Exam 2 - Neurology Meds (Part 2) Flashcards
(122 cards)
PARKINSONS DISEASE
PARKINSONS DISEASE
What drugs can cause Parkinson’s disease?
Antipsychotics Dopamine antagonists Methyldopa Reserpine MPTP (made by scientist) Hydrogen sulfide Methanol
Pathophysiology of Parkinson’s disease
PARKINSONS DISEASE -
Depletion of dopamine neurons from substantia nigra, less activity on D1 and D2.
D1 - striatum sends out less GABA, which means GPi sends out more GABA.
D2 - has some dopaminergic activity; GABA is decreased, more glutamate stimulates GPi to release more GABA from GPi. More GABA means more inhibitory transmitters on Thalamus. Less movement on motor cortex.
Less dopamine leads to overactivity of acetylcholine.
Huntington’s Disease
- Involuntary motion and corea
- Don’t have enough inhibitory D2 action, which leads to overactivity and more movement initiated at the Thalamus.
How do you treat Huntington’s disease?
Tetrabenazine
- Depletes catelcholamines (Serotonin, NE, dopamine) to inhibit the involuntary movements.
- ADR: Can cause hypotension, depression, suicide.
Patient with an acute dystonic reaction from dopamine blocker, how do you treat condition?
You know they have too much Ach (flexed), so you use an anticholinergic:
- Benadryl
- Cogentin
Want to restore balance between Ach and dopamine.
If we have too little dopamine in CNS, how can we fix that problem?
Inhibit metabolic enzymes so dopamine can stay longer and have more activity.
OR
Provide patient with more precursor dopamine (L-DOPA) to help them produce more dopamine.
- Levodopa
- Carbodopa
How do you diagnose Parkinson’s disease?
- Clinical diagnosis
- Can also use levodopa or apomorphine (precursors to dopamine)
- If s/s decrease, can help to confirm dx.
What are non-pharmacologic options for Parkinson’s patients?
- Education and support
- Exercise and speech therapy
- Surgical: thalamotomy or deep brain stimulation
What types of drugs are neuroprotective and used to slow progression of PD?
- MAO-B inhibitors
- Dopamine agonists
What drugs are used for symptomatic treatment of PD?
- Anticholinergics
- MAO-B inhibitors
- COMT inhibitors
- Dopamine agonists, like ergot and non-ergot derivatives
- Dopamine precursors
What’s an advantage to neuroprotective drugs affect on dopamine metabolism?
- Dopamine agonists
- MAO-B inhibitors
Dopamine is metabolized by MAO-B enzymes, which yields dopamine and H2O2 as products.
H2O2 turns into free radicals and can damage cells/denature proteins. With more oxidative stress, neurons can be damaged and cause progression of disease.
Inhibiting enzyme = less free radical damage and dopamine stays around with longer duration of action.
When treating PD, how can you avoid oxidative stress from MAO-B enzyme?
If you keep giving precursor drugs that stimulate MAO-B, it can lead to progression of disease!!! BAD.
+ If you inhibit MAO-B enzyme, you can have less oxidative stress and excitatory toxicity. Dopamine neurons can work for longer.
+ Dopamine agonists can be used to replace normal dopamine to delay dyskinesia caused by oxidative stress.
What drugs, specifically, inhibit MAO-B?
- Selegiline
- Rasagiline
Selegiline
MAO-B inhibitor
- Delays need for levodopa
- Initial effects are not sustained
- Amphetamine derivative; is metabolized into amphetamine. False positive drug screen.
ADR
-Agitation, insomnia, hallucinations, orthostatic hypotension
-Hypotension - when standing, body sends out catecholamines to regulate BP. When you go to stand, you don’t have the reserves for extra to compensate as well for sitting-standing.
Rasagiline
MAO-B inhibitor
- Not metabolized into an amphetamine
- Fewer side effects
Rasagilline preferred over Selegiline.
When prescribing a patient Selegiline or Rasagiline; what is a risk?
Serotonin Syndrome
-By decreasing MAO-B, they can increase activity of other catecholamines, like dopamine.
Too much in synapse = serotonin syndrome.
When is it most appropriate to use MAO-B inhibitors?
- Mild PD, early on in treatment
- Don’t prescribe with tramadol, methodone, amphetamines, ephedra, dextromethorpan, MAO-inhibitors, or cyclobenzaprine…
- Will INCREASE risk of Serotonin Syndrome!!!!!
When prescribing MAO-inhibitors, what dietary restrictions should patient be placed on?
Tyramine
- Broken down into serotonin and NE
- If you inhibit MAO-B, you can get too high activity: increases Serotonin Toxicity risk.
High amounts in aged cheeses, meats, fava beans, red wine, dark chocolate, beer
If a patient on a MAO-B inhibitor ingests foods high in Tyrosine, what S/S may they experience?
Serotonin Syndrome
- Increased BP, tachycardia, hallucinations
- Good education point
In early, uncomplicated PD, how do you manage symptoms?
Anticholinergics - blocks Ach in XS to restore balance and limit side effects.
- Benztropin (Cogentin)
- Trihexyphenidyl (Artane)
- Diphenhydramine (Benadryl)
-Good for patients with tremor, but little hypokinesia.
-If they have cognitive impairment, DO NOT GIVE anticholinergic –
Will cause altered mental toxicity!!
Patient diagnosed with PD; main features are a tremor with no cognitive impairment. What drug would you use to treat?
-Benztropin (Cogentin)
Amantidine (Symmetrel)
Unclear MOA
- Amphetamine-like activity to increase release of dopamine.
- Anticholinergic effects
- MDMA antagonist affects
-Used in mild PD and in in ICU for patients with prolonged coma to reset CNS and wake them up.
- Renal elimination - adjust dose!!
- Can cause SEIZURES if drug level is too high!!
- Tolerance develops over time, will see decreased release of effect. :(
Dopamine Agonists
- First line therapy; delay treatment with L-DOPA.
- Goal: Keep patients off L-DOPA as long as possible to prevent the wearing of neurons.
- Can add to L-DOPA, but need to reduce the dose or you might see toxicity
- Slow progression of disease by replacing dopamine
- Drugs can work on D1, D2, and D3.
ADR
-Somnolence, confusion, hallucinations, punding, orthostatic hypotension, dyskinesia, peripheral edema