Health Essays – Parkinson’s Disease

The Treatments of Parkinson’s Disease

Parkinson’s disease is a neurological condition that affects the sufferer’s mobility and speech. It affects the central nervous system, leading to a person’s inability to control muscles throughout the body. It is a disease whose treatment does not intend to cure it but instead, aims at controlling its manifestation. There are various ways in which this can be done. It may involve the use of drugs or the performance of surgery. Doctors strongly recommend exercise to try to keep muscles strong. It progresses gradually or severely from the early stages with mild symptoms to later stages with severe symptoms.

The disease is a result of lowered formation and action of dopamine which is produced by the dopaminergic neurons found in the brain. This knowledge led to the formation of drugs that will either increase the formation or mimic the actions taken by dopamine in the brain. This was important because an increase in the levels of dopamine would lead to a reduction of the effects of the disease. All the drugs used to control the disease include dopamine as their main active agent regardless of how it works. Depending on which class of drugs it belongs to, it may either mimic or produce dopamine.

Among the earliest forms of treatments are the anticholinergics. These were used even before the introduction of Levodopa, which is now the most widely used drug. The anticholinergics had very little benefits when compared to the harmful side effects caused by usage. The side effects include having a dry mouth, urine retention (which especially occurs among men), and very severe constipation and nausea. There are some other side effects that occur that are more serious and are among the major reasons why the use of these drugs has become minimal. These include confusion, memory loss, and hallucination (http://www.mayoclinic.com).

The realization that the benefits seen were much less than the side effects it causes has led to the reduction of its prescription. Since some anti-depressants and antihistamine’s tend to have almost the same effect as the anticholinergics, doctors will prescribe them to older people who are suffering from this terrible disease. Once an individual experiences any of the serious severe symptoms, it is advised that the use of the drug be stopped immediately.

Levodopa is a drug that was introduced in 1967 and is currently the most commonly used drug. It is most commonly referred to as Sinemet and is used to help restore ones control over ones muscles. Levodopa is referred to as the gold standard of Parkinson’s treatment because it is usually used as the first line of defense. The reason a sufferer of Parkinson’s can’t just take Dopamine itself is because Dopamine cannot breakthrough the blood-brain barrier. Levodopa can get through this barrier and is converted to Dopamine once it reaches the brain. It therefore increases the level of Dopamine and counters the effects of the disease. The conversion to Dopamine is what leads to the positive effects that a patient experiences when using the drug (Henkel).

Levodopa however has very serious side effects which include nausea and dyskinesias (involuntary movement). This occurs because only a small percentage of the drug actually reaches the brain to be transformed into Dopamine. The rest of it is transformed into dopamine in the body. It therefore becomes necessary to use Carbidopa, which delays the metabolism of Levodopa until it reaches the dopaminergic neurons in the brain. The combination helps reduce the side effects caused by the drug. Carbidopa delays the metabolism of Levodopa, keeping it from metabolizing in the body. This helps to greatly reduce the side effects felt by the user.

The other problem posed by the use of this drug is that its dosage needs to be increased over time. It has also been observed to work on and off without any explanation or reason. This makes it unreliable because its effects are not constant, and at times the patient gets violent attacks while still under medication. The various side effects and unreliability of levodopa leads to the necessity to combine it with various other drugs to make it more effective. Some of these drugs can be used on their own while others actually require to be used with the Levodopa-Carbidopa combination.

A cluster of drugs called Dopamine agonists are usually used in a combination with the Levodopa-Carbidopa drugs. They can however also be used on their own if the disease has not greatly progressed. Also, it is recommended that these drugs only be used alone in young adults. This class of drugs does not produce or help in the production of dopamine but instead imitates the effects that Dopamine has in the body. They tend to act on behalf of Dopamine (http://www.mayoclinic.com).

This class of drugs include; Apokyn, Requip, Parlodel and Mirapex. Parlodel has been used very little of late. This is because it had very serious side effects that endangered the patient more than it benefited him/her. It would cause inflammation in the lungs and/or heart valves of the user and would lead to further deterioration of the patient’s health. In general this class of drugs has side effects that are almost similar to those of carbidopa-levodopa but with slight differences. The effects of having involuntary movement are reduced while those of hallucinations and/or sleepiness are increased.

The drug Mirapex takes up the role of dopamine in the body as it is one of the dopamine agonists. When it is used in the absence of Levodopa-Carbidopa, it causes a 30% improvement in the health of the patient. When used in combination, it is able to reduce the intake of the Levodopa dosage by about 25%. Requip is also a dopamine agonist that can also be used either alone or with Levodopa. When used together with Levodopa, it can reduce the intake of Levodopa by around 31%. The reduction of Levodopa dosage decreases side-effects to the patient (Henkel).

Catechol-o-methyltransferace inhibitors, which are usually abbreviated as COMT inhibitors, are used to block the enzymes that break down the Levodopa into Dopamine before it reaches the brain. They can be used in combination with the Carbidopa-Levodopa therapy. The two main COMT inhibitors are Tasmar and Entacapone. Tasmar is rarely used because of its severe impact on the health of the user. It causes severe liver damage and hence is only used as a last resort if the patient has failed to respond to any other therapy (http://www.mayoclinic.com).

Entacapone does not have side-effects as severe as those of Tasmar and is therefore recommended over Tasmar. Its major side-effect is the involuntary movements experienced by the user. It works in conjunction with the Carbidopa-Levodopa therapy by increasing their availability. This is done by blocking the enzymes that break down the substance into Dopamine until the drug is already in the brain. This then means that the effects of Levodopa-Carbidopa are prolonged because they occur only in the brain. Stalevo, another drug, is the result of a combination of Carbidopa, Levodopa and Entacapone.

Selegiline, also referred to as Eldepryl, is another drug that can either be used with or without the presence of Carbidopa-Levodopa therapy. It works by preventing the metabolism of Dopamine. It does this by slowing down the activity of one of the enzymes that metabolize Dopamine. This is the monoamine oxidase B which is abbreviated as MAO-B. The use of Selegiline has other positive effects like delaying the need of Carbidopa-Levodopa. When combined with Carbidopa-Levodopa it improves the effectiveness of the drug. It can however have some adverse toxic reactions when combined with Demerol which is a narcotic drug.

Apart from ingesting drugs, they can be administered through the skin through the use of a silicon-based patch. Rotigotine is a dopamine agonist drug that can be administered through the skin, but can only be used in the early stages of the disease. This is called Neupro-rotigotine transdermal system. The patch has to be changed every 24 hours. It works by stimulating the Dopamine receptors in the body. Its side-effects include skin reaction where the patch is, hallucinations, insomnia, drowsiness, sleep-attacks, nausea, vomiting and the most severe is the reduction in blood pressure once the person stands up (http://www.fda.gov).

Amantadine is another drug that is used in treatment of Parkinson’s disease but its use was discovered by accident. Initially it was created to be an antiviral used in the treatment of influenza and was approved as such in 1976 by the Food and Drug Administration. It was however discovered to provide short term relief when used alone in the early stages of the Parkinson’s disease. When it is combined with Carbidopa-Levodopa it can be used by those in the later stages. It has side effects that mostly involve swelling of the ankles and turning skin color purple (http://www.mayoclinic.com).

In every human beings body, there is the presence of coenzyme Q10 which is produced by the mitochondria. This enzyme is used in the transport of electrons so that they can gain energy from the oxygen inhaled. This is done in the process called cellular respiration. The levels of this enzyme are very low in those suffering from Parkinson’s disease. These people can therefore benefit greatly by having more of this enzyme. This can only be achieved by taking supplements which can be bought from a pharmacy. This aids in helping to slow down the onset of the disease.

Apart from the use of drugs, there are various surgeries that can be used to control the effects of the disease. One of the surgeries is pallidotomy which involves the destruction of a small bit of the globus pallidus. Doctors believe all people who are suffering from Parkinson’s have an overactive globus pallidus. The procedure is done by drilling a small hole in the skull and using an electric probe to kill part of the pallidus. It can only be done when the patient is sedated but awake so the doctor can judge the patients reactions to stimuli. There is a globus pallidus on each side of the brain, but the operation can only be done on one side at a time. Its side effects mostly involve impaired speech (http://www.fda.gov).

Thalamotomy is another surgical procedure used in the control of Parkinson’s disease. It is only performed on those patients who are experiencing tremors in either the hands or the arms that become too severe to handle. Usually the tremors are so bad they disable the person. It involves the destruction of a specific group of cells that are located in the thalamus in the brain. The surgery reduces or completely eliminates the tremors in around 90% of those who undergo the procedure (http://www.fda.gov).

There is also the presence of a gadget that can be compared to the pacemaker used for cardio problems. It is known as the brain pacemaker (http://www.fda.gov).

This form of therapy is referred to as Active Tremor Control Therapy. It involves the surgical implantation of an insulated wire to the brain. It is placed in the thalamus region of the brain, the subthalamic nucleus, and also the globus pallidus area of the brain.

The whole system includes three components which are the: lead, extension and the neurostimulator. This system is referred to as Deep Brain Stimulation because it occurs directly inside the brain. A small hole is made in the skull and through it the lead is inserted into the brain. The lead is a very thin insulated wire. The tip of the lead is in contact with the area that has been targeted. Once it has been implanted, it is connected to the neurostimulator by the extension which is also an insulated wire (http://minds.nih.gov).

The extension passes under the skin and moves from the head, to the neck, the shoulder and finally to where the neurostimulator is located. The neurotransmitter is located either under the collarbone, in the abdomen or the lower chest area just directly under the skin. The neurotransmitter involves a battery pack that sends electrical impulses to the brain. This is done through the extension and the lead. When the person is undergoing tremors, he or she is supposed to pass a handheld magnet over the location of the neurostimulator.

The electrical impulses that are sent by the neurostimulator work by blocking the electrical signals that are the cause of the Parkinson’s disease symptoms. They are dysfunctional brain signals and they are the cause of the tremors. This procedure is preferred because it does not destroy the nerve cells and when one wants to stop its use it is as easy as having the system surgically removed.

Works Cited

• “Deep Brain Stimulation for Parkinson’s Disease Information.” NINDS. 22 Nov. 2007 <http://www.ninds.nih.gov/disorders/deep_brain_stimulation/deep_brain_stimulation.htm>.
• “Henkel, John. “Parkinson’s Disease: New Treatments Slow Onslaught of Symptoms.” FDA. 22 Nov. 2007 <http://www.fda.gov/fdac/features/1998/498_pd.html>.
• “Neupro Patch for Parkinson’s Approved.” FDA. 22 Nov. 2007 <http://www.fda.gov/consumer/updates/neupro051407.html>.
• “Parkinson’s Disease: Treatment.” MayoClinic. 22 Nov. 2007 <http://www.mayoclinic.com/health/parkinsons-disease/DS00295/DSECTION=8>