Prescribing in Clinical Dentistry Flashcards
What does enteral administration?
oral
What are the advantages of oral administration of a drug?
socially acceptable
What are the 4 disadvantages of oral administration?
slow onset
variable absorption
gastric acid may destroy drug
‘first pass’ metabolism
Where does blood from the GI tract enter?
liver
How does the blood from the GI tract travel to the liver?
hepatic portal vein
Where do drugs absorbed sublingually go?
straight to systemic circulation
When do drugs reach systemic circulation?
only after passing through the liver once
What is an example of a drug which need to be absorbed not orally?
glyceryl trinitrate
Why is more glyceryl trinitrate needed to achieve the desired effect?
as it is inactivated by the liver when taken orally, need to have higher dose or take sublingually/intravenous
When can first pass metabolism (through liver) activates a drug?
simvastatin
less needed
Why is it important to consider liver function/health when prescribing?
it metabolises the drug, making it active or inactive.
Does non-oral drug admiration have first pass metabolism?
no
What can you predict about non-oral drug administration?
plasma levels
What are disadvantages of non-oral administration?
allergic reactions more severe
access difficulties/self-medication
drug cost higher
What are factors effecting oral absorption?
lipid solubility and ionisation
drug formulation
GI motility
interactions with other substances in gut
GI tract disease (chron’s)
What is bioavailability?
proportion of an ingested drug that is available for clinical effect
How is a drug distributed?
tissue fluid
Is the drug distributed equally to all tissues?
no
example, drugs transported in blood, tissues with high blood flow receive high levels of the drug
How does the drug distribute around the body? (2 ways)
plasma proteins and fatty tissue (lipid binding)
What tissue absorbs the drug and releases it slowly back into plasma?
fatty tissue
(lipid binding)
What are ways plasma proteins effect drugs?
- inactivate
- competitive binding warfarin and aspirin
What is an example of competitive binding of drugs?
warfarin and aspirin
What is phase 2?
preparing the drug for elimination from the body
What are examples of phase 1 reactions?
oxidation
reduction
hydrolysis
What are phase 2 reactions?
CONJUGATION
- glucuronidation, sulphation, methylation, acetylation …
What are examples of drug excretion methods?
renal - urine
liver - bile
lungs - exhale
sweat
saliva
What can saliva samples test?
nicotine levels, smoking compliance
If the method of secretion of the drug is faulty, e.g. liver disease/renal disease, what should be done?
reduce drug dose
What does the blood alcohol elimination curve show?
the level of alcohol at a specific time, you can trace back the predicted levels
