Lecture-20 - Toxicology Toxicology is the study of the...

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Toxicology Toxicology is the study of the adverse effects of chemical agents on biological systems. A number of classifications can be used to subdivide the general field of toxicology.
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Toxic agents themselves may be classified according to: (1) the potential for a compound to produce toxicity , (2) the source of the toxin (eg. snake or spider venom or poison ivy), (3) chemistry of toxins, (4) mechanism of action.
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Three assumptions : 1. observed response actually due to compound administered. 2. degree of response related to magnitude of dose 3. response is quantifiable The concentration- response curves for the effective , toxic and lethal doses of a drug are independent of one another.
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Threshold dose : the lowest dose that evokes a given response . For example, different doses of ASA produce g.i. bleeding, tinnitus and generalized acidosis. Some toxicities develop rapidly and reversibly (eg. inebriation due to methanol) while others develop more slowly and may be irreversible (eg. methanol producing retinal nerve toxicity, leading to blindness).
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50 : the dose required to kill 50% of exposed test animals. Depends on species, strain, sex, age & route of drug administration. Eg., dioxin LD 50 s vary 1000-fold between guinea pig and hamster. Some chemicals may produce minimal acute toxicity but can have long-lasting effects (eg. carcinogens and teratogens). Remember that LD
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This note was uploaded on 04/01/2009 for the course BIO 51310 taught by Professor Sisson during the Spring '08 term at University of Texas at Austin.

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Lecture-20 - Toxicology Toxicology is the study of the...

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