Toxicology Flashcards
Who is the father of the science of toxicology❓
Paracelsus
Define:
- Toxicity
- Acute toxicity
- Chronic toxicity
- LD50
- ED50
- Therapeutic index
Toxicity: intrinsic tendency to produce an adverse effect
Acute toxicity: toxic effect of an agent observed with 24hrs of a single exposure
Chronic toxicity: toxic effects of an agent observed after long term exposure
LD50: dose that will kill 50% of the population
ED50: dose that will produce a desirable effect in 50% of the population
Therapeutic index: used in determining the safety of drugs.
LD50/ED50
What are the processes of risk management❓
Hazard identification
Dose-response assessment
Exposure assessment
Risk characterization
- What is a chelate❓
- How is it formed❓
- Are chelating agents specific in their affinity for metals❓
- What do they do❓
- A chelate is a chemical compound in which one atom is enclosed within a larger cluster of atoms that surround it like an envelope
- Chelating agent+metal ion
- Chelating agents are non-specific in their affinity for metals
- ⬆️excretion of metals, used in metal overdose/toxicity
List some examples of chelating agents and their uses
Dithiocarbamate:
Nickel
Arsenic
Mercury poisonings
Penicillamine:
Cooper poisoning
Dimercaprol:
Arsenic
Mercury poisoning
Desferoxamine:
Iron poisoning
EDTA:
Lead poisoning
British antilewisite BAL
Diethylene triamine penta acetic acid
What are the toxic effects of arsenic❓
Which chelating agent can be used❓
Chelation doesn’t reverse damage from delayed effects of acute arsenic poisoning
True or false❓
1.
Neurotoxicity
Liver toxicity (ascites/cirrhosis)
Teratogenicity (congenital abnormalities)
Hypersensitivity rxn
2. BAL D-penicillamine Dithiocarbamate Dimercaprol
- True
What are the toxic effects of mercury❓
Which chelating agent can be used❓
1. CNS effects: Ataxia Loss of hearing and vision Tremor ⬆️excitability
Respiratory effect:
Bronchitis
Pneumonitis
2.
BAL
D-penicillamine
What are the toxic effects of lead❓
Which chelating agent can be used❓
1.
Neurotoxicity
Nephrotoxicity
Haematological effects
- EDTA
BAL
D-penicillamine
What are the toxic effects of cadmium❓
Which chelating agent can be used❓
- GIT effects:
Nausea/vomiting
Respiratory effect:
Chronic pulmonary dx
Renal tubular dx
Carcinogenicity
2.
DMSA
Beryllium toxicity has effects mainly in the lungs
True or false
True
Chromium toxicity has effects mainly on the renal tubules
True or false
True
What are the toxic effects of cyanide❓
Which chelating agent can be used❓
1. GI effects/Salivation Anxiety/Confusion Paralysis Cardiac arrhythmias Respiratory failure Coma
- D-pencillamine
BAL
What are the properties of an ideal chelator❓
Water soluble Resistant to biochemical transformation Able to reach site of toxicity Form non-toxic compounds Have ⬇️affinity for essential metals
How would you evaluate for specific diagnosis of a poison❓
History: Food/Chemical consumed
Physical examination: BP/Pulse/Temp
Lab tests: liver/kidney/electrolytes/ECG/X-ray findings
What are the specific Rx methods of poisonings❓
•Prevent future absorption of poisons:
Emesis
Gastric lavage
Chemical adsorption
Antidotes
•Enhance elimination of poisons:
Purgation
Dialysis
Alkalinization/Acidification of urine
What drugs can one use to induce emesis❓
•Ipecac syrup:
(irritant effect on enteric tract and chemoreceptor trigger zone CYZ)
15ml for children
30ml for adults
•Apomorphine:
SC administration
6mg/kg for adults
0.06mg/kg for children
Stimulation of CYZ as a method to induce emesis is not used in which type of pts❓
Why❓
Respiratory
CNS depressed pts
It is a respiratory depressant
How is a gastric lavage done❓
Insertion of tube into the stomach
Washing with water/normal saline to remove unabsorbed poison
Used in life threatening situations
Oral/nasogastric
How does one induce chemical adsorption in poisoned pts❓
10:1 ration of charcoal to drug
50mg/10 tablespoonful glass of water
Oral/gastric tube
Chemical adsorption techniques shouldn’t be used concurrently with emetic agents and antidotes
True or false
True
What are some examples of purgatives❓
Sorbitol
Sodium sulfate
Magnesium sulfate
Use osmotic cathartic
An acidic drug should be alkalinized in the urine with❓
Sodium carbonate
An basic drug should be acidified in the urine with❓
Ammonium chloride
Ascorbic acid
What is the antidote for formaldehyde toxicity❓
What product is formed❓
Ammonia
Hexamethylene tetramine
What is the antidote for mercury toxicity❓
What product is formed❓
Sodium formaldehyde sulfoxylate
Less soluble metallic mercury
What is the antidote for ferrous ion paracetamol toxicity❓
What product is formed❓
Sodium bicarbonate acetylcysteine
Ferrous carbonate
What harmful substances may chlorinated hydrocarbon insecticides contain❓
What do they cause❓
What are the side effects❓
1. DDT (dichloro-diphenyltrichloroethane) Cyclodienes Toxaphenes Lindane Aldrin
2.
Interfere with active transport of Na+ and K+
- CNS: convulsion/vertigo/tremor/muscle paralysis
Liver: hypertrophy/neoplasm
What harmful substances may organophosphate insecticides (Anti ACh agents) contain❓
What do they cause❓
What are the side effects❓
1. Parathion Malathion Dimethoate Dichlorvos Trichlorfon
2.
Excess ACh-paralysis
What harmful substances may botanical (natural) insecticides contain❓
What are the side effects❓
- Pyrethrum
Rotenone
Nicotine - Depolarization of membranes of NMJs of parasympathetic ganglia
What harmful substances may rodenticides contain❓
What are the side effects❓
Warfarin-anticoagulant
Red squill- CNS paralysis
Indocid- hemorrhage
