Chapter 24 Antiparkinsonism agents Flashcards
Dopaminergic agents MEDS
Levodopa (Inbrija) Carbidopa-Levodopa (Duopa, Rytary) Amantadine (Gocovri, Osmolex ER)
Apomorphine
(Apokyn)
Bromocriptine
(Parlodel)
Pramipexole
(Mirapex, Mirapex ER)
Rasagiline (Azilect) Ropinirole (Requip, Requip ER) Rotigotine (Neupro)
MOA dopaminergic agents
increase or stimulate dopamine to balance acetylcholine/dopamine balance
Indications: dopaminergic agent
Parkinson’s disease and parkinsonism
Pharmacokinetics
Mostly orally administered, except for apomorphine (subcutaneous) and rotigotine (transdermal).
Metabolized in the liver and peripheral tissues; excreted via urine.
Crosses the placenta and enters breast milk, making them contraindicated in pregnancy and lactation.
CI dopaminergic agents
Allergy to the drug components
Angle-closure glaucoma.
Use with nonselective
MAO inhibitors (risk of hypertensive crisis).
Severe cardiovascular disease (e.g., myocardial infarction, arrhythmias, hypertension).
History of peptic ulcers, psychiatric disorders, urinary retention.
Extended-release amantadine is contraindicated in end-stage renal disease.
AE dopaminergic agents
Central Nervous System (CNS):
Anxiety, nervousness, headache, fatigue, confusion, hallucinations, psychosis.
Gastrointestinal (GI): Nausea, vomiting, dysphagia, constipation/diarrhea.
Cardiovascular: Arrhythmias, orthostatic hypotension, palpitations.
Others: Urinary retention, excessive sweating, flushing, muscle twitching.
Bone marrow suppression and hepatic dysfunction in some cases.
DDI dopaminergic
MAO inhibitors: Increased therapeutic effects but risk of hypertensive crisis (must be stopped 14 days before starting dopaminergic therapy).
Iron salts and dopamine antagonists: Decreased effectiveness of carbidopa- levodopa.
Vitamins: Patients should avoid over-the-counter multivitamins, as they may contain Vitamin B6, which reduces dopaminergic drug effectiveness.
Rasagiline users should avoid tyramine-containing foods, St. John’s wort, and certain pain medications (e.g., meperidine, acetaminophen) to prevent severe reactions.
Nursing interventions dopaminergic
Assessment:
- Check for contraindications like glaucoma, cardiovascular disease, renal/liver dysfunction.
- Monitor mental status, reflexes, and gait to assess CNS effects.
- Evaluate cardiac function (BP, heart rate, ECG).
- Monitor GI function, urine output, and hepatic/renal lab
values.
Interventions:
- Administer with food if GI upset occurs.
- Monitor bowel function to prevent constipation.
- Ensure hydration and prevent overheating (dopaminergics
may increase sweating and flushing).
- Monitor for signs of drug toxicity (e.g., confusion,
hallucinations, cardiac irregularities).
- Educate on medication timing, side effects, and dietary restrictions (e.g., avoiding iron-rich foods with carbidopa- levodopa).
- Safety precautions due to risk of dizziness, orthostatic hypotension, and psychosis.
Anticholinergic Agents MEDS
Benztropine (Cogentin)
Diphenhydramine (Benadryl)
Trihexyphenidyl (generic)
MOA anticholinergic
These drugs block acetylcholine receptors in the central nervous system (CNS), reducing excitatory effects in the basal ganglia.
By suppressing acetylcholine activity, they help restore neurotransmitter balance, improving muscle control and reducing rigidity, tremors, and drooling.
They also have some peripheral anticholinergic effects, such as reducing secretions, slowing GI motility, and relaxing smooth muscles.
Indications anticholinergic
Idiopathic, atherosclerotic, and postencephalitic Parkinsonism.
Relief of extrapyramidal symptoms caused by certain drugs (e.g., phenothiazines).
Adjunctive therapy
in Parkinson’s disease for patients who no longer respond well to levodopa.
Pharmacokinetics anticholinergic
Absorption: Variably absorbed from the GI tract; peak levels reached in 1-4 hours.
Metabolism: Processed in the liver.
Excretion: Eliminated through cellular pathways.
Placental & Breast Milk Transfer: These drugs cross the placenta and enter breast milk.
Routes of Administration: Benztropine and diphenhydramine: Available in oral, intramuscular (IM), and intravenous (IV) forms. Trihexyphenidyl: Only available in oral form.
CI to anticholinergic
Allergy to anticholinergic agents.
Narrow-angle glaucoma (may worsen
intraocular pressure).
Gastrointestinal (GI) or genitourinary (GU) obstruction. Prostatic hypertrophy (risk of urinary retention).
Myasthenia gravis (exacerbation due to further acetylcholine blockage).
Use in children is not well established.
Use with Caution in Patients With:
- Tachycardia, dysrhythmias, hypertension, or hypotension (due to increased sympathetic activity).
- Liver dysfunction (due to metabolism concerns).
- Pregnancy and lactation (only if benefits outweigh risks).
- Hot environments (due to reduced sweating and increased risk of heat prostration).
AE anticholinergic
Central Nervous System (CNS) Effects:
- Disorientation, confusion,
memory loss.
- Agitation, nervousness,
delirium.
- Dizziness, light-headedness,
weakness.
Peripheral Anticholinergic Effects:
- Dry mouth, nausea,
vomiting.
- Paralytic ileus and
constipation (due to reduced
GI secretions and motility).
- Tachycardia, palpitations, hypotension (due to loss of parasympathetic control).
- Urinary retention and hesitancy (due to bladder muscle relaxation).
- Blurred vision, photophobia (due to pupil dilation).
- Flushing, decreased sweating (risk of heat prostration in hot environments)
DDI anticholinergic
Tricyclic antidepressants and phenothiazines:
- Increased risk of
paralytic ileus and
toxic psychosis.
- If combined, dose
adjustments and close monitoring are required.
Antipsychotic medications: May reduce the effectiveness of the antipsychotic therapy due to opposing mechanisms.
Nursing interventions anticholinergic
Assessment:
- Check for contraindications, including glaucoma, urinary
retention, cardiac conditions, GI issues, and myasthenia
gravis.
- Monitor CNS function (disorientation, confusion, reflexes,
tremors).
- Assess cardiovascular function (pulse, blood pressure,
ECG).
- Evaluate GI motility (check for constipation, ileus).
- Check urinary output and bladder distension.
Interventions:
- Reduce dose if dry mouth is severe and provide sugarless
lozenges or frequent mouth care.
- Avoid excessive heat exposure and reduce dosage in hot
weather to prevent heat stroke.
- Administer with meals if GI upset occurs; give before
meals for dry mouth and after meals for drooling.
- Monitor bowel function and initiate a bowel program if
constipation is severe.
- Ensure the patient voids before taking the drug to prevent
urinary retention.
- Institute fall precautions if dizziness or CNS effects
occur.
- Monitor liver and kidney function to prevent toxicity.
Patient Teaching:
- Take the medication exactly as prescribed.
- Avoid alcohol and other CNS depressants.
- Stay hydrated and avoid overheating.
- Be cautious with activities requiring alertness (e.g.,
driving).
- Report severe side effects, including blurred vision, confusion, hallucinations, urinary retention, or extreme dizziness.
- Monitor for reduced sweating and avoid prolonged exposure to heat.
Adjunctive Agent MEDS
Entacapone (Comtan)
Safinamide (Xadago)
Selegiline (Eldepryl)
Tolcapone (Tasmar)
MOA adjunctive agents
Entacapone & Tolcapone:
- Inhibit catechol-O- methyltransferase
(COMT), an enzyme that breaks down dopamine and levodopa.
- Increases plasma levels and duration of action of levodopa, leading to more stable dopamine receptor stimulation.
Safinamide & Selegiline:
- Monoamine oxidase type B (MAO-B)
inhibitors, preventing dopamine degradation in the central nervous system.
- Increase dopamine levels in synapses to improve motor function.
Indications adjunctive agents
Adjunct therapy with carbidopa-levodopa for patients with Parkinson’s disease who experience “off” episodes.
Selegiline is also used for depression (in transdermal form).
Pharmacokinetics adjunctive agents
Entacapone & Tolcapone:
- Oral
administration.
- Metabolized in
the liver, excreted in urine and feces.
- Tolcapone has a risk of fatal liver
damage.
Safinamide & Selegiline:
- Oral
administration.
- Absorbed well
via the GI tract.
- Selegiline is
extensively metabolized in the liver and excreted in urine.
- Safinamide has a long half-life (20- 26 hours).
CI adjunctive agents
Known hypersensitivity to the drug.
Severe liver disease (tolcapone can
cause fatal hepatotoxicity).
Use of nonselective MAO inhibitors within the past 14 days (risk of hypertensive crisis).
Pregnancy and lactation: These drugs cross the placenta, and potential fetal risks exist.
Patients with severe psychiatric disorders (risk of hallucinations and impulse control issues).
AE adjunctive agents
Central Nervous System (CNS) Effects:
- Dizziness, confusion,
hallucinations, agitation,
psychosis.
- Headache, anxiety, and
depression.
Cardiovascular Effects:
- Orthostatic hypotension,
palpitations, tachycardia.
Gastrointestinal (GI) Effects:
- Nausea, vomiting, diarrhea,
abdominal pain.
- Liver toxicity (especially
with tolcapone).
Other Effects:
- Dyskinesia and worsening
Parkinson’s symptoms.
- Excessive sweating, muscle
cramps, fatigue.
DDI adjunctive agents
MAO inhibitors (including other MAO-B inhibitors): Risk of hypertensive crisis.
Carbidopa-Levodopa interactions: Increased levodopa levels, which may worsen dyskinesia.
Tyramine-containing foods
(for safinamide and selegiline users): Can cause dangerous increases in blood pressure.
Selegiline interactions: Should not be combined with meperidine (opioid pain reliever) or St. John’s wort due to risk of serotonin syndrome.
Nursing interventions adjunctive agents
Assessment:
- Evaluate liver function before and during tolcapone therapy.
- Monitor for worsening of dyskinesia or psychiatric symptoms.
- Assess blood pressure to prevent hypotension.
- Review dietary intake (avoid tyramine-rich foods).
Interventions:
- Monitor for signs of liver toxicity, including jaundice,
dark urine, abdominal pain.
- Educate patients to avoid high-protein meals, which may
reduce drug absorption.
- Encourage slow position changes to prevent orthostatic
hypotension.
- Monitor for impulse control issues, such as gambling,
compulsive behaviors.
- Selegiline users should avoid over-the-counter
decongestants, which may cause severe hypertension.
Patient Teaching:
- Take medications exactly as prescribed.
- Report any signs of hallucinations, confusion, or unusual
behaviors.
- Avoid foods high in tyramine (aged cheese, wine, cured
meats).
- Watch for liver-related symptoms (if taking tolcapone).
- Inform all healthcare providers about these medications,
especially before surgery or new prescriptions.
