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!
Neurotransmitters that MAO A affects:
Dopamine Epi Norepi Tyrosine Serotonin
MAO-A puts DENTS in NTs
Neurotransmitters that MAO B affects:
Phenylethylamine
Dopamine
Side effects of MAOIs:
Orthostatic hypotension (most common) Anticholinergic-like Impotence/anorgasmy Weight gain Sedation
Bodily locations of MAO enzymes (4):
Liver (MAO A)
GI tract (MAO A)
Kidneys
Lungs
Dietary restrictions on MAOIs and reason:
Avoid tyramines in order to avoid hypertensive crisis, hyperpyrexia, CVA
Tyramines: cheese, fava beans, wine, avocado, liver, cured meats
Drugs cautions for MAOIs (4):
Tricyclic antidepressants
Opioids, esp. meperidine
Sympathomimetics
SSRIs
S/s of hypertensive crisis:
Serious headache
Vomiting
Chest pain
Adverse interaction between Demerol and MAOIs:
Type I (excitatory): Agitation, skeletal muscle rigidity, hyperpyrexia
Type II (depressive): MAOI inhibits enzyme that breaks down Demerol Hypotension, respiratory depression, coma
Adverse interaction between sympathomimetics and MAOIs:
Exaggerated response from indirect acting drugs (i.e. ephedrine)
Use direct acting agents instead and reduce dose by 1/3rd
Anesthetic considerations with MAOIs:
Minimize SNS stimulation and drug induced hypotension
Cautious with sympathomimetics
Caution with opioids and NO demerol
Maybe need higher MAC with IAs
S/s of MAOI overdose:
Excess SNS discharge: Tachycardia Hyperthermia Mydriasis Seizure Coma
S/s of antidepressant discontinuation syndromes:
Dizziness Myalgias & parasthesia Irritability Insomnia Visual disturbances Tremors Lethargy N/V/D
Indications for benzodiazepines:
Anxiety & insomnia
Indications for buspirone:
Anxiety disorder, but not panic disorder
MoA of benzodiazepines:
Facilitates GABA action
Five pharmacologic effects of benzodiazepines:
SAAAM: Sedation Anxiolysis Anterograde amnesia Anticonvulsant Muscle relaxation
Muscle relaxation effect of benzodiazepines:
At the spinal level - i.e. not good for surgical relaxation but great for post-op muscle spasm control
Pharmacokinetics of benzodiazepines:
Highly protein bound
Highly lipid soluble
Hepatic metabolism (CYP-450)
Eliminated via kidneys
CNS effects of benzodiazepines:
↓ CBF, CMRO2
Preserves cerebrovascular response to CO2
Does not change ICP response to laryngoscope
Anticonvulsant, amnestic
RARE: paradoxical excitement
Respiratory effects of benzodiazepines:
Dose dependent ↓ ventilation
Hypoxemia and hypoventilation enhanced with opioids
Depresses reflex swallowing
Flattens (does not shift) CO2 response curve
CV effects of benzodiazepines:
↓ SVR at high (induction) doses, which ↓ BP
CO unchanged
Pharmacokinetics of midazolam:
Water soluble Imidazole ring structure 2-3x the potency of diazepam Highly (90-98%) protein bound Rapid redistribution, so short duration of effect Et1/2: 1-2 hrs
Pediatric premedication dose of midazolam:
0.5 mg/kg PO
Adult IV sedation dose of midazolam:
1 - 2.5mg IV (up to 5mg)
Induction dose of midazolam:
0.1 - 0.2 mg/kg over 30-60 sec
Pharmacokinetics of diazepam:
Highly lipid soluble Highly protein bound Prolonged duration of action pH 6.6-6.9 Painful IV/IM injection Rapidly absorbed from GI tract Et1/2 21-37 hrs (inc. with age)
Commercial solvents of diazepam:
Propylene gylcol
Benzyl alcohol
Active metabolite of diazepam and its Et1/2:
Desmethyldiazepam, 48-96 hrs
Premedication IV/PO dose of diazepam:
0.2 mg/kg IV
10-15 mg PO
Induction dose of diazepam:
0.5 - 1.0 mg/kg
Anticonvulsant dose of diazepam:
0.1 mg/kg
Three classes of antipsychotics:
Phenothiazines
Thioxanthenes
Butryophenones
Examples of phenothiazones:
Chlorpromazine/ Thorazine
Thioridazine / Mellaril
Pherphenazine / Trilafon
Trifluoperazine / Stelazine
Example of thioxanthenes:
Thiothixene / Navane
MoA of phenothiazones and thioxanthenes:
Blockade of dopamine receptors in basal ganglia/limbic system
Blockade of dopamine receptors in CTZ of medulla
Indications for phenothiazones and thioxanthenes:
Psychosis
Nausea/vomiting
Pharmacokinetics of phenothiazones and thioxanthenes:
Erratic PO absorption Highly lipid soluble Highly protein bound Oxidized/conjugated in liver Inactive metabolites Et1/2: 10-20 hrs
Extrapyramidal side effects of phenothiazones and thioxanthenes:
Tardive dyskinesia (20% of tx > 1yr and permanent)
Acute dystonic reactions (during first few weeks, muscle rigidity/resp distress from laryngospasm, responds to Benadryl)
CV side effects of phenothiazones and thioxanthenes:
↓ BP d/t depression of vasomotor reflexes, relaxant effect on smooth muscle, direct cardiac depression
Prolonged QT interval
No dysrhythmic effect
CNS side effects of phenothiazones and thioxanthenes:
Sedation - α1, musc, hist receptor antagonism
↓ seizure threshold
Skeletal muscle relaxation by CNS action
Metabolic side effects of phenothiazones and thioxanthenes:
Neuroleptic malignant syndrome (hyperthermia, hypertonicity, ANS instability, LOC fluctuations)
Drug interactions with phenothiazones and thioxanthenes:
Potentiation of opioids (↑ sedation, vent. depression, analgesia)
Examples of butyrophenones:
Droperidol / Inapsine
Haloperidol / Haldol
Pharmcokinetics of droperidol:
Perfusion dependent clearance
Maximal excretion of metabolites first 24 hrs
CNS side effects of droperidol:
Extrapyramidal rxns
Cerebral vasoconstriction
Dysphorias
CV side effects of droperidol:
↓ BP from α blockade - minimal
Antidysrhythmic (protects against epinephrine dysrhythmias)
Prolonged QT
Torsades de pointes
Indications for droperidol:
Prolong and enhance opioid analgesia
Antiemetic (except motion sickness)
Indications for lithium:
Tx of bipolar d/o
MoA of lithium:
Not well understood
Competes with Na+, Ca+, Mg+ at cell membranes
Pharmacokinetics of lithium:
Excreted by kidneys; competitive reabsorption of Li and Na+
Et1/2: 24 hrs
Steady state is 4-5x Et1/2, so 4-5 days
Side effects of lithium:
Impairment of renal concentration ability and renal function EKG T-wave changes Hypothyroidism Psoriasis/acne Hand tremor Sedation Memory/cognitive slowing
S/s of lithium toxicity:
Sedation Nausea Skeletal muscle weakness Wide QRS AV heart block Hypotension Dysrhythmia Seizure
Tx of lithium toxicity:
Medical emergency - aggressive tx
Hemodialysis
Osmotic diuresis, IV bicarb
Anesthesia considerations for lithium:
Pre-op labs (lytes, BUN, Cr) and EKG
Anesthetic requirements may be ↓
NMBs may be prolonged
MoA of antiepileptics:
↓ neuronal excitability or enhance inhibition
Alteration of intrinsic membrane ion currents
Enhancement of GABA
Pharmacokinetics of antiepileptics:
Slow PO absorption
Protein binding varies widely (0-90%)
Most metabolized in liver, excreted in kidneys
Et1/2 time range hrs-days
Lab monitoring of antiepileptics:
Plasma concentration guides dosing, but plasma levels do not correlate to individual responses - titrate to clinical effect
Side effects of antiepileptics:
Bone marrow suppression
Hepatotoxicity
Examples of antiepileptics:
Phenobarbital Phenytoin / Dilantin Fosphenytoin / Cerebyx Primidone / Mysoline Carbamazepine / Tegretol Valproate / Depakote Levetiracetam / Keppra
Indications for phenytoin:
Partial or generalized seizures
MoA of phenytoin:
Regulates Na+ and Ca2+ ion transport across neuronal membranes
Pharmacokinetics of phenytoin:
PO absorption variable
Highly protein bound (90% to albumin)
pH 12; precipitates in solutions with pH < 7.8
Infusion no faster than 50 mg/min (adults) or 1-3 mg/kg/min (peds)
Effect of rapid phenytoin administration:
Profound hypotension
Metabolism of phenytoin:
Hepatic microsomal enzymes
Inactive metabolites
First order kinetics if plasma conc < 10mcg/ml; zero order kinetics if > 10mcg/ml
Side effects of phenytoin:
CNS toxicity (visual/balance/coordination) Acne Rash/SJS GI irritation Hepatotoxicity Hepatic enzyme induction
MoA of fosphenytoin:
Na+ channel blockade
Pharmacokinetics of fosphenytoin:
Highly protein bound
Water soluble phenytoin prodrug
Dosing for fosphenytoin:
10-20mg/kg loading dose
Indications for fosphenytoin:
Hospital - status epilepticus
NSU - prevent/tx seizures
MoA of phenobarbitol:
Modulates postsynaptic GABA and glutamate
Enhances CYP450
Side effects of phenobarbitol:
Cognitive/behavioral impairment
Sedation (adults), hyperactivity (peds)
Depression
Confusion in elderly
MoA of benzodiazepines:
Potentiates GABA-mediated neuronal inhibition
↑ Cl- permeability
Hyperpolarization
Inhibition of neuron firing
Side effects of benzodiazepines:
Sedation
Ataxia/incoordination
Hypotension
Respiratory depression