Parkinson’s Disease And Analgesics

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Question :

Pharma Homework Parkinson's Disease and Analgesics

Lehman College: Pharmacologic Basic of Nursing Practice (NUR 330)

1. Describe the pathophysiology and symptoms of Parkinson’s disease. 

2. Selegiline (Eldepryl), ropinirole (Requip) and bromocriptine (Parlodel) represent different classes of drugs used to treat Parkinson’s Disease. For each drug, give the mechanism of action and explain how it relates to the pathophysiology of Parkinson’s Disease.   

3. The combination of levadopa and carbidopa is a drug called Sinemet.  Describe the functions of these two drugs in Sinemet.  What is the advantage of having carbidopa given with levadopa as opposed to giving levadopa alone? 

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Answer :

 Pharma HW Parkinson disease

Pharmacologic Basis Of Nursing Practice (Lehman College)

1. Describe the pathophysiology and symptoms of Parkinson’s disease. Parkinson’s disease is a degenerative disorder of the CNS caused by atrophy of neurons that produce the neurotransmitter dopamine in certain region of brain. Fibers or neuron pathways project from substantia nigra to the corpus striatum, where the neurotransmitters are vital to the control of complex body movements. Through the neurotransmitters acetylcholine (excitatory) and dopamine (inhibitory), stratal neurons relay messages to the higher motor centers that control and refine motor movements. The loss of dopamine stores in this area of the brain results in more excitatory neurotransmitters than inhibitory neurotransmitters, leading to an imbalance that affects voluntary movement. (Hinkle, Cheever, Overbaugh 2022) 

Sign and Symptoms of Parkinson’s disease: Tremor- A slow unilateral tremor is present in majority of patient at the time of diagnosis. Pill-rolling is a common behavior in which patients rub the thumb and forefinger together as if a pill were between them. Muscle rigidity- passive movement of an extremity may cause the limb to move in a jerky increments, referred to as lead-pipe or cog-wheel rigidity. Involuntary stiffness of the extremity increases when another extremity is engaged in voluntary movement. Stiffness of the arms, legs, face, and posture are common. Rigidity of the pharyngeal muscles may lead to difficulties in chewing and swallowing.

Patients with PD have difficulties initiating movement and controlling fine muscle skills. Walking often becomes difficult. Postural instability- patient commonly develop postural and gait problems. Due to a loss of postural reflexes, the patient stands with the head bend forward and walks with a propulsive gait, called shuffling gait. The posture is caused by froward flexion of the neck, hips, knees, and elbows. Gait impairment and postural instability place the patient

at increased risk for falls. Affective flattening- patient often have a masked face where there is little facial expression or blinking of the eyes. Other effects of PD includes excessive and uncontrolled sweating, drooling, paroxysmal flushing, orthostatic hypotension, gastric and urinary retention, constipation, and sexual dysfunction.

2. Selegiline (Eldepryl), ropinirole (Requip) and bromocriptine (Parlodel) represent different classes of drugs used to treat Parkinson’s Disease. For each drug, give the mechanism of action and explain how it relates to the pathophysiology of Parkinson’s Disease.

Selegiline : It inhibits MAO type B (mainly found in the brain) enzyme which slows downdopamine metabolism. May also directly increase dopaminergic activity by decreasing thereuptake of dopamine into nerve cells. Selegiline is a selective inhibitor of the enzymemonoamine oxidase B, which suppresses dopamine -inactivation processes and increase itslevel in the neuronal synapse.

Ropinirole is a non-ergoline dopamine agonist, it stimulates the post-synaptic dopaminereceptors D2 in the central nervous system. it helps to improve the typical symptoms of PD likebradykinesia, shuffling gait, muscle rigidity etc.

Bromocriptine acts as a dopamine receptor agonist by activating postsynaptic dopaminereceptors. This helps to compensate the symptoms of PD by improving the dopaminergicactivity in the CNS. The overall effect is improved dementia and bradykinesia.

The combination of levadopa and carbidopa is a drug called Sinemet. Describe thefunctions of these two drugs in Sinemet. What is the advantage of having carbidopa
given with levadopa as opposed to giving levadopa alone?

Levodopa, a dopamine precursor, relieves parkinsonian symptoms by being converted todopamine in the brain. Carbidopa inhibits the decarboxylation of peripheral levodopa, whichallows more intact levodopa to reach the brain. Carbidopa reduces some of Levodopa’s sideeffects such as nausea, vomiting, hypotension etc. Taking levodopa by itself produces nauseaand vomiting. Carbidopa and levodopa are combined to prevent this side effect. thecombination reduces the dosage of individual drugs and increases compliance.

3. Patients who are taking levodopa alone need to be told to avoid a certain vitamin.What vitamin is it? Does this interaction occur with the combination of levodopa andcarbidopa?

Patient taking levodopa should avoid taking vitamin B6 as it reduces the effectiveness oflevodopa. Vitamin B6 or pyridoxine can be taken with the combination of levodopa andcarbidopa as there is not interaction when taking both.

4. The combination of levadopa, carbidopa and entacapone is drug known as Stalevo.What is the function of entacapone?
The function of entacapone is to help levodopa last longer by blocking a substance calledCOMT enzyme. This enzyme breaks down levodopa into another product. So Entacapone ismaking the half-life of Levodopa longer and also increasing its bioavailability.