Modeling of cardiac uptake, binding kinetics and inotropic response of amidarone, verapamil and {α_tn1-adrenergic [alpha 1-adrenergic] agents in isolated perfused rat heart [Elektronische Ressource] / von Pakawadee Sermsappasuk

Modeling of Cardiac Uptake, Binding Kinetics and
Inotropic Response of Amiodarone, Verapamil and
a -Adrenergic Agents in Isolated Perfused Rat Heart 1

D i s s e r t a t i o n
zur Erlangung des akademischen Grades
doctor rerum naturalium (Dr. rer. nat)


vorgelegt der

Naturwissenschaftlichen Fakultät I
Biowissenschaften

der Martin-Luther-Universität Halle-Wittenberg

von
Frau Pakawadee Sermsappasuk
geb. am 24.01.1976 in Bangkok, Thailand

Gutachter:
1. Prof. Dr. Michael Weiss
2. Prof. Dr. Reinhard Neubert
3. PD Dr. Willi Weber


Halle (Saale), 19. Dezember 2007
urn:nbn:de:gbv:3-000012862
[http://nbn-resolving.de/urn/resolver.pl?urn=nbn%3Ade%3Agbv%3A3-000012862]


Table of Contents

1. Introduction ................................................................................................. 1
1.1. Pharmacokinetic/ Pharmacodynamic Modeling Concept................................ 1
1.2. Cardiophysiology........................................................................................... 3
2. Langendorff Heart....................................................................................... 7
2.1. Principle ........................................................................................................ 7
2.2. Langendorff Isolated Perfused Rat Heart System ........................................... 9
2.3. Langendorff Isolated Perfused Heart Preparation ......................................... 11
3. Model Development Process.......................................................................12
3.1. Measurement Model .................................................................................... 13
3.2. Parameter Estimation................................................................................... 13
3.3. Model Selection........................................................................................... 14
4. Amiodarone.................................................................................................15
4.1. Background ................................................................................................. 15
4.2. Materials and Methods................................................................................. 16
4.2.1. Drugs and Chemicals ........................................................................... 16
4.2.2. Experimental Protocol.......................................................................... 16
4.2.3. Quantification of Amiodarone.............................................................. 17
4.2.4. PK/PD Model and Data Analysis ......................................................... 18
4.3. Results......................................................................................................... 22
4.4. Discussion ................................................................................................... 29
5. Verapamil....................................................................................................31
5.1. Background ................................................................................................. 31
5.2. Materials and Methods................................................................................. 33
5.2.1. Drugs and Chemicals ........................................................................... 33
5.2.2. Experimental Protocol.......................................................................... 33
5.2.3. Quantification of Verapamil................................................................. 35
5.2.4. PK/PD Model and Data Analysis ......................................................... 35
5.3. Results and Discussion ................................................................................ 40
5.3.1. Effect of Amiodarone on PK/PD Modeling of Verapamil..................... 40
5.3.2. Effect of Endotoxemia on PK/PD Modeling of Verapamil ................... 53
6. a -Adrenergic Agents................................................................................61 1
6.1. Background ................................................................................................. 61
6.2. Materials and Methods................................................................................. 63
6.2.1. Drugs and Chemicals ........................................................................... 63
6.2.2. Experimental Protocol.......................................................................... 63
6.2.3. Quantification of Prazosin.................................................................... 64
6.2.4. Cumulative Dose-Response Curve of Phenylephrine............................ 64
6.2.5. PK/PD Model and Data Analysis ......................................................... 64
6.3. Results......................................................................................................... 71
6.4. Discussion ................................................................................................... 76
7. Summary.....................................................................................................79
8. Zusammenfassung ......................................................................................81
9. References ...................................................................................................83


i Abbreviations
AIC Akaike information criteria
AR Agonist receptor occupation
2+Ca Calcium
Ci Curie
CL Permeation clearance (distribution clearance, transcapillary uptake P
clearance)
C(t) Concentration at time t
C (t) Concentration in effect site e
C (t) Input concentration to the heart in
C (t) Output concentration from the heart out
CV Approximate coefficient of variation of parameter estimate
CVR Coronary vascular resistance
DMSO Dimethyl sulfoxide
E Baseline effect 0
EC Excitation-contraction
EC Concentration required to produce 50% maximal response 50
E (t) Direct negative inotropic effect D
E Maximum response max
E(t) Inotropic effect
E (t) rebound inotropic effect T
f Free fraction in plasma u
g Extent of tolerance development
h Hour
HR Heart rate
HPLC High-performance liquid chromatography
I Dosing rate
ip Intraperitoneal
K Equilibrium dissociation constant A
K AR producing 50% of f E max
k First-order uptake rate constant in
k First-order rate constant of irreversible tissue binding ir
k Association rate constant on
k Dissociation rate constant off
k First-order rate constant of transport from extravascular out
compartment to vascular compartment
K Partition coefficient p
K Partition coefficient related to unbound drug concentration pu
l Liter
LPS Lipopolysaccharides

ii LVDP Left ventricular developed pressure
LVEDP Left ventricular enddiastolic pressure
LVSP Left ventricular systolic pressure
M Molar
min Minute
ML Maximum likelihood
mol Mole
M Transit compartment i i
MTT Mean transit time
N Hill coefficient
PE Phenylephrine
PK/PD Pharmacokinetic/pharmacodynamic
Pgp P-glycoprotein
PRZ Prazosin
Q Flow rate
2R Coefficient of determination
R Amount of receptor sites available for binding tot
s Second
S.D. Standard deviation
S.E.M. Standard error of mean
SR Sarcoplasmic reticulum
t Delay time constant
t Half-life 1/2
V Volume of an additional compartment to account for the mixing in 0
nonexchanging elements of system
V Volume of distribution at steady state ss
V Vascular volume vas
x drug amount in compartment i i
f Chain of cellular process

iii 1. Introduction

1. Introduction
1.1. Pharmacokinetic/ Pharmacodynamic Modeling Concept
Pharmacokinetics involves the kinetics of drug absorption, distribution,
metabolism and excretion, or in other words, it is defined as the use of mathematical
models to quantitate the time course of drug absorption and disposition in man and
animals (Riviere, 1999). Pharmacodynamics has been defined as the study of the
biologic effects resulting from the interaction between drugs and biologic systems
(Holford and Sheiner, 1981). Modeling “provides a systematic way of organizing
data and observations of a system at cell, tissue, organ, or whole animal (human)
levels” and “affords the opportunity to better understand and predict physiological
phenomena” (Epstein, 1994). Pharmacokinetic/pharmacodynamic modeling has been
used as a tool to understand the impact of dose or drug concentration on
pharmacological response.
Assuming a compartmental structure, pharmacokinetic models can be written
in form of sums of exponentials, or differential equations based on mass-balance, or
mass-action principles. For pharmacodynamics, many mathematical models have
been proposed. The most widely used pharmacodynamic models are the E -model max
and the sigmoid E -model which are often regarded as empiric mathematical max
functions that describe the shape of the concentration-effect relationship for a
particular drug. However, these models cannot distinguish between the occupation
and the activation of a receptor by an agonist. In contrast, the operat