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Drugs For Parkinson's Disease
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History of Parkinson's Disease l First characterized in 1817 by James Parkinson : An Essay On The Shaking Palsy
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l Dr. Parkinson characterized the disease: l rigidity l tremor l mask face l stooped body posture l festinating gait
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Epidemiology n The Real Cause Is Under Investigation l Loss of dopamine production and release in the basal ganglia
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l Presence of persistent cholinergic output in the basal ganglia in the absence of dopaminergic influences
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l Environmental Toxins - Possible Causes? l Manganese Workers In Chile l Tetrahydroisoquinoline (TIQ) - A Toxic Chemical Also Causes Parkinsonism
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l N-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) - A Toxic Chemical Causing Parkinsonism - Is Refractory To Treatment
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Parkinsonian Drugs l Anticholinergic Agents l Dopaminergic Agents l Dopamine-Like Agents
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Anticholinergic Drugs l Trihexyphenidyl HCl (Artane) l Benztropine Mesylate (Cogentin) l Biperiden HCl (Akineton) l Procyclidine HCl (Kemadrin) l Ethopropazine HCl (Parsidol) l Diphenhydramine HCl (Benadryl)
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l Mainline Medications Until The Early 1960's l Now Are Used In A Supportive Role l Useful In Patients With Minimal Symptoms
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l Useful In Patients Who Cannot Tolerate Levodopa l Useful In Patients In Whom Levodopa Does Not Appear Effective
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Mechanism Of Action l Mainly Controls Salivation and Drooling l Anticholinergics Blunt Excitatory Effects Of Acetylcholine l Anticholinergics Competitively Block The Adrenergic Receptors Thus Reduce The Effects Of Acetylcholine
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Adverse Side Effects Of Anticholinergics l Tachycardia l Photosensitivity Of The Skin l Constipation l Urinary Retention l Psychiatric Disturbances
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l Dry Mouth (Xerostomia) l Blurred Vision l Pupillary Dilatation (Mydriasis) l Hallucinations l Confusion
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Dopaminergic Drugs u True Dopamine Medications l Levodopa (Larodopa, Levodopa) l Carbidopa-Levodopa (Sinemet)
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The Problem With Levodopa l When Levadopa is taken orally, it is changed in the gut into dopamine by an enzyme called dopa decarboxylase.
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l Herein lies the problem ….. Dopamine cannot cross the blood-brain barrier. So, it is useless to the Parkinson’s patient if it never gets into the brain !!
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l So….. the key is to keep levadopa as levadopa until it reaches the blood-brain barrier. l How do we keep levadopa from being converted to dopamine ?
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l You have to combine levadopa with a dopa decarboxylase inhibitor to insure that levadopa gets to and can cross over the blood-brain barrier.
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l Carbidopa is the name of the dopa decarboxylase inhibitor that is combined with levadopa which enables levadopa to get to and cross over the blood-brain barrier l This medication combination is called Sinemet
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l At the blood-brain barrier, carbidopa is cleaved from levadopa. l Levadopa than easily crosses over the blood-brain barrier into the brain.
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l In the brain, levadopa is converted to dopamine where it exerts its inhibitory effects and calms the tremors, and other symptoms of Parkinson’s Disease
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Medical Uses Treat The Symptomatology Treat The Symptomatology l To Improve Fine Motor Control l To Improve Gross Motor Control & Balance During Ambulation
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l To Decrease Tremor, Rigidity, Bradykinesia l Improve Speech l Improve Handwriting l Improve Swallowing l Normalization Of Respiratory Movement
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Adverse Side Effects u Levodopa u Tachycardia - Dopamine has beta- 1 effects on the cardiovascular system u Postural Hypotension - Is lessened when Levodopa is taken with Carbidopa (Sinemet)
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l Tics l Spasms l Ballistic Movements
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l Behavioral Changes l Depression, Manic Behavior, Anxiety Attacks, Confusion, Hallucinatory Behaviors l May Require A Drug Holiday
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Dopamine-Like Drugs l Amantadine HCl (Symmetrel)
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Amantadine Mechanism Of Action u This Medication Is An Antiviral Medication u Its Mechanism Of Action Is Unknown l Believed to facilitate release of dopamine from storage sites in the basal ganglia
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Adverse Side Effects l Orthostatic Hypotension l Nightmares l Confusion l Depression l Hallucinatory Behavior
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Dopamine-Like Drugs l Bromocriptine Mesylate (Parlodel) l Pergolide Mesylate (Permax)
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l These Medications Are Ergot Alkaloids & Belong To The Same Family As LSD
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l These Medications Are Used To Decrease The Untoward Side Effects Seen In Patients Using Levodopa - i.e. Involuntary Movements
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Ergolines : Adverse Side Effects l Nausea l Vomiting l Postural Hypotension l Visual and Auditory Hallucinations l Livedo Reticularis - Purple Discoloration Of The Skin
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Dopamine-Like Drugs l Selegiline HCl (Eldepryl)
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Selegiline Mechanism Of Action l This Medication Is A Monoamine Oxidase (MAO) Inhibitor l It inhibits MAO, the enzyme which destroys dopamine l Selegiline prolongs the biological half-life of dopamine
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l This Medication Is More Effective When Given To New Parkinson's Patients
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l Selegiline allows the patient to: l Take a lower dose of Levodopa l Lengthens out the dosing intervals l Side effects are insignificant
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Selegiline : Adverse Reactions n Nausea & Vomiting n Orthostatic Hypotension *** n Fainting & Dizziness *** n Hallucinations *** n Loss Of Balance & Syncope *** n Depression
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Dopamine-Like Drugs n Pramipexole (Mirapex) n Ropinrole (Requip)
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Mechanism Of Action n Mechanism is not exactly clear u Stimulates the dopamine receptors of the Corpus Striatum
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Adverse Side Effects n Drowsiness n Orthostatic Hypotension n Hallucinations n Dizziness n Syncope
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Clinical Considerations l Schedule The Rehab Session One Hour After The Morning Dose l The patients will be rested from the night's sleep l The drug will be at its peak effectiveness
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n Maintain Joint Range Of Motion During A Drug Holiday
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l Maintain As Much Cardiovascular Fitness As Possible During The Drug Holiday l Monitor The Patient's Blood Pressure - Orthostatic Hypotension l Be Aware Of The Patient's Balance & Gross Motor Control - Protect Against Falling
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