Psyc ppt (Part 2) Flashcards
What is the pathological finding of Parkinson’s?
Degeneration of the neurons
The degeneration of Neurons originate where in the Brain
The substantia nigra of the midbrain and terminate in the basal ganglia
Name the 2 most reliable and effective drugs to treat Parkinson’s
Levodopa and Carbidopa
Levadopa crosses the blood brain barrier and is converted by what enzyme ______into what?
L-aromatic amino acid decorboxylase
Dopamine
Does dopamine cross the BBB?
NO
Levadopa works for Parkinson’s disease because it is a ________ to _______ and is converted upon crossing the BBB
precursors
Dopamine
Does Carbidopa cross the BBB?
NO
Carbidopa is classified as a ________ ________ ?
decarboxylase inhibitor
Carbidopa inhibits decarboxylase in the Liver, Kidneys and GI tract and prevents the breakdown of _________?
Levadopa (Carbidopa just prevents Levadopa from being broken down before it crosses the BBB)
First symptoms to improve with the use of Levodopa/Carbidopa are?
rigidity and bradykinesia late improvement is the tremors
Levodopa/Carbidopa side effects
NV and anorexia D/T activation of the chemoreactive trigger zone in the medulla oblangata
orthostatic hypotension
Cardiac arrythmias D/T Beta adrenergic dopamine stimulation
Long term therapy Side Effects
Abnormal Choreiform movements of the limbs and hands, trunk and tongue.
serious mental disturbances such as psychotic episodes and a need for a 1 week drug holiday
Levodopa/Carbidopa contraindications
MAO Inhibitors narrow angle glaucoma cardiac arrythmias recent MI Phenothiazines, butrophenones and reserpine can cause extrapryamidal symptoms
Selegiline first line drug for parkinsons before moving to levodopa by?
Enhancing endogenous dopamine
Interacts with TCA’s causing
Fever agitation deilerium and coma
Belladonna Alkaloids
Used in mild cases
combats tremors and dystonia
Antihistamines like benadryl
Can be used to control minor tremors in the elderly
What % of people respond favorably to Dopamine agonists
only 20-30%
Names of Dopamine agonists
Bromocriptine (parlodel), Pergolide (permax)
Dopamine agonists side effects are
Anorexia and Nausea due to stimulation of the Chemotatic trigger Zone (CTZ)
Anesthetic Implications
- Have Pt take meds preoperatively effects last 6-12 hrs
- Avoid Phenothiazines, butyrophenones, metoclopramide
- Muscle rigidity may impede mask ventilation
- Increased aspiration risk
- Intravascularly volume depleted
Anesthetic Implications
- Normal response to muscle relaxants
- Increased risk of post op laryngospasm
- violent tremors on emergence
- No ephedrine in taking Deprenyl
- Ketamine can cause exaggerated sympathetic response
- Potential hyperkalemic response to Sucs
Anesthetic Implications
- Skeletal muscle tremor may mimic VFIB on ECG
- May have diminished reserve due to poor exercise tolerance
- Muscle relaxants will relax even the most rigid of patients
Anticonvulsants _______ the Seizure threshold
Raise
Only ____ % of Pts become SZ free on meds
40%
______% of Pts get no benefit from currently avalilable meds
20%
Anticonvulsants MOA
Inhibition of neuronal Na+ channels in hyperexcitable cells
Disinhibition may increase SZs
Reduction in GABA increases SZs
Anticonvulsants Classes
I-IV based on MOA
Type I
Blocks sustained high frequency repetitive firing by enhancing Na+ channel inactivation
- Phenytoin
- Carbamazepine
Type II
Multiple actions: enhances GABA inhibition reduces T calcium currents, possibly blocks SRF
- Valproic Acid
- Benzos
- Phenobarbital
Type III
Blocks T calcium currents only
-Trimethadione
Type IV
only enhances GABA inhibition
-Gabapentin
Na+ Channel blocking agents such as
Dilantin used for general tonic clonic and partial SZ
Dilantin adverse effects
Overdose- nystagmus, ataxia, vertigo, diplopia
Common- enlarged lips and nose, gingival hyperplasia
idiosyncratic- dermatitis, hepatic necrosis
Carbamazepine (Tegretol)
Used for tonic clonic and absent SZ
common SE id drowsiness
Increases metabolism in other anticonvulsants
Barbiturated
Increases GABA inhibition
main SE sedation and disturbance in cognitive function
Valproic Acid
Blocks Na+ channels and increases GABA in the brain
SE hepatotoxic and Fetal neural tube defects
Benzos
interacts with GABA and causes sedation with a rapid development of tolerance
Phenytoin
resistant to NDNMB
causes decreased duration of muscle relaxants
rate of administration is 25-50 mg / min to avoid hypotension
Stevens-Johnson syndrome
Anesthetic Implications
Induction w/ thiopental or propofol
N2O/Narcotic techniques
Avoid enflurane and methohexital
opoid tolerance r/t enzyme activation by the anticonvulsants
