Neurologically Active drugs Flashcards
Movement disorders are classified as either
Hypo or Hyper kinetic
Voluntary movements come from
Corticospinal (pyramidal) tracts
Basal Ganglia
Cerebellum (motor coordination center)
Extrapyramidal system is modulated by
Basal ganglia
Cerebellum
Cerebral Cortex
In the Extrapyramidal system, direct output is through the
Cerebral Coretx
Extrapyramidal system involves
Involuntary Actions
Reflexes
Locomotion
Complex movements
Postural control
Neural lesions causing movement (Extrapyramidal disorders)
Notable characteristics of Parkinson’s Disease
Resting tremor
Stiffness & Rigidity
Bradykinesia
Gait & Postural Instability
Juvenile Parkinsonism occurs
Early onset 21-40 years
General Parkinson’s occurs
Mean age of 57 years
In Parkinson’s, this aggregates and causes cell death, which accumulated in nigrostriatal system
This property is also neuronal & a glial cell protein
Synuclein
Parkinson’s is often characterized as this in the system
Lewy Bodies
In Parkinson’s there is _______& a loss of substantia nigra neurons, which causes a depletion in ________in the ____________
Degeneration; Dopamine; Basal Ganglia
Dopamine is ______in the Extrapyramidal system
Inhibitory
Acetylcholine is ______in the Extrapyramidal system
Excitatory
In Parkinson’s, there is generally a loss of______action and an overproduction of ________
Inhibitory; Excitatory
80% of the brains dopamine is in the
Basal Ganglia
In Parkinson’s, the percentage of dopamine in the basal ganglia can be as low as
10%
Excess excitatory cholinergic activity can cause
Progressive Tremor
Muscle Rigidity
Bradykinesia
Postural Disturbances
Common treatments of Parkinson’s
Restore Dopamine function
Levodopa/ Carbidopa
Dopamine Agonists
MAO-B inhibitors
Amantadine
Stereotactic deep brain stimulation targets the
Thalamus
Subthalamic Nucleus
Globus Pallidus
Autonomic dysfunctions of Parkinson’s
Ortho HOTN
Poor temperature control
Sialorrhea
Maintain Volume Status
Parkinson’s suffer from pulmonary dysfunction such as
Bradykinesia
Rigidity of Respiratory Muscles
Parkinson’s suffer from swallowing impairment & dysphasia which is caused by _______& can lead to_______
Bradykinesia (rigidity of pharyngeal muscles)
Exacerbated by ET intubations
Risk for Aspiration
Parkinson’s can cause cognitive impairment, leading to
Postop delirium
GABA inhibition in the basal ganglia can worsen or abolish
Microelectrode recordings (MER)
What medication should be avoided if testing for tremors
Beta Blockers
When should DBS be discontinued?
15 minutes before MER
Dexmedetomidine may abolish
MER, HOTN, & paradoxical agitation
Propofol depresses
Neuronal discharge & induced dyskinesia
Fentanyl & Remifentanil May
Worsen rigidity & suppress tremor
Benzodiazepines May
Abolish MER, suppress tremor & induce dyskinesia
Levodopa crosses
BBB & is a dopamine precursor
Levodopa is converted by
Enzyme to dopamine in basal ganglia
( Dopa decarboxylase)
Can dopamine pass BBB?
No it does not and it’s elevated levels can cause side effects
Of levodopa, ___% is rapidly converted to dopamine during___________
95%; first hepatic pass
Levodopa metabolites are converted to ________&_________
Dopamine & Homovanillic Acid which metabolizes further into NE & E
Requires adequate levels of COMT to metabolize excess catecholamines (methionine from diet)
Levodopa/Carbidopa inhibits______in the peripheral tissues
Decarboxylase
Levodopa/Carbidopa inhibits
Levodopa breakdown
(Levodopa + decarboxylase inhibitors)
Levodopa/ Carbidopa maximizes
The amount of levodopa reaching the brain before conversion to dopamine, which allows lower levodopa dose
Levodopa adverse effects on GI
N/V-dopamine stimulation of CRT
Carbidopa may decrease N/V
Avoid dopamine antagonists antiemetics (promethazine & metoclopramide)
Levodopa adverse effects on Endocrine
Inhibits prolactin secretion
Increased aldosterone leading to hypokalemia
Levodopa adverse effects on CV
Potential adrenergic receptor activation from dopamine, Epi & NE (increased inotropy)
ORTHO HOTN
Tachy, PVCs/PACs, Afib, VTach
Skin flushing
Levodopa adverse effects on neuromuscular
Abnormal involuntary movements (facial tics & grimacing, rocking of extremities & trunk)
Irregular gasps (diaphragmatic dyskinesia)
Change in mobility
Levodopa psychiatric adverse effects
Confusion
Hallucination
Paranoia
Impulsive/ compulsive behavior
AVOID HALDOL
What is Parkinsonism-Hyperpyrexia Syndrome
Life threatening related to abrupt withdrawal or dose reduction
Resembles Neuroleptic Malignant Syndrome
Signs and symptoms of Parkinsonism Hyperpyrexia Syndrome
Rigidity
Pyrexia
Autonomic Instability
Depressed Consciousness
Risk for Parkinsonism Hyperpyrexia Syndrome
DVT/PE
Renal Failure
Aspiration PNA
Treatment of Parkinsonism Hyperpyrexia Syndrome
Give antiparkinsonian therapy
Levodopa PO or NGT
Supportive measures
Levodopa adverse effects with antipsychotics
Antagonize effects of dopamine
Levodopa adverse effects with MAOIs
Interfere with inactivation of dopamine causing HTN & hyperthermia
Levodopa adverse effects with Anticholinergic drugs
Synergism improves symptoms
Levodopa adverse effects with Vitamin B6
enhances decarboxylase activity (levodopa metabolism)
Common dopamine agonists
Bromocriptine
Pramipexole
Ropinirole
Rotigotine
Characteristics of Dopamine Agonists
Mimic Dopamine at receptor site
Synthetic
Don’t require transformation or transport across BBB
Adverse effects of Dopamine Agonists
Hallucinations
HOTN
Dyskinesia
Pulmonary Fibrosis
Vertigo
Nausea
Amantadine is also a/an
Antiviral for influenza A
Amantadine can
Improve PD symptoms like muscle rigidity & Bradykinesia
Adverse effects of Amantadine
Anticholinergic effects
Peripheral edema
Confusion
Psychosis
MAO-B inhibitors…
Breaks down dopamine in the CNS