Pharmacokinetic/ Pharmacodynamics in Drug Discovery, Development and Evaluation

Conference given at the Therapeutics and Goods Administration (TGA), 
Australian Federal Ministry of Health, Canberra, ACT, Australia, April 9th, 2001

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Table of Contents

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Personnal presentation 

Personnal presentation 

Registering a new antibiotic : the issues

The ideal antibiotic ...

Will it always be ideal ?

Main causes of antibiotic failures...

Microbiological evaluation is (classically) static

Static techniques are (partly) inappropriate for in vivo projections of sensitivities

Breakpoints introduce artificial (and not always scientific) discontinuties in what is essentially a continuous distribution 

PK / PD ...

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Pharmacokinetic/ Pharmacodynamics in Drug Development and Evaluation of Efficacy

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PK/PD in drug develop-ment A view from FDA

Pharmacokinetic/ Pharmacodynamics and antibiotic resistance...

PK/PD and drug devlop-ment A view from EMEA

Are PK / PD important in resistance ?

Just a few of them… 

Pharmacokinetic/ Pharmacodynamics in Drug Development and Evaluation

Pharmacokinetic/ Pharmacodynamics: What are the goals ?

PK / PD of antibiotics in 2001 ?

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The rest of the talk ...

Methods use to determine which are the pertinent PK/PD parameters

Methods

In vitro dynamic models

Dilution models

Dilution models: a simple, useful system ...

Dilution models: more sophisticated ones...

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The goal is to mimic potentially useful and achievable serum concentration variations

Why in vitro dynamic models ...

Methods

Animal models

Dissociating PK covariables

A typical animal model to establish which PK parameters is associated with efficacy

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End-points of animal models

Relationship Between 24 Hr AUC/MIC and Mortality for FQs in immunocompromised Animal Models with Gram (-) bacilli infection (Craig, 2000) *

Relationship Between 24 Hr AUC/MIC and Mortality for FQs in Immunocompetent Animal Models with Str. pneumoniae infection (Craig, 2000) *

Known PK problems (with solutions) linked with animal models 

Known PD problems with animal models 

Demonstrated advantages of animal models 

Methods

PK/PD of fluoroquinolones in clinics

24h AUC / MIC : what were the data ?

24h AUC / MIC : what were the data ?

What is the 24h-AUC / MIC ratio (AUIC) ?

What is the 24h-AUC / MIC ratio (AUIC) ?

Modeling of the clinical data

Application to 24h AUC /MIC

AUC - - AUC /MIC - - Cmax/MIC - - T > MIC ?

Why are the conclusions of the clinical trials apparently (sometimes and apparently) contradictory ?

Methods

Doctor or Regulator ?

PK/PD and population-based recommendations : the issues

Examples of variations

Obtaining population cumulative frequencies

The rest of the talk ...

PK/PD patterns of antimicrobial activity

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?-lactams : at least 50 % of the time above the MIC...

PK / PD in action: what can you do with a model ?-lactam *

Improving ?-lactam efficacy by reducing the interval

?-lactams PK / PD and resistance

PK/PD patterns of antimicrobial activity (2 of 3) (after WA. Craig, 2000)

AUC / MIC - dependent antibiotics and resistance

AUC / MIC - dependent antibiotics and resistance

PK/PD patterns of antimicrobial activity (3 of 3) (after WA. Craig, 2000)

Aminoglycosides : obtain a peak !

PK / PD in action ... 

PK /PD in action ... 

PK PD in action ... 

Fluoroquinolones : get both a peak and an AUC !

24h-AUC / MIC as a tool to determine acceptable sensitivities to standard doses of FQ

Peak concentrations as a tool to determine acceptable sensitivities to standard doses of FQ

Combining it all …(Peak and 24h-AUC / MIC) as predictors of efficacy standard doses of FQ ...

Combining it all …(Peak and 24h-AUC / MIC) as predictors of efficacy standard doses of FQ ...

Which value of AUC / MIC ?

To increase efficacy of FQ, you need to increase both the AUC and the peak … 

Breakpoints ??

The rest of the talk ...

What does Industry do ?

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The end of the talk ...

What can Regulatory Bodies require ? 1. Preclinical data

What can Regulatory Bodies require ? 2. Clinical data

What can Regulatory Bodies require ? 3. Package insert

Do you do that in your own country ?

Better approaches in antibiotic approval ...

And remember: we are not so far away from one another ...

Author: Paul M. Tulkens 

Email: tulkens@facm.ucl.ac.be

Home Page: http://www.md.ucl.ac.be/facm/facm-conferences.htm

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