EFFECT OF HYPERLIPIDEMIA ON DRONEDARONE DISPOSITION By YOUSEF ABDULLAH M

167 Pages·2017·4.52 MB·English

by  Bin Jardan, Yousef

EFFECT OF HYPERLIPIDEMIA
ON DRONEDARONE DISPOSITION

By

YOUSEF ABDULLAH M BIN JARDAN

A thesis submitted in partial fulfillment of the requirements for the degree of

Doctor of Philosophy
in
Pharmaceutical Sciences
Faculty of Pharmacy and Pharmaceutical Sciences
University of Alberta

© YOUSEF ABDULLAH M BIN JARDAN, 2017

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Abstract
The pharmacokinetics of dronedarone, effect of hyperlipidemia on dronedarone disposition and
dronedarone tissue distribution in normolipidemic (NL) and hyperlipidemic (HL) rats were
studied. Novel and sensitive HPLC-UV and LC-MS reverse phase assay methods were
developed. Rat plasma (100 μL) was subjected to a one-step liquid-liquid extraction followed by
separation of the residues after injection into C18 analytical columns. Both methods had excellent
linear relationships between peak height ratios and plasma concentrations. The lower limit of
quantification of HPLC-UV (dronedarone and desbutyldronedarone) and LC-MS (dronedarone)
based on 100 μL of rat plasma were 25 ng/mL and 5 ng/mL, respectively. The HPLC method was
then used to characterize the pharmacokinetic profile of dronedarone in the rat. Single doses were
administered to rats intravenously (4 mg/kg), orally (55 mg/kg) and intraperitoneally (65 mg/kg).
To induce hyperlipidemia (HL), some of the rats to be given oral dronedarone were administered
intraperitoneal doses of poloxamer 407 (P407). Dronedarone was found to possess a high volume
of distribution and moderate clearance in the rat. The drug showed poor bioavailability (<20%)
after oral and intraperitoneal administration. HL increased dronedarone plasma concentrations
measured by area under the plasma concentration vs. time curve. Tissue distribution and hepatic
microsomal metabolism experiments were conducted to explore the cause of these changes in HL.
After oral single doses of dronedarone, rats were anesthetized and plasma and tissue specimens
(heart, lung and liver) were collected. Liver and intestinal microsomal proteins from control, P407
and dietary induced obese rats were harvested and used to measure velocity of
desbutyldronedarone (metabolite) formation from dronedarone. HL increased the geometric mean
area under the concentration vs. time curves of dronedarone by 2.3 to 5-fold. In tissues (heart,
liver and lung), however, concentrations of drug selectively increased or decreased. Heart, the
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site of action of the drug, had the highest levels of dronedarone. Reductions in liver and intestinal
metabolic efficiency (intrinsic clearance) were observed in rats with increased serum lipids (P407
and dietary induced obese) rats compared to controls. The data suggested down regulation in
enzymes involved in dronedarone metabolism occurs in the presence of increased lipid levels in
the serum, which may explain the higher plasma concentrations in rats given P407.

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Preface
This thesis is an original work by YOUSEF ABDULLAH M BIN JARDAN. The research project,
of which this thesis is a part, received research ethics approval from the University of Alberta
Research Ethics Board, Project Name “The Influence of lipids on the pharmacokinetics and
pharmacodynamics of some representative lipoprotein binding drugs”, No. AUP227 and A25.
The method of dronedarone analysis in Methods and Materials section 2.2.1 was published as
Jardan YA, Gabr RQ, Brocks DR., “Pharmacokinetics of dronedarone in rat using a newly
developed high-performance liquid chromatographic assay method”. Biomedical
Chromatography. 2014 Aug;28(8):1070-4. Also, dronedarone pharmacokinetic study in section
2.4 was published as Jardan YA, Brocks DR.,” The pharmacokinetics of dronedarone in
normolipidemic and hyperlipidemic rats”. Biopharmaceutics Drug Disposition. 2016
Sep;37(6):345-51. I was responsible for the experiments, data generation and collection as well
as the manuscripts preparation. The rest of work has not been previously published.

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Dedication
To my parents, Abdullah and Nourah
To my lovely wife and son Tagreed and Fahad
To my brothers and sisters

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Acknowledgements
First of all, I would like to thank my supervisor Dr. Dion Brocks for his continuous guidance,
help and support throughout the PhD program and my supervisory committee Dr. Ayman El Kadi
and Dr. Arno Siraki for their guidance and support during the PhD program. Especially, Dr.
Ayman for his help and guidance with microsome studies and for the unlimited accessibility of
his laboratory facilities.
Also, I would like to thank my lab mates Dr. Raniah, Hetal, Mohammad, Ali, Marwa and Hamdah
for having a friendly work environment in the lab.
Special thanks to Saudi Cultural Bureau, King Saud University for their financial support for my
PhD research.
Lastly, I would like to deeply thank my wife (Tagreed) for her sincere encouragement, and
emotional support throughout my study. Also, I am very grateful to my parents for their prayers
and emotional support.

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Contents
Chapter1: Introduction ............................................................................................. 1
1.1. Lipid and lipoproteins ........................................................................................ 2
1.2. Hyperlipidemia .................................................................................................. 5
1.2.1. Animal models used to assess the effects of hyperlipidemia ...................... 6
1.2.2. P407- induced HL ........................................................................................ 9
1.3. HL and link to obesity ..................................................................................... 10
1.4. Diet-Induced Obesity (DIO) Models ............................................................... 10
1.5. Genetic models of obesity ............................................................................... 11
1.6. Treatment options for HL ................................................................................ 11
1.6.1. Lifestyle changes .......................................................................................11
1.6.2. Pharmacological treatment ........................................................................11
1.6.2.1. Statins or (HMG CoAR) inhibitors .....................................................12
1.6.2.2. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors .....12
1.6.2.3. Bile acid sequestrants ..........................................................................12
1.6.2.3. Ezetimibe .............................................................................................13
1.6.2.4. Nicotinic acid (Niacin) ........................................................................13
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1.6.2.5. Fibrates ................................................................................................13
1.7. Treatment approach in obesity ........................................................................ 14
1.7.1. Lifestyle changes .......................................................................................14
1.7.2. Pharmacological treatment ........................................................................14
1.7.3. Surgical treatment ......................................................................................14
1.8. Effect of HL and obesity on drug disposition ................................................. 15
1.9. Cardiac Arrhythmia ......................................................................................... 21
1.10. Cardiac electrophysiology ............................................................................. 21
1.11. Type of cardiac arrhythmias .......................................................................... 24
1.11.1. Premature (Extra) Beats ..........................................................................24
1.11.2. Supraventricular Arrhythmias .................................................................25
1.11.3. Atrial Fibrillation .....................................................................................25
1.11.4. Atrial Flutter ............................................................................................25
1.11.5. Paroxysmal Supraventricular Tachycardia (PSVT) ................................25
1.11.6. Ventricular Arrhythmias ..........................................................................26
1.11.7. Ventricular Tachycardia ..........................................................................26
1.11.8. Ventricular Fibrillation ............................................................................26
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1.11.9. Bradyarrhythmia ......................................................................................27
1.12. Treatment approaches .................................................................................... 27
1.13. The benzofuran antiarrhythmics .................................................................... 31
1.13.1. Amiodarone .............................................................................................31
1.13.2. Dronedarone ............................................................................................32
1.13.2.1. Absorption .........................................................................................33
1.13.2.2. Distribution ........................................................................................33
1.13.2.3. Metabolism and Excretion ................................................................34
1.14. Rationale, Hypotheses, Objectives ................................................................ 35
1.14.1. Rationale ..................................................................................................35
1.14.2. Hypotheses...............................................................................................36
1.14.3. Objectives ................................................................................................36
Chapter 2. Materials and Methods .......................................................................... 37
2.1. Materials and reagents ..................................................................................... 38
2.2. Methods ........................................................................................................... 39
2.2.1. Development of a reverse phase HPLC-UV assay of dronedarone in rat
plasma. .................................................................................................................39
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2.2.1.1. Instrumentation and chromatographic conditions ...............................39
2.2.1.2. Standard and stock solutions ...............................................................39
2.2.1.3. Extraction procedure ...........................................................................40
2.2.1.4. Recovery ..............................................................................................41
2.2.1.5. Calibration, accuracy and validation ...................................................41
2.2.1.6. Stability of dronedarone in rat plasma ................................................42
2.2.1.7 Assay of desbutyldronedarone .............................................................43
2.3. Development of a liquid chromatography-mass spectrometry (LC/MS) assay
method for the quantification of dronedarone in rat plasma. ................................. 44
2.3.1. Instrumentation and chromatographic conditions .....................................44
2.3.2. Calibration, accuracy and validation .........................................................44
2.3.3. Assessment of matrix effect ......................................................................45
2. 4. Pharmacokinetics of dronedarone in normolipidemic and hyperlipidemic
rats ........................................................................................................................... 45
2.4.1. Animals and experimental procedures ......................................................45
2.4.2. Drug administration and sample collection ...............................................46
2.4.3. Protein binding in plasma ..........................................................................47
2.5. Tissue distribution and microsomal metabolism of dronedarone in rat .......... 48
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