Antiparkinsonian Drugs Flashcards
Parkinson’s is a chronic, progressive disorder that affects the __________ - producing neurons in the brain
Dopamine
Symptoms occur when around ___% of the dopamine stored is depleted
80
Classic symptoms include TRAP
Tremors, Rigidity (resistance to passive movement), Akinesia (inability to move muscles), Postural instability
What is on-off phenomenon regarding levodopa
On is when the med is working and symptoms are controlled. Off is when the medication is wearing off and symptoms worsen
What are the two common types of dyskinesia?
Chorea: involuntary movements of limbs and facial muscles. Dystonia: abnormal muscle tone leading to abnormal movements
What is the goal of drug therapy regarding Parkinsons
Slowing the progression of the symptoms rather than the disease
How do direct-acting dopamine receptor agonists work
Direct stimulation of presynaptic or postsynaptic dopamine receptors
Can bromocriptine work if the substantia nigra is damaged? Why?
No, because it activates presynaptic dopamine receptors to stimulate the production of dopamine. If it’s damaged there’s nothing to stimulate
As PD progresses, it becomes harder for levodopa to control it. How long does it take levodopa to become less effective
Generally 5 to 10 years after the start of the therapy.
What is a major contraindication of levodopa-carbidopa therapy? And when should be you be cautious?
Contraindication: Angle-closure glaucoma. Cautious: Open-angle glaucoma.
Monoamine Oxidase (MAO)
Breaks down catecholamines in the CNS, primarily in the brain
Anticholinergic Therapy (Parkinson’s)
Blocks the effects of ACh. It’s used to treat muscle tremors and rigidity which are caused by excessive cholinergic activity
What is SLUDGE and what is responsible for it?
Salivation, Lacrimation, Urination, Diarrhea, increased GI motility and Emesis(vomiting). ACh
What are initial signs and symptoms of PD
Masklike expression, speech problems, shuffling gait.
what are the adverse effects levodopa?
Confusion, Involuntary movements, Gi distress, hypotension, cardiac dysrhythmias
What drug interactions are there with levodopa?
pyridoxine, nonselective MAOIS, benzodiazepines, antipsychotics, dietary protein
When is Carbidopa-levodopa (Sinemet) best taken?
On an empty stomach but it can be taken with food to minimize GI adverse effects
How does Sinement CR affect the on-off phenomenon?
Increases on time and decreases off time
What is the purpose of administering carbidopa alone?
Adjunct to treat nausea from carbidopa-levodopa (Sinemet) therapy
What are 2 examples of MAO-B inhibitors and when are they used?
Selegiline HCL and rasagiline mesylate(Azilect). Use supplementary with levodopa.
What do dopamine modulators do and name one
Release dopamine and other catecholamines from their storage sites in presynaptic fibres that haven’t been destroyed yet. Blocks reuptake of dopamine into nerve fibres resulting in higher dopamine levels in synapses and improved dopamine transmission in neurons. Amantadine HCL
When can dopamine modulators be used and for how long
Used early in the course of the disease and usually only effective for 6 to 12 months
What are adverse effects of amantadine?
Dizziness, insomnia, nausea
Amantadine drug interactions?
Increased anticholinergic adverse effects when given with anticholinergic drugs
What is the purpose of catechol ortho-methyltransferase (COMT) inhibitors and name one
Block COMT which is the enzyme that catalyzes the breakdown of the body’s catecholamines. They prolong the duration of the action of levodopa. Entacapone (Comtan)
How does entacapone (comtan) affect the on-off phenomenon
Reduces off time
What are adverse effects of COMT inhibitors
Upset GI, Urine discoloration, Can worsen dyskinesia that may already be present
What effects do anticholinergic drugs have (opposite of SLUDGE)
Dry mouth, urinary retention, Constipation, Dilated pupils (mydriasis), and smooth muscle relaxation
Name one anticholinergic drug
Benztropine mesylate
What are adverse effects of Benztropine mesylate?
Tachycardia, confusion, disorientation, toxic psychosis, urinary retention, dry throat, constipation, nausea and vomiting
Selegiline hydrochloride and rasagiline mesylate (Selective MAO-B inhibitors) Cause an increase in _____________
levels of dopaminergic stimulation in the CNS
