The journey from administration site into the plasma.
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What are lipid-soluble drugs?
Lipid-soluble drugs are drugs that can be transported across cell membranes and into the circulation.
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What is bioavailability?
Bioavailability is the proportion of drug that is available in the blood in an active form.
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Name a factor that can influence absorption.
GI tract disorder, food in the stomach, reduced blood flow and surface area can all influence absorption.
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What is the first-pass effect?
Substances administered the GI tract via portal circulation are partially metabolized by the liver, so a lower amount of the drug reaches the circulation.
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Distribution is the journey from ______ to _______?
The journey from the circulation across cell membranes to a specified tissue.
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Many drugs bind to what in the blood?
Plasma protein carriers - whilst binded, these have no pharmacological effect.
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Name a factor that can influence distribution.
Blood flow, body temperature, activity levels, inflammation etc.
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What must a drug be in order to cross the blood-brain barrier or the placenta?
Lipid-soluble.
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What is metabolism?
Metabolism refers to how the drug is broken down into a form that can be excreted.
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What are 'pro-drugs'?
These drugs are pharmacologically inactive until metabolized by the liver to their active form.
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Where does metabolism occur?
Mainly in the liver by enzyme action, but also in the kidneys, intestines, lungs and plasma.
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The two phases of metabolism are...?
1 - Various chemical reactions alter the chemical properties of the drug (eg oxidation), 2 - Conjugation: the drug metabolite is made water-soluble, ready for removal by kidneys or via bile
Excretion refers to how the metabolised drug is removed from the body.
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The metabolite is usually eliminated in ________ or _______?
In bile or urine.
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What is the biliary system?
The biliary system involves bile removal by faecal elimination.
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What is the main method of renal elimination?
Glomerular filtration by the kidneys.
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What is enterohepatic recirculation?
This is when some of the drug is reabsorbed from the gut and represented to the liver for further metabolism.
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What are replacement drugs?
These address a deficiency in the body and replace it, e.g. iron and anaemia.
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What are enzyme inhibitors?
These attach themself to an enzyme and stop its activity.
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What are ion channel inhibitors?
These fit into an electrolyte channel to stop it opening.
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Name two laws governing medicines.
The Medicines Act (1968) and the Misuse of Drugs Act (1971).
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What is the therapeutic range?
This is the range of drug concentration in the blood between the minimum amount to give a therapeutic affect and the maximum safe concentration before toxic effects begin to appear.
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What is half-life?
The time required for the concentration of the drug in the plasma to fall to one-half of its initial level.
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What does enteric-coated mean?
These drugs have a special coating that stops the pill from dissolving in the stomach and irritating the lining, or rendering the medication ineffective.
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What are agonists?
These drugs activate receptors.
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What are antagonists?
These drugs block receptors.
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What should you check when administering medication?
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