Exam 2: Psychopharmacologic Therapies Flashcards
Natural catecholamines:
Epinephrine
Norepinephrine
Dopamine
Synthetic catecholamines:
Isoproterenol
Dobutamine
Relative magnitude of catecholamine response to α receptors:
Norepi > epi > isoproterenol
Relative magnitude of catecholamine response to β receptors:
Isoproterenol > epi > norepi
Synaptic location of α1 receptors:
Postsynaptic only
Tissues with α1 receptors:
Vasculature
Heart
Glands
Gut
Activation of α1 receptors causes:
Vasoconstriction
Relaxation of GI tract
Synaptic location of α2 receptors:
Pre- and post-synaptic
Tissues with presynaptic α2 receptors:
Peripheral vessels, coronary vessels, brain
Activation of presynaptic α2 receptors causes:
Inhibition of norepi release Inhibition of SNS outflow ↓ BP ↓ HR Inhibition of CNS activity
Tissues with postsynaptic α2 receptors:
Coronary vessels, CNS
Activation of postsynaptic α2 receptors causes:
Vasoconstriction
Sedation
Analgesia
Tissues with β1 receptors:
Myocardium
SA node & conduction system
Coronary arteries
Kidneys
Activation of β1 receptors causes:
↑ inotropy and chronotropy
↑ myocardial conduction speed
Renin release (indirectly leads to ↑ BP)
Tissues with β2 receptors:
Vascular, bronchial, uterine, skin smooth muscle Myocardium Coronary arteries Kidneys GI tract
Activation of β2 receptors causes:
Vasodilation Bronchodilation Uterine relaxation Gluconeogenesis Insulin release Potassium uptake into cells
Tissues with postsynaptic dopaminergic-1 receptors:
Renal mesenteric, splenic, coronary vessels
Renal tubules
Activation of dopaminergic-1 receptors causes:
Vasodilation
Activation of presynaptic dopaminergic-2 receptors causes:
Inhibition of norepi release
Activation of postsynaptic dopaminergic-2 receptors causes:
Vasoconstriction
Long ass name for serotonin:
5-Hydroxytryptamine
Three tissues with highest serotonin concentrations:
Wall of intestine
Blood
CNS
Three classes of antidepressants:
SSRIs
TCAs
MAOIs
Indications for SSRIs:
Mild to moderate depression Panic disorder OCD PTSD Social phobia In combination tx for bipolar d/o
MoA of SSRIs:
All block reuptake of serotonin
Newer drugs also act on norepi or dopamine
Some produce α2 blockade
Five true SSRIs:
Fluoxetine / Prozac Sertraline / Zoloft Paroxatine / Paxil Fluvoxamine / Luvox Escitalopram / Lexapro
Five SNRIs:
Buproprion / Wellbutrin Trazodone / Desyrel Nefazodone / Serzone Venlafaxine / Effexor Duloxetine / Cymbalta
Time to clinical effect for SSRIs:
2-3 weeks
Relative safety of SSRIs:
Safer than other classes of antidepressants
Side effects of SSRIs:
Insomnia/fatigue Agitation Orthostatic hypotension* Headache N/V Sexual dysfunction Increased appetite
Major anesthestic considerations with SSRIs (3):
Inhibition of CYP-450
Antiplatelet activity
Serotonin syndrome
S/s of serotonin syndrome:
Confusion Fever Shivering Ataxia Diaphoresis Hyperreflexia Muscle rigidity
Indications for tricyclic antidepressants:
Depression
Chronic pain syndrome (lower doses)
Examples of tertiary amine tricyclic antidepressants:
Amytriptyline / Elavil
Imipramine / Tofranil
Clomipramine / Anafranil
MoA of tertiary amine tricyclic antidepressants:
Inhibit serotonin and norepi uptake
Examples of secondary amine tricyclic antidepressants:
Desipramine / Norpramin
Nortryptyline / Pamelor
MoA of secondary amine tricyclic antidepressants:
Inhibit only norepi reuptake
Pharmacokinetics of tricyclic antidepressants:
Highly lipid soluble Highly protein bound Et1/2: 10-80 hrs Metabolized in liver Active metabolites
Side effects of tricyclic antidepressants:
Anticholinergic
Cardiovascular: orthostatic hypotension, ↑ HR (modest), ↓ conduction
CNS: ↓ seizure threshold, weakness, fatigue
Overdose can be FATAL - cardiotoxicity, seizures, CNS depression
Drug interactions with tricyclic antidepressants:
MAOIs - CNS toxicity (hyperthermia, seizure, coma) Sympathomimetics Inhaled anesthetics Anticholinergics Antihypertensives Opioids
Sympathomimetic drug interactions with tricyclic antidepressants:
Drug action will be unpredictable; indirect-acting drugs (i.e. ephedrine) may have exaggerated responses due to large amounts of norepi available
Either lower dose or use direct acting drug (i.e. phenylephrine)
Anesthetic considerations for pts using tricyclic antidepressants (5):
May need ↑ MAC of IAs
Exogenous epinephrine -risk of dysrhythmias
Opioids - ↓ dose
Barbiturates - ↓ dose
Anticholinergics - central anticholinergic syndrome (flushing, dry mouth/skin, mydriasis, confusion/delirium)
S/s of overdose of tricyclic antidepressants:
Life threatening!!
Intractable myocardial depression/dysrhythmias
Agitation, excitement/delirium, seizures, coma, respiratory depression, cardiac s/s, hypotension, anticholinergic s/s, death
Tx of overdose of tricyclic antidepressants:
Ventilatory support Manage CNS/cardiac Physostigmine for anticholinergic psychosis Prevent acidosis to keep drug bound Wean TCAs slowly
Location of MAO enzyme system:
Outer mitochondrial membrane
Monoamines that MAOIs inactivate:
DENS Dopamine Epinephrine Norepinephrine Serotonin
MoA of MAOIs:
Block the enzyme that metabolizes the amines, increasing their availability
Four example MAOIs:
Phenelzine / Nardil
Isocarboxazid / Marplan
Tranylcypromine / Parnate
Selegiline / Eldepryl
MAOIs are the PITS!