pharmacokinetics - drug administration Flashcards
(22 cards)
what does drug administration refer to
the many techniques in which drugs can be given
what are the 5 main methods of drug administration?
intravenously (IV)
oral drugs
topically
transdermally
mucosal membranes
intravenous (IV) drug administration definition
when drugs are injected directly into bloodstream
give 3 advantages of IV administration
- skips first pass metabolism, where drug could get broken down
- immediately 100% bioavailable
- patient doesn’t need to be conscious
give 2 disadvantages of IV administration
intrusive method (injection)
potential site for infection
give 3 examples of oral drug administration
pills, tablets, liquids/syrups
give 2 advantages of oral drugs
- easy administration, don’t need to be a trained professional
- non invasive
give 3 disadvantages of oral drugs
- slow to get into systemic circulation
- cannot be given to an unconscious / vomiting / uncooperative patient
- physicochemical properties may lead to poor absorption via oral route
Cmax definition
the maximum concentration of drug in systemic circulation
i.e. extent of bioavailability
Tmax definition
time taken to achieve Cmax
compare Cmax for IV vs oral administration
Cmax for IV administration is the time of administration, it decreases steadily/exponentially as drug is excreted
Cmax for oral drugs is much lower than IV but is achieved after some time, then decreases as it is excreted (distribution curve shape)
compare Tmax for IV vs oral administration
Tmax for IV is the time of administration = 0
Tmax for oral drugs is after some time, later than IV
topical administration definition
when drugs are applied to the area directly e.g. as creams
give 3 areas that often are targets of topically administered drugs
eyes, ears, skin
why are topical drugs used for eyes?
eyes , like the brain, are enclosed within membranes that are difficult for drugs to penetrate from systemic circulation
transdermal administration definition
when drugs are applied to the skin and slowly absorb into the body/circulation (skin must be permeable to drug)
give 1 advantage of transdermal administration
can be used as a slow release mechanism, as membranes allow continual slow dosing of the drug
give 1 disadvantage of transdermal administration
very specific physicochemical properties are needed for this route, as must be able to permeate the skin
mucosal drug delivery / administration via mucosal membranes definition
when drug is administered to very moist areas + dissolves, such as mouth, vagina, rectum
give 5 advantages of mucosal drug delivery
- comparatively short distance to site of action
- bypasses frist pass metabolism
- avoids harsh pH in GI tract
- often painless
- patient can be unconscious
give 2 disadvantage for mucosal drug delivery
few drugs have the correct chemical properties to allow this route
patient discomfort
give one example of mucosal drug delivery
asthma treatment is delivered directly to lungs via inhalation - originally orally formulated but had side effects relating to the heart - inhalation has a more rapid response, even though only 15% of drug reaches lungs (most gets stuck on tongue/back of throat)
