chemical toxicology

Created by

Pierre Gasly

Cards (55)

What is LD 50
The lethal dose. It is the amount of a chemical which causes death in 50% of a test population
What are the units for LD 50
mg / Kg
What does a low value of LD 50 mean
That the chemical has high toxicity
What is pharmacokinetics
Studying how the drug is metabolised by the body
What is pharmacodynamics
The effects of the drug
What is an analyte
The chemical being examined
What is a metabolite
The metabolic product of a chemical
Describe heroin pharmacokinetics
It is quickly metabolised.
The acetyl groups are removed to form 6-monoacetylmorphine (6-MAM) and then ,morphine which is conjugated with glucuronic acid.
Glucuronic acid is hydrophilic and excreted in the urine.
Describe the metabolism of alcohol
Ethanol is converted to acetaldehyde using alcohol dehydrogenase.
Which is then converted to acetate using aldehyde dehydrogenase.
Acetate is broken down into carbon dioxide and water.
What contributes to a hangover
The breakdown of ethanol into acetaldehyde and dehydration.
What are the effects of 5-6 units of alcohol on vision
Impaired peripheral and blurred vision.
What are the effects of 8-10 units of alcohol on vision
Tunnel vision.
Night blindness.
Impacts on night vision.
What is 1 unit of alcohol in g
8
What is 1 unit of alcohol in ml
10
How is alcohol detected
In breath or blood.
What is the use of the Blood Breath Ratio
To convert the amount of alcohol in a known volume of air into the amount of alcohol in 1 ml of blood.
What is the blood breath ratio in the US
2,100 : 1
What is the blood breath ratio in the UK
23,000 : 1
How does a breathalyzer measure alcohol content
The alcohol reacts with potassium dichromate in the presence of sulfuric acid.
There is a colour change from orange to green and the absorbance can be measured.
What are the modern methods for breath alcohol
Infrared and fuel cells
How is infrared used to measure alcohol
The alcohol absorbs the infrared light.
Absorbance is proportional to the concentration of alcohol in the breath.
It can then be converted to the amount in the blood using the Blood Breath ratio.
How are fuel cells used in alcohol measuring
The alcohol is used as a fuel to react with oxygen, producing an electrical current.
What is the name for aspirin
Acetylsalicylic acid
What amount of acetylsalicylic acid causes fatal intoxication in adults
10 to 30 g
What amount of acetylsalicylic acid causes fatal intoxication in children
3 g
What are the symptoms of aspirin toxicity
Nausea
Vomiting
Increased temperature
Balance
Tinnitus
Hyperventilation
What causes balance and tinnitus in aspirin toxicity
Affects on the central nervous system
What does severe aspirin toxicity cause when it affects the CNS
Coma and eventually death
Why is aspirin a pro-drug
It must first be metabolised into an active molecule.
Describe the metabolism of aspirin
It is converted into salicylate and acetate using the acidic environment of the stomach.
The salicylate is absorbed into the blood stream.
How is aspirin measured
Use chromatography or spectroscopy to determine the plasma salicylate levels.
Measure every 4 hours after consumption and then every 2 hours once the salicylate levels decrease.
When do peak levels of salicylic acid arise
1 hour after consumption but may be delayed in an overdose.
What forms of chromatography are used in aspirin measurement
Gas (GC) and high performance liquid chromatography (HPLC).
How is spectroscopy used in aspirin measurement
Salicylic acid reacts with Fe 3+ to produce ferric salicylate and hydrochloric acid.
The colour change is from colourless to purple.
What is metabolic acidosis
When the pH of the extracellular fluid decreases.
What is the effect of metabolic acidosis in aspirin toxicity
The decreased pH of the extracellular fluid results in an increased level of protonated salicylate acid which can cross cell membranes more easily.
What are the bodies mechanisms to combat metabolic acidosis
Hyperventilation [Kussmaul respiration] to remove carbon dioxide.
And a renal compensation mechanism.
Which method of combatting metabolic acidosis is slower
The renal compensation mechanism
Which method of combatting metabolic acidosis is faster
Kussmaul respiration known as hyperventilation
Which method of combatting metabolic acidosis is more effective
The renal compensation mechanism