Toxicology
Definitions
Poison
A Substance capable of causing illness /death when introduced / absorbed
Xenobiotic
Foreign chemical substance
LD50
50% of the lethal dose
Fundementals of Toxicology
Exposure must occur first
Magnitude of risk is proportional to both potency, and extent of exposure
Certain chemicals cause non-specific damage by altering proteins, nucleic acids, lipids
Biotransformation of chemicals may result in reactive metabolites / free radicals / oxygen radicals
The dose makes the poison - Toxicity determined by amount of chemical at target site
Mechanism of Toxicity
- Inflammation and immune mediated
Penicillin
- Altered enzyme and receptor function
Organophosphates
3.Organ directed damage
Acetaminophen, methanol, alcohol, cigarette smoke
- Human development - Teratogens
Alcohol, Thalidomide
Inflammatory and Immune Mediated Toxicity
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Organophosphates
Mechanism of Toxicity
Altered enzyme function
- Serine residue of AChE phosphorylated and ages
- ROH group replaced by hydroxyl
- Stable and irreversible ageing (can be reversed if caught early enough)
Antidote
Pralidome
- Breaks bond between organophospate and serine
- Release of organophosphate and regeneration of serine hydroxyl group on AChE
Symptoms
Lacrimation 💧
Muscle paralysis 🗽
Diarrhoe 💩
Paracetomol Overdose
Mechanism of Toxicity