Toxicology 1 Flashcards
Toxicology. Study with psychiatry deck, lots of crossover.
What are clinical effects of sympathimimetics? (10)
- CNS excitation - delirium
- Dysrhythmias
- HTN emergency
AoD, ACS, CVA, pulmonary edema, - Diaphoresis
- Mydriasis
- Tachycardia
- Tachypnea
- Hyperthermia**
- Rhabdomyalysis, electrolyte imbalances, renal failure
- intestinal infarction, mesenteric ischemia.
- retinal vasospasm
- Seizures
- SAH
cocaine: Inhalational barotrauma: PTX, pneumomediastinum,
At a pharmacological level, how does cocaine work? (2)
- Local anesthetic (Na channel blockade)
2. Prevents reuptake of catecholamines (NE and DA) and serotonin from central and peripheral terminals.
What is speedballing?
Mixing of Cocaine and Heroin and injected intravenously.
What is one way to distinguish cocaine intoxication with PCP? (hint eyes)
PCP may have multidirectional nystagmus.
What is the general approach to management of cocaine intoxication?
- Delirium:Rapid Sedation! Benzodiazopines! 10 mg diazapam q 5 minutes. titrate to effect.
- Hyperthermia: Cool within 20 mins * important if duration longer - can go into DIC and organ failure
- Aggressive fluid resuscitation
- HTN: benzos, ntiroglycerin, phentolamine (alpha blocker - 1 mg q 3minutes). NO BB (unopposed alpha = worsened HTN, coronary a. vasoconstriction)
- Dysrthymias: Benzos, can consider CCB. Check electrolytes, may need NaHCO3! to narrow QRS
- Chest Pain: if STE, treat as MI.
Whats the difference between a body pack and a body stuffer?
Packer - carefully packs to transport drugs. If a packet breaksdown in GIT then they usually die because of the amount.
Stuffer: smaller amount ingested usu when being pursed by police.
What is the dose of Activated Charcol for acute cocaine ingestion (may be usu dose too)
1g/kg
What electrolyte AbN is common in MDMA abuse?
Hyponatremia - MDMA and its metabolites causes secretion of vasopression = incr reabs of free water.
- Also get SIADH type syndrome.
- Concentrated high Na urine.
In MDMA ingestion why would Normal saline or cyrstalloids worsen hyponatremia?
Because they will retain more free water than sodium
- If they are seizing then give hypertonic saline.
What is the cholinergic syndrome?
Sludge Salivation Lacrimation Urination Diarrhea GI upset Emesis Miosis- constriction of pupil
What is the anti-cholinergic syndrome
Hyperthermia Mydraiasis - large pupils Dry skin Urinary retention No bowel sounds Hallucinations/agitations Tachycardia Ileus Red skin- vasodilation
What is the ddx for pinpoint pupils?
- Cholinergic syndrome (organophosphates)
- Opiate OD
- Central pontine stroke (hemorrage)
- Neurosyphilis apparently..
- Pilocarpine drops..
What symptoms do you get with TCA OD? (early symptoms, electrolye AbN and later sx)
- Early: get anticholinergic syndrome
- Na Channel blockade (see widened QRS)
- Block K+ efflux (get QT prolongation)
- combined effects on various ion channels (aLOC, seizures, hypotension, wide complex tachycardia)
How is the ECG prognostic in TCA overdose?
What are ECG findings of TCA OD?
- QRS duration >100ms is predictive of seizures
- QRS duration >160 ms is predictive of ventricular dysrhythmias
- Additional ecg findings: R ward axis shift, Interventricular conduction delay — QRS > 100 ms in lead II
Right axis deviation of the terminal QRS:
Terminal R wave > 3 mm in aVR
R/S ratio > 0.7 in aVR
- QT prolongation is less important clinically
Do serum TCA levels correlate with severity of illness?
NO
The constellation of early anticholinergic symptoms, decr.LOC followed by seizures, wide QRS and CV collapse is highly suggestive of which OD?
TCA!
Management of TCA OD?
Address: Tachycardia, anticholinergic symptoms, HTN, hypoTN, Dysrythmias, Seizures, Last resort.
- ABC’s intubate if needed.
- If sinus tach only - supportive, monitor for wide QRS
- Early Hypertension should NOT be treated
- Hypotension: crystalloids, if refractory choose direct acting vasopressors (NE,E) NOT dopamine. Some data E better
- NaHCO3 - only if dysrythmia or wide QRS (>100ms)
1-2mEq/kg repeated in few minutes until narrowing of QRS. Bicarb infusion can be initiation with goal pH7.5-7.55. - If refractory to NaHCO3 (ventricular dysrythmia persists), then 3% hypertonic saline
- Seizures: Lorazepam, diazepam, phenobarbitol if refractory
- Intralipids (last resort) 1.5cc/kg 20% lipid solution
What are some medications that are contraindicated in TCA OD?
- Antidysrhythmics (can worsen cardiac toxicity)
- Physostigmine (cases of asystole)
What are the clinical effects of SSRI overdose? (4)
- Rarely fatal, can ingest 30 times daily dose with no sx
- GI upset
- Mild CNS depression
- Coma/Seizure 1-2%
- Serotonin syndrome (14%)
Of the SSRI’s which one has a higher rate of QT prolongation and seizures?
Citalopram
- The QTc prolongation may also be delayed for up to 13 hours.
Which electrolyte disturbance is associated with SSRIs?
Hyponatremia
- has been assc with SIADH
What is the treatment of SSRI overdose?
Support ABCs
Supportive treatment
Benzos if seizure
Magnesium if QT prolongation
Like TCA’s what time frame of no symptoms after ingestion is safe to discharge home in SSRI or SNRI ingestion.
6 hours.
BUT some advocate for 13 hours if they ingest >1000mg Citalopram or escitalopram because of possible delay in QT prolongation
There is no serum or urine test to detect SNRIs, or SSRIs for that matter. But which SNRI is associated with a false + PCP screen?
Venlafaxine (Effexor)
What are common clinical features of Bupropion ingestion or overdose?
- Sinus Tachycardia
- Tonic clonic seizures
- Agitation
What are symptoms of serotonin syndrome?
'HARMED' Hyperthermia Autonomic instability Rigidity (not as much as NMS) Myoclonus (clonus more pronounced in lower extremities) Encephalopathy Diaphoresis
There is a Hunter criteria for serotonin syndrome, what does it say?
In the setting of exposure to a known serotonin exposure the syndrome can be diagnoised by the presence of any of the following
- spontaneous clonus
- Inducible clonus and agitation or diaphoresis
- Ocular clonus and agitation or diaphoresis
- Tremor and hyper-reflexia
- Hypertonic with temp >38 and ocular clonus or inducible clonus
i will likely never remember this..
What is the onset frame of serotonin syndrome and how do you treat it? when does it typically resolve
Serotonin Syndrome
- Onset: within 24 h
- Neuromuscular findings: Hyperreactivity (tremor, clonus, reflexes)
- Causative agents: Serotonin agents
- Treatment: Benzos
- Resolution: within 24 hours
Which withdrawal syndromes are life threatening?
GABA withdrawal from
- ETOH
- Benzodiazepines
- Barbituates (phenobarbital an ex) - act on same place on GABA receptor as ETOH.
Withdrawals from SSRIs, opiods, sympathemimetics are not life threatening but uncomfortable. Require gradual taper for SSRIs
What clinical effects do benzodiazepines have by enhancing the inhibitory effects of GABA?
- Sedative
- Hypnotic
- Anxiolytic
- Anti-convulsant
Explain how Benzos work on GABA receptor
- Benzos have specific site that it binds to on the chloride channel at the GABA receptor –>potentiates GABA
- Leads to intracellular flux of chloride ions and hyperpolarizing the cell
- Net effect is diminished ability of nerve cell to initiate an action potential, inhibiting neural transmission.
Leads to sedation, Hynotic effects, anxiolysis, anti-convulsant
Which benzodiazepines are not metabolized in the liver?
they are water soluble, excreted by the kidney
LOT
Lorazepam
Oxapam
Temazepam
Why aren’t urine tests the greatest tool for Benzodiazepines?
they only detect benzos that are metabolized to oxazepam glucuronide. So many will not detect Clonazepam, lorazepam, midazolam..
What is the general management of Benzo OD?
ABCs, supportive
Generally expectant
NO routine flumazenil - can precipitate seizures, and dsyrythmias. Esp in presence of TCA
What is Flumazenil?
Nonspecific competitive antagonist of benzodiazepine receptor
What are indications for Flumazenil? (only 2)
- Isolated benzodiazepine overdose in non habituated user (ex accidental peds OD)
- Reversal of conscious sedation
What are Absolute contraindications to Flumazenil? name 4
Name 2 relative CI
- Suspected co ingestion that lowers sz threshold (TCA, cocaine, lithium, methylxanthines, isoniazide, MAOIs).
- Patient taking benzo for control of seizures
- Concurrent sedative hypnotic withdrawal
- Seizure activity or myoclonus
- Patient with neuromuscular blockade
- Hypersenitivity
Relative CI
- Chronic Benzo use, not taking for life threatening
- known sz d/o not treated with benzos
- Head injury
- Panic attacks
- Chronic alcoholism
What are the 3 types of opiod receptors?
mu, kappa, delta
What is the time frame that people abusing heroine and methodone start to get withdrawal symptoms? What is the typical duration of withdrawal symptoms?
heroine: 30 minutes
methadone:24-48 hours
Duration of symptoms for 1-2 weeks.!
Why do you get miosis in opiod overdoses?
Stimulation of mu receptors in the Edingerwestphal nuclei of the 3rd nerve results in pin point pupils..