Transcript Biological Basis for Understanding Psychotropic Drugs

Psychiatric Nursing: Biological
Basis for Understanding
Psychotropic Drugs
NUR 145
Sandy Mishkin, RN, BC, MSN, MEd
© 2008
The Nervous System
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The Central Nervous System (CNS)
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Brain
Spinal Cord
The Peripheral Nervous System (PNS)
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Sensory nerves
Motor nerves
Physiological Organization of the
Nervous System
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Somatic Nervous System
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Sensory nerves: React to the external environment
Motor nerves: Regulate skeletal muscle
Autonomic Nervous System
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Regulates the internal environment
Two subsystems:
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Sympathetic
Parasympathetic
Autonomic Nervous System
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Sympathetic System
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Prepares the body for stressful situations
Parasympathetic System
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Regulates the internal environment during
rest
Function of the Brain
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Brain as coordinator and director of the
body’s reaction to the internal and external
environments
Goal: Maintain homeostasis in order to
preserve life
The Brain’s Response to the
External World
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Peripheral nerves
relay sensory
information to the
brain
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Dysfunction leads to
hallucinations and
illusions of
schizophrenia
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Brain controls
skeletal muscle
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Dysfunction of
movement can result
from the psychiatric
illness itself or the
medications used to
treat it.
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Respiratory rate
Speech
The Brain’s Response to the
Internal World
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The autonomic nervous
system & stress
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Sympathetic division
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The hormonal system &
stress
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Activates arterioles to
increase BP
Parasympathetic division
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Activates the GI tract
and causes
hypermotility and
diarrhea
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Hypothalamus releases
corticotropin- releasing
hormone (CRH) that
causes the pituitary to
release corticotropin
which results in the
release of cortisol by the
adrenal glands
All three hormones
overactive during states
of anxiety and
depression.
Areas of Brain Dysregulation
Common In Psychiatric Disorders
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Sex drive
Appetite
Circadian rhythm
Alertness
Focus/concentration
Cognition
Speech
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Reality testing
Memory
Learning
Social skills
Cellular Composition of the Brain
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Neurons (nerve cells of the brain)
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Three functions: 1) respond to stimuli, 2)
conduct electrical impulses, 3) release
neurotransmitters
Conduction of electrical impulse
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Inward flow of sodium ions (positive charge from
outside to inside membrane) and outward flow of
potassium ions ( positive charge from inside to
outside membrane)
Activity of Neurons
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Electrical impulse causes release of
neurotransmitter from presynaptic neuron.
Neurotransmitter travels across synapse to
postsynaptic neuron.
Neurotransmitter attaches to postsynaptic
receptors.
Postsynaptic neuron either initiates or
inhibits electrical impulse.
Fate of Neurotransmitters
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Some are destroyed : For example,
acetylcholine destroyed by the enzyme
acetylcholinesterase
Some are reabsorbed by the presynaptic
neuron (reuptake): They are either reused
or destroyed.
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Monoamine oxidase (MAO) breaks down
monoamine transmitters (norepinephrine,
dopamine, serotonin)
Other Chemicals Influencing
Brain Function
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Steroid hormones
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Estrogen, testosterone, and cortisol exert
short-term and long-term influence on
neurons
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Cortisol and prednisone can cause psychosis.
Organization of the Nervous System
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Brainstem
Cerebellum
Cerebrum
Brainstem
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Regulation of internal organs and vital functions,
processing of sensory input
Hypothalamus
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Reticular Activating System (RAS)
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Basic drives
Link between thought and emotion and internal
organs
Regulation of sleep-wake cycle
Conscious mental activity
Mesolimbic and mesocortical pathways
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Linked to limbic system (emotional and
psychological status)
Cerebellum
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Skeletal muscle coordination
Maintenance of equilibrium
Cerebrum
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Cerebral cortex (outer layer)
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Basal ganglia
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Conscious sensation
Initiation of movement
Touch, sound, vision
Language
Movement
Amygdala and hippocampus
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Emotions, learning, memory, basic drives
Disturbances of Mental Function
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Genetics, the environment (including
psychosocial stress), and physical disease all can
increase the probability of psychiatric disorders.
Specific neurotransmitters also are associated
with mental dysfunction.
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Reduced norepinephrine & serotonin: depression
Increased dopamine: thought disorders, psychosis
Reduced response to γ-aminobutyric acid (GABA):
anxiety
Overview of Psychotropic
Medications
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First-generation antipsychotics
Second-generation/atypical antipsychotics
Mood stabilizers
Antianxiety (Anxiolytic) drugs
Herbal formulations
First-Generation Antipsychotics
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Antagonists of dopamine (D2) receptors
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Reduce positive symptoms of schizophrenia:
hallucinations, delusions, & disorganized thinking
Can cause extrapyramidal side effects (EPS)
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Increase prolactin
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Block D2 receptors in basal ganglia
Parkinsonism, akinesia, akathisia, dyskinesia, tardive
dyskinesia
Amenorrhea, galactorrhea, gynecomastia
Can cause Neuroleptic Malignant Syndrome (NMS)
First-Generation Antipsychotics
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Block muscarinic receptors (reducing effect of
acetylcholine)
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Block receptors for norepinephrine (reducing
smooth muscle contraction)
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Anticholinergic effects: Confusion, blurred vision,
dry mouth, tachycardia, constipation, urinary
hesitancy/retention
Orthostatic hypotension, prevent ejaculation
Block receptors for histamine
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Sedation, weight gain
Second-Generation/Atypical
Antipsychotics
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Less blocking of D2
receptors basal ganglia
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Less risk of EPS
Less risk of NMS
Reduce negative as well
as positive symptoms of
schizophrenia
May also improve
cognition in
schizophrenia
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Preferential blocking
of dopamine
receptors in limbic
system
Block 5-HT2
receptors for
serotonin
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May explain
reduction in negative
symptoms
Second-Generation/Atypical
Antipsychotics
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Clozapine (Clozaril)
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Risperidone
(Risperdal/Risperdal
Consta)
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Agranulocytosis
Regular WBC count
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Increased risk CVA
in elderly
Quetiapine (Seroquel)
Olanzapine (Zyprexa)
Ziprasidone (Geodon)
Aripiprazole (Abilify)
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Partial dopamine
agonist
Very long-acting
Paliperidone (Invega)
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Active metabolite of
risperidone
Mood Stabilizers
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Lithium
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Positively charged ion
May stabilize electrical
activity in brain
First-line treatment for
bipolar disorder
Numerous side effects
Low therapeutic index
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0.6-1.2 mEq
Regular blood levels
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Antiepileptics
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Carbamazepine (Tegretol)
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Baseline lab
Regular blood levels
Divalproex/Valproic Acid
(Depakote/Depakene)
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Baseline lab
Regular blood levels
First-line treatment for
bipolar disorder
Mood Stabilizers
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Deficiency of
norepinephrine &/or
serotonin in limbic
system major cause of
depression
Tricyclic antidepressants
(TCAs)
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Mostly increase NE
Anticholinergic effects
Antihistaminic effects
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Sedation, drowsiness,
weight gain
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Selective Serotonin
Reuptake Inhibitors
(SSRIs)
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Less anticholinergic and
antihistaminic effects
Excess serotonin can
cause Serotonin
Syndrome
Current drugs of choice
for depression
Mood Stabilizers
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Monoamine Oxidase Inhibitors (MAOIs)
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Interfere with the breakdown of monoamine
neurotransmitters (norepinephrine,
epinephrine, dopamine, serotonin)
Can interfere with breakdown of tyramine, a
monoamine in GI tract
Can cause hypertensive crisis
 Avoid foods with tyramine (aged cheese, pickled
or smoked fish, wine)
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Mood Stabilizers
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Atypical antidepressants
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Venlafaxine (Effexor)
Desvenlafaxine (Pristiq)
Duloxetine (Cymbalta)
Buproprion (Wellbutrin)
Mirtazapine (Remeron)
Trazodone (Desyrel)
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Used only for hypnotic effect
Antianxiety Drugs
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Enhance effect of GABA
to reduce anxiety
Benzodiazepines
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Diazepam (Valium)
Clonazepam (Klonopin)
Alprazolam (Xanax)
Can cause respiratory
depression when
combined with other
CNS depressants
Tolerance and addiction
Avoid in the elderly
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Buspirone
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Buspar
No CNS depression
Less risk of
tolerance or
addiction
Psychotropic Medication For
Various Disorders
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Antidepressants for various anxiety disorders and
eating disorders
Second-generation antipsychotics for depression
and bipolar disorder
Psychostimulant drugs for ADHD
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Nonstimulant drug: atomoxetine HCL (Strattera)
Anticholinesterase drugs for AD (DAT)
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Donepezil (Aricept), rivastigmine (Exelon), and
galantamine (Reminyl)
N-methyl-D-aspartate (NMDA) receptor antagonist:
memantine (Namenda, Ebixa)
Herbal Formulations for
Psychiatric Disorders
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Not FDA-regulated
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Effectiveness?
Adverse effects?
Long-term effects?
St. John’s Wort: Serotonin Syndrome when
taken with other drugs that increase
serotonin
References
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Varcarolis, E., Carson, V., & Shoemaker, N.
(2006). Foundations of psychiatric mental
health nursing: A clinical approach (5th
ed.). St. Louis: Saunders.