Chapter 1:
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
▪
...
Chapter 1:
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 Factors that Influence Metabolism:
▪ Age – dysfunction of liver
▪ Children – metabolism is not mature yet
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
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