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
ï‚§ Food can SLOW this down
ï‚§ pH juices play a role
ï‚§ 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€
o HIGH TI = wide safety margin, no need for routine monitoring
o LOW TI = small safety margin; NEEDS MONITORING; HIGH risk of toxicity
ï‚§ 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€
o Oral:
ï‚§ May need to mix with apple sauceï€
ï‚§ Want patient to sit up/Fowler’s positionï€
ï‚§ “Chin to chest†to help with swallowingï€
ï‚§ REMEMBER! NEVER chew enteric-coated capsulesï€
ï‚§ REMEMBER! Never break/chew extended-release capsules ï€
o Sublingual/buccal:
ï‚§ Keep medication in place until it is completely dissolvedï€
ï‚§ DO NOT eat/drink until it is completely dissolvedï€
o Transdermal:
ï‚§ Wash and dry thoroughlyï€
ï‚§ Place patch on a hairless areaï€
ï‚§ Rotate patch sitesï€
o Eyes:
ï‚§ Put into conjunctival sac