Anti-Tremor Medications for Parkinson's Disease

Introduction

Parkinson’s disease is a chronic and progressive disorder. In this disorder, the movements of the individual are affected. When we say progressive, it means that as time passes by, the symptoms related to the disease tend to worsen. Parkinson’s disease does not have a complete cure and studies have not been able to find its exact cause. However, to manage the symptoms to a larger extent, there are available treatment options. In Parkinson’s disease, there is either a malfunction or death of the nerve cells called neurons, which are essential in the brain.

Parkinson’s disease is thought to originate in the substantia nigra of the brain. Thus, the neurons in this area are affected first. Dopamine is a chemical that sends a message to the brain. It helps control the movements and coordination. These dying neurons produce dopamine. As Parkinson’s disease advances, dopamine is thought to decrease, and thus result in uncontrollable movements of the person’s body.

Symptoms of Parkinson’s Disease

• Tremors that initially start with the hands and then in other parts of the body
• Muscle stiffness
• Having a difficulty in eating or swallowing
• Having a difficulty with walking, balance, and lack of coordination
• Digestion-related issues
• Speech problems such as slurred speech
• Memory and thinking problems

Causes of Tremor

One of the most common characteristics of Parkinson's disease is resting tremor. The initial phase of this illness starts from trembling or shaking sensations in the hands. Tremor usually occurs in the hands and it is noticeable when the muscles of the hands are resting or in a relaxed position. However, tremors can also occur in other parts of the body such as the feet, face, and jaws. Since the tremor occurs when the hand is resting, it has been given the term as resting tremor. There have been no confirmatory studies done to tell us the exact cause of these tremors.

One of the main reasons for tremors is the loss of dopamine in certain areas of the brain, which helps support body movements. These sites are perfectly organized into circuits, which are specialized in producing different types of movements. Out of so many circuits, one of them is a brain regulatory region, which is also called as the thalamus. The thalamus functions by transmitting information about sensory nerves that regulate body movements from the senses up to the brain. This sensory feedback is then used by the brain to control other complex movements of the body. The normal operation of the thalamus gets disrupted due to the loss of dopamine in brain circuits. There have been studies suggesting that the loss of dopamine had already happened many years prior to the start of the disease or tremor. When there is a very low dopamine level, it tends to get critical in the thalamus, which then loses the normal regulatory input leading to tremors. The brain is unable to get accurate feedback of the senses and it fails to recognize how well the movements need to happen. It then leads to an ineffective or slow rate of movements. The first affected movements are the complex movements of the fingers and hands.

Treatment

A lack of dopamine in the brain is one of the common causes that lead to the symptoms of Parkinson's disease. The main aim of the Parkinson’s treatment is to either temporarily replace the dopamine or imitate the actions of dopamine. These types of drugs fall under the category of dopaminergic medications. They help reduce muscle rigidity, improve the speed of body movements, and also improve the coordination of movements by reducing tremors in the body. Below are various treatment options that can help control the disease from worsening:

• Therapy -  The doctor can suggest certain therapies apart from medicines such as occupational therapy, speech and language therapy, physiotherapy, and complementary therapy.

• Medications - Certain drugs can be prescribed for managing the symptoms of the disease. They include levodopa and dopamine agonists.

• Surgery - If the symptoms are still uncontrolled with the above methods, then the doctor can suggest for surgery.

A person suffering from Parkinson’s disease can get some help from medications and drugs. They help improve the quality of life for many years. The choice of medication depends on the long-term path of illness. Consult a neurologist before taking any medicine if you suspect any illness. But that's not all. You specifically need to consult a movement disorder specialist.

Drugs are given to enhance the level of dopamine in the brain. Medications will not cure the disease, but only help manage the symptoms. The choice of medication depends on the symptoms and progress of the disease. The doctor and patient need to work together to decide the best drug while keeping various factors into consideration. Along with medications, a suitable diet plan and exercise will also help in the treatment process.

The various treatment options for tremors would include dopaminergic agents, blockers, anticholinergics, and deep brain stimulation (DBS). Levodopa and dopamine agonists help reduce the symptoms of Parkinson's disease, which also include tremors, but the tremor control is unsatisfactory. There are still no convincing data to prove that dopamine agonists can cause a greater improvement of tremors than levodopa.

Dopamine Agonists

Dopamine agonists are a different class of drugs than levodopa. While levodopa gets converted in the brain, dopamine agonists are known to imitate the effects of the natural dopamine without actually being converted in the brain. Dopamine agonists are the first drugs prescribed for the treatment of Parkinson's disease. However, in certain cases, these drugs can also be used in later stages along with levodopa or carbidopa. Below are the commonly prescribed brands of dopamine:

• Mirapex (pramipexole):  This drug was approved in the year 1997. This drug is quite effective in the initial stages of the disease to treat motor-related symptoms. It also plays an important role in controlling motor fluctuations.

• Requip (ropinirole): This drug was approved in the year 1997 and it is also effective in the early stages of this disease wherein it controls any symptoms pertaining to motor fluctuations.

• Rotigotine Patch (Neupro): This has been formulated as a once daily skin patch and needs to be changed every 24 hours. This medicine is similar to the oral form of dopamine such as pramipexole and ropinirole. However, it also has side effects such as mild skin irritation. The patients are known to tolerate the patch in a better way when they rotate the sites where they stick the patch.

• Apokyn (apomorphine): This medicine has been first used to treat Parkinson's disease in the year 1950, but the actual use was associated with a lot of side effects mostly vomiting and nausea. Later in the year 1990, this medicine was released in the market in the injection form. Now, it is mostly used as a rescue medicine for those people who are at the advanced stage of the disease. This medicine can be used as often as five times a day and is often called as a “rescue agent”.

Side Effects

The following are some of the side effects of dopamine agonists:

• Feelings of confusion
• Hallucination
• Excessive sleepiness during the day
• Swollen ankles and feet 
• Compulsive behavior such as an urge to go shopping, eating, gambling, or increased sexual drive

Benztropine

Benztropine is an anticholinergic and is used in combination with other medications to treat the symptoms of Parkinson's disease such as muscle stiffness. Benztropine is also given to control tremors. Benztropine decreases the effect of acetylcholine in the brain, thereby reducing muscle stiffness and tremors. Do not take this medication if you have any of the following conditions:

• Allergy to any ingredient of benztropine
• Have angle-closure glaucoma
• Myasthenia gravis
• Bleeding problems
• Intestinal or urinary blockage
• Ulcerative colitis

 Precautions

• Pregnancy, planning on becoming pregnant, and lactation
• Taking any prescription or nonprescription medicine, herbal preparations, or dietary supplements
• Allergy to foods, certain medications, and other substances
• Enlarged prostate
• Irregular heartbeat
• Glaucoma or its risk factors
• Tardive dyskinesia
• Urinary retention

Interactions

Benztropine may interact with medications such as phenothiazines or tricyclic antidepressants and may cause serious side effects such as heat stroke or paralysis of the intestines.

Usually, Benztropine is given as an injection, and if you are taking it at home, you will be taught by your healthcare provider on how to use it. Sometimes, it may cause a blurry vision, which can become worse along with the intake of alcohol or certain medicines. It may cause drowsiness, lightheadedness, or fainting. Hot weather, fever, or exercises may worsen the side effects.

Due to Benztropine, the body may overheat since it may reduce the ability of the person to sweat. While the person is on this medication, laboratory tests should be carried out to monitor important body functions such as the liver, kidney, and lung functions. Certain laboratory tests can also monitor the levels of blood cholesterol and to check for any side effects. Other side effects include:

• Drowsiness
• Dry mouth
• Constipation
• Difficulty urinating

Call your doctor right away if you experience the following symptoms:

• Skin rash
• Fever
• Confusion
• Depression
• Eye pain
• Hallucinations
• Fast and irregular heartbeat

Other symptoms may include:

• Excitement
• Nervousness
• Dizziness
• Muscle weakness
• Blurred vision
• Rapid heartbeat
• Vomiting
• Painful urination
• Skin rash
• Headache
• Blood in vomit
• Confusion
• Seizure
• Coma
• Heat stroke

Common Brands

Tremor-predominant Parkinson's disease is characterized by predominant tremors, which include one or more limbs. There is a relative lack of significant rigidity and bradykinesia. The tremors can be very disabling. Treatment for tremors includes oral medications, injections with botulinum toxin, and neurosurgical procedures. Levodopa,

Levodopa, dopamine agonists, and anticholinergics are some of the first lines of medication, which are very effective in controlling tremors. However, some are unresponsive to these drugs and a second line of medication may be needed as treatment. They include clozapine, amantadine, clonazepam, propranolol, and gabapentin.

In some cases, neurosurgical interventions may be needed. People with Parkinson's disease normally experience parkinsonian tremors, which usually occur in the hands at rest and eventually in the head, lips, tongue, and feet. The following are medications used for the treatment of tremors caused by Parkinson's disease:

• Carbidopa - It is a dopaminergic antiparkinson agent and its brand name is Lodosyn.

• Zonisamide - It is a carbonic anhydrase inhibitor anticonvulsant under the brand name of Zonegran.

• Belladonna Tincture - It is an anticholinergic and antispasmodic medication.

• Corgard - It is a noncardiovascular beta blocker.

• Scopolamine -  It is an anticholinergic and antiemetic drug. Some of the common brand names of scopolamine are Transderm-Scop, Maldemar, and Scopace.

Therapies

Various kinds of therapies are available to cope with the symptoms of Parkinson's disease. They include:

• Speech and Language Therapy - At the early stage of the disease, this type of therapy should be given. The therapist will help with the patient's ability to communicate as effectively as possible and deal with eating problems as well as coping with different kinds of settings such as silent and noisy environments.

• Occupational Therapy - This type of therapy can help patients in handling difficult tasks with ease. Any difficulty the patient is experiencing can be made easy through the help of an occupational therapist by providing certain strategies on handling the tasks and to cope up with other future tasks.

• Physiotherapy - This therapy will help identify how the disease is affecting the mobility of the patient and how the patient is able to carry out different daily tasks. A physiotherapist helps maintain good physical movements such as walking, maintaining balance, and keeping the body fit. A physiotherapist will also give inputs to family and friends on how they can help the patient with the treatment process.