6. Routes of administration Flashcards
What are the advantages of oral administration?
-convenient
-placed at site of action
What are the disadvantages of oral administration?
-delayed absorption
-reduced or increased absorption following food
-can have uneven drug distribution
-slow or irregular absorption
-swallowing tablets without liquid can lodge in the oesophagus
What are the advantages of rectal administration?
-can give as suppositories or suspensions
-rich blood and lymph supply
-can give drugs which the stomach would find irritant
-suitable to route if patient is vomiting, unable to swallow, migraine, lack of cooperation
What are the disadvantages of rectal administration?
-dose requirements may be slightly greater than oral requirement
-psychological/ embarrassment/ like route too much
-repeated use can produce rectal inflammation
-absorption can be unreliable
What does topical/ transdermal administration involve?
-skin
-eye
-ear
-lungs
-rectal
-vagina
e.g creams, inhalers, drops and creams
What are the advantages of topical administration?
-provision of high concentration locally
-transdermal- release drug through a rate controlling membrane into the skin which absorbs into the stream
What are the disadvantages to topical administration?
-if there is tissue damage, absorption into the bloodstream can occur (and first-pass metabolism is bypassed)
What are the advantages of intravenous (e.g bolus or infusion) administration?
-rapid injection- delivered to organs with high blood flow
-rapid, effective, predictable blood concentration levels
-useful drugs that can’t be absorbed from the gut/ too irritant
What are the disadvantages of intravenous (e.g bolus or infusion) administration?
-rapid concentration rise if given too quickly can be a problem
-irritant medicines can cause thromboses
-cannula inserted can be painful
What are the advantages of intramuscular administration?
-reliable route, suitable for irritable drugs, suitable depot injections
-absorption in more rapid than subcutaneous
-bypasses first metabolism
What are the disadvantages of intramuscular administration?
-not acceptable self administration
-painful
What are the advantages of inhalation (e.g gas, aerosol) administration?
-drugs are rapidly absorbed or eliminated
-self administration is practical
-local concentration can be using it topically to act on bronchi which minimises wider effects within the body
What are the disadvantages of inhalation (e.g gas, aerosol) administration?
-specific equipment required e.g nebuliser/ inhaler can be difficult to use
-training needs to be given to use equipment
-obstructions in the lungs e.g mucus plugs can cause lack of absorption
What is first pass metabolism?
-drugs administrated orally are absorbed by the gastrointestinal tract
-these are transported via the hepatic portal vein to the liver
-liver metabolises the drug
-once metabolised the drug is then distributed via the bloodstream around the body
-so less active drug reaches the intended target issues
What are the advantages of buccal (in the cheek) and sublingual (under the tongue) administration?
-absorption in the mouth through the mucous membranes
-bypasses rest of gut
