Toxicology and Biotransformation Flashcards
Toxicology
The study of the adverse effects of chemical, biological and physical agents on living organisms and the environment.
Toxin, poison and venom
A toxin is a naturally occurring harmful agent. Poison is ingested or absorbed, venom is injected.
Phase I and Phase II biotransformation
Phase I includes oxidation, reduction and hydrolysis. Phase II includes conjugation with various compounds.
Death cap mushroom
Amanita phalloides, contains alpha-amanitin which causes apoptosis through RNA polymerase inhibition.
Therapeutic index
TI is the ratio of the dose causing toxicity TD50 to the dose causing effectiveness ED50 in 50% of the population.
Role of mixed-function oxidase
Catalyzes the oxidation of substances involving Cytochrome P450 proteins crucial for Phase 1 biotransformation.
Significance of Glutathione in Phase II reactions
Acts as a nucleophile to bind electrophiles in conjugation reactions.
Aromatic amines
Enzyme mediated reactions lead to their formation, which can cause cell damage in the bladder.
Organ selective toxicity
Xenobiotics cause toxicity in specific organs due to metabolic activation, distribution, or organ susceptibility.
Xenobiotic
A foreign chemical substance that is not naturally produced.
Cytochrome P450
Involved in drug biotransformation through phase I system.
Bioactivation vs bioinactivation
bioactivation converts less toxic substances into more toxic substances, while bioinactivation involves converting substances into less toxic substances.
Aflatoxin B1
Reactive epoxide that forms DNA adducts, inducing liver cancer.
Benzene biotransformation
Biotransformed to phenol in phase I and phenyl in phase II.
Narrow Therapeutic Index
NTI drugs have a very small margin of safety between therapeutic and toxic doses.
Body reaction to lipophilic substances
These substances are slowly released from body fat undergoing biotransformation into more water soluble forms.
