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Pharmacokinetics
Therapeutic Drug Monitoring
Therapeutic Drug Monitoring
 Calculations at Steady State:
 Constant infusion rate of 80mg/hr is given to a patient to achieve a steady state
level of 15mg/L. Pt’s CL=5.3L/h, V=30.8 L.
 If the infusion is stopped immediately, how long until the concentration will
reach 3.75 mg/L?
Therapeutic Drug Monitoring
 When is a specific drug monitored by drawing
concentrations?
 Pharmacodynamic or Pharmacokinetic variability?
 Wide or Narrow therapeutic index?
 Therapeutic effect easy or difficult to monitor
 Concentrations are related or not related to therapeutic and
adverse effects
Therapeutic Drug Monitoring
 Hepatic Elimination
 Low E drug: CL=
 High E drug: CL=
F*=
F*=
 Css=
 Css,u=
 Be able to reproduce chart in notes on slide 25 using these
formulas
Therapeutic Drug Monitoring
 Rifampin, an enzyme inducer is added to a patient’s drug
regimen. What happens to:
 Vmax
 Km
 CLint
 When will it happen?
 Erythromycin, an enzyme inhibitor, is added to a patient’s
drug regimen. What happens to:
 Vmax
 Km
 CLint
 When will it happen?
Hepatic Disease
 When a patient has cirrhosis, what happens to measured




hepatic enzymes such as ALT and AST?
(increase/decrease/stays same)
Are the lab tests quanitative or qualitative?
What happens to INR and albumin?
If a patient with cirrhosis is given oral propranolol, what will
happen to the Css,u?
Does DR need to be changed?
Therapeutic Drug Monitoring
 A patient has liver disease. Drug A undergoes
glucuronidation, whereas Drug B undergoes oxidation.
Which of the following is true:
 A. Drug A will be less affected by liver disease
 B. Drug B will be less affected by liver disease
 C. Drug A will be more affected by liver disease
 D. Drug B will be more affected by liver disease
 E. A and D
Therapeutic Drug Monitoring
 Kidney function:
 Calculate CrCl for a 58 YO female weighing 177 lbs (5 feet, 4
inches), SCr 2.4
Therapeutic Drug Monitoring
 Which is the rate-limiting step for a drug that is formulated
as an extended release version?
 A. Half-life
 B. Volume of distribution
 C. Elimination rate constant (k)
 D. Elimination absorption constant (ka)
 Will it take a short/longer/same time to reach steady state?
Article
Article
 What is it about?
 Basically it talks about risk tolerance vs risk aversion
 Especially focuses & discusses risk aversion (and the effects of
being too cautious about approving drugs based on fear of
adverse effects
Article
 What is a Type I error?
 What is a Type 2 error?
 Type 1: aka false +, basically licensing a drug/causing it to
stay on market, BUT it is causing more HARM than GOOD
 Type 2: aka false -, basically denying a drug license/pulling it
from the market, where it would have caused more GOOD
than HARM
Drug Interactions
Drug Interactions—PK or PD?
 Alcohol + Alprazolam?
 Lovastatin + Ketoconazole?
 Fluconazole + Warfarin?
Drug Interactions--PK
 Can affect ADME
 Explain the interaction with digoxin and amiodarone.
 For what type of drug (HIGH/LOW extraction, ORAL or
IV) must you account for changes in F*?
 Is propranolol a High or Low E drug?
 Patient is started on an oral regimen of propranolol. Does
the dosing rate need to be changed if patient has decreased
liver blood flow?
Drug Interactions
 Grapefruit juice inhibits CYP3A4 in liver, intestines, or
both?
 Rifampin induces CYP3A4 in liver, intestines, or both?
Drug Interactions
 LD=
 A patient (81 kg) develops acute renal failure while in the hospital,
but requires vancomycin to treat her infection. A LD in a person
with normal renal function is 20 mg/kg. Her eGFR is 21 ml/min.
The most appropriate LD is:




A. None, choose alternative to vanc that isn’t renally elimianted
B. Reduce Vanc LD to 500mg
C. Give LD of 1500 mg
D. Give LD of 1000 mg
 When do you change LD?
 Calculate the LD for a patient (80 kg) needed to reach 20 mg/L, if
the patient’s last drug level was 9 mg /L. Vss=0.7 L/ kg.
Drug Interactions
 What does it mean if DMR urine is high?
 DMR= [parent]/ [metabolite]
 What may happen if a child, who is a ultra-fast metabolizer of
CYP2D6, is given codeine?
 A. The child will not experience pain relief, due to metabolizing
the drug too fast
 B. The child will experience pain relief, due to not being able to
metabolize the drug to the active metabolite
 C. The child will experience pain relief, but may also
experience respiratory depression due to excessive metabolite
formation
 D. The child will not experience pain relief, but may experience
respiratory depression due to excessive metabolite formation
Drug Interactions
 Which CYP enzymes do NOT exhibit polymorphisms?
 A. 2C9
 B. 1A2
 C. 3A4
 D. 2C19
Review
 Know warfarin interactions
 Memorize PK tables?
FDA Lecture
FDA Lecture
 What is CDER’s main job?
 What are the two types of applications submitted to FDA?
 If a sponsor wants to submit an application for a small
molecular drug that has previously been FDA approved for an
indication, which of the following describe the application:
 A. BLA, New molecular entity
 B. BLA, sNDA
 C. NDA, New molecular entity
 D. NDA, sNDA
FDA Lecture
 If a drug has just been developed that will meet an unmet





medical need, should it undergo standard or priority review?
How long will that process take?
T/F: Post marketing commitments should be considered, if
the FDA is concerned about safety with a new drug.
What is the difference between PK and PD?
Difference between exposure and response?
What do use we the exposure and response curves to
determine?
What is pharmacometrics?
GOOD LUCK!
Merry Christmas!