Nervous System Pharmacology Notes

Nervous System Pharmacology

Nervous System Part I: Drugs Used For Autonomic Nervous System, Parkinson’s Disease, Seizures, and Anxiety/Mood Disorders and Psychoses

Learning Objectives:

• Describe major classes of drugs used to treat diseases/illnesses of the nervous system, including the Autonomic Nervous System, Parkinson’s Disease, seizures, and anxiety/mood disorders and psychoses.
• Describe the main nursing considerations related to this group of drugs.
• Explain drug interactions, polypharmacy, and food/drug effects of medications used across the lifespan, particularly in older adults.

Nervous System

Sympathetic System

• Dilates pupils.
• Inhibits salivation.
• Relaxes bronchi.
• Accelerates heartbeat.
• Inhibits peristalsis and secretion.
• Stimulates glucose production and release.
• Stimulates secretion of adrenaline and noradrenaline.
• Inhibits bladder contraction.
• Stimulates orgasm.

Parasympathetic System

• Constricts pupils (Nerve VI, Nerve I, Nerve IX).
• Stimulates saliva flow.
• Constricts Bronchi (Nerve X - Vagus).
• Slows heartbeat.
• Stimulates peristalsis and secretion (Pelvic splanchnic nerves).
• Stimulates bile release.
• Contracts bladder.

Autonomic Nervous System Basics

Divisions of the Nervous System

• Central Nervous System (CNS)
• Peripheral Nervous System (PNS)
  • Motor
    • Somatic
    • Autonomic (ANS)
  • Sensory
  • Autonomic
    • Sympathetic (SNS)
      • Alpha 1
      • Alpha 2
      • Beta 1
      • Beta 2
    • Parasympathetic (PNS)
      • Nicotinic
      • Muscarinic

Autonomic Nervous System Drugs

• Sympathomimetics (adrenergic drugs): Drugs that stimulate the sympathetic system, such as epinephrine and dopamine.
• Sympatholytics (adrenergic blockers): Drugs that inhibit the sympathetic system, such as beta-blockers like propranolol.
• Parasympathomimetics (cholinergic drugs): Drugs that stimulate the parasympathetic system, such as pilocarpine.
• Parasympatholytics (anticholinergic drugs): Drugs that block parasympathetic responses, such as atropine.

Parkinson’s Disease

• Substantia nigra: Dopamine-producing cells.
• Parkinson's Disease: Diminished substantia nigra leads to motor control issues.

Parkinson’s Disease Drugs

• Dopaminergic agents: (e.g., levodopa) Increase dopamine levels.
• Dopamine agonists: (e.g., pramipexole) Mimic dopamine effects.
• Anticholinergic drugs: (e.g., benztropine) Help balance dopamine and acetylcholine.

Seizure Classification

Partial Seizures

• Seizure activity starts in one area of the brain.
  • Simple: Patient remains alert e.g. jerking of a limb, déjà vu, nausea, strange taste or smell.
  • Complex: Altered awareness and behaviour e.g. confusion, repetitive movements.
• May become generalised (spreading from one area to the whole brain).

Generalised Seizures

• Seizure involves whole brain - consciousness is lost at the onset.
  • Tonic Clonic: 'grand-mal' or convulsion with loss of consciousness, stiffening of body then jerking of limbs.
  • Absence: 'petit-mal' or staring or trance-like state.
  • Tonic or Atonic: 'drop attack' or abrupt fall, either with stiffening (tonic) or loss of muscle tone (atonic or astatic attacks).
  • Myoclonic: Sudden muscle jerks.
• Brain Lobes: Frontal, Parietal, Temporal, Occipital, Cerebellum

Seizure Medications

• Anticonvulsants: (e.g., phenytoin, valproate, carbamazepine) Reduce seizure frequency.
• Benzodiazepines: (e.g., diazepam) Acute management of seizures.

Antidepressants

• 1 in 10 Americans take antidepressants, making them the third most common prescription drug in the U.S.

Types of Antidepressants & Common Side Effects

• Tricyclics
  • Side Effects: Tremors, Indigestion & Nausea, Headache, Dry Mouth, Drowsiness, Blurred Vision, Increased Blood Pressure, Nervousness, Muscle Aches, Low Blood Pressure, Dry Mouth, Sexual Side Effects, Nervousness, Dizziness.
  • Common Brand Names: Elavil, Asendin, Anafranil, Adapine, Norpramin, Sinequan, Ludiomil, Tofranil, Pamelor, Vivactil.
• SSRIs
  • Side Effects: Sweating, Headache, Dry Mouth, Sexual Side Effects,Common Brand Names: Celexa, Lexapro, Luvox, Prozac, Paxil, Zoloft, Serzone, Desyrel.
• SNRIs
  • Side Effects: Tremors, Nausea, Drowsiness, Sexual Side Effects, Dizziness.
  • Common Brand Names: Wellbutrin, Cymbalta, Effexor, Remeron.
• MAOIs
  • Side Effects: Insomnia, Elevated Heart Rate, Need to Avoid Decongestants & Certain Foods (Fish, Chocolate, Fermented Foods).
  • Common Brand Names: Marplan, Nardil, Parnate.
• Newer Combinations
  • Side Effects: Indigestion & Constipation, Headache, Dry Mouth, Insomnia, Sweating, Nervousness, Sexual Side Effects, Vomiting.

Anxiety, Mood and Psychosis Drugs

• Antidepressants: (e.g., SSRIs like fluoxetine, SNRIs like venlafaxine) Improve mood by altering serotonin and norepinephrine levels.
• Antipsychotics: (e.g., risperidone, haloperidol) Treat symptoms of schizophrenia and severe mood disorders.
• Anxiolytics: (e.g., lorazepam) Treat anxiety.