Clinical Pharmacokinetics

Question 1

what provides the basis for “usual dose”

Answer 1

population pharmacokinetics which are derived from averages of healthy adults +/- pediatric population

Question 2

what to consider when giving the drug topically, transdermally, or subcutaneously

Answer 2

• thick vs thin skin
• intact vs impaired skin
• lipophilic vs hydrophilic drug
• skin temp

Question 3

calcium levels and serum albumin

Answer 3

• reported calcium levels measure calcium bound to albumin, so decr albumin can result in falsely low calcium level (80% bound)
• hypercalcemia can occur if the level isn’t interpreted correctly
• ionized calcium=nonbound calcium

Question 4

metabolism basics

Answer 4

how a medication is broken down to less active, more water soluble by products

Question 5

phase I metabolism reactions

Answer 5

-reduction, oxidation, hydrolysis with Cyp450

Question 6

phase II metabolism reactions

Answer 6

• conjugation

- glucuronidation, acetylation, sulfation

Question 7

most drugs undergo _____ elimination

Answer 7

renal

Question 8

can overestimate renal function if using actual creatinine level if….

Question 9

hemodialysis can filter out hydro-_____ drugs of ____ molecular weight

Answer 9

hydrophillic; small

Question 10

acute renal failure causes

Answer 10

• dehydration
• dye
• medications

Question 11

chronic renal failure causes

Answer 11

-diabetes, hypertension, lupus, transplant

Question 12

What four questions should you ask to individualize drug therapy?

Answer 12

1) what is the best route to enhance absorption?
2) Will the drug get to where I want it? (target site, perfusion, obese vs wasting, and edematous vs dehydrated)
3) assessment of hepatic and renal function
4) concomitant medications

Question 13

PK variations in neonates

Answer 13

• immature skin has increased skin hydration— incr absorption of topical products
• incr extracellular fluid— incr Vd of water soluble drugs
• metabolic paths mature at different times
• GFR, tubular secretion, and reabsorption are immature at birth

Question 14

PK variations in the elderly

Answer 14

• skin thinning =incr absorption of topical products
• incr adipose tissue = incr Vd of fat soluble drugs
• decr extracellular fluid — decr Vd of water soluble drugs
• age related changes in renal function = decr GFR

Question 15

Therapeutic drug monitoring

Answer 15

• check drug levels to modify the dose based on your pt because originally, you prescribe a dose based on population pharmacokinetics
• you should make adjustments when the patient is at steady state
• assess the test drawn in relation to when it was drawn in relation to the administered dose and from where it was drawn

Question 16

Drug interactions and ADME

Answer 16

• absorption: drug A affects Drug B, pH changes, and chelation
• Distribution: binding site competition (albumin) and disease state alterations in plasma proteins, fluid status, and adipose
• Metabolism: hepatic= Cyp450 enzymes= induction or inhibition
• Elimination: competition for pathways= mainly renal

Question 17

types of interactions

Answer 17

• drug-drug: drug A incr/decr drug B, drug A causes toxic effect of Drug B, or incr adverse drug reactions
• drug-nutrient reaction: primarily oral and bioavailabilyt/efficacy/metabolism
• Drug-Disease state: drug may worsen disease state or disease stay could affect drug
• interactions can be intentional or unintentional