Agonists, Antagonists And Various Key Points

GABA antagonists

  • Colchicine (Mandrake, Mayapple)
  • Clozapine (chlorpromazine?)
  • Cicutoxin (water hemlock aka cowbane)
  • Bicuculline
  • B-lactams (piperacillin/tazobactam)
  • Lindane (aldrin)
  • Pyrethroids/pyrethrins (AND Na channel opener)
  • Picrotoxin
  • Thujone (absinthe)
  • Tetramine (cage convulsant)
  • TCAs

GABA-B agonists

Glycine antagonists

  • Similar to GABA but glycine receptor is a Cl- inhibitory receptor in the spinal cord.
  • Strychnine
    • Normal mental status until late phases when metabolic complications from convulsions cause AMS. Then resembles sympathomimetic toxidrome
  • Brucine
  • Tetanus toxin
    • Prevents the release of glycine, not inhibiting the receptor, but a similar clinical picture, although delayed onset rather than immediate onset with strychnine

Sodium channel openers

  • Acronym “ABCD(no e)FGH” 
  • Aconite (monkshood) / Atracotoxin
  • Batrachotoxin (frogs)
  • Brevetoxin (Neurotoxic shellfish poisoning) (PSP/TTX is Na block)
  • Ciguatoxin
  • DDT/pyrethrins (mums)
  • Frogs
  • Grayanotoxin (mah Huang/rhododendron)
  • Hexachlorocyclohexane
  • AC+Sorbitol (strongly consider use)
  • Botulism (decreased motility)
  • Aspirin (aspirin desorbed from AC in alkaline milieu)

Kappa 2 opioid agonists

  • Pentazocine (psychosis)
  • Salvinorin A

Seizures in overdose

  • Benzonatate
  • Topiramate/zonisamide
  • CBZ
  • Gabapentin
  • Lamotrigine/Tiagabine
  • VPA
  • Cholinesterase inhibitors
  • Cholinomimetics
  • Pilocarpine
  • Carbachol
  • Methacholine
  • Bethanechol
  • Donepezil
  • Rivastigmine

Confusing T–s

  • 1,1,1,-Trichloroethane (methyl chloroform): GABAa-agonist
  • Trichloroethylene (TCE)- degreaser (carcinogenic) {TCE gets the extra e so ethylene (not ethanol)}
  • Trichloroethanol (Chloral hydrate)
  • Tetrachloroethylene=Dry cleaning agent
  • Tricresyl phosphate (TOCP) – Ginger Jake (organophosphate)

Green urine

  • Amitriptyline
  • Cimetidine
  • Indomethacin
  • Methylene blue
  • Metoclopramide
  • Propofol
  • Promethazine
  • Thymol

Metal fume fever

  • Copper
  • Manganese

Hard metal disease

  • Cobalt (Tungsten carbide)
  • Pneumonitis
  • Cadmium (death in 3-5 days)

Renal tox

  • Toluene (RTA)
  • Ethylene glycol
  • Orellanine containing mushrooms (Cortinarius orellanus)
  • Allenic norleucine containing mushrooms (Amanita smithania)

MPP+

  • MPTP → MPP+ via MAOb, therefore, can be inhibited by SELEGILINE

Disulfiram reaction

  • Disulfiram inhibits dopamine beta-hydroxylase (DBH) metabolism of dopamine to norepinephrine/epinephrine
  • Metabolized to DDC then to Carbon disulfide (CS2) and diethylamine. So methemoglobinemia from amine.
  • CS2 – fumigant – causes pyridoxine deficiency -> seizures
  • Carbamates
  • NMTT cephalosporins (Cefazolin, cefotetan)
  • Calcium carbimide (used as a disulfiram alternative)
  • Chlorpropamide
  • Coprine (inky cap)
  • Griseofulvin
  • Metronidazole
  • Nitrofurantoin
  • Procarbazine
  • Tolbutamide (first-generation sulfonylurea)
  • Thiram derivatives (dithiocarbamates)

Disulfiram ADR

  • Inhibition of DBH (inc dopamine, decrease NE/E)
  • Metabolism to DDC – Ni and Cu chelation
  • Metabolism to CS2 – Atherosclerosis, heart disease, pyridoxine deficiency/seizures
  • Diethylamine – MetHg
  • Can be used for cocaine abstinence?

Shellfish poisoning

  • Paralytic shellfish poison (SAXITOXIN)
  • Neurotoxic shellfish poison (Brevetoxin – simultaneous GI and neurotoxicity)
  • Amnestic shellfish poison (Domoic acid)
  • Diarrhetic shellfish poison (okadaic acid)

NEGATIVE anion gap

  • Bromide
  • Lithium carbonate
  • Polymyxin b
  • Hypoalbuminemia
  • Hyper Ca, K or Mg
  • Multiple myelomas

Radiation

  • Roentgen – exposure
  • Gray – Absorbed dose
  • Sievert – dose equivalent (rad type and tissue)
  • t=l/n+e (toxicity=lymphocyte/neutrophil+emesis)

For more chapters, visit the ABAT Study Guide homepage

Agonists, Antagonists And Various Key Points