Pharma toxicology

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ppy by : Ma. Minda Luz M. Manuguid, M.D

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Pharma toxicology

  1. 1. Toxicology Minda Luz Meneses-Manuguid, M.D. All substances are poisons. There is none which is not a poison. The right dose differentiates a poison & a remedy. - Paracelsus 1532
  2. 2. definitions Toxicology – the study of adverse effects on humans of prophylactic & therapeutic drugs, food & beverage additives, and industrial chemicals incorporated into consumer products Poison – any compound which in relatively small quantities & by a chemical reaction can cause death or disability Poisoning – may be accidental, suicidal, or criminal
  3. 3. definitions Toxicology – the study of the adverse effects of chemicals on living things Toxin – naturally derived, naturally exposed toxic chemical Toxicant – manmade toxic chemical or of natural origin but manipulated, concentrated, or dispersed by humans Poison – any substance which, when introduced into or absorbed by a living organism, destroys life or injures health; any compound which, in relatively small quantities & by a chemical reaction, can cause death or disability Antidote – medicine given to counteract the influence of poison or an attack of disease
  4. 4. most common causes of Poisoning circa 1964 death  Barbiturates  Carbon monoxide  Phenols; Cresols  Methanol  Ethanol  Cyanide  Arsenic fluoride  Mercury  salicylates disability  Ethanol  Barbiturates  Lesd  Arsenic  Salicylates  Carbon monoxide  Methanol  Antihistamines  Nonbarbiturate hypnotics  phenothiazines
  5. 5. antidotes Emetics – should be used only in conscious patients Gastric lavage – except in corrosive poisons or in unconscious / convulsing patients Chemical antidote – combines with the poison & inactivates it Physiologic antidote – opposes the actions of the poison Tannic acid in strong tea can precipitate Strychnine; Apomorphine, Cinchona alkaloids, Nicotine & Cocaine can neutralize Zn, Co, Cu, Hg, Ni, & Pb
  6. 6. Chemical Antidotes Dimercaprol / British Anti-Lewisite (BAL)  Originally against Arsenic-containing lewisite  Effective vs. mercury, Arsenic, Antimony, Gold, Cadmium, Bismuth & Chromium  NOT effective vs. Silver, Lead, Selenium, Thallium EthyleneDiamineTetraAcetic acid (EDTA)
  7. 7. Mechanisms of Action: Antidotes  decrease absorption: emetics: Ipecac, activated Charcoal, mustard in warm water, CuSO4, Apomorphine 5mg subQ  neutralize the chemical: Iron & Deferoxamine; Paracetamol & N-acetyl Cysteine  enhance elimination: Salicylates & urinary alkalinization  replace activity: Warfarin & vit K  pharmacodynamic intervention: Heroin & Naloxone Organophosphate effects
  8. 8. toxicity screening  acute toxicity  administration of progressively larger single doses up to the lethal dose  “No-Effect” dose – largest dose at which a specific toxic effect is NOT seen  Minimum Lethal Dose – smallest amount of the drug that can kill a study animal  LD50 – dose that kills half of the experimental animal population  subacute / chronic toxicity  administration of multiple doses to detect any adverse effects
  9. 9. toxicity screening mutagenicity –  detection of possible ability to induce genetic alteration (mutation) carcinogenicity –  detection of possible ability to induce abnormal clonal uncontrolled proliferation of genetically altered cells teratogenicity –  detection of possible deleterious effects on the developing fetus
  10. 10. toxicity screening mutagenicity –  detection of possible ability to induce genetic alteration (mutation) carcinogenicity –  detection of possible ability to induce abnormal clonal uncontrolled proliferation of genetically altered cells teratogenicity –  detection of possible deleterious effects on the developing fetus

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