psychotropics - acmt...0 benzodiazepines n all are indirect agonists at post-synaptic gaba-a...
TRANSCRIPT
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Psychotropics
G. Patrick Daubert, MD
Some (most) material plundered from various mentors and other talentedtoxicologists, with permission
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n 2.1.11.9 Psychotropicsn 2.1.11.9.1 Anxiolytics and sedative-hypnoticsn 2.1.11.9.2 Antidepressantsn 2.1.11.9.3 Antipsychoticsn 2.1.11.9.4 Mood stabilizers
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Anxiolytics and Sedative-hypnotics
n Benzodiazepinesn Barbituratesn Sedative-Hypnotics
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Benzodiazepines
“There are very few toxicological problems thatcannot be solved through the suitable (and liberal)
application of benzodiazepines” Suzanne White, MD
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Benzodiazepines
n Roughly 50,000 benzodiazepine OD casesreported annually
n 65% intentionaln Few deathsn Most are combination exposuresn Mixed drug overdose or IV administration =
increased morbidity
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Benzodiazepines
n About 15 types marketed in the USn 50 types worldwiden Vary in half-life and metabolism
n All rapidly absorbedn CNS redistribution variesn Half-life � duration of actionn Conjugation only
n Oxazepam, lorazepam, temazepamn IM administration
n Lorazepam, midazolam
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Benzodiazepines
n All are indirect agonists at post-synaptic GABA-Achannelsn Can’t open the channel without GABAn BZD1 receptorsn Increase frequency of Cl channel opening
n BZD2 receptors (spinal cord) affect muscle relaxationn All produce tolerance with cross-reactivityn Predispose to physical dependence
n BZD2 receptorsn Withdrawal : worse for short half-life agents
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Benzodiazepine Overdose
n Nonspecificn CNS: drowsiness, dizziness, slurred speech,
nystagmus, confusion, ataxia, coma (rare)n Children: 17% isolated ataxian Other: respiratory depression, hypotension with IV
administration
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Benzodiazepine Pearls
n Increase frequencyfrequency of Cl channel openingn Propylene glycol: lorazepamn Clonazepam:
n Anticonvulsantn Mood stabilizer
n Flunitrazepam (RoHypnol): “Date Rape”n EMIT: Oxazepam false negatives
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Barbiturates
n GABAAn Direct increase in durationduration of channel openingn GABA not needed
n 4 Categoriesn Ultrashort: methohexital, thiopentaln Short: pentobarbital, secobarbitaln Intermediate: butalbitaln Long-acting: phenobarbital
n Enzyme induction: drug interactions
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Barbiturate Toxicity
n Symptoms similar to other sedativesn More likely to see respiratory depression
n CNS tolerance � Respiratory tolerancen Common
n Nystagmus, dysarthria, ataxia, drowsiness, respiratorydepression, and coma
n Less commonn hypotension, cardiovascular collapse, and hypothermia
n Bullous skin lesions (“barb burns”), noncardiogenicpulmonary edema
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Phenobarbital (PHB)
n Long-acting barbituraten Normal range 15-40 mg/Ln PHB tolerance does not usually involve
respiratory tolerancen Levels > 80 mg/L typically result in coman Death is uncommon with good supportive caren Primidone
n Metabolized to PEMA and PHB
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Treatment
n Supportive caren Passive warmingn Positive barbiturate on urine drugs of abuse screen
n Phenobarbital vs butalbitaln IVF, norepinephrine for hypotensionn Urinary alkalinization
n Stop alkalinization when PHB < 40 mg/Ln MDAC
n Listed on MDAC position statement (The ‘A’ List)n MDAC demonstrates better elimination than urine
alkalinization
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‘Z’ Drugs
n Zolpidem (Ambien,Stilnox)
n Zaleplon (Sonata)n EcZopiclone (Lunesta,
Estorra)n Ramelteon (RoZerem)
n Non-benzodiazepinesedatives
n Selective for GABAA BZ-1receptors
n Less physical dependencen Flumazenil may precipitate
withdrawaln Ramelteon may alter
testosterone and prolactinlevels
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“Z” Drug Overdose
n CNS depression, coman Respiratory depressionn Nausea and vomitingn Hypotensionn Miosis, mydriasisn Hallucinationsn Flumazenil reverses Z agent effect and may precipitate
withdrawaln Same precautions as with benzodiazepines
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Sedative-Hypnotics
n Buspirone (Buspar)n Chloral hydraten Meprobamaten Methaqualonen Glutethimiden Ethchlorvinyl
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Chloral Hydrate
n Commonly used by alcoholics in the late 19th centuryto induce sleep
n Solutions of alcohol and chloral hydrate often called“knockout drops” or “Mickey Finn”
n Sedation with minimal respiratory depression andhypotension
n Used recreationally only by a small number of peoplen Common trade names are Noctec, Somnos and
Felsules
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Pharmacology
n Trichlorocetic acidn Highly protein boundn May displace acidic drugs from plasma protein
n Trichloroethanol exerts barbiturate-like effects on theGABAA receptor channels
n Trichloroethanol inhibits ethanol metabolism
Chloral Hydrate
TrichloroaceticAcidTrichloroethanol
ADH P450
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Clinical Highlights
n Hemorrhagic gastritisn Cardiac arrhythmias
n Attributed largely to trichloroethanoln Myocardium sensitized to circulating catecholamines
n Radioopaque
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Sedative-Hypnotic Pearls
n Meprobamate (Miltown, Equanil, Meprospan)n Active metabolite of carisoprodoln Concretions/bezoars in overdose
n Glutethimide (Doriden)n 2D6 inducer – codeine abusen “Doors and Fours” with Tylenol#4
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Sedative-Hypnotic Pearls
n Ethchlorvynol (Placidyl)n “Jelly-bellies”n Used by William Rehnquist (oversedation then
withdrawal)n Methaqualone
n Quaaludes, Mandraxn Recent abuse in South African Can see hyperreflexia, clonusn Residual paresthesias and polyneuropathies after
overdose
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Antidepressants
n Cyclic antidepressantsn Monoamine oxidase inhibitors (MAOIs)n Serotonin reuptake inhibitorsn Miscellaneous
n Buproprionn Citalopram/Escitalopramn Mirtazapinen Trazadonen Venlafaxine
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Usual Suspects
n Tertiary aminesn Amitriptylinen Clomipraminen Doxepinn Imipraminen Trimipramine
n Secondary aminesn Desipraminen Nortriptylinen Protriptyline
n Tetracyclicn Amoxapinen Maprotiline
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TCA Screen Cross Reactivity
n Cyclobenzaprine (Flexeril)n Diphenhydramine (Benadryl)n Cyproheptadine (Periactin)n Carbamazepine (Tegretol)n Thioridazine (Mellaril)n Quetiapine (Seroquel)
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Pharmacokinetics
n Peak serum concentration 1-8 hrsn Antimuscarinic – delayed gastric emptyingn Lipophilic – large Vdn Hepatic phase I: Demethylation
n Imipramine g desipraminen Amitriptyline g nortriptyline
n Hydroxylation: CYP2D6n Slow vs Rapidn Desipramine: 81-131 vs 12-23 hours
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CA Toxicity
n Rapid onset of symptomsn Early sedation and coman Early antimuscarinic symptomsn Cardiovascular
n Hypotensionn Dysrhythmias
“T” =Tremor (seizures)“C” = Cardiovascular“A” = Antimuscarinic
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Cardiovascular Toxicity
n Rapid inward Na+ currentn QRS prolongation
n RBB more susceptible (leads V1, V2, aVR, I)n Rate dependentn pH dependent
n R axis deviation in terminal 40 msecn AV node blocks
n K+ channel blockade (Ikr)n Increased QT but TdP uncommon with tachycardian Seen with therapeutic dosing
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Cyclic Antidepressants Toxicology
n Membrane effectsn Blockade of fast Na+ channels phase 0 of the action
potential
1
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2
3
4
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Axis Change in Toxicity
V1 R
R’
I
aVR Terminal R
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MAOI pharmacology
n Intracellular enzyme found on mitochondrialmembrane
n Degrades biogenic aminesn Increases neurotransmitter activity in CNS,
down-regulates post-synaptic 5HT andadrenergic receptorsn Post-synaptic DA unaffected
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MAOI pharmacology
n Irreversible bindingn Phenylzinen Tranylcyprominen Isocarboxiziden Selegilinen Pargyline
n Reversible bindingn Moclobemiden Brofarominen Cimoxatonen Toloxatonen Harmaline
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MAOI pharmacology
n Selectiven Clorgyline (A)n Moclobemide (A)n Toloxatone (A)n Harmaline (A)n Selegiline (B)n Pargyline (B)
n Nonselectiven Tranylcyprominen Phenylzinen Isocarboxazid
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Signs and Symptoms (Overdose)
n Phase In Latent period: 6-12 hrs in
pts on medicationn 24-36 hrs in “naïve”
patients
n Phase IIn Excitatory phase
n Hyperadrenergic appearingn “Ping-pong” nystagmusn Hyperreflexive with rigidityn Writhing, opisthotonus, facial
grimacing
n Progressionn CNS depressionn Fever, diaphoresis, salivationn Rigidty, myoclonus, carpopedal
spasmn Myocardial ischemia, ICH,
seizures
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Treatment
n Expect prolonged period of toxicityn ICU for 24 hrs after resolution of signs and
symptomsn Restricted diet for 2-3 weeksn Check ALL medications for interactionsn Treat as signs and symptoms appear
n Use SHORT acting agentsn Use DIRECT acting agents-COMT metabolism
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MAO-Tyramine reaction
n Not an overdosen Onset within 2 hrs after eatingn Ingested tyramine normally inactivated by gut MAO-An Inhibition of gut MAO-A: absorption of dietary
tyramine and byproductsn Tyramine releases NE formed by inhibition of neuronal
MAO-An Hyperadrenergic staten Treat symptomatically
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Serotonin Reuptake Inhibitors
n Paroxetine (Paxil)n Fluoxetine (Prozac, Sarafem)n Citalopram (Celexa) n Escitalopram (Lexapro) n Sertraline (Zoloft)n Fluvoxamine (Luvox)n Fluoxetine + olanzepine (Symbyax)
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Pearls
n SSRI in overdose: CNS depression andtachycardia most common
n Citalopram and escitalopram: reports of seizuresand widened QT interval
n Fluvoxamine inhibits CYP1A and CYP2Cn Paroxetine, fluoxetine, and metabolites strong
inhibitors of CYP2D6
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SSNRI and Others
n Buproprionn Excitation in overdose, SEIZURES, XL products
n Mirtazepine (Remeron)n Sedation, mild symptoms in toxicity
n Nefazadone (Serzone), Trazadone (Desyrel)n Prolonged QT, orthostatic hypotension, priapism
n Venlafaxine (Effexor, aka side-effectsor)n Seizures, QRS prolongation
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Serotonin Syndrome
n Stimulation of post-synaptic 5HT1A and5HT2 brain receptors
n Mechanismn Two or more serotonergic agentsn SSRI + neurolepticn SSRI + agent with serotonergic propertiesn Change in dosen Metabolic inhibition
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Serotonin Syndrome
n Modified Sternbach criteria: A, B, C must be met:n A. Syndrome occurs after addition of known serotonergic
agentn B. List of symptoms to be met (at least 3) and other causes
ruled outn C. No neuroleptic involved
n NEJM M. Shannon articlen Hyperthermian Mental status changesn Autonomic instabilityn CLONUS
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Serotonin Syndrome-Treatment
n Good supportive caren Benzodiazepinesn External coolingn Paralysis with a nondepolarizing agentn Specific agents
n Cyproheptadine: nonspecific 5HT1-2 antagonist (4-8 mg q1h)n NTG: nitric acid mediated downregulation of 5HT (drip
titrated to effect)n Propranolol: 5HT1A antagonism (1-5 mg IV)n Chlorpromazine: 5HT2 antagonist
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SS vs NMS
++++
++++
++++
++++--
--
Days
GradualNMS
+++Autonomic dysfunction
++Altered mental status
++Muscle rigidity
+/-Metabolic acidosis
++Hyperreflexia
++Myoclonus
< 24 hourResolution
RapidOnset
SSSigns/Symptoms
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Neonatal SSRI Withdrawal
n Fetus exposed to an SRI late in the third trimestern Symptoms
n Respiratory distress (apnea)n Cyanosis, apnean Feeding difficultiesn Vomitingn Hypoglycemian Tremors, jitteriness, irritability
n Onset hours to days after delivery, which resolved indays or weeks
n Prolonged hospitalization, respiratory support, and tubefeeding
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Question
Acute overdose of selective serotonin reuptakeinhibitor (SSRI) antidepressant medicationsmost often result in
A. Cardiac dysrhythmiasB. CNS depression and tachycardiaC. Hallucinations and deliriumD. Profound hyperthermia and rigidityE. Seizures
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Question
Acute overdose of selective serotonin reuptakeinhibitor (SSRI) antidepressant medicationsmost often result in
A. Cardiac dysrhythmiasB. CNS depression and tachycardiaC. Hallucinations and deliriumD. Profound hyperthermia and rigidityE. Seizures
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Antipsychotics
n Traditional antipsychoticsn D2 antagonists
n Atypicaln Selective for limbic vs EP sitesn Mixed DA receptor affinities (D1,D2 etc)n Looser binding to D2, less EPSn Mixed affinity for DA, 5HT, alpha
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Antipsychotic Classification
n Low potency (sedating, antimuscarinic, miosis)n Chlorpromazine (most sedating in overdose)n Chlorprothixenen Mesoridazinen Thioridazine (most cardiotoxic in overdose)
n Medium potencyn Droperidoln Loxapine (more seizures in overdose)n Molindonen Perphenazine
n High potency (more EPS, less sedation)n Fluphenazinen Haloperidol (most common cause of NMS)n Trifluoperazinen Thiothixene
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Reversible EPS: Acute Dystonia
n Facial grimacingn Trismusn Blepharospasmn Oculogyric crisis
n Tongue protrusionn Torticollisn Opisthotonisn Abnormal posture, gait
n Intermittent spasmodic and involuntary contractions offace, neck, trunk
n Idiosyncraticn Males 5-45 yearsn Depot prepsn Resolves during sleep
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Reversible EPS
n Akathesian Subjective uneasen Motor restlessnessn Dose relatedn Womenn High potency
n Parkinsonismn Muscle rigidityn Bradykinesian Tremorn Elderly womenn High potency
n Dopamine-cholinergic basal ganglia balance disruptedn Excess choline with dopamine depletion
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Irreversible EPS: Tardive Dyskinesia
n Involuntary movements of orofacial structuresn Lip smackingn Facial grimacingn Eye blinkingn Grunting
n Late onset > 2 years after therapy onsetn More common in women > 50 years
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Antipsychotic Pearls
n Thioridazinen Peak serum level can be delayed 120 hoursn QTc but not QRS correlates closely with peak concentrationn Most lethal in overdose
n Most common cause of NMS (> 90%)n Haloperidol
n Agranulocytosisn Chlorpromazine (Thorazine)
n Cholestatic jaundicen Chlorpromazine (Thorazine)
n Acute reversible oligurian Chlorprothixene (Taractan)
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Atypical Antipsychotics
n Aripiprazole (Abilify)n Longest potential e-half-life in overdose (146 hrs)
n Clozapine (Clozaril)n Aplastic anemia, seizures, drug-induced DM, myocarditis,
fevern Olanzapine (Zyprexa)
n Highest incidence of NMSn Highest antimuscarinic activity but salivation commonn Drug-induced DMn Classically resembles opiate toxidrome
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Atypical Antipsychotics
n Paliperidone (Invega)n Active metabolite of risperidone
n Risperidone (Risperdal)n Highest rate of dystonian Most reported seizuresn Potent alpha blockaden No antimuscarinic effects; miosisn Unusual dysrhythmias for class (aflutter, heart blocks)
n Ziprasidone (Geodon)n Highest rate of increased QTn Miosis common
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Quetiapine Pearls
n CNS depression, prolonged QT, tachycardian 3 grams predicted ICU/prolonged LOSn Cross reacts with TCA assayn Most sedating of class
n Highest antihistamine activityn High alpha blockaden Less miosisn Half-life longer in overdose
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New! Improved!
n Asenapinen Hypotensionn Agitation, alteredn QT?
n Iloperidonen Hypotension, antimuscarinicn QT prolongation
n Lurasidonen Hypotension, confusion, leukopenia
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Mood Stabilizing Lithium
n Main therapy for bipolar disordern Narrow therapeutic index (0.6-1.2 mEq/L)n Slow distribution across cell membranes
n Delay between peak blood levels and CNS effectsn Most cases chronic due to a reduction in GFR
n Volume lossn NSAIDs, diuretics, ACE inhibitorsn Age
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Acute vs Chronic Lithium
n Increased intaken Delayed toxicity due to
delayed distributionn High serum levels initially do
not correlate with toxicityn GI symptoms more severen Tremor, muscle weakness,
ataxia, hyperreflexia
n Decreased excretionn Serum levels lower since
inracellular levels highn Subacute/nonspecific
neurologic symptomsn GI symptoms less severen Encephalopathy, myoclonus,
severe rigidity, seizuresn ECG
n Bradycardian T-wave flattening/inversionn QT prolongation
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Lithium Management
n D/C lithium and offending drugsn Improve GFR
n 20% reduction in Li over 6 hoursn Hemodialysis (guidelines vary)
n Renal failuren Encephalopathy, myoclonus, severe rigidity, seizuresn Acute > 4.0 mEq/L?n Chronic > 2.5 mEq/L?
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Question
A 23-year-old woman is taking ziprasidone for herschizoaffective disorder. Her ECG reveals a QRS 86msec, and QTc 560 msec. Her physician wants toknow what medication you would recommend inplace of her ziprasidone?
A. Chlorpromazine (Thorazine)B. Haloperidol (Haldol)C. Olanzapine (Zyprexa)D. Quetiapine (Seroquel)E. hioridazine (Mellaril)
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Question
A 23-year-old woman is taking ziprasidone for herschizoaffective disorder. Her ECG reveals a QRS 86msec, and QTc 560 msec. Her physician wants toknow what medication you would recommend inplace of her ziprasidone?
A. Chlorpromazine (Thorazine)B. Haloperidol (Haldol)C. Olanzapine (Zyprexa)D. Quetiapine (Seroquel)E. hioridazine (Mellaril)
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Questions?
Good Luck!!