Strychnine Flashcards
Is strychnine a general use or restricted use pesticide?
restricted use not as common as other toxicants but can be used maliciously
Is strychnine an acid or a base?
Weak base - will be absorbed and non ionized when it is in an alkaline environment
T/F: Strychnine may cause vomiting when ingested
TRUE
What is the rate of strychnine absorption?
RAPID no tissue accumulation
What is the toxic dose of strychnine in dogs?
0.5 - 1.2 mg/kg HIGHLY TOXIC
Why would food in the stomach increase or decrease the toxicity of strychnine when ingested?
Increase toxicity: food in the stomach may decrease the chance of vomiting and auto decontamination Decrease toxicity: food in the stomach may slow absorption
Does strychnine cross the BBB?
YES
Where is strychnine metabolized and excreted?
In the liver and excreted in the urine - unchanged and as metabolites Most of the does is eliminated within 24 hours Does undergo enterohepatic recirculation
What is the MOA of strychnine?
-NEUROTOXIN (blocks motor neurons in spinal cord-controls movement;
(blocks interneurons in CNS);
competitive inhibition of glycine on POSTsynaptic neurons
-ANTAGONIST of GLYCINE and ACh RECEPTORS
Block post synaptic effect of glycine on the spinal cord (glycine is an inhibitory neurotransmitter to motor neurons and interneurons in the CNS Leads to: exaggerated reflex arcs, muscle spasms, severe extensor rigidity, tonic seizures
MOA of strychnine contd.
competitive blocking of glycne at post synaptic neurons——>
reduces the efflux of sodium ions from the spinal nerves——–>
reduces the hyperpolarization of the postsynaptic neurons——>
causes hyperexcitability
What clinical signs are observed in a patient with strychnine poisoning?
Rapid onset - 10mins - 2 hrs and rapid death Early: apprehension, panting, nausea/vomiting, mydriasis, stiffness, muscle twitching, hyperthermia Progresses to tonix sz, opisthotonos death from respiratory failure
For survivors- Secondary effects could include lactic acid acidosis, renal failure
Are seizures caused by strychnine poisoning elicitable?
YES by external stimuli (light, touch, sound)
What lesions are associated with strychnine poisoning?
Generally few or no lesions hemorrhage, cyanosis, congestion, rapid rigor mortis stomach contents may still contain bait
What are the preferred specimens for chemical detection of strychnine?
antemortem: stomach contents, bait, serum, urine Post mortem: stomach contents, liver $$$$$$/5-7 day turn around time
What is the treatment protocol for strychnine poisoning?
Decontamination - Emesis: if patient is neurologically normal, gastric lavage (avoid bicarb or antiacids) Activated charcoal - repeated doses *can enhance renal excretion with ammonium chloride or methionine Supportive: IVF, O2, Muscle relaxors and anticonvulsants, keep patient in a calm environment avoid opiods/NMB/ketamine
