Clinical Pharmacokinetics Flashcards
(23 cards)
Clinical considerations with tube feeds
Jejunal tubes are not great for enteral absorption
Not all tablets can be crushed or opened (sustained-/controlled-release drugs)
Blood-brain barrier - variation in permeability
Non-inflamed: tight web with minimal penetration
Inflamed: increased spaces, possibly better penetration
Less protein binding: more crossing the BBB
First and second phase of hepatic metabolism
Phase I: reduction-oxidation, hydrolysis
Phase II: conjugation
Must drugs are eliminated through the __
Kidneys
Actual serum creatinine instead of creatinine clearance could do what to the estimate of true renal function?
Overestimate it
Compare acute vs chronic renal insufficiency in regards to pharmacologic considerations.
With acute renal failure, you must readjust to more normal dosage after kidney injury is reduced. CKD will continue on that altered dosing regimen.
What can happen with hemodialysis?
Some of the drug can be filtered out, especially if they’re hydrophilic and small
What is another consideration with renal disease?
The dose will generally not need adjustment if the drug is primarily excreted through means other than the kidneys
Interpatient variabilites
Renal function, hydration status
Intrapatient variability
Clinical status
Skin of neonates
Increased hydration leads to increased absorption of topical products
Vd in neonates
Higher Vd of water soluble drugs due to increased extracellular fluid
What processes are immature at birth?
Phase II metabolism, tubular secretion, reabsorption
Skin of elderly patients
Thin; increased absorption
Vd in elderly patients
Increased Vd of fat soluble drugs due to increased adipose tissue
Decreased Vd of water soluble drugs due to decreased ECF
Renal function in elderly patients
Decreased
Steady state is dependent only on what?
Half-life
Examples of drugs that need TDM
Some antibiotics, antiepileptic agents, and anticoagulants
Types of drug interactions
Drug-drug
Drug-nutrient
Drug-disease state
Level of drug action
Examples of pharmacokinetic incompatibility: absorption
Chelation and changes in stomach pH
Examples of pharmacokinetic incompatibility: distribution
Competition for binding sites
Changes in protein binding due to disease
Changes in extracellular fluid or adipose
Examples of pharmacokinetic incompatibility: metabolism
Inducers/inhibitors of CYP450
Examples of pharmacokinetic incompatibility: elimination
Competition for elimination pathways (renal is most common)
Decreased or increased elimination
