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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
ï‚· Therapeutic Indexï€Â
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
ï‚· Nursing Considerations for Routes of Administrationï€Â
o Oral:
 May need to mix with apple sauceï€Â
 Want patient to sit up/Fowler’s positionï€Â
 “Chin to chest†to help with swallowingï€Â
 REMEMBER! NEVER chew enteric-coated capsulesï€Â
 REMEMBER! Never break/chew extended-release capsules ï€Â
o Sublingual/buccal:
 Keep medication in place until it is completely dissolvedï€Â
 DO NOT eat/drink until it is completely dissolvedï€Â
o Transdermal:
 Wash and dry thoroughlyï€Â
 Place patch on a hairless areaï€Â
 Rotate patch sitesï€Â
o Eyes:
 Put into conjunctival sac
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