16 – CNS Depressants Flashcards
1
Q
Opioids
A
- Alkaloids from poppy plant
- Agonists, partial agonists, antagonists
o Most worried about the pure mu-opioid agonists - First line therapy for pain management in vet med
- Minimum lethal dose varies by drug
2
Q
Opioids: exposure scenarios
A
- Calculation errors
- Narcotics detection dogs
- Ingestion of fentanyl patches
- Consumption of human drugs
- Animal cruelty
3
Q
Opioids: mechanism
A
- Interaction with opioid receptors in spinal cord, limbic system and brain
o Mu receptors: analgesia, sedation, respiratory depression, bradycardia
4
Q
Opioids: target organs
A
- CNS
- CV
- Respiratory
- GI
5
Q
Opioids: relevant toxicokinetic
A
- Some are more lipophilic: heroin, fentanyl, buprenorphine
- Some metabolized via glucuronidation
- Renal excretion
6
Q
Opioids: onset
A
- Within minutes of injection
- Within 30mins of ingestion
7
Q
Opioids: clinical features
A
- Vomiting, constipation
- Depression/sedation (dogs), excitation (cats)
- Bradycardia, sinus arrythmias
- Miosis (dogs), mydriasis (cats)
- Hypothermia (dogs), hyperthermia (cats)
- *severe: RESPIRATORY DEPRESSION, cyanosis, constipation, seizures, coma
o Cause of death: hypoxia, respiratory failure
8
Q
Opioids: management
A
- Decontamination: if injected=no, but if ingested=maybe
- *Antidote: naloxone (pure mu-opioid antagonist)
o What if no naloxone? Butorphanol - Monitor for CNS and respiratory depression
- Blood gas: ventilation, pulse oximeter
- CV monitoring: ECG, BP
- Thermoregulation
- Serotonin syndrome: cyproheptadine
- *make sure you are wearing proper PPE
9
Q
Opioids: diagnosis
A
- Working dog ADR after completing a search
- Overdose in clinic
- Access to owner drugs
o urine drug test
10
Q
Opioids: prognosis
A
- Good with rapid recognition of toxicity, naloxone and appropriate supportive care
- Guarded with delayed intervention or hypoxemia
- Positive response to therapy=good prognostic indicator
11
Q
Benzodiazepines
A
- Diazepam, midazolam (pam or lam drugs)
- First line treatment for seizure control
o Sedatives, anxiolytics, muscle relaxants
o VM: treat anxiety, phobias, behavioural disorders - Toxicity: generally low due to wide margin of safety
o Exception: oral diazepam in CATS
12
Q
Benzodiazepines: exposure scenarios
A
- Ingestion of huma prescription medication
- Overdose in clinical setting
13
Q
Benzodiazepines: mechanism
A
- *Enhance binding of GABA to receptors in CNS = CNS depression
14
Q
Benzodiazepines: onset
A
- 30-60mins after ingestion/exposure
15
Q
Benzodiazepines: clinical features
A
- CNS depression
- Bradycardia, hypotension
- Vomiting
- Tremors, hypothermia, weakness
- Paradoxical excitation and hyperactivity possible
- Severe overdose, respiratory depression, coma, seizures
16
Q
Benzodiazepines: CATS clinical features
A
- Fulminant liver failure with repeated oral diazepam
o Exact mechanism is unknown (related to glucuronidation)
o Anorexia and lethargy
o Clin path: increased liver enzyme, indicators of liver failure - Management: acute liver failure=hepatoprotectants, lactulose, vitamin K, metronidazole
17
Q
Benzodiazepines: management
A
- Decontamination if oral ingestion
- **antidote: FLUMAZENIL
o Short half life (may need to treat again) - Supportive care measures: thermoregulation, IVFT, maybe IVLE
18
Q
Benzodiazepines: diagnosis
A
- History of ingestion
- Overdose in clinical setting
- Analysis in blood and urine
19
Q
Benzodiazepines: prognosis
A
- Good with antidote and adequate supportive care
o Oral diazepam in cats=guarded to poor
20
Q
Barbiturates
A
- Phenobarbital (long acting) vs. pentobarbital (short acting)
o Pheno: epilepsy in dogs - Therapeutic use: sedatives, anticonvulsants
21
Q
Barbiturates: exposure scenarios
A
- Accidental ingestion of medication
- Iatrogenic overdose
- Accidental administration of euthanasia solution
- Ingestion of tissue of euthanized animals
22
Q
Barbiturates: mechanism
A
- Activation of GABA receptors
- Inhibition of glutamine receptors
- Inhibition of NE and ACh release
- *CNS depression
o Suppression of hypoxic drive and chemoreceptor drive
23
Q
Barbiturates: onset
A
- Within minutes to several hours post-exposure
24
Q
Barbiturates: clinical features
A
- Weakness
- CNS depression
- Hypothermia
- Hypoventilation
- CV: tachycardia or bradycardia
o *high doses: myocardial depression
o *death due to respiratory depression - Hepatoxicosis in patients on long-term PB treatment for idiopathic epilepsy
o **HEPATIC CIRRHOSIS
25
Q
Barbiturates: management
A
- No specific antidote
- Recent ingestion: emesis with A/C
- Respiratory monitoring and support
- CV monitoring and support
- IVFT
- IVLE
- Long acting: prolonged treatment required (phenobarbital)
26
Q
Barbiturates: diagnosis
A
- Accidental administration of euthanasia solution
- Ingestion of euthanized animal
- Overdose of prescribed medication
- *human OTC urine drug test, analysis in stomach contents and blood
27
Q
Barbiturates: prognosis
A
- Good with early management
28
Q
Veterinarians and pentobarbital
A
- Responsibility to INFORM clients about proper disposal of animals euthanized with pentobarbital
- MUST be documented in medical record or on a SIGNED CONSENT FORM
- A vet may be liable if the client WAS NOT informed of the risks
29
Q
Local anesthetics
A
- Lidocaine, bupivacaine
- Therapeutic use: local anestic, antiarrhythmic, prokinetic
- Human OTC and Rx products
30
Q
Local anesthetics: exposure scenarios
A
- Clinical setting: accidental IV injection, overdose during local block
- Consumption of topical ointments
31
Q
Local anesthetics: target organs
A
- CNS
- CV
- *lidocaine: more neurotoxic
- *bupivacaine: more cardiotoxic
32
Q
Local anesthetics: mechanism
A
- Block voltage gated Na channels in nerves and myocardium
33
Q
Local anesthetics: clinical features
A
- *see CNS first
o Sedation, weak
o Muscle twitching to seizures - CV
o Bradycardia, decreased contractility
o Can progress to cardiac arrest - Bupivacaine: more cardiotoxic (CNS and CV signs occur concurrently)
34
Q
Local anesthetics: management
A
- *Antidote: IVLE
- Supportive care
35
Q
Local anesthetics: prognosis
A
- Dictated by severity of clinical signs and response to medical management
- Good with lidocaine
- Guarded with bupivacaine
36
Q
Marijuana
A
- Cannabis
- Lots of cannabinoids
- Most exposures result from owner’s use (ex. edibles, vapes, smoke inhalation, human feces)
- Therapeutic uses of marijuana for animals is an active area of research
o No vet products currently approved for use - *very common poisoning
o Decriminalization, accessibility
o Mostly in dogs
37
Q
Marijuana: mechanism
A
- Binds to CB1 and CB2 receptors in CNS
- Relevant toxicosis: lipophilic, different hepatic metabolism between dogs and humans
38
Q
Marijuana: toxicity
A
- NOT acutely toxic
- Behaviour effects occur at 1000x less than minimum lethal oral dose
39
Q
Marijuana: onset
A
- Within 30mins of ingestion
40
Q
Marijuana: clinical features
A
Marijuana: clinical features
- Vomiting possible
- Tachycardia or bradycardia
- Dullness/depression
- **ataxia
- Weakness
- *hyperesthesia
- *mydriasis and urinary incontinence
41
Q
Marijuana: management
A
- No specific antidote
- Decontamination if not contraindicated
- Symptomatic and supportive care
o Monitor HR and temperature
o Low stimulation environment
o Antiemetics - Severe: atropine, intubation and mechanical ventilation, IVLE
42
Q
Marijuana: diagnosis
A
- History of exposure and clinical signs
- *human OTC urine test=FALSE NEGATIVES
43
Q
Marijuana: prognosis
A
- Good to excellent
44
Q
What is the treatment protocol for marijuana intoxication?
A
- Emesis induction: apomorphine (within 2 hrs of ingestion)
- Activated charcoal
- IVFT if vomiting and for temperature regulation
- Monitor heart rate, temperature, respiratory rate
- Antiemetics for persistent vomiting
- Severely poisoned animals: considered IVLE
45
Q
Xylazine
A
- Alpha-2 agonist (large animal for sedation and pain management)
- *emerging public health issue: ADULTERANT IN STREET DRUGS
46
Q
Xylazine: exposure scenarios
A
- Administration of ‘wrong’ xylazine
- Miscalculation
- Exposure to illicit drugs laced with xylazine (working canines)
47
Q
Xylazine: mechanism
A
- Alpha-2 adrenergic receptor agonist
48
Q
Xylazine: target organs
A
- CNS, CV
o Therapeutic: sedation, muscle relaxation, analgesia
o Overdose: profound sedation
49
Q
Xylazine: clinical features
A
- Similar to opioid overdose and LACK OF RESPONSE TO NALOXONE
o Bradycardia, vasodilation, hypotension
o Progressive CNS depression, can proceed to respiratory depression
o Muscle twitching, miosis, hypothermia
o Intracarotid administration=convulsions
50
Q
Xylazine: management
A
- *antidote: ATIPAMEZOLE (also yohimbine)
o IM better, but intra-nasal did work (50% bioavailability) - Supportive care: BP support, oxygen, ventilation support
o Frequent monitoring of CV and respiratory systems - Decontamination if not contraindicated
