Transcript Opiate Overdose

Opiate Overdose
J. Ryan Altman, MD
AM Report
17 February 2010
Papaver somniferum, Opium poppy, common poppy
Opiate Overview
 Opiates are extracted from the poppy plant
Papaver somniferum.
 Opiates belong to a larger class of drugs, the
opioids, which include synthetic and semisynthetic drugs
 Opioid pharmaceuticals are analagous to the
three families of endogenous opioid peptides:
enkephalins, endorphins, and dynorphin
 There are three major classes of opioid
receptor, with several minor classes (μ, κ, δ,
nociceptin/orphanin)
Opiate Overview
 Receptors in CNS and PNS; linked to variety of
neurotransmitters
 Analgesic effect
 Inhibition of nociceptive information at points of
transmission from peripheral nerve to spinal cord to
brain
 Euphoric effect
 From increased dopamine released in mesolimbic
system
 Anxiolysis Effect
 From effect of noradrenergic neurons in locus
ceruleus
Opiate kinetics
 Variable protein binding (89% methadone, 7.1%
hydrocodone)
 Given volume of distribution, difficult to remove via
hemodialysis
 Most are renally eliminated
 Many metabolized in liver to active metabolites
 Hydrocodone metabolized to hydromorphone by CYP2D6
 Morphine metabolized to morphine-6-glucuronide
 Overdose issues
 If multiple tablets are taken, dissolution and absorption will be
delayed, prolonging the apparent half-life.
 Duration of action may be shortened in overdose
 Ex: when sustained release formulation of oxycodone is
crushed before ingestion, the drug is rapidly absorbed.
Opioid Issues
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Natural
 Morphine (1.9h), codeine (2.9h)
 Metabolized to active drug morphine in liver
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Semi-synthetic
 Hydromorphone (2.4h), oxycodone (2.6h), hydrocodone (4.24h),
diacetylmorphine (heroin)
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Synthetic
 Meperidine (3.2h)
 Excitatory neurotoxicity may occur when the renally excreted metabolite,
normeperidine, accumulates. Seizures and serotonin syndrome.
 Methadone (27h)
 Very long acting; may cause QT prolongation, torsades de pointes
 Propoxyphene
 Seizures, IA antidysrhythmic properties (leads to widened QRS and negative inotropy)
 Tramadol (5.5h)
 Effects not completely revered by naloxone, seizures
 Fentanyl (3.7h)
 Ultrashort acting
The Physical Exam
 Vitals
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HR decreased or unchanged
BP decreased or unchanged
RR decreased (decreased tidal volume)
Temp decreased or unchanged
 GI
 Decreased bowel sounds
 Neurological
 Sedation or coma
 Seizure (meperidine, propoxyphene, tramadol, or 2/2 hypoxia)
 Ophthalmologic
 miosis
PE Points to Ponder
 Users of meperidine and propoxyphene may have nl pupils, and
presence of coingestants (sympathomimetics or anticholinergics)
may make pupils normal or large.
 Best predictor of opioid poisoning is RR<12 (predicted response to
naloxone in one study)
 Mild hypotension (from histamine release) may be present
 Hypothermia results from combination of environmental exposure
and impaired thermogenesis may be present
 In severely obtunded patients, room temperature may produce
significant hypothermia
 Elevated temperature may suggest early aspiration pneumonia or
complications if IVDU (endocarditis)
 Rales may indicate the presence of aspiration or acute lung injury
 Examine the skin for medication patches that must be removed,
track marks, or soft tissue infections
The DDx to the OD
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Antihistamine
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(anticholinergic toxidrome: dry skin and mouth, blurred vision, mydriasis, tachycardia, flushing of skin, hyperthermia, abdominal distension, urinary
urgency/retention, confusion, hallucinations/delusions, excitation, coma) [atropine or belladonna alkaloids, tricyclics, phenothiazines, jimson seed]
Antipsychotics
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(pupils and bowels normal)
Barbituates
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(mild to severe hypotension, serum concentration)
Beta-adrenergic antagonists
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(hypotension and bradycardia more prominent than mental status findings)
Calcium channel blockers
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(hypotension, bradycardia, tachycardia more prominent that mental status findings)
Carbamazepine
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(serum concentration)
Carbon monoxide
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(carboxyhemoglobin level)
Clonidine
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(bradycardia, hypotension more prominent than miosis and obtundation)
Cyclic antidepressants
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(QRS prolongation, hypotension, tachycardia)
Ethanol
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(pupils and bowels normal, serum concentration)
Ethylene glycol
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(pupils and bowel sounds normal)
Hypoglycemic agents
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(serum glucose concentration)
Isoniazid
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(h/o seizure, nl pupils and bowel sounds)
Isopropanol
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(pupils and bowels nl)
Lithium
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(tremor, hyperreflexia, serum concentration)
Methanol
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(pupils and bowels normal)
Organic phosphorous compounds
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(cholinergic toxidrome: hypersalivation, bronchorrhea, bronchospasm, urination, defecation, neuromuscular failure, lacrimation) [acetylcholine, insecticides,
bethanechol, methacholine, wild mushrooms]
Phencyclidine
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(nystagmus: horizontal, vertical or rotary)
Sedative-hypnotic agents
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(pupil size nl to decr, bowel sounds nl, less respiratory depression)
Opiate Overdose
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Labs
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Check serum glucose
Serum APAP level
Salicylate level (consider if tachypnea or incr anion gap)
CK (to exclude rhabo in setting of prolonged immobilization)
Serum creatinine
Electrolytes
Urine toxicology screen
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EKG
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Should not be routinely obtained
Positive test can indicate recent use but not current intoxication, or may represent false negative
Many opioids (especially synthetics) will produce false negative results in commonly available urine
screens
Propoxyphene can produce prolongation of QRS and is responsive to sodium bicarbonate
Methadone can cause prolonged QTc and Torsades
CXR
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Reserved for those patients with adventitious lung sounds or hypoxia that does not correct
when ventilation is addressed.
May eval for body packing and stuffing
OMG it’s OOD Mgmt
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Initial focus on airway and breathing
Administer IV naloxone
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Apneic pts and pts with extremely low RR should be ventilated by bag-valve mask
attached to O2 to reduce ALI.
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When spontaneous ventilations are present, give initial dose of 0.05mg and titrate upward
every few minutes until RR >12.
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Apneic pts should receive 0.2-1mg
Pts in cardiopulmonary arrest should be given minimum of 2mg
The goal of naloxone is NOT a nl level of consciousness, but adequate ventilation.
In the absence of signs of opioid withdrawal, there is no maximum safe dose; if clinical
effect does not occur after 5-10mg, reconsider your diagnosis.
Naloxone Infusion
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If hypoventilation recurs following initial bolus, give additional boluses to restore adequate
ventilation.
When ventilation is adequate, an infusion may be initiated at a rate of 2/3 the total dose of
naloxone needed to restore breathing, delivered every hour
If respiratory depression develops despite an infusion, administer naloxone bolus (using ½
the original bolus dose) and repeat if necessary until adequate ventilation returns, then
increase the infusion rate.
OMG it’s OOD Mgmt
 Remember your NAVEL (an “inny”) for ET Tube code drugs
 Narcan Atropine Vasopressin Epinepherine Lidocaine
 If the clinician “overshoots” the appropriate dose in an opioiddependent individual, withdrawal will occur. Manage expectantly,
not with opioids.
 Activated charcoal and gastric emptying are almost never
indicated in opioid poisoning. The large volume of distribution of
opioids precludes removal of a significant quantity of drug by
hemodialysis.
 In most cases, the pt may be discharged or transferred for
psychiatric evaluation once respiration and mental status are
normal and naloxone has not been administered for 2-3 hrs.
Additional Antidotes
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APAP
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N-Acetylcysteine
Anticholinesterases
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atropine, pralidoxine [2-PAM]; if muscle weakness or fasciculations or respiratory distress
Benzodiazepines
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Flumazenil
Carbon Monoxide
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Oxygen
Cyanide
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Amyl nitrate THEN sodium nitrate THEN sodium thiosulfate
Digoxin
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Antidigoxin Fab’ fragments
Ethylene Glycol
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Fomepizole or Ethanol
Extrapyramidal signs
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Diphenhydramine or benztropine
Heavy metal
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Chelators (calcium EDTA or dimercaprol [BAL] or Penicillamine or 2,3-Dimercaptosuccinic acid [DMSA, Succimer]
Iron
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Deferoxamine mesylate
Isoniazid
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Pyridoxine
Methanol
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Ethanol
Methemoglobinemia
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Methylene blue
Warfarin
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Vitamin K1 or FFP
Bibliography
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"Poisonous Plants of North Carolina," Dr. Alice B. Russell, Department of Horticultural Science; Dr.
James W. Hardin, Botany; Dr. Larry Grand, Plant Pathology; and Dr. Angela Fraser, Family and Consumer
Sciences; North Carolina State University. All Pictures Copyright @1997Alice B. Russell, James W. Hardin,
Larry Grand. Computer programming, Miguel A. Buendia; graphics, Brad Capel.
Cooper, D. et. al. The Washington Manuel of Medical Therapeutics. 32 nd Ed. 2007.
Opioid Intoxication in Adults. Uptodate.com