Parkinson’s disease lacks a cure but certain medicines can help manage the symptoms. These medications function to offer a substitute for dopamine, the signaling neurotransmitter in the brain.
Carbidopa-levodopa is hitherto the most effective medicine to manage Parkinson’s disease. This chemical moves to the brain and is converted to dopamine. The chemical levodopa is mixed with carbidopa preventing it from being converted to dopamine prematurely out of the brain hence potential side effects such as nausea are lessened. Potential side effects with this medication however include orthostatic hypotension or feeling light headed and nausea. With continued use however, the drug’s effectiveness wanes off. Occasionally, a patient on this drug may also experience dyskinesia. Carbidopa-levodopa may also augment the risk of upper gastrointestinal hemorrhage among patients with peptic ulcer history.
Dopamine agonists including pramipexole, ropinirole, apomorphine and rotigotine, is also used for Parkinson’s disease patients and instead of producing dopamine, it mimics its effects on the patient’s brain. In as much as they are less effective compared to levodopa, they have more lasting effects and can be used to ease levodopas effects. Dopamine agonists side effects resemble that of levodopa but also includes hallucinations, compulsive character including gambling, hyper sexuality, eating and also sleepiness. Additonally, weight loss, anorexia, orthostatic hypotension, syncope and pericardial effusion may be experienced.
MAO-B inhibitors are also used to manage Parkinson’s disease. Medicine in this category includes rasagiline and selegiline. MAO-B inhibitors function by preventing the breaking down of dopamine in the brain by hindering the activity of the brain’s enzyme monoamine oxidase B (MAO-B). Potential side effects of using this drug include insomnia, dry mouth, confusion, lightheadedness and nausea. MAO-B inhibitors are not used alongside other antidepressants or narcotics because of the risk of documented reactions, albeit rare, as Youdim, et al., (243-250) documents.
Catechol-O-methyltransferase (COMT) inhibitors are also used with Entacapone being the main medication in this category to manage Parkinson’s disease. Catechol-O-methyltransferase takes part in inactivating catecholamine neurotransmitters such as dopamine, nerepinephrine and epinephrine by introducing a metyl to the catecholamine. Hence, any compound with a catechol structure is Catechol-O-methyltransferases. COMT protracts levodopa’s effects mildly by blocking dopamine breaking enzymes. The side effects of Catechol-O-methyltransferase include the risk of dyslinesia due to the effects of levodopa. Diarrhea may also ensue. Tolcapone is a Catechol-O-methyltransferase inhibitor that is seldom prescribed owing to its potential risk of damaging the liver causing failure.
Anticholinergics have been used for many years hitherto, in managing the tremor that comes with Parkinson’s disease. Anticholinergics function by blocking the action of acetylcholine- a neurotransmitter. It also functions to block dyskinesia in Parkinson’s disease. Several anticholinergics medicines are in existent including trihexyphenidyl, atropine, flavoxate, benztropine mesylate, flavoxate and benztropine. However, the effects of these drugs are far outweighed by the resultant side effects including constipation, urination, confusion, dryness of the mouth, amnesia and hallucinations.
Amantadine may also be prescribed to manage Parkinson’s disease in its mild form in the early stages. It blocks the reuptake of dopamine hence is a weak treatment against Parkinson’s disease as Onofrj, et al., (341) notes. Amantadine thus only offers temporary relief. It may be administered together with carbidopa-levodopa in the foremost stages of Parkinson’s disease in order to curb involuntary movements caused by carbidopa-levodopa. Some of its side effects include nervousness, insomnia, exacerbations of seizure, nervousness, agitation , anxiety and concentration issues.
Works cited
Onofrj, Marco, et al. "Amantadine and antiglutamatergic drugs in the management of Parkinson’s disease." Parkinson's Disease: Current and Future Therapeutics and Clinical Trials (2016).
Youdim, Moussa BH, and Marta Weinstock. "Therapeutic applications of selective and non- selective inhibitors of monoamine oxidase A and B that do not cause significant tyramine potentiation." Neurotoxicology 25.1 (2004): 243-250.
