BCH 313 Xenobiochemistry Flashcards
What is a xenobiotic?
A chemical substance that is foreign animal life this includes
1. plant constituents
2. drugs
3. pesticides
4. cosmetic flavorings
5. fragrances
6. food additives
7. industrial chemicals and 8. environmental pollutants
How many xenobiotics are humans exposed to the lifetime?
1-3 million
- Media of xenobiotics consumption 2. how does your body react to xenobiotics what does it do to the xenobiotic
Most of these chemicals that gain access to the body via the 1. diet, air, drinking water, drug administration and lifestyle choices 2. undergo broad range of processes of detoxification that in general render them less toxic more polar and readily excretable
How are foreign molecules produced in the intestine?
Foreign molecules are produced in the intestine bacterial enzymatic action upon normal digestion products
What are the effects that xenobiotics produce?
- Pharmacological response
- toxicity
- immunologic reactions
- cancer
What is the name for harmless xenobiotics
Innocular
What is the primary purpose of the biotransformation process?
The primary purpose of the biotransformation process is to convert the lipophilic, non-polar, toxic compound to a more polar, water-soluble form to decrease the permeability of the toxic compound through lipid cell membrane thus protecting cell interior and to facilitate their excretion from the body through urine or bile
Describe negatives or harmful biotransformation reaction with vinyl chloride
Bio transformation of vinyl chloride to vinyl chloride epoxide which covalently binds to DNA and RNA a step leading to cancer of the liver
Describe biotransformation of a paracetamol (in normal dose and in excess) what is its other name?
Acetaminophen also known as paracetamol normally undergoes rapid biotransformation with the metabolites quickly eliminated in the urine and feces hence no toxicity is observed
At high doses the normal level of enzymes may be saturated.
Excess acetaminophen undergoes additional biosynthetic pathway which produces a metabolite that is toxic to the liver
How is paracetamol toxicity treated
Acetaminophen toxicity is treated using N-acetylcysteine
What is the fate of lipophilic xenobiotics
Lipophilic xenobiotics are transformed into more polar and hence readily excreted products
The role metabolism plays in the inactivation of lipids soluble drugs can be quite dramatic e.g.lipophilic barbiturates such as thiopental and pentobarbital would have extremely long half-life if it were for the metabolic conversions to move water-soluble compounds
What is the principal organ of drug metabolism and what are some others?
Liver
GIT
Lungs
Skin
Kidney
What is the first pass effect give examples
Following oral administration many drugs (eg. Isoproterenol, meperidine, pentazocine, morphine etc) are absorbed intact from the swine intestine and transported fast by the portal system to the liver where they undergo extensive metabolism
In what situation would an individual rely on first pass effect
An individual with a compromise liver function may increasingly rely on such intestinal metabolism for drug elimination
Negative traits of first pass effect examples
First pass effect may also limit the bioavailability of orally administer drugs e.g. lidocain, that alternative route of administration must be used to achieve therapeutically effective blood levels
