Drugs-CNS depressants Flashcards
Opioids
-alkaloids from poppy plant
-first line pain therapy in vet med
Exposure scenarios of opioids
-calculation errors
-narcotics detection dogs
-ingestion of fentanyl patches
-consumption of human drugs
-animal cruelty
Mechanism and target organs for opioid toxicity
Mechanism: interaction with opioid receptors in spinal cord, limbic system, brain
*resp depression, bradycardia, analgesia, sedation
Target: CNS, cardiovascular, respiratory, GI
Opioid toxicokinetics
-some more lipophilic (heroin, fentanyl, buprenorphine)
-some metabolized via glucuronidation
-renal excretion
Onset of opioid toxicity
Within mins of injection and within 30mins of ingestion
Clinical signs of opioid toxicity
-vomiting, constipation or defecation, salivation
-depression/sedation in dogs, excitation in cats
-bradycardia and arrthmias
-miosis in dogs, mydriasis in cats
-hypothermia in dogs, hyperthermia in cats
*if severe= resp depression, cyanosis, constipation, seizures, coma
*Death= hypoxia, resp failure
Opioid toxicity management
-antidote=naloxone (mu antagonist) or butorphanol
-monitor for CNS and resp depression
-ventilation and pulse oximeter
-ECG and blood pressure monitoring
-thermoregulation
-serotonin syndrome=cyproheptadine
Management of opioid toxicity
-Wear PPE and if given narcan, dont stand in front of dog
Diagnosis of opioid toxicity
-working dogs ADR after search
-overdose in clinic
-access to owners drugs (urine drug test)
Prognosis of opioid toxicity
-good with rapid recognition of toxicity, naloxone, supportive care
-guarded with delayed intervention or hypoxemia
Benzodiazepines
Diazepam, midazolam, other human drugs (pam and lams), sleep drugs, anxiolytics
*used for seizure controls
Exposure scenarios for benzodiazepines
-ingestion of human prescription meds
-overdose in clinical setting
Mechanism of benzodiazepines
Enhance binding of GABA to receptors in CNS = CNS depression
Toxicity likelihood of benzodiazepines
Low! wide margin of safety
Exception: oral diazepam in cats
Benzodiazepine toxicity onset
within 30-60mins after ingestion/exposure
Clinical signs of benzodiazepine toxicity
-confusion, ataxia, incoordination, lethargy
-bradycardia, hypotension
-vomiting
-tremors, hypothermia, weakness
-Paradoxical excitation and hyperactivity
*severe overdose= resp depression, coma, seizures
Special clinical sign seen in cats with benzodiazepine toxicity
Fulminant liver failure with repeated oral diazepam
-related to glucuronidation
-anorexia, lethargy
-liver failure and increased liver enzymes
*must mange with hepatoprotectants, lactulose, vitK, metronidazole
Benzodiazepine toxicity management
-decontamination if oral
-antidote= flumazenil
-care: thermoregulation, IVFT, IVLE
Diagnosis of benzodiazepine toxicity
-history of ingestion of human meds
-overdose in clinics
-analysis of blood and urine
Prognosis of benzodiazepine toxicity
Good with antidote and supportive care
*guarded to poor in cats given oral diazepam
Barbituates
-phenobarbital and pentobarbital
-used for sedatives and anticonvulsants
Exposure scenarios of barbiturates
-accidental ingestion of medication
-iatrogenic overdose
-accidental administration of euthanasia solution
-ingestion of tissues or euthanized animals
Mechanism of barbituates
Activation of GABA receptors, inhibition of glutamine receptors. Leads to inhibition of release of NE and ACh
=CNS depression and suppression of hypoxic drive and chemoreceptor drive
Onset of barbiturate toxicity
Within mins to several hours post exposure
Clinical signs of barbiturate toxicity
-weakness
-CNS depression, ataxia, disorientation, mydriasis, recumbency, coma
-hypothermia
-hypoventilation
-tachycardia or bradycardia = death from resp depression
Clinical signs for long term use of phenobarbital
Hepatotoxicosis
-anorexia, vomiting, diarrhea
-sedation, ataxia
-icterus, ascites
-high bilirubin, low albumin, increased ALT, ALP, hepatic cirrhosis
Management of barbiturate toxicity
-no antidote
-recent ingestion= emesis or gastric lavage
-resp and CV monitoring
-IVFT and forced diuresis
-IVLE
**long acting so need long term care
Diagnosis of barbiturate toxicity
-accidental administration of euthanasia solution
-ingestion of euhanized animals
-overdose of prescribed medication
-human OTC urine drug test
-analysis of stomach contents and blood
Pentobarbital use and animal disposal
Vets responsible for proper disposal of animals euthanized with pentobarbital
-need documentation and signed consent form
-vet liable if client not informed
Local anesthetics
-lidocaine and bupivicaine
-sometimes combined with epinephrine
*used as local anesthetic, antiarrhythmic, prokinetic
Exposure scenarios of local anesthetics
-accidental IV injection
-overdose during local block
-consumption of topical ointments
Local anesthetics mechanism and target organ
Mechanism: block voltage gated Na channels in nerves and myocardium
=CNS depression first and myocardial depression second
Target: CNS, CV
Local anesthetic toxicity clinical signs
Local anesthetic system toxicity (LAST)
-CNS first: sedation, weakness, CNS excitation like twitching/seizures, then higher concentration leads to resp arrest, coma, CNS depression
CV: bradycardia, decreased contractility, vasodilation
Difference with bupivicaine compared to lidocaine
More cardiotoxic
-CNS and CV occur concurrently
-leads to hypotension, CV collapse
Local anesthetic management
-Antidote= IVLE
-anticonvulsants, IVFT, oxygen, positive inotropes, CV monitoring
Local anesthetics diagnosis
-recent admin of local anesthetics
-inadvertent IV admin
-chewed ointment
Local anesthetic tox prognosis
-depends on severity of clinical signs and response to medical management
*good with lidocaine
*guarded with bupivicaine
Marijuana
Cannabis sativa
-Psychoactive= delta9-THC
Marijuana exposures in animals
-mostly owner use (edibles, vapes, smoke inhalation, human feces)
-therapeutic uses for animals is active area
Mechansim of marijuana toxicity
Binds to CB1 and CB2 receptors in CNS
-CB1= psychoactive; memory, perception, movement (cerebellum)
-CB2= analgesia, anti inflammatory = PNS, immune system
Toxokinetics of marijuana
-lipophilic
-different hepatic metabolism between dogs and humans
Onset of marijuana toxicity
within 30mins of ingestion
Clinical signs of marijuana toxicity
-vomiting
-tachycardia or bradycardia
-dullness/depression
-ataxia
-weakness
-hyperesthesia
-seizures, coma
-mydriasis
-blood shot eyes
-urinary incontinence
-vocalization
-ptyalism
-hypo or hyperthermia
Management for marijuana
-no antidote
-decontamination
-monitor HR, temp
-low stimulation environment
-antiemetics
*if severe: atropine, intubation, IVLE
Diagnosis of marijuana
-history
-clinical signs
-human OTC urine test
Xylazine
alpha 2 agonist commonly used in large animal med, less in small animal
Xylazine exposure scenarios for animals
-administration of wrong xylazine
-miscalculation
-exposure to drugs laced with xylazine
Mechanism of xylazine toxicity
Alpha-2 adrenergic receptor agonist
-targets CNS and cardiovascular= sedation, muscle relaxation
Clinical signs of xylazine toxicity
-Presents similar to opioid overdose but is not responsive to naloxone
-bradycardia, vasodilation, hypotension, CNS and resp depression
-muscle twitching, miosis, hypothermia, vomiting, salivation
-convulsions in intracarotid administration
Management of xylazine
-Antidote: atipamezole (Antisedan) or yohimbine
-BP support, oxygen, ventilation
-decontamination
CNS depressant drugs
