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As part of my advanced pharmacokinetics course for students here I
require a formal debate of PK "controversies." The purpose is not to
win or lose (though that tends to become part of it) but rather to
examine papers carefully and come up with reasoned responses to the
Below are some of the topics used each year. My request is for IDEAS
ON OTHER TOPICS that I might use. Any suggestions will be
1. Pharmacokinetic monitoring services are cost-effective!
2. Theophylline concentrations are useful predictors of effectiveness
3. Interpretation of phenytoin concentrations should be based on
measurement of unbound drug!
4. Ideal body weight should be used to predict creatinine clearance
from serum creatinine!
5. Large dose, extended interval (sometimes called "once-daily")
dosing of aminoglycosides is better than traditional dosing!
6. All patients receiving gentamicin should have troughs less than 2
mg/L to prevent toxicity!
7. Peak concentrations of aminoglycosides are valuable predictors of
8. Measuring concentrations of tricyclic antidepressants is necessary
to ensure safe and effective therapy!
9. Vancomycin dosing and pharmacokinetic evaluation should be based on
a one-compartment model (rather than two compartment)!
10. There is no need to measure vancomycin concentrations!
11. All patients receiving aminoglycosides for more than two days
should have concentrations measured!
12. Measuring digoxin concentrations is a waste of time and money!
13. Bayesian analysis improves therapeutic drug monitoring!
14. Neonates do not get toxic on aminoglycosides!
15. Estimates of creatinine clearance from serum creatinine and
patient factors is as accurate as measuring creatinine clearance with
16. Laboratory assays of drug concentrations are very accurate and
can be trusted!
17. The therapeutic range for procainamide is well established and
18. Aminoglycoside "peak" concentrations should be drawn one-half hour
after the end of a dose infusion and "trough" concentrations should be
drawn one-half hour before the next dose!
19. A panel (three or more) of aminoglycoside concentrations is more
accurate than only measuring a peak/trough! (See Zaske et al.)
20. Pharmacokinetic monitoring of phenytoin is unnecessary - "seat of
the pants" dosing is just as effective!
21. When monitoring lithium concentrations, the blood for measurement
should always be taken approximately 12 hours after a dose!
22. Therapeutic drug monitoring is underutilized for many drugs!
23. Measuring saliva concentrations of drugs offers a reliable
approach to therapeutic monitoring!
24. Accurate phenytoin dosing requires measurement of two steady-state
25. Phenytoin dosing should be based on ideal body weight!
26. Aminoglycoside dosing should be based on ideal body weight!
27. Carbamazepine concentrations are useful predictors of
effectiveness and safety!
John E. Murphy, Pharm.D.
Professor and Head
Department of Pharmacy Practice and Science
(520) 626-5730 (P), (520) 626-7355 (FAX)
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Let me throw in a suggestion for controversy subjects that will really get
the discussion going:
Measurements of drugs in blood only provides data on what happens in the
blood. Noninvasive methods are required to measure the time course of drugs
at organ and tissue sites.
Let me hear your comments.
=========================================================================| Professor Walter Wolf, Ph.D. E-Mail: wwolfw.-a-.hsc.usc.edu |
| Director, Pharmacokinetic Imaging Program |
| Department of Pharmaceutical Sciences Telephone: 213-342-1405 |
| University of Southern California Fax: 213-342-9804 |
| 1985 Zonal Ave., Los Angeles, CA 90033 |
| Center for Noninvasive Pharmacology, Los Angeles Oncologic Institute |
| MRI at St. Vincent Medical Center Telephone: 213-484-7235 |
| 2131 Third St., Los Angeles, CA 90057 Fax: 213-484-7447 |
Date: Mon, 13 May 1996 17:31:48 -0500
From: Prasad Tata
Subject: pharmpk Analysis of placebos in placebo controlled studies
Date: 05/10/1996 07:54 pm (Friday)
From: Steve Bramer
Subject: Analysis of placebos in placebo controlled studies
Are there any FDAers out there or experienced individuals running these
types of trials? If so, I need your opinion.
Is it necessary to analyze placebo samples in open-labeled or blinded
studies for all phases of drug development? If so, would it be
acceptable to analyze a fraction of them at random?
from: Prasad Tata
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How about debating the pros and cons of detailed multicompartmental
modeling of pharmacokinetic data as contrasted with classical PKPD
Another good one might be: Linear models are perfectly adequate for
description of pharmacokinetics, and nonlinear models are always a
solution in search of a problem.
Sounds like a fun course....
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How about :
"Most kinetic Drug interations are of theoretical rather than practical
Noel E Cranswick.
,--_|\ noel.-at-.melbpc.org.au fax+61-3-9455 1345
/ Oz \ 0NZ In real life: Noel E Cranswick
\_,--\M/ 0 Melbourne PC User Group, Australia.
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