Pharmacokinetics and Routes of Administration

 Absorption – how quickly or how well it is absorbed; DEPENDS ON THE ROUTE

o Oral – takes a while, must pass through the GI tract

 Food can SLOW this down

 pH juices play a role

 Liquids vs extended release tablets

o Sublingual – quick, under the tongue

o Intradermal/topical – slow, gradual

o Intravenous (IV) – the FASTEST route; immediate absorption

 Distribution – requires binding proteins of medication

o Albumin is a common binding protein

 Metabolism – medication is inactivated

o Occurs primarily in the LIVER

o Factorsthat Influence Metabolism:

 Age – dysfunction of liver

 Children – metabolism is not mature yet

o First-pass effect – medications are inactivated through their first pass of the liver;

THEREFORE, you may need a HIGHER DOSE of the medication to reach therapeutic

effects

 Excretion – primarily done by the KIDNEYS

 Therapeutic Index

o HIGH TI = wide safety margin, no need for routine monitoring

o LOW TI = small safety margin; NEEDS MONITORING; HIGH risk of toxicity

 Ex: vancomycin; need to draw peak/trough blood levels

 Half-life – the amount of time it takes for the medication in the body to drop by 50%

o Short half-life – leaves the body quickly

o Long half-life – lingers in the body for long periods; HIGH risk of toxicity

 Agonist – medication designed to produce an action

 Antagonist – opposes the action

 Nursing Considerations for Routes of Administration

o Oral:

 May need to mix with apple sauce

 Want patient to sit up/Fowler’s position

 “Chin to chest” to help with swallowing

 REMEMBER! NEVER chew enteric-coated capsules

 REMEMBER! Never break/chew extended-release capsules 

o Sublingual/buccal:

 Keep medication in place until it is completely dissolved

 DO NOT eat/drink until it is completely dissolved

o Transdermal:

 Wash and dry thoroughly

 Place patch on a hairless area

 Rotate patch sites

o Eyes:

 Put into conjunctival sac