Nervous System Flashcards
muscarinic antagonists
atropine
muscarinic agonists (parasympathomimetic)
bethanechol
ganglionic-stimulating agents
nicotine
cholinesterase inhibitors (ChE)
physostigmine, neostigmine
neuromuscular-blocking agents
tubocurarine
adrenergic agonists (sympathomimetic)
epinephrine (adrenaline)
adrenergic antagonists (block alpha and beta receptors)
prazosin (alpha adrenergic antagonist), propanolol (beta adrenergic antagonist)
nicotine receptors
release of epinephrine from adrenal medulla; located at neuromuscular junction of skeletal muscle; causes skeletal muscle contraction
muscarinic receptors
decreased secretions from lungs, stomach, intestines, sweat glands; decrease in HR; smooth muscle contraction in bronchi and GI tract; miosis (sphincter contraction) and accommodation (ciliary contraction); voiding due to contraction of detrusor muscle and relaxation of trigone and sphincter muscles
alpha 1 receptors
mydriasis d/t radial muscle contraction; veins and arterioles are activated to constrict; decreased peripheral resistance and increased blood pressure; male sex organs are activated to promote ejaculation; contraction of prostatic capsule, trigone, and sphincter muscles
dopamine receptors
dilates blood vessels in the kidneys
beta 1 receptors
predominant receptor found on the heart; decreased HR, increased contraction force, and increased conduction through AV node; increased lipolysis; release of renin by the kidneys
beta 2 receptors
dilates bronchi; relaxes uterine smooth muscle; vasodilation of arterioles in heart, lungs, and skeletal muscle; slightly decreased peripheral resistance; increased glycogenolysis in the liver and muscles; skeletal muscle contraction
medications affecting the nervous system: general points
adaptive changes within brain with prolonged exposure; increased therapeutic effect; decreased side effects; tolerance and physical dependence; do not stop abruptly
Parkinson’s disease
treatment uses two main classes: medications that activate dopamine receptors (directly or indirectly) and medications that block acetylcholine receptors
seizure disorders
different types of seizures respond to different medications; usually require life-long management; medications must be discontinued slowly over 6 weeks to several months
schizophrenia
clinical course includes semi-remission punctuated by acute exacerbations; positive symptoms (agitation, delusions) medications: conventional antipsychotic [thorazine], atypical antipsychotic [clozapine]; negative symptoms (social withdrawal, poor self-care) medications: atypical antipsychotic [clozapine]; cognitive symptoms (difficulties with memory and learning); initial doses are high and given throughout the day; Maintenon doses given at bedtime
depression
symptom relief can take 1 to 3 weeks and possibly 2 to 3 months; three main groups: tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), and monoamine oxidase inhibitors (MAOIs)
bipolar disorder
typically managed with mood stabilisers; antipsychotics and antidepressants may be used during acute episodes of mania or depression; lithium, valproic acid [Depakote], and carbamazepine [Tegretol]
cholinesterase inhibitors: expected action
prevents ACh degradation; increased transmission of nerve impulses by increased ACh
cholinesterase inhibitors: therapeutic uses
increased muscle strength by increasing ACh at neuromuscular junction in myasthenia gravis; reversal of nondepolarising neuromuscular blocking agents (tubocurarine)
cholinesterase inhibitors: adverse effects
excessive muscarinic stimulation; increased GI motility and secretions, bradycardia, and urinary urgency (side effect can be treated with atropine); cholinergic crisis: above plus respiratory depression from neuromuscular blockade
cholinesterase inhibitors: contraindications and precautions
pregnancy C; CI in obstruction of GI and GU systems; caution with seizures, asthma, bradycardia, hypotension, and peptic ulcer disease
cholinesterase inhibitors: interactions
tubocurarine: neostigmine reverse blockade; atropine: counteracts; succinylcholine: increased neuromuscular blockade
cholinesterase inhibitors: education
wear medic-alert bracelet
cholinesterase inhibitors: prototypes
neostigmine, physostigmine
neuromuscular blocking agents: expected action
block ACh at neuromuscular junction (doesn’t cross blood-brain barrier)
neuromuscular blocking agents: prototypes
nondepolarising: tubocurarine, pancuronium; depolarising: succinylcholine
neuromuscular blocking agents: therapeutic uses
control spontaneous respiration in ventilated patients; adjuncts to general anaesthesia; diagnose myasthenia gravis; succinylcholine for: electroconvulsive therapy (ECT), intubation, and endoscopy
neuromuscular blocking agents: adverse effects
hypotension from histamine release and ganglionic blockade; respiratory arrest; bradycardia and dysrhythmias; succinylcholine: low pseudocholinesterase activity causing apnea, malignant hyperthermia (dantrolene), pain, and hyperkalaemia
neuromuscular blocking agents: contraindications
pregnancy C; SCh: CI for hyperkalaemia (trauma, burns)
neuromuscular blocking agents: interactions
general anaesthetics; aminoglycosides and tetracyclines causing increased NM blockade; neostigmine and ChE inhibitors causing decreased nondepolarising and increased alpha depolarising
dopaminergics (anti-Parkinson’s): expected action
levodopa taken up and converted to dopamine; carbidopa augments levodopa by preventing conversion to dopamine in intestine and periphery (increased DA in CNS)
dopaminergics (anti-Parkinson’s): prototypes
levodopa, carbidopa, sinemet
dopaminergics (anti-Parkinson’s): therapeutic uses
symptomatic relief from dyskinesias
dopaminergics (anti-Parkinson’s): adverse effects
dyskinesias; discolouration of sweat and urine; nausea and drowsiness; orthostatic hypotension; psychosis (clozapine); activation of malignant melanoma
dopaminergics (anti-Parkinson’s): contraindications and precautions
cardiac and psychiatric disorders; CI melanoma; 2 weeks from MAOI; pregnancy C
dopaminergics (anti-Parkinson’s): interactions
proteins interfere with absorption and transport; conventional antipsychotics (haldol, compazine) decreased alpha; pyridoxine decrease alpha; MAOI cause hypertension; carbidopa, dopamine agonists, anticholinergics, COMT inhibitors and dopamine tea leaders increase therapeutic effects
COMT (catechol O-methyltransferase)
catechol O-methyltransferase; deactivates catecholamines (e.g. dopamine, norepinephrine, acetylcholine, epinephrine, serotonin, histamine, etc); found in post-synaptic cell membranes of adrenergic neurons where it degrades norepinephrine; also found in the gut
dopamine agonists (antiparkinson’s): expected action
act directly on dopamine receptors
dopamine agonists (antiparkinson’s): prototype
pramipexole, ropinirole, bromocriptine
dopamine agonists (antiparkinson’s): therapeutic uses
monotherapy early; combined with levodopa in later stages
dopamine agonists (antiparkinson’s): adverse effects
orthostatic hypotension; psychosis; sleep attacks; daytime sleepiness; dyskinesias; nausea
dopamine agonists (antiparkinson’s): contraindications and precautions
pregnancy C; caution with liver and kidney impairment
dopamine agonists (antiparkinson’s): interactions
levodopa can decrease motor-control fluctuations permitting lower dose; levodopa can also increases risk of orthostatic hypotension and dyskinesias
centrally acting anticholinergics (antiparkinson’s): expected action
block ACh at muscarinic receptors which helps maintain ACh and dopamine balance
centrally acting anticholinergics (antiparkinson’s): prototype
benztropine [Cogentin], trihexyphenidyl [Artane]
centrally acting anticholinergics (antiparkinson’s): adverse effects
nausea (take with food); atropine-like effects (e.g. dry mouth, blurred vision, mydriasis, constipation); antihistamine effects (e.g. sedation, drowsiness)
centrally acting anticholinergics (antiparkinson’s): contraindications and precautions
CI in narrow-angle glaucoma
antiviral (antiparkinson’s): expected action
stimulate dopamine release; prevent dopamine reuptake; may block cholinergic and glutamate receptors
antiviral (antiparkinson’s): prototype
amantadine
antiviral (antiparkinson’s): therapeutic uses
Parkinson’s disease
antiviral (antiparkinson’s): adverse effects
CNS effects; discolouration of skin (temporary); atropine-like effects
antiepileptic medications: barbiturates
phenobarbital [Luminal]
antiepileptic medications: hydantoins
phenytoin [Dilantin]
antiepileptic medications: benzodiazepines
diazepam [Valium], lorazepam [Ativan], carbamazepine [Tegretol], ethosuximide [Zarontin], valproic acid [Depakote], gabapentin [Neurontin]
antiepileptic medications: other medications
lamotrigine [Lamictal], oxcarbazepine [Trileptal], clozanepam [Klonopin]
antiepileptic medications: mechanisms
slow ca2+ and na+ reentry to neuron; potentiating inhibitory effect of GABA; suppress neuron firing
barbiturate (antiepileptic): therapeutic uses
partial seizures and generalised tonic-clonic seizures; not effective against absence seizures
barbiturate (antiepileptic): prototype
phenobarbital [Luminal]
barbiturate (antiepileptic): adverse effects
CNS effects (e.g. adults as sedation and anxiety, kids as irritability and hyperactivity); toxicity: nystagmus, ataxia, respiratory depression, pinpoint pupils
barbiturate (antiepileptic): contraindications and precautions
pregnancy D; CI with intermittent porphyria
hydantoins (antiepileptic): therapeutic uses
effective against all major forms except absence seizures
hydantoins (antiepileptic): prototype
phenytoin [Dilantin]
hydantoins (antiepileptic): adverse effects
CNS effects; skin rash; teratogenic; gingival hyperplasia; cardiovascular;endocrine effects; vitamin D metabolism
hydantoins (antiepileptic): contraindications and precautions
CI: sinus bradycardia, SA blocks, second and third degree AV blocks
hydantoins (antiepileptic): interactions
oral contraceptives; warfarin; glucocorticoids, decrease alpha of these; EtOH, diazepam, cimetidine, valproic acid: increase phenytoin levels; carbamazepine, phenobarbital, chronic EtOH: decrease phenytoin levels; CNS depressants (e.g. barbiturates, EtOH): additive effects with concurrent use
hydantoins (antiepileptic): education
use IV route for status epilepticus; antidysrhythmics
carbamazepine (antiepileptic): therapeutic uses
partial seizures; tonic-clonic seizures; bipolar disorder; trigeminal neuralgia
carbamazepine (antiepileptic): prototype
tegretol
carbamazepine (antiepileptic): adverse effects
skin disorders; cognitive function is minimally affected but CNS effects can occur; blood dyscrasias; teratogenic; hypoosmolarity (increased ADH secretion)
carbamazepine (antiepileptic): contraindications and precautions
CI: marrow suppression, bleeding disorders
carbamazepine (antiepileptic): interactions
grapefruit juice (inhibits metabolism and increases carbamazepine); phenytoin and phenobarbital: decrease carbamazepine; oral contraceptives and warfarin: carbamazepine stimulates hepatic enzymes which decrease levels of these medications
ethosuximide (antiepileptic): therapeutic uses
indicated only for absence seizures
ethosuximide (antiepileptic): prototype
zarontin
ethosuximide (antiepileptic): adverse effects
GI effects (take with food); CNS effects (fatigue, dizziness)
valproic acid (antiepileptic): therapeutic uses
partial, generalised, and absence seizures; bipolar disorder; migraines
valproic acid (antiepileptic): prototype
depakote
valproic acid (antiepileptic): adverse effects
GI effects (take with food); hepatotoxicity; thrombocytopenia; pancreatitis as evidenced by nausea, vomiting, and abdominal pain
valproic acid (antiepileptic): contraindications and precautions
avoid children younger than 3 (hepatotoxicity); liver disorders
valproic acid (antiepileptic): interactions
phenytoin and phenobarbital: concurrent use increases these medications
gabapentin (antiepileptic): therapeutic uses
single agent used for partial seizures; neuropathic pain; prevents migraines
gabapentin (antiepileptic): prototype
neurontin
gabapentin (antiepileptic): adverse effects
CNS effects (drowsiness, nystagmus)
benzodiazepines (antiepileptic): therapeutic uses
status epilepticus
benzodiazepines (antiepileptic): prototype
diazepam [Valium]
benzodiazepines (antiepileptic): adverse effects
respiratory depression; anterograde amnesia; teratogenic
muscle relaxants and antispasmodics: centrally acting muscle relaxants
diazepam [Valium], baclofen [Lioresal], cyclobenzaprine [Flexeril], metaxalone [Skelaxin]
muscle relaxants and antispasmodics: peripherally acting muscle relaxants
dantrolene [Dantrium]
diazepam (muscle relaxant and antispasmodic): expected action
acts in CNS to enhance GABA and produce sedation; acts in CNS to depress spasticity of muscles
diazepam (muscle relaxant and antispasmodic): prototype
diazepam [Valium]
diazepam (muscle relaxant and antispasmodic): therapeutic uses
relief of spasticity related to cerebral palsy and/or MS; anxiety and panic disorders; EtOH withdrawal; insomnia; status epilepticus; anaesthesia induction; relief of spasm related to injury
diazepam (muscle relaxant and antispasmodic): adverse effects
CNS depression; physical dependence from long-term use
diazepam (muscle relaxant and antispasmodic): interactions
CNS depressants (EtOH, opioids, antihistamines, barbiturates): addictive CNS depressive effect an with concurrent use
diazepam (muscle relaxant and antispasmodic): contraindications and precautions
pregnancy D; caution with impaired liver or renal function
centrally acting (muscle relaxant and antispasmodic): expected action
acts in CNS to depress spasticity of muscles
centrally acting (muscle relaxant and antispasmodic): prototype
baclofen, cyclobenzaprine, metaxalone
centrally acting (muscle relaxant and antispasmodic): therapeutic uses
relief of muscle spasm related to injury; relief of spasticity related to cerebral palsy or multiple sclerosis
centrally acting (muscle relaxant and antispasmodic): adverse effects
CNS depression; physical dependence from long-term use; metaxalone: hepatotoxicity; baclofen: nausea, urinary retention, constipation
centrally acting (muscle relaxant and antispasmodic): contraindications and precautions
caution in patients with impaired liver or renal function; baclofen: pregnancy C
centrally acting (muscle relaxant and antispasmodic): interactions
CNS depressants (EtOH, opioids, antihistamines): additive CNS depressants effects with concurrent use
cue (muscle relaxant and antispasmodic):
response
peripherally acting (muscle relaxant and antispasmodic): expected action
only peripherally acting muscle relaxant; inhibits muscle contraction by preventing release of calcium in skeletal muscles
peripherally acting (muscle relaxant and antispasmodic): prototype
dantrolene [Dantrium]
peripherally acting (muscle relaxant and antispasmodic): therapeutic uses
relief of spasticity related to cerebral palsy or multiple sclerosis; treatment of malignant hyperthermia
peripherally acting (muscle relaxant and antispasmodic): adverse effects
CNS depression; hepatic toxicity
local anaesthetics: expected action
decreases pain by blocking local conduction of pain impulses
local anaesthetics: amide type
lidocaine
local anaesthetics: ester type
tetracaine, procaine
local anaesthetics: adverse effects
CNS excitation: treat with midazolam [Versed] or diazepam; hypotension; bradycardia; heart block; cardiac arrest; allergic reactions (more likely with esters); decreased uterine contractibility; spinal headache (lay flat for 12 hours); freely cross placenta; urinary retention (call after 8 hours)
local anaesthetics: contraindications and precautions
CI in dysrhythmias and/or heart block; caution with liver and kidney dysfunction, heart failure and myasthenia gravis
general inhalation anaesthetics: expected action
loss of consciousness; loss of sensation; relaxation of muscles; amnesia
general inhalation anaesthetics: prototype
halothane [Fluothane], isoflurane [Forane], nitrous oxide
general inhalation anaesthetics: adverse effects
hepatotoxicity; gastric aspiration; hypotension; malignant hyperthermia (treatment: medications, ice or saline infusion, and dantrolene); respiratory and cardiovascular depression
general inhalation anaesthetics: interactions
CNS depressants: additive effect; opioids: constipation and urinary retention
general inhalation anaesthetics: education
succinylcholine: used as a muscle relaxant; encourage early ambulation; assist with lung expansion
peripherally acting (muscle relaxant and antispasmodic): contraindications and precautions
pregnancy C; caution with impaired liver and renal function
peripherally acting (muscle relaxant and antispasmodic): interactions
CNS depression: additive effects
intravenous anaesthetics (key points): medications
barbiturates: thiopental [Pentothal]; ketamine [Ketalar]; benzodiazepines: diazepam [Valium], midazolam [Versed], lorazepam [Ativan]; propofol [Diprivan]
intravenous anaesthetics (key points): therapeutic uses
adjunct to inhalation anaesthesia; induction and maintenance of anaesthesia; amnesia; midazolam and an opioid result in conscious sedation; ketamine can be used with children
intravenous anaesthetics: adverse effects
respiratory and cardiovascular depression: propofol: bacterial infection (use opened vial with 6 hours); ketamine: psychologic reaction (premedicate with diazepam to decrease risk)
intravenous anaesthetics: contraindications and precautions
ketamine should be avoided with psychiatric disorders
intravenous anaesthetics: interactions
CNS depressants and stimulants: additive effects: opioid analgesics: constipation and urinary retention
intravenous anaesthetics: education
midazolam [Versed]: inject over more than 2 minutes; propofol [Diprivan]: inject into large vein and prep site with lidocaine
antipsychotics (conventional): expected action
dopamine, acetylcholine, histamine, and norepinephrine receptors in brain and periphery are blocked; symptom inhibition related to dopamine blockade in brain
antipsychotics (conventional): prototype
⬇️ n: chlorpromazine [Thorazine], ⬆️ n: haloperidol [Haldol]; others: fluphenazine, molindone, perphenazine, thiothixene
antipsychotics (conventional): therapeutic uses
tourette’s syndrome; delusional disorder; bipolar disorder; dementia; schizophrenia; schizoaffective disorder; Huntington’s chorea
antipsychotics (conventional): adverse effects
agranulocytosis; sedation; photosensitivity; anticholinergic effects; orthohypotension; neurone doctrine effects; seizures; parkinsonism; sexual dysfunction; dysrhythmias; dystonia; akathisia; tardive dyskinesia; neuroleptic malignant syndrome
antipsychotics (conventional): interactions
anticholinergics: increase n; CNS depressants: additive effects; levodopa: counteracts antipsychotics by stimulating dopamine receptors
antipsychotics (conventional): education
consider depot preparations; protect liquid prep from the sun; early EPS symptoms with anticholinergics, beta blockers, and benzodiazepines
