Nervous System Meds / Drugs Part 2

You can find part 1 here –

CI means Contra Indicated


Medications Affecting the Nervous System

(General Points)

  • Adaptive changes within brain with prolonged exposure
  • increased therapeutic effect
  • decreased side effects
  • Tolerance, physical dependence
  • Do not stop abruptly
  • Highly variable individual response to mediations


Parkinson’s Disease

  • Treatment uses two main classes:
  • Meds that activate dopamine receptors (directly or indirectly)
  • Meds that block acetylcholine receptors


Seizure Disorders

  • different types of seizures respond to different medications
  • Usually require life-long management
  • Meds must be discontinued slowly over 6 weeks to several months



  • Clinical course includes semi-remission punctuated by acute exacerbations
  • Positive symptoms (Agitation, delusions)
  • Conventional antipsychotic -> Thorazine
  • Atypical antipsychotic -> Clozapine
  • Negative symptoms (Social withdrawal, poor self-care)
  • Atypical antipsychotic -> Clozapine
  • Cognitive symptoms (Difficulties with memory and learning)
  • Initial doses are high and given throughout day; maintenance doses given at bedtime.



  • Symptom relief can take 1-3 weeks and possibly 2-3 months
  • Three main groups:
  • Tricyclic antidepressants (TCAs)
  • Selective serotonin reuptake inhibitors (SSRIs)
  • Monamine oxidase inhibitors (MAOIs)


Bipolar Disorder


  • Typically managed with mood stabilizers. Antipsychotics and antidepressants may be used during acute episodes of mania or depression.
  • Lithium
  • Valproic acid (Depakote)
  • Carbamazepine (Tegretol)


Cholinesterase Inhibitors

Expected Action:

Prevents ACh degradation -> increase transmission of nerve impulses by increasing [ACh]

Examples: Neostigmine, Physostigmine

Therapeutic Uses:

  • Increases muscle strength by increasing [ACh] at neuromuscular junction in myasthenia gravis
  • Reversal of nondepolarizing neuromuscular blocking agents (tubocurarine)

Adverse Effects:

  • Excessive muscarinic stimulation: increase GI motility & secretions, bradycardia, urinary urgency (side effect can be treated with atropine)

Cholinergic crisis: Above plus resp. depression from neuromuscular blockade.

Adverse Effects:

Pregnancy (C)

CI in obstruction of GI/GU systems / caution with seizures, asthma, bradycardia, hypotension, peptic ulcer disease


Tubocurarine – Neostigmine reverses blockade

Atropine – counteracts

Succinylcholine – increase neuromuscular blockade


Wear medic-alert bracelet


Neuromuscular Blocking Agents


Expected Action:

Block ACh at neuromuscular junction – don’t cross blood-brain barrier

Examples: Nondepolarizing: tubocurarine, pancuronium Depolarizing: succinylcholine

Therapeutic Uses:

Adjuncts to general anesthesia

Control spontaneous respiration in ventilated pts.

Diagnose myasthenia gravis

Succinylcholine for: electroconvulsive therapy, intubation, endoscopy

Adverse Effects:

Hypotension from histamine release & ganglionic blockade

Bradycardia, dysrhythmias

Respiratory arrest

Succinylcholine: Low pseudocholinesterase activity -> apnea

Malignant hyperthermia (dantrolene)




Pregnancy (C)

SCh: CI for hyperkalemia (trauma, burns)


General anesthetics

Aminoglycosides/tetracyclines – increase NM blockade

Neostigmine/ChE inhibitors: decrease η nondepolarizing / increase  η depolarizing




Expected Action:

Levodopa taken up and converted to dopamine. Carbidopa augments levodopa by preventing conversion to dopamine in intestine and periphery (increase [DA] in CNS).

Examples: Levodopa, carbidopa, Sinemet

Therapeutic Uses: Symptomatic relief from dyskinesias

Adverse Effects:


Discoloration of sweat & urine

Nausea / drowsiness

Orthostatic hypotension

Psychosis (clozapine)

Activation of malignant melanoma


!! with cardiac or psychiatric disorders

CI with melanoma

2 weeks from MAOI

Pregnancy (C)


Proteins interfere with absorption and transport

  • Conventional antipsychotics (haldol, compazine) decreaseη

Pyridoxine decrease η

MAOI ’ hypertension

Carbidopa, dopamine agonists, anticholinergics, COMT inhibitors and dopamine releasers ñ therapeutic effects



  • Catechol O-Methyltransferase
  • Deactivates catecholamines (dopamine, norepinephrine, acetylcholine, epinephrine, serotonin, histamine, etc)
  • Found in post-synaptic cell membranes of adrenergic neurons where it degrades norepinephrine.
  • Also found in gut


Dopamine Agonists


Expected Action:

Act directly on dopamine receptors

Examples: Pramipexole, ropinirole, bromocryptine

Therapeutic Uses: Monotherapy early / combined with levodopa in later stages

Adverse Effects:

  • Sleep attacks (nightmares)
  • Orthostatic hypotension
  • Daytime sleepiness
  • Psychosis
  • Dyskinesias
  • Nausea


Pregnancy (C)

Caution with liver & kidney impairment


  • Levodopa: Can decrease motor-control fluctuations permitting lower dose

Levodopa: Also increase risk of orthostatic hypotension and dyskinesias


Centrally Acting Anticholinergics


Expected Action:

Block ACh at muscarinic receptors which helps maintain ACh, dopamine balance

Examples Benztropine (Cogentin), trihexyphenidyl (Artane)

Adverse Effects:

Nausea (take ĉ food)

Atropine-like effects (dry mouth, blurred vision, mydriasis, constipation)

Antihistamine effects (sedation, drowsiness)


CI in narrow-angle glaucoma




Expected Action:

Stimulate dopamine release, prevent dopamine reuptake, and may block cholinergic and glutamate receptors

Examples: Amantadine

Therapeutic Uses: Parkinson’s Disease

Adverse Effects: CNS Effects, Discoloration of skin (temporary), Atropine-like effects


Next week we’ll continue.

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