Lecture 1: Pharmacology 101 Flashcards
What is the difference between pharmacodynamics and pharmacokinetics?
Pharmacokinetics is how the body breaks down and processes a drug.
Pharmacodynamics involves the drugs effect on the body.
What concepts are involved in pharmacokinetics?
ADME.
Factors such as protein binding, lipophilic or hydrophilic, rate or metabolism, type of elimination, method of administration.
What is an full agonist?
A drug that fully binds to a receptor and triggers a response from it.
What is a partial agonist?
A drug that only partially binds to a receptor, leading to a weaker response from the receptor than a full agonist.
What is an antagonist?
A drug that forms a complex with a receptor but does demand a response from it, thus preventing endogenous agonists from exerting effects. (e.g. caffeine blocking adenosine receptors).
What is an inverse agonist?
Inverse agonists, (stronger than antagonists) produce inverse effect of endogenous agonist
Give a brief explanation of the formation of prostaglandins from tissue injury. What enzymes are involved?
When tissue is damaged, phospholipids are released, these are converted to arachidonic acid. Arachidonic acid is converted to prostaglandin H2, from which other PGs are derived. COX-1 and COX-2 are involved in greatly increasing the rate at which these are produced, however arachidonic acid naturally degrades to these products.
What is the function of COX-1? How do inhibitors cause stomach ulcers? Give 2 examples of protective prostaglandins.
COX-1’s primary role involves the production of regulatory and cytoprotective prostaglandins, for example Prostaglandin E2 is crucial for inhibiting gastric acid and pepsin secretion. Thromboxane A is a prostaglandin responsible for amplification of platelet activation and platelet recruitment.
When non-selective inhibitors of COX enzymes are used for long periods of time, damage to the stomach lining can build up, and due to decrease in platelet activation and recruitment, blood is thinner and does not clot as easily exacerbating bleeding caused by ulcers.
Give an example of a COX-1/2 inhibitor vs a selective COX-2 inhibitor.
A non-specific COX inhibitor would be ibuprofen.
A selective COX-2 inhibitor would be celecoxib.
What mechanisms can drugs use to cause an effect?
Non-modifying drugs (e.g. antacids)
Receptor agonists/antagonists
Enzyme inhibitors/agonists
Membrane ionic channel modification (e.g. calcium channel blockers)
Give examples of an ion channel blocking drug, and how it is used. 3 points
Ketamine, nitrous oxide, and PCP (phencyclidine), are all involved in the inhibition of NMDA receptors.
Lidocaine was the first sodium channel blocker to be invented, and blocks sodium ion channels along the axon, making it harder for an action potential to be produced.
Digoxin blocks Na/K/ATPase pumps in cardiac cells, increasing myocardial contractility.
Give 4 examples of non-specific drug classes, and their brief mechanism of action.
- Antacids (reduces pH of stomach acid)
- Astringents, topical, (remove water to tighten skin, or narrowing capillaries to reduce inflammation in case of haemorrhoids).
- Osmotic laxatives (draws water into bowel from bloodstream by osmosis)
- Emollients, topical, (moisturise skin by reducing water loss.
What does A D M E stand for in pharmacology?
A - Absorption
D - Distribution
M - Metabolism
E - Excretion
Where do drugs go basically straight after the stomach once orally ingested? What significance does this have?
To the liver, therefore if these drugs are easily broken down by cytochrome p450 enzymes then other administration methods should be considered.
Why methods of administration are there?
- Ocular delivery
- Buccal delivery
- Sublingual delivery
- Oral delivery
- Intravenous delivery
- Intramuscular delivery
- Topical delivery
- Subcutaneous delivery
- Parenteral delivery
- Epidural / Intrathecal
- Transdermal delivery
- Pulmonary/Nasal delivery
- Vaginal/Rectal delivery
What are the basic concepts/jargon of pharmacokinetics?
Cmax - maximum concentration
Tmax - time at which cmax occurs
What is the difference between an epidural and an intrathecal?
What characteristics would you see in the pharmacokinetics of an orally ingested drug?
What characteristics would you see in the pharmacokinetics of an intravenous delivery of a drug?
What characteristics would you see in the pharmacokinetics of a nasal delivery of a drug?
What can affect drug distribution?
Protein binding levels can be different in different age groups, such as old patients, or those with liver disease will produce less albumin.
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What is the volume of distribution and how is it calculated?
Give some well known examples of drug interactions with food.
What is the order of kinetics? What 2 orders are there?
How the amount of drug is eliminated from the body over time.
Zero order elimination is where the same AMOUNT of drug is eliminated per unit of time (drug elimination is dependant on time and not amount of drug ingested). (2mg eliminated a minute)
FIrst order elimination is when the same proportion of drug gets eliminated per unit of time (2% of drug eliminated per minute)
