Clinical pharmacology Flashcards
what is a drug?
external substance that acts on living tissue to produce a measurable change in the function of that tissue
give 3 types of drugs used in dentistry
analgesics - reduce post op pain
local anaesthetics - prevent pain
antimicrobials - prevent infection
anxiolytics - reduce anxiety
which messages communicate to ALL tissues?
hormonal
which messages give targeted information for specific tissues?
neural
what drug can replace missing T3 and T4?
thyroxine
how does the sympathetic nervous system affect heart rate?
increases HR via beta receptors
how does the parasympathetic nervous system affect heart rate?
decreases heart rate via cholinergic receptors
what nervous system causes release of adrenaline?
autonomic sympathetic
what nervous system causes release of acetylcholine?
autonomic parasympathetic
give an example of a beta agonist drug
adrenaline
give an example of a beta blocker drug
atenolol
give an example of a cholinergic agonist drug
pilocarpine
give an example of a cholinergic blocker drug
atropine
give 3 possible drug hazards
- drug interactions
- acute toxic reaction
- anaphylaxis/allergy to drug
what drugs should be avoided if on warfarin and/or aspirin?
NSAIDs
how long is a prescription valid for?
6 months
give examples of some prescribing errors
- the decision to prescribe
- wrong drug
- incorrectly completing prescription
- dose
what are the 4 main modes of drug action?
- activation or blocking of receptors
- activating or blocking enzyme function
- facilitating or blocking transport systems
- opening or blocking transport systems
what determines the response to drug-receptor interaction?
- the affinity of the drug binding to the receptor
- the occupancy of the drug
describe how an agonist works
binds to receptor and activates it to produce natural response
describe how a partial agonist works
the drug/receptor effect is more difficult to produce than with an agonist
describe how an antagonist works
they bind to the receptor and do not activate them
- competitive or non-competitive
- reversible antagonists effect can be reduced by increasing agonist concentration
- irreversible antagonist binds and reduces available receptors for agonist
how can drugs change enzyme action?
- competitive substrate antagonism
- non-competitive substrate inhibition
give a drug that affects ion channels
local anaesthetic
what are pharmacokinetics?
what the drug does to the body
what are pharmacodynamics?
what the body does to the drug
what are disadvantages of oral administration?
- first pass metabolism
- GI disease can reduce surface area for absorption
- gastric acid can destroy drug
- food can interact
where does first pass metabolism take place?
liver
where does GI tract blood drain to?
hepatic portal vein which drains to the liver
what is first pass metabolism?
- liver metabolises drug and the drug only reaches systemic circulation after passing through the liver
- FPM can activate or inactivate the drug
where can the drug directly enter the systemic circulation?
rectal and sublingual veins
why is glyceryl tri-nitrate administered sublingually?
FPM inactivates the GTN and very little enters systemic circulation. giving sublingually bypasses hepatic portal system
what is the effect of liver disease on drug metabolism?
reduced metabolism will lead to drug accumulation and toxicity
give an example of a drug activated by FPM
valaciclovir produces aciclover in liver so less doses are needed than aciclover
advantages of intravenous and intramuscular
no drug lost as no FPM
rapid onset
disadvantages of intravenous and intramuscular
severe allergic reactions
high cost
short duration of action
transdermal and subcutaneous advantages
no FPM
prolonged action
transdermal and subcutaneous disadvantages
slow onset due to low blood flow
what is bioavailability?
the proportion of an injected drug available for clinical effect
what may affect bioavailability?
route of administration dosage food in gut poor absorption FPM
how does blood flow affect drug distribution?
drug is distributed pending on blood flow, tissues with the highest blood flow receive highest level of drug
how are drugs distributed?
drug dissolves in blood and is transported bound to plasma protein carriers such as albumin
what is the most common drug metabolism pathway?
p450 mono-oxygenate system
describe the 2 main reactions of drug metabolism
phase 1 changes the drug - oxidation, hydrolysis, reduction
phase 2 - conjugation e.g. sulphation, methylation
what can cause issues with excretion of drugs?
- renal disease will affect renal blood flow and therefore renal ability to excrete drugs - reduce dose
- liver disease can lead to liver failure, reduce doses
what is the plasma half life of a drug?
the time taken to eliminate half the drug
what does it mean if a drug follows first order kinetics?
drug metabolism increases as drug concentration increases
excretion by passive diffusion only
what does it mean if a drug follows zero order kinetics?
drug metabolism is at a fixed rate, not affected by drug concentration
can lead to accumulation if saturation exceeded
