Drug delivery systems Flashcards
what are the three key factors that determine the drug delivery system we use?
The dose of drug to be given
The frequency of administration
The timing of administration
what other things should we take into account when choosing a dosage regime?
Recommended dose (BNF / BNFc) renal and hepatic function age and weight starting dose and what do we want to increase the dose too?
Does oral medication have a systematic or a local affect?
systematic.
Where does absorption take place (usually) when the drug is taken orally?
GI tract
what does a solution administration allow?
Naso - gastric - good if the patient has swallowing difficulties.
What is a suspension?
A dispersion of a course drug particles in a liquid phase.
When taking tablets, what determines the rate of reaction?
Dissolution / tablet break down
What are enteric coated tablets?
Tablets in which disintegration is delayed until they reach the small intestine.
why may a tablet be enteric coated?
1) to protect drug from stomach (omeprazole)
2) to protect stomach from drug (aspirin)
Why are prolonged delayed response formulations useful?
their good for disorders that require prolonged therapy.
they maintain drug levels within a therapeutic range
they reduce the need for frequent dosing.
How are some prolonged delayed response drugs administered?
orally -
parental
surgical implants - ‘the rod’
what does a pro drug depend on?
metabolism to activate it.
what are the benefits of using pro drugs?
prolonged duration of action
avoidance of degradation of drug in the gut.
what type of drugs is buccal and sublingual administration good for?
drugs that have extensive pre- systematic or first pass metabolism.
Does rectal administration provide a local or systematic response?
can do both!
Does vaginal administration provide a local or systematic response?
local
What are good ways of administering drugs that have a short half life?
IV or injection based.
what are some benefits of injection based administration?
it is fast, bypasses first mass metabolism, can be given to unconscious patients.
Why might IV medication be given slowly?
to prevent toxic effects.
what is good about intramuscular injections?
they allow a more sustained duration of action - up to months.
Why are subcutaneous injections good?
they bypass the need for venous access.
what is a transdermal drug delivery system?
adhesive patches containing drug are stuck to the skin.
what is percutaneous administration? local or systematic
creams ointments and skin patches
local and systematic
What do skin patches allow?
Controlled, sustained blood levels of drug.
Where does inhalation direct the drug?
Directly to the lungs.
Does inhalation have systematic or local effects?
systematic (anaesthetic) and local (salbutamol for asthma)
what is essential for inhalation administration?
patient education
what are the benefits of inhalation?
they are rapid, direct, not many side effects
How can monoclonal antibodies be used to help treat disease?
A toxic drug can get attached to them - and they will travel straight to the cancer site.
What is good about liposomal drug delivery.
Since the drugs are packed into liposomes it reduces their toxicity, more drug makes it to the diseased site and less effects other sensitive tissue.
What are some nano carriers?
nano shells, nanoparticles, nano tubules.
whats good about nano carriers?
they take drugs to a specific location, and have less toxicity and side effects.
What happens in a genetic transfer system?
A natural virus with a therapeutic gene injected goes to target cells.
