best for the people who make the best of the way things turn out.” John Wooden
Levodopa, together with carbidopa, is the ‘gold standard’ of treatment of motor signs and symptoms. Carbidopa is a peripheral decarboxylase inhibitor (PDI), which provides for an increased uptake of levodopa in the central nervous system. As shown above, levodopa (denoted as L-DOPA) is converted to dopamine by the dopaminergic neurons. Levodopa is still the most effective drug for managing Parkinson’s motor signs and symptoms. Over time, levodopa use is associated with issues of “wearing-off” (motor fluctuation) and dyskinesia. For further information about levodopa and dopamine, please see this previously posted topic (click here).
Catechol-O-methyl transferase (COMT) inhibitors prolong the half-life of levodopa by blocking its metabolism. COMT inhibitors are used primarily to help with the problem of the ‘wearing-off’ phenomenon associated with levodopa.
Dopamine agonists are ‘mimics’ of dopamine that pass through the blood brain barrier to interact with target dopamine receptors. Dopamine agonists provide symptomatic benefit and delay the development of dyskinesia compared to levodopa. Dopamine agonists are not without their own side-effects, which can occur in some patients, and include sudden-onset sleep, hallucinations, edema, and impulse behavior disorders. For more information about dopamine agonists, please see this previously posted (click here).
Finally, monoamine oxidase (MAO)-B is an enzyme that destroys dopamine; thus, MAO-B inhibitors help prevent the destruction of dopamine in the brain. MAO-B inhibitors have some ability to reduce the symptoms of Parkinson’s. The most common severe side effects of MAO-B inhibitors include constipation, nausea, lightheadedness, confusion, and hallucinations. There may also be contraindications between MAO-B inhibitors with other prescription medications, vitamins, and certain foods/drinks (e.g., aged cheese and wine). Definitely talk to your doctor and pharmacist about potential drug interactions if you are considering an MAO-B inhibitor in your therapeutic regimen.
“You should just do the right thing.” Dean Smith
What are clinical trials? The simple description is that a clinical trial determines if a new test or treatment works and is safe. The National Institutes of Health (NIH) defines a clinical trial (paraphrased here) as a research study where human subjects are prospectively assigned1 to one or more interventions2 (which may include placebo or other control) to evaluate the effects of those interventions on health-related biomedical or behavioral outcomes.3 [1The term “prospectively assigned” refers to a predefined process (e.g., randomization) in an approved protocol that stipulates the assignment of research subjects (individually or in clusters) to one or more arms (e.g., intervention, placebo, or other control) of a clinical trial.2An intervention is defined as a manipulation of the subject or subject’s environment for the purpose of modifying one or more health-related biomedical or behavioral processes and/or endpoints. 3Health-related biomedical or behavioral outcome is defined as the prespecified goal(s) or condition(s) that reflect the effect of one or more interventions on human subjects’ biomedical or behavioral status or quality of life.] For the complete NIH definition, please click here.
As described by ‘ClinicalTrials.gov’, clinical trials are performed in phases; each phase attempts to answer a separate research question. Phase I: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects. Phase II: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.Phase III: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely. Phase IV: Studies are done after the drug or treatment has been marketed to gather information on the drug’s effect in various populations and any side effects associated with long-term use. A more complete description is included here (click here).
What is important to remember is that clinical trials are experiments with unknown outcomes that must follow a rigorous approach to safely evaluate and possibly validate potential treatments.
“Nothing has ever been accomplished in any walk of life without enthusiasm, without motivation, and without perseverance.” Jim Valvano
NET-PD-LS1 clinical trial went bust on creatine use in treating Parkinson’s: The NET-PD-LS1 clinical trial went from March 2007 until July 2013. NET-PD-LS1 was a multicenter, double blind, placebo-controlled trial of 1741 people with early Parkinson’s. The goal of NET-PD-LS1 was to determine if creatine could slow long-term clinical progression of Parkinson’s (to learn more about this clinical trial go here or go here) . NET-PD-LS1 was one of the largest and longest clinical trials on Parkinson’s . This clinical trial was stopped after determining there was no benefit to using creatine to treat Parkinson’s.
“It’s what you learn after you know it all that counts.” John Wooden
NET-PD-LS1 clinical trial gets a ‘gold star’ for MAO-B inhibitors in treating Parkinson’s: NET-PD-LS1 was a thorough and well organized clinical trial. New results have been published in a secondary analysis of the clinical trial to determine if MAO-B inhibitors for an extended time affected the symptoms of Parkinson’s. Almost half (784) of the patients in NET-PD-LS1 took an MAO-B inhibitor. The MAO-B inhibitors used in NET-PD-LS1 were Rasagiline (Brand name Azilect) and Selegiline (Brand names Eldepryl, Zelapar, or EMSAM). More than 1600 of the patient’s completed both baseline and one year evaluation/assessment measuring changes in their symptoms (this was done using a combination of five different measurement scales/systems). Their results were exciting; the patients that were taking an MAO-B inhibitor for a longer time (1 year) had a slower clinical decline (~20% benefit in the magnitude of the decline compared to the patients not taking an MAO-B inhibitor). These results indicate that MAO-B inhibitors somehow are able to slow the progression of the symptoms of Parkinson’s.
“Always look at what you have left. Never look at what you have lost.” Robert H. Schuller
Does this prove that MAO-B inhibitors are neuroprotective in Parkinson’s? The hopeful person inside of me wants this answer to be yes; however, the scientist that also resides inside of me says no not quite yet. The goal of neuroprotection is to slow or block or reverse progression of Parkinson’s; and by measuring changes in dopamine-producing neurons. Early basic science results with MAO-B inhibitors found some neuroprotection in model systems. This new publication reignites the storyline that MAO-B inhibitors are potentially neuroprotective.
“Efforts and courage are not enough without purpose and direction.” John F. Kennedy
A personal reflection about the strategy for treatment of Parkinson’s: MAO-B inhibitors have never been part of my strategy for treating my disorder. I have been using a traditional drug therapy protocol [Sinemet and Ropinirole] (click here), supplemented by a relatively comprehensive CAM approach (click here), bolstered hopefully by a neuroprotective (experimental) agent [Isradipine] (click here), and fortified with as much exercise in my day that my life can handle (click here). However, there is a constant and dynamic flux/flow of ideas regarding treatment options for Parkinson’s. Thus, my strategy for treating my disorder needs to be fluid and not fixed in stone. Over the next few weeks, I will be reading more about MAO-B inhibitors, having some serious conversations with my Neurologist and Internist, with my care partner assessing the risk and benefits of taking an MAO-B inhibitor, and coming up with a consensus team opinion about whether or not I should start taking an MAO-B inhibitor.
Addendum- FDA Approves Xadago for Parkinson’s Disease:
As the Eagles sing in New Kid In Town, “There’s talk on the street; it sounds so familiar / Great expectations, everybody’s watching you”. The first new drug in a decade to treat Parkinson’s is an MAO-B inhibitor named Xadago (Safinamide). This drug has an interesting past with the FDA before getting approved this week. Is it different? Xadago is for patients using levodopa/carbidopa that are experiencing troublesome “off episodes”, where their symptoms return despite taking their medication. Thus, Xadago is being marketed as an add-on therapy, which is different than existing MAO-B inhibitors because they can be used as stand alone monotherapy. In two separate clinical trials for safety and efficacy of Xadago, compared to patients taking placebo, those taking Xadago showed more “on” time and less “off” time. Interestingly, this is exactly what you’d expect for an MAO-B inhibitor (sustaining dopamine, see drawing above). The most common adverse side-effects reported were uncontrolled involuntary movement (side-note: isn’t this what we’re trying to prevent in the first place?), falls, nausea, and insomnia. Clearly, taking Xadago with another MAO-B inhibitor would not be good. Xadago joins a list of other MAO-B inhibitors that are FDA approved for Parkinson’s including Selegiline (Eldepryl, Zelapar, EMSAM) and Rasagiline (Azilect). Whether the efficacy of Xadago is different or improved from existing MAO-B inhibitors remains to be shown; however, having another MAO-B inhibitor may allow Parkinson’s patients the possibility to use the one with the least adverse reactions. Clearly, close consultation with your Neurologist will be very important before adding any MAO-B inhibitor to your daily arsenal of drugs. The good news is now you’ve got another option to join the stable of possible MAO-B inhibitors to be used with levodopa/carbidopa.
For the background/rationale behind using “Go the distance” in the title, watch this video clip: Field of Dreams (3/9) Movie CLIP – Go the Distance (1989) HD by Movieclips (click here to watch Go the Distance).
“Only the mediocre are always at their best. If your standards are low, it is easy to meet those standards every single day, every single year. But if your standard is to be the best, there will be days when you fall short of that goal. It is okay to not win every game. The only problem would be if you allow a loss or a failure to change your standards. Keep your standards intact, keep the bar set high, and continue to try your very best every day to meet those standards. If you do that, you can always be proud of the work that you do.” Mike Krzyzewski
Dopamine neurons for the drawing wermodified from http://www.utsa.edu/today/images/graphics/dopamine.jpg