Poisons and Antidotes Flashcards
Paraquat mechanism
Pulmonary fibrosis -selective uptake by pulmonary alveolar cells, oxidized by NADPH oxidase, creates free radicals which lead to lipid peroxidation and cell death
Organophosphates/Carbamates mechanism
Metabolized to paraoxon which phosphorylates acetylcholinesterase, which leads to inactivation and cholinergic crisis - SLUDGE (like sarin)
Organophosphates/ Carbamates antidote
Atropine, just like nerve gas, deactivate muscarinic receptors.
Methemoglobinemia inducers
Nitrates, aromatic amines, nitro compounds, antibiotics, local anaesthetics
Methemoglobinemia toxicity mechanism
Oxidize HbFe++ to HbFe+++ which can’t accept oxtgen
Methemoglobinemia treatment
Methylene Blue - reduces HbFe+++ back to HbFe++
Cyanide mechanism
Binds to cytochrome oxidase, blocks aerobic respiration
Cyanide antidote
Two step - Amyl/Sodium Nitrite to generate methemoglobin
Hydroxycobalamin - binds to CN
Sodium Thiosulfate - Form SCN
Iron toxicity mechanism
Corrosive - necrotizing gastroenteritis
Mercury toxicity mechanism
Reacts with Sulfhydryl group on proteins, interacts with selenium. CNS toxicant, low exposure causes developmental disase.
Mercury toxicity treatment
Succimer/DMSA, Unithiol, N-acetylcysteine
Lead toxicity mechanism
Many mechanisms - reacts with SH groups, carboxy groups, mimics calcium, zinc, iron. Causes alteration in membrane function, neurotransmitter, redox reactions. Causes multiple toxicities - especially in CNS.
Lead toxicity treatment
Chelation - EDTA, BAL, Succimer (DMSA)
Can you name a substance which is not poisonous?
No - toxicity depends on dose. You can die from too much water.
Explain the U-shaped dose-response curve for essential vitamins and minerals
Too little or too much = adverse response. The bottom of the U is the region of homeostasis
