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

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. 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. 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. 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. 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. 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. 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. 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. 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. 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