Hyperlipidemia can influence the pharmacokinetics and pharmacodynamics of some highly lipophilic drugs like ketoconazole by altering protein binding, distribution to tissues, and drug metabolism. This study investigated the effects of induced hyperlipidemia on the stereoselective pharmacokinetics of ketoconazole enantiomers in rats as well as its interaction with midazolam. Key findings include hyperlipidemia causing higher volume of distribution for ketoconazole and decreasing its liver uptake, as well as potentiating the drug interaction between ketoconazole and midazolam by decreasing midazolam clearance.

1. The Effects of Hyperlipidemia
on the Pharmacokinetic and
Pharmacodynamic Aspects of
Ketoconazole
Supervisor: Dr. Dion Brocks
1
PhD Student : Dalia Hamdy El Sayed
(2005/2010)

2. Hyperlipidemia
Definition:
An elevation of one or more lipids
including cholesterol, cholesterol esters,
phospholipids and triglycerides in the
bloodstream
Causes:
genetic effect
diet
drugs
diseases
2

3. Hyperlipidemia
Centre of Disease Control, 2004
Adults age ≥ 20 with
high cholesterol serum
levels
17%
3

4. Lipoproteins
4
Apolipoproteins responsible for identification and uptake
by lipoprotein receptors

5. LDL Receptors family: group of cell surface receptors that transport a
number of macromolecules into cells through receptor mediated
endocytosis
LDL Receptors :Highly expressed in Liver & Adrenal glands
Uptake at cellular level
Plasma membrane
Nucleus
Golgi
Chung NS, Adv Drug Deliv Rev. 56(9). 2004 5

6. VLDL Receptors: Highly expressed in heart , brain, adipose and muscle
tissues
Uptake at cellular level
VLDL
Chylomicron
LPL
IDL (VLDL remnant)
Chylomicron remnant
Free Fatty acids
VLDL receptor
Myocardium
FAT/CD36
FATP
FABPpm
Simple
diffusion
Takahashi S, Mol Cell Biochem. 48(1-2):.2003 6
LPL
LDL
LDL
receptor

7. Hyperlipidemia and PK
Recent studies have shown that HL could
influence PK of some highly lipophilic
drugs.
7

8. Hyperlipidemia and PK
Recent studies have shown that HL could
influence PK of some highly lipophilic
drugs.
Metabolising enzymes
8
Clearance and volume
of distribution

9. Hyperlipidemia and PK
Recent studies have shown that HL could
influence PK of some highly lipophilic
drugs.
Nifedipine
Amiodarone
Halofantrine
Cyclosporine A
9

10. Hyperlipidemia and PD
trend of decreasing
mean arterial
pressure
Eliot LA et al.
Unbound
plasma
concentration
Nephrotoxicity was observed after
repeated doses in HL
Aliabadi et al.
Cyclosporine:
10

11. I. Effect of HL
11

12. Ketoconazole
First orally introduced azole antifungal drug.
Chiral drug that is clinically administered as
(1:1) racemate of the cis-enantiomers
12

13. Enantiomers??
13

14. Enantiomers??
polarizer observeranalyzer
14

15. Enantiomers??
15

16. Mechanism of Action
 CYP450 mediated 14-α-
demethylation of lanosterol
Ergosterol biosynthesis
(fungi, mammalian tissues)
Ketoconazole

17. Pharmacodynamics
 (-)-KTZ ~ 2 fold more potent CYP3A inhibitor and more
antifungal activity than its antipode
 KTZ use has been limited by
-serious drug-drug interactions (CYP3A and others)
-adverse effects
In drug development, KTZ is used to study the
possibility of drug interactions due to its ability to inhibit
CYP3A isoforms
Ketoconazole

18. Protein Binding
Ketoconazole

19. Hypothesis
19

20. Rationale
20

21. 21

22. 1ST Stereospecific HPLC Assay in
Biological Specimen
Hamdy DA and Brocks DR. Biomed Chromatogr. 2008 May;22(5):542-7.
22
Chiral Column

23. StereoselectivePKofKTZinRat
(+)-KTZ average
plasma concentration
(Cavg), clearance and
volume of distribution
was ~2.1, 0.5, 0.6 fold
different than (-)-KTZ,
respectively
 same terminal
phase half life
Moderate Extraction
ratio 0.30 and 0.60 for
the (+)-and (-)
enantiomers,
respectively.
Hamdy DA and Brocks DR. . Chirality . 2008
23

24. StereselectivePKofKTZinRat
Hamdy DA and Brocks DR. . Chirality . 2008
(+)-KTZ Cavg is ~2.4
fold higher than
(-)-KTZ
Similar absorption
rate (t max)
 There was no
difference between
oral bioavailability of
both enantiomers
The half life
increase with
increasing dose
24

25. The C max and AUC
showed disproportional
increase with escalating
dose
StereoselectivePKofKTZinRat

26. StereoselectivePKofKTZinRat
Hamdy DA and Brocks DR. . Chirality . 2008
There was no
evidence of
stereoselective
metabolism in
microsomal system.
26
0
1
2
3
4
10mg/L 40mg/L
%unboundfraction
(+)KTZ (-)KTZ
*†
*†
Stereoselectivity in
protein binding

27. Conclusion
KTZ enantiomers show stereoselective
pharmacokinetics
(+)-enantiomer showing
higher concentrations and lower clearance
which is due to its higher protein binding
 KTZ enantiomers showed non linear
pharmacokinetics
27

28. Rationale
28

29. 29
KTZlipoproteindistributioninvitro
0
10
20
30
40
50
60
70
80
90
100
LPDP TRL LDL HDL
(+)KTZPercentassociation(as%ofrecovereddrug)
NL HL
*
*
0
10
20
30
40
50
60
70
80
90
100
LPDP TRL LDL HDL
(-)KTZPercentassociation(as%ofrecovereddrug)
NL HL
*
†
†
*
(+)-KTZ (-)-KTZ
• In NL plasma LPDP bound > 95% of the
KTZ enantiomers
• In HL plasma > 20% of the KTZ recovered
in the lipoprotein plasma fractions
Hamdy DA and Brocks DR. AAPS conference . 2008

30. Conclusion
 KTZ binds to lipoproteins
HL changed the pattern by which the
lipophilic KTZ enantiomers bind to plasma
proteins in vitro
potential change in
pharmacokinetics in HL in vivo ??
30

31. Rationale
31

32. KTZ PK
(+)-KTZ (-)-KTZ
HL no change in
Cavg But higher
Vdss
Time (h)
32
0.1
1
10
100
0 2 4 6
(+)-KTZplasmacConcentration(mg/L)
Time (h)
0.1
1
10
100
0 2 4 6
(-)-KTZplasmaconcentration(mg/L)
Time (h)
HL
NL
Hamdy DA and Brocks DR. Xenobiotics submitted

33. KTZ PK
Stereoselectivity was
changed in HL rats
33Hamdy DA and Brocks DR. Xenobiotics submitted

34. Plasma and Liver PO
HL did not significantly
alter drug in liver
34
†Significant difference between liver and plasma AUC in the
same lipidemic state (α =0.05)
Hamdy DA and Brocks DR. Xenobiotics submitted

35. Liver uptake Confirms the trend
with individual time
points
(-)-KTZ(+)-KTZ
35
0
2
4
6
8
10
12
14
16
18
0 1 2 3 4 5 6
(+)-KTZKp
Time(h)
NL HL
0
2
4
6
8
10
12
14
16
18
0 1 2 3 4 5 6
(-)-KTZKp
Time(h)
***
*
Hamdy DA and Brocks DR. Xenobiotics submitted

36. Conclusion
 Severe HL caused higher Vss
(unable to measure unbound fraction in
HL)
 Decrease in liver uptake of the (-)
enantiomer
Does this affect the
inhibitory potency of KTZ on CYP???
36

37. Rationale
37

38. Background
38

39. Simultaneous Assay for MDZ and
KTZ in Rat Specimen
Hamdy DA and Brocks DR. J. Pharm and Biomed Anal. 2010;53(3):617-22.
39

40. Simultaneous Assay for MDZ and
KTZ in human Specimen
Hamdy DA and Brocks DR. J. Pharm and Biomed Anal. 2010;53(3):617-22.
40

41. 41
KTZ–MDZDrugInteraction
10
100
1000
10000
0 1 2 3 4 5 6 7 8 9
PlasmaConcentration(ng/mL)
Time (h)
NL MDZ NL MDZ + KTZ
NL MDZ KTZ+MDZ
AUC
mg.h/L
2.41±0.597 3.23±0.450
CL
L/h
2.17±0.458 1.57±0.200
Fu
(%)
1.97±0.38 1.78±0.15

42. 42
KTZ–MDZDrugInteraction
10
100
1000
10000
0 1 2 3 4 5 6 7 8 9
PlasmaConcentration(ng/mL)
Time (h)
NL MDZ HL MDZ
NL MDZ HL MDZ
AUC
mg.h/L
2.41±0.597 2.06±0.338
CL
L/h
2.17±0.458 2.48±0.445
Fu
(%)
1.97±0.38 0.760±0.29*

43. 43
KTZ–MDZDrugInteraction
10
100
1000
10000
0 1 2 3 4 5 6 7 8 9
PlasmaConcentration(ng/mL)
Time (h)
NL MDZ NL MDZ + KTZ HL MDZ + KTZ
NL MDZ NL MDZ
+KTZ
HL MDZ
+KTZ
AUC
mg.h/L
2.4±0.59 3.2±0.45 4.8±0.98*
CL
L/h
2.2±0.46 1.5±0.20 1.1±0.22*
Fu(%) 1.9±0.38 1.7±0.15 1.0±0.21*

44. KTZ–MDZDrugInteraction
10
100
1000
10000
100000
0 1 2 3 4 5 6 7 8 9 10 11
KTZplasmaconcentration(ng/mL)
Time (h)
NL HL
HL did not affect the KTZ
parameters in presence of
MDZ
44

45. Conclusion
 HL decreased the unbound fraction of
MDZ but did not affect its PK
HL decreased liver uptake of KTZ
It potentiates the KTZ-
MDZ drug interaction causing higher MDZ
Cavg and lower CL
MDZ did not affect the PK of KTZ in NL
and HL
45

46. II. Effect of HL
46

47. HL
47
1. Increased AM heart uptake
and electrocardiographic
changes
2. and HL serum decreased AM
metabolism in rat hepatocytes

48. Future Directions
 Study the mechanism by which HL
affects the uptake of the lipoprotein bound
drugs
 Investigation of MDZ lipoprotein binding
Effect of HL on the antifungal activity of
KTZ
48

49. Thank You
49
 Dr. Dion R. Brocks
 Dr. Ayman El-Kadi
 Dr. Fakhreddin Jamali
 Dr. Kishor Wasan
 Jackie Fleischer
Lab colleagues
Egyptian Scholarship
Dissertation Fellowship