Investigation of Cerebrospinal Fluid (CSF) Pharmacokinetics of Ondansetron
Phase: NA
Conditions: Pain
Sponsor: Washington University School of Medicine

 
Simon Haroutounian, PhD © 
1 
 
RESEARCH PROTOCOL 
 
 
Investigation of cerebrospinal fluid (CSF) pharmacokinetics of 
ondansetron 
 
Simon Haroutounian, PhD 
Assistant Professor 
Division of Clinical and Translational Research 
Department of Anesthesiology 
Washington University School of Medicine  
660 S. Euclid Ave, Campus Box 8054 
Saint Louis, MO, 63110 
Tel: 314-286-1715  
Fax: 314 286-2948 
E-mail: simon.haroutounian@wustl.edu 
 
 
Co-investigators: 
 
Evan Kharasch, MD, PhD 
Russell D. and Mary B. Shelden Professor of Anesthesiology 
Director, Division of Clinical and Translational Research 
Department of Anesthesiology 
Washington University School of Medicine  
Tel: 314-362-8796 
kharasch@wustl.edu  
 
Carl Nielsen, MD 
Professor of Anesthesiology 
Department of Anesthesiology 
Washington University School of Medicine  
E-mail: nielsenc@anest.wustl.edu  
 
Chris C. Lee, MD, PhD 
Associate Professor of Anesthesiology 
Department of Anesthesiology 
Washington University School of Medicine 
E-mail: climd@wustl.edu 
 
 
 
 
 
 
 
 
 
 
Version Date:  October 18, 2016 

 
Simon Haroutounian, PhD © 
2 
 
1.  SYNOPSIS 
 
Study Title 
Investigation of cerebrospinal fluid (CSF) pharmacokinetics of 
ondansetron 
 
Brief Title 
CSF PK of ondansetron 
Objective 
To determine human cerebrospinal fluid (CSF) and plasma 
pharmacokinetic parameters of 5HT3R antagonist ondansetron after 
intravenous administration. 
Hypothesis 
Approaches to enhance CNS penetration of ondansetron might be useful 
for obtaining analgesic effect with 5HTfev antagonists in neuropathic 
pain. 
Study Period 
Planned enrollment duration: Approximately 3 months 
Planned study duration: One (4-hour) study day per subject, on the day 
of knee/hip arthroplasty surgery. 
Number of Subjects 15 evaluable subjects having elective hip or knee arthroplasty with 
spinal anesthesiafrom up to 30 consented subjects. 
Study Treatment  
Single intravenous 15-min infusion of 16mg ondansetron. 
Study Design 
Prospective, open-label, pharmacokinetic pilot study.  
Inclusion and 
Exclusion Criteria 
Inclusion criteria: 
1. Age between 18 and 70 years old;  
2. Patients planned to undergo  hip or  knee arthroplasty with spinal 
anesthesia; 
 
3. Ability to provide informed consent 
Exclusion criteria: 
4. Not giving consent to participate in the study; 
5. Patients with history of or current hepatic or renal insufficiency; 
6. Patients with BMI ≥ 33; 
7. Patients with heart failure or active arrhythmias; 
8. Patients with severe systemic disease that is a constant threat to 
life; 
9. Contraindication or allergy to ondansetron; 
10. Pregnancy or lactation. 
11. Prisoners 
Measurements 
Ondansetron CSF and plasma Pharmacokinetics: 
1. A single 4-mL CSF sample per subject. 
2. Serial blood sampling at 0 (pre-infusion), 15, 30, 60, 120, and 
180 min after ondansetron administration. 
Genotyping: A blood sample will be obtained at baseline for 
determining the following single nucleotide polymorphisms (SNPs) as 
confounders of ondansetron PK parameters: 
1. ABCB1 gene (p-Glycoprotein transporter): C3435T, G2677T, T-
129C, G1199A, C1236T.  

 
Simon Haroutounian, PhD © 
3 
 
2. In SLC22A1 gene (OCT1 transporter): R61C, C88R, G401S, 
M420del, G456R. 
Statistical 
Methodology 
This is a pilot/feasibility study. Individual plasma concentration-time 
data will be analyzed using non-compartmental methods in Phoenix 
WinNonlin® 6.1, to determine ondansetron PK parameters such as 
volume of distribution (Vd), clearance (CL), maximum plasma 
concentration (Cmax), and the time to reach maximum concentration 
(Tmax). 
A compartmental population-based PK model will be constructed, to 
determine the pharmacokinetic variables of ondansetron in CSF, and 
allow for the estimation of the partition coefficient between the plasma 
and CSF.  
 

 
Simon Haroutounian, PhD © 
4 
 
2.  STUDY PROTOCOL  
 
2.1 Background and Significance 
Neuropathic pain [NeuP] affects 7-8% of the adult population and is particularly challenging 
to treat. More than 30% of neuropathic pain patients continue to suffer despite treatment; and there is 
clearly an urgent need for new treatment approaches. However, the translation of findings from 
current neuropathic pain animal models to clinical trials have been extremely disappointing, with 
multiple pre-clinically promising agents failing to show robust clinical effectiveness; suggesting that 
1) additional pharmacodynamic (PD) and pharmacokinetic (PK) factors responsible for effective 
animal-to-human translation need to be considered, and 2) because of a large inter-subject variability 
in pain mechanisms and treatment response, an “all-comers” approach is suboptimal in yielding 
significant leaps forward in the success of treating neuropathic pain. Therefore, addressing possible 
PK and PD translational gaps and investigating genotypic and phenotypic predictors of response can 
improve the translational process and allow more effective drug discovery and individual analgesic 
tailoring in neuropathic pain. 
Serotonergic 5HT3Rs in the central nervous system (CNS) have been identified as a 
promising pharmacological target in neuropathic pain [1, 2]. After peripheral nerve damage the 
character of serotonergic descending modulation changes from inhibitory to facilitatory through 
5HT3Rs in the spinal cord [3, 4]. This finding is supported by studies demonstrating that intrathecal 
(IT) administration of 5HT3R antagonists such as ondansetron alleviates mechanical and thermal 
hypersensitivity in animal nerve injury models [1, 5]. In contrast to IT administration, systemic 
ondansetron does not produce consistent analgesia. However, this is not surprising, considering that 
CNS concentrations of 5HT3R antagonists such as ondansetron highly depend on the expression level 
of P-glycoprotein (Pgp) - an efflux transporter at the capillaries of the blood-brain barrier (BBB) 
which transports xenobiotics out of the CNS to the systemic circulation [6, 7]. 
Clinical trials performed with 5-HT3 antagonists for treating pain have yielded mixed results. 
Two studies with tropisetron in fibromyalgia have yielded somewhat positive results, but had 
methodological shortcomings, and a well-designed tropisetron study in 30 patients with low back 
pain was negative. Two studies with ondansetron in neuropathic pain were overall negative, but in 
one of the studies, pain reduction 2h after ondansetron administration was larger than with placebo 
[8, 9]. In both these studies individual data (personal communication with the authors) indicate that 
certain patients had good analgesic response to intravenous ondansetron, warranting further 
investigation into the individual response profiles. 
We suggest that one of the caveats leading to unsuccessful clinical translation of the 
promising animal data is related to the essential pharmacokinetic criterion that probably determined 
the lack of efficacy of systemic ondansetron in rodents - i.e. inability to achieve effective 
concentration at the site of action. We propose that sufficient exposure of 5HT3R antagonists at their 
site of action in the CNS, as well as the choice of appropriate pain condition are of key importance 
for testing the clinical effectiveness of 5HT3R antagonists in NeuP. Consequently, the goal of the 
project is to establish detailed CNS pharmacokinetic (PK) parameters of ondansetron, to provide 
sound basis for a future study with enhanced CNS penetration of ondansetron in neuropathic pain. 
Two genetic factors shown to affect the pharmacokinetics and the antiemetic efficacy 
ondansetron are 1) polymorphism in the ABCB1 gene expressing P-glycoprotein, a transporter which 
controls the transport of ondansetron to the CNS via the BBB; and 2) polymorphism in the SLC22A1 
gene expressing organic cation transporter-1 (OCT1), a transporter responsible for hepatic uptake of 

 
Simon Haroutounian, PhD © 
5 
 
ondansetron. We will collect the genetic data on these polymorphisms to account for inter-subject 
variability in pharmacokinetic parameters of ondansetron. 
 
2.2 Preliminary Data 
None 
 
2.3 Objective 
The primary objective of the study is:  
To test the feasibility of: 
1. Determining human cerebrospinal fluid (CSF) and plasma pharmacokinetics of 5HT3R 
antagonist ondansetron, after intravenous administration. 
2. Determining single nucleotide polymorphisms in transporters involved in hepatic uptake 
(organic cation transporter-1 [OCT1]) and CNS disposition (P-glycoprotein) of ondansetron 
in human subjects. 
 
2.4 Patient Selection 
 
Overall, 15 evaluable subjects planned to undergo hip or knee arthroplasty with spinal anesthesia at 
Washington University / Barnes Jewish Hospital. We anticipate that we will need to consent 
approximately 30 subjects to achieve the enrollment goal. 
 
2.4.1 Inclusion Criteria 
 
Inclusion criteria: 
1. Age between 18 and 70 years old;  
2. Patients having elective  hip or  knee arthroplasty with spinal anesthesia; 
 
3. Ability to provide informed consent 
 
2.4.2 Exclusion Criteria 
Subjects will not be enrolled if any of the following criteria exist: 
 
1. Not giving consent to participate in the study; 
2. Patients with history of or current hepatic or renal insufficiency; 
3. Patients with BMI ≥ 33; 
4. Patients with heart failure or active arrhythmias; 
5. Patients with severe systemic disease that is a constant threat to life; 
6. Contraindication or allergy to ondansetron; 
7. Pregnancy or lactation. 
8. Prisoners 
 
The following ondansetron contraindications will disqualify subjects from participating: 
1. Congenital QT syndrome 
2. QTc interval>450ms 
3. Concomitant therapy with any of the following drugs: 

 
Simon Haroutounian, PhD © 
6 
 
 
First 
generation 
antipsychotic 
medications 
Thioridazine, 
Haloperidol, 
Chlorpromazine, and Pimozide 
 
Second generation antipsychotic medications Ziprasidone and Quetiapine 
 
Azole antifungals Ketoconazole and Fluconazole 
 
Antihistamine Terfenadine, 
 
Antidepressants Trazodone, Citalopram, and Bupropion,  
 
Antiarrythmics Propafenone, Flecainide, and Procainamide 
 
Fluoroquinolone antibiotics  Norfloxacin, Ofloxacin, and Ciprofloxacin 
 
Macrolide antibiotics Erythromycin and Azithromycin 
 
Antiretrovirals of Protease inhibitor (e.g. Ritonavir, Saquinavir) or Non-nucleoside 
reverse transcriptase inhibitors (e.g. Efavirenz, Zidovudine) family. 
 
Cisapride  
 
Other potent inhibitors of Cytochromes P450 2D6 or 3A4. 
 
 
 
2.5 Design and Procedures 
 
2.5.1 Study Design and Methodology 
 
The potential subjects will be recruited from the Washington University / Barnes Jewish Hospital 
center for perioperative assessment and planning (CPAP) and the Washington University Orthopedics 
outpatient clinics, before their scheduled visit for elective knee or hip arthroplasty. Subjects may also 
be recruited from BJH Surgery Registration and the preoperative holding area on the day of surgery. 
Subjects who are potential candidates for the study will be provided with written and oral description 
of the study procedures, benefits, and potential risks. They will be given the opportunity to ask 
questions regarding the study. Informed consent will take place at Washington University/Barnes-
Jewish Hospital medical center campus. 
If agreeing to participate in the study, each subject will sign the informed consent document. Each 
subject who qualifies for entry into the study on the basis of inclusion/exclusion criteria and 
completion of informed consent will be assigned the next available patient number. This indicates 
enrollment in the study. In subjects with a history of or suspected renal or hepatic disorder, blood 
tests will be ordered following consent and reviewed prior to study participation for plasma 
creatinine, Alanine aminotransferase (ALT), Aspartate aminotransferase (AST) and albumin. 
Subjects with moderate or severe renal or hepatic failure will be excluded from the study at the 
discretion of the PI. Subjects with any history of cardiac arrhythmias will undergo 12 lead ECG to 
rule out QTc interval >450ms and will be excluded from the study. 
Patients’ demographic data will be recorded; height and weight will be measured for calculating 
BMI. Subjects who drop out of the study prior to completing the study will be replaced by using the 
next available subject number. 
 
2.5.2 Study Period 
 

 
Simon Haroutounian, PhD © 
7 
 
Subjects will be studied in the Department of Anesthesiology of Washington University-Barnes 
Jewish Hospital, prior to and during their scheduled hip or knee arthroplasty surgery. 
An intravenous catheter will be inserted in an arm for drug administration and in the opposite arm for 
obtaining blood samples to evaluate the plasma concentrations of ondansetron. The former will be 
used also for pre/intraoperative fluids and anesthesia drug administration. 
At baseline, a 5ml blood sample will be collected for pharmacokinetics and another 5ml sample for 
genetic analysis. 
Ondansetron will be administered in a 16mg single dose as a 15 min intravenous  infusion. Although 
up to 32mg doses of intravenous ondansetron have been used in clinical trials, 16mg is currently the 
highest FDA-recommended dose for single administration. Two additional 4mg doses of either IV or 
oral ondansetron will be allowed for postoperative nausea and vomiting treatment in the study 
subjects, at the discretion of the treating physicians. 
A single CSF sample of 4ml will be collected immediately after spinal needle insertion and before 
administration of spinal anesthesia. This procedure is routinely performed in the holding area, 
approximately 30 min before the patient enters the operating room (OR) for planned surgical 
procedure with spinal anesthesia. As only one sample of CSF is obtained from each subject, the 
timing of the infusion will be scheduled at approximately 30, 60, or 120 min before planned pre-
surgical spinal needle insertion. This will allow 3 time-points of CSF samples from the aggregate 
study cohort. For determination of the above timing, the patients will be randomized in blocks of 3 
for infusion timing (approximately 5 subjects per block), to allow even distribution of CSF PK 
sample time-points.  
Six 5mLserial venous blood samples will be obtained from all subjects at 0 (pre-treatment), 15, 30, 
60, 120, and 180 min from the beginning of infusion in each patient, regardless of timing for CSF 
sampling. The samples will be put on ice, centrifuged for 10 min at 5000 rpm. Plasma will be 
transferred to two 1.5mL vials and stored at -80°C until analysis by HPLC-MS. 
The CSF ondansetron pharmacokinetic profile will be constructed using population PK approach, 
according to the exact time of CSF sampling. Ondansetron concentration in plasma (expected 40-
120ng/mL) and CSF (expected 3-12ng/ml) will be determined by HPLC-MS-MS analysis [10].  
 
Ondansetron may cause QT interval prolongation in rare cases; therefore, the subjects’ heart rhythm 
will be monitored throughout the infusion and for approximately 30 min after the end of infusion 
using standard 4 lead monitors in the holding area. No changes will be made to the routing 
intraoperative management and hemodynamic physiological monitoring. with the exclusion of the PK 
blood sampling period. 
 
The DNA isolation and genotyping will include analysis of single nucleotide polymorphisms (SNPs) 
in OCT1 and P-glycoprotein transporters. We will genotype for the following five P-glycoprotein 
(ABCB1) SNPs:  C3435T, T-129C, G1199A, C1236T, G2677T [11-14], and for five OCT1 
(SLC22A1) SNPs: R61C, C88R, G401S, M420del, or G456R that have reported to affect 
ondansetron pharmacokinetics or clinical antiemetic effect. The genotyping will be performed at 
Washington University Genome Technology Access Center. The whole blood samples will be 
extracted using the QiIAamp DNA mini Blood kit (QIAGEN). The DNA will be quantified and 
quality controlled using nanodrop and gel readings. The SNPs will be interrogated using Taqman 
probes (Applied Biosystems).  Each SNP will have its own 20μl reaction well with a final 

 
Simon Haroutounian, PhD © 
8 
 
concentration of 1X Taqman probe mix, 1X Taqman PCR master mix, and 20-40ng of DNA.  The 
samples will be cycled and analyzed on CFX96 Real-time PCR Detection System (Bio-Rad). The 
collected blood and DNA samples will be de-identified and coded to ensure patient confidentiality 
and HIPPA compliance. 
 
2.5.3 Minimization of Bias 
There will be no specific sex, ethnic or racial background for enrollment. Plasma and CSF 
ondansetron concentration is not affected by subjects’ or investigators’ knowledge of study aims and 
hypothesis. 
 
2.5.4 Observations and Measurements 
 
 
2.5.4.1 Primary Outcome Measures 
Primary outcome:  
Plasma and CSF concentrations of ondansetron, and CSF to plasma concentration ratio. 
 
2.5.4.2 Secondary Outcome Measures 
Secondary outcomes: 
Non-compartmental modeling to determine plasma PK parameters of ondansetron – i.e. volume of 
distribution (Vd), clearance (CL), maximum CSF and plasma concentration (Cmax), and the time to 
reach these maximum concentrations (Tmax).  
Compartmental modeling using population PK approach to determine CSF pharmacokinetic 
parameters of ondansetron. 
 
2.5.4.3 Pharmacokinetic data analysis: 
Individual plasma concentration-time data will be analyzed using non-compartmental methods. The 
following PK parameters will be calculated and compared between subjects with different transporter 
expression level: volume of distribution, systemic clearance, the elimination half-life, and the total 
area under the concentration-time curve. In addition, a compartmental population-based 
pharmacokinetic model will be constructed, which will evaluate inter-subject variability in 
pharmacokinetic parameters. Preliminary assessment of published data indicates that the systemic 
disposition of ondansetron follows two-compartment model with linear elimination following 
intravenous administration in humans.  
The population model will include a “CSF distribution compartment”, which will allow for the 
estimation of the partition coefficient between the plasma and CSF. The effect of transporter 
expression level phenotypes on individual pharmacokinetic parameters will be evaluated using a 
standard covariate analysis. Utilization of population approach will allow for estimation of population 
mean and individual patients parameters. This pharmacokinetic methodology is especially useful for 
analysis of sparse data (i.e., a single CSF sample from each patient). 
 
2.5.5   Sample Size 
 

 
Simon Haroutounian, PhD © 
9 
 
We plan to recruit 15 subjects to the current study, and propose additional enrollment of 60-80 
patients to the subsequent study, upon securing sufficient extramural funding 
Typically, 10-15 subjects per study have been used for the assessment of drug pharmacokinetic 
parameters and is sufficient for a pilot study.  
Weekly, more than 30 total hip or knee arthroplasties with spinal anesthesia are performed at our 
institution. This corresponds to approximately 1000 eligible patients a year that may fulfill the 
inclusion criteria.  
 
2.5.6  Study design considerations 
. A large number of patients undergo total joint arthroplasty at our institution, and spinal anesthesia is 
standard care; therefore, it will be possible to recruit patients who meet the inclusion criteria without 
the added risk of spinal needle insertion. Ondansetron is routinely administered in these patients for 
the prophylaxis or treatment of postoperative nausea and vomiting. 
The dose of 16mg ondansetron was chosen, as this is currently the highest recommended dose by 
FDA for a single administration and was shown safe among patients between ages 18-75. Intravenous 
15-minute infusion is chosen over bolus administration to reduce QTc prolongation risks. We did not 
choose lower doses to be able to reliably measure CSF concentrations, as sampling volume is 
typically limited to about 4mL, to reduce the risk of post spinal headache. The timing of CSF 
sampling was based on intravenous ondansetron PK data [17]. 
 
2.5.7 Clinical Procedures and Laboratory Tests 
Due to the risk of QT interval prolongation with high doses of ondansetron, we exclude patients with 
QTc > 450ms, and any concomitant administration of drugs that increase the pro-arrhythmic risk with 
ondansetron. In addition, all subjects will be monitored with ECG for potential arrhythmias. 
However, it should be noted that ondansetron administration is standard of care in these patients. 
Blood hepatic function and renal tests will be performed and evaluated prior to study treatment for 
any subjects with suspected or known kidney and or liver disease. 
 
3.0 Management of Intercurrent Events 
 
3.1 Adverse Experiences 
The investigators will closely monitor subjects for evidence of ondansetron adverse events.  All 
adverse events will be reported and followed until satisfactory resolution.  The description of the 
adverse experience will include the time of onset, duration, severity, etiology, relationship to the 
study drug (none, unlikely, possible, probable, highly probable), and any treatment required. The 
clinicians will manage any postoperative event related to the spinal anesthesia as standard of care. 
 
3.2 Premature Discontinuation 
If a subject withdraws from the study, the subject will be replaced in order to provide the required 
number of evaluable subjects. Subjects will be withdrawn if the investigator decides that 
discontinuation is in the best interest of the subject, or the subject requests withdrawal from the study. 
 
3.3 Potential Risks 
 
3.3.1 Potential risks from ondansetron 

 
Simon Haroutounian, PhD © 
10 
 
Ondansetron systemic effects associated with high plasma concentration may cause cardiac 
arrhythmias.  
In addition, subjects may experience diarrhea, constipation, headache, dry mouth, malaise, elevation 
of liver enzymes (incidence of 5% - when administered with chemotherapy to treat nausea and 
vomiting), and injection site reaction. 
 
Rarely reported adverse effects include: 
Hypokalemia, Fever, Anaphylaxis, Seizures, Temporary blindness. 
 
However, this dose is used frequently for postoperative or chemotherapy-induced nausea and 
vomiting, and is considered safe. In previous studies with 16mg intravenous ondansetron 
administration, no patient had arrhythmias or other serious side effects; headache and malaise were 
the main adverse effects [8, 9]. No psychological risks to subjects are envisioned. 
 
 
3.3.2 Other Potential Risks 
Intravenous catheter placement can cause a bruise. The amount of blood drawn is approximately 35cc 
and will not constitute a risk to subjects since this amount is well below the recommended limits for 
this population. Spinous catheter placement is a part of the routine perioperative care in this patient 
group; therefore there is no additional risk as a result of study participation. The collection of a 4mL 
CSF sample will be performed by an anesthesiologist immediately following spinal needle insertion 
for standard of care anesthesia. This additional collection of CSF is not expected to increase the risk 
of post-dural puncture headache, but it may occur, especially in younger patients. No psychological 
risks to subjects are envisioned. Subjects may experience a loss of confidentiality.  Investigators will 
keep subjects’ participation confidential to the extent permitted by law.  However, it is possible that 
others may become aware of subjects’ participation in this study and may inspect and copy records 
pertaining to this research.  Some of these records could contain information that personally identifies 
subjects. The results of genotyping will not result in identifiable, clinically diagnostic genetic 
information that has a known association with a medical condition. The data from the analysis will 
not be included in the patients’ medical records. 
 
3.4 Procedures to Minimize Potential Risks 
Studies are conducted in the Washington University Clinical Research Center under the supervision 
of the PI and Co-investigators. The PI is trained and experienced in performing research in human 
subjects, and the co-investigators are board-certified anesthesiologists with extensive clinical and 
research experience in the perioperative setting. 
Subjects are also continuously monitored by trained research (RN) nursing personnel throughout the 
study session and by their clinical team during surgery and recovery in the Past Anesthesia Care Unit 
(PACU),  as a part of routine care. Subjects will be monitored by electrocardiogram for any potential 
cardiac abnormalities associated with ondansetron administration.  Full patient monitoring and 
resuscitation capabilities are immediately available. 
The 16mg dose of ondansetron, when infused over 15 minutes  in adults 18-74 years old, was shown 
not to increase the QTc interval by more than 10ms, even if additional two doses of 8mg are 
administered later in the day [18]. Based on these data, and the current FDA recommendation, we 
will administer 16mg dose by 15-min infusion, and apply an upper age limit of 70 years on the study 
population. 

 
Simon Haroutounian, PhD © 
11 
 
Inclusion and exclusion criteria, monitoring, and the clinical protocol are designed to ensure that risks 
are absolutely minimal. Subjects are informed that participation is voluntary and they may refuse to 
participate and may withdraw from the study at any time without penalty. A pregnancy test will be 
performed on women of childbearing potential and subjects excluded if pregnant. Subjects will be 
told that in the event of a physical injury as the direct result of study procedures, they will be cared 
for by a member of the investigating team at no cost, within the limits of the Washington University 
compensation plan. 
 
With regard to confidentiality; 1) all subjects will be assigned a study ID number, 2) Samples will be 
kept confidentially.  They will be coded, with a key to the code linking code numbers to names kept 
at a separate location, under lock and key.  3) The link to identifiers will be destroyed at the end of 
the study. 4) Data will be stored under lock and key (office, file cabinet) and only the investigators 
and research team will have access.  If data are published, there will be no link to identifiers.  Study 
data will not be revealed to any organization, individuals other than the subjects, or the subjects 
themselves. 5) Study data will not be entered in subjects' medical records.  
 
3.5   Data and Safety Monitoring Plan 
The specific monitoring plan for this investigation is commensurate with the risks and the size and 
complexity of the investigations planned. The potential risks are attributable to the ondansetron 
infusion. Based on these considerations, the monitoring plan involves engaging a colleague from the 
Department of Anesthesiology not involved in the study to serve in a monitoring capacity. Based on 
the relatively low risks nature of the protocol, only a third person (the colleague), rather than a full 
Data Safety Monitoring Board will be used. The colleague will be an anesthesiologist knowledgeable 
in the risks associated with 5HT3 antagonist administration. This individual will review the annual 
summary of adverse events. In addition, this colleague will review all reports of a Serious Adverse 
Event, or an Unexpected Adverse Event. 
 
4.  HUMAN SUBJECTS RESEARCH 
 
4.1 Protection of Human Subjects 
The study will be conducted under appropriate Washington University Institutional Review Board 
protocols and consent forms approvals.  The study will be conducted under the supervision of the PI, 
a licensed pharmacist with several years of experience in the conduct of human studies, and the co-
PIs, board-certified anesthesiologists with many years of experience in spinal and regional anesthesia 
for surgeries. 
 
4.2 Sources of Materials 
Subjects will be recruited from Washington University Orthopedics and the Center for Perioperative 
Assessment and Planning (CPAP), as well as from BJH Surgery registration and the preoperative 
holding area. 
 
Data on comorbidities and concomitant medication use are provided by subjects. Specimens include 
blood obtained for transporter genotyping and for determining ondansetron plasma concentration.  
CSF samples are obtained for determining ondansetron CSF concentration. 
 

 
Simon Haroutounian, PhD © 
12 
 
4.3 Recruitment and Informed Consent 
Participants will be recruited primarily through Washington University Orthopedics and the Center 
for Perioperative Assessment and Planning (CPAP). 
Two primary recruitment mechanisms will be utilized: 
1. Participants will be referred from Washington University Orthopedics by the corresponding 
physicians. Interested subjects will contact the investigators.  
2. A weekly list of patients scheduled for CPAP visit before knee or hip arthroplasty will be 
generated from SIS system. The potential subjects will be approached by the study 
coordinator for inclusion consideration. 
Subjects may also be consented in the surgery registration area and the preoperative holding area. 
Subjects will be given verbal (initially) and then written descriptions of the study aims, procedures, 
risks, and benefits, and will be required to give written informed consent. A member of the 
investigative team provides all study descriptions, informed consent, and answers all questions. 
Subjects are informed verbally and in writing that participation is voluntary and they may refuse to 
participate and may withdraw from the study at any time without penalty. Subjects that participate, 
but do not complete all study procedures because their surgery is cancelled or rescheduled by their 
treating physician may re-consent to participate and be re-enrolled as long as there has been a 
minimum of 48 hours between the last study procedure and the re-consent event.  
 
4.4 Potential Benefits of the Proposed Research to the Subjects and Others 
We do not know if the patients will benefit from the intervention. Perioperative ondansetron 
administration may decrease postoperative nausea and vomiting, and is used as standard of care in 
this setting.  
Potential understanding of which patients are more likely to have higher CSF concentration of 
ondansetron may lead to introducing a potential analgesic treatment, from which patients with 
neuropathic pain may benefit in the future. 
The society may benefit from a new approach of treating neuropathic pain with CNS-penetrating 
5HT3R antagonists. 
 
4.5 Inclusion of Women 
Studies actively encourage the participation of women in the research. As a matter of operational 
policy, our studies routinely and deliberately attempt to include equivalent numbers of women and 
men. However, the nature of the current study precludes enrollment of a set number of female or 
male patients since the main criteria for inclusion is  hip or knee replacement surgery. Women of 
childbearing potential are not excluded from our research protocols.  
 
4.6 Inclusion of Minorities 
All of our studies actively encourage the participation of minorities in the research.  Our minority 
recruiting typically matches the demographic composition of the Washington University community 
from which subjects will be recruited (78% white, 21% Black, <1 % Hispanic). 
 
4.7 Inclusion of Children 
Children <18 yr will not be studied in this investigation. Children rarely undergo hip or knee 
replacement procedures. Including children may expose them to an unnecessary risk without the 
benefit of generalizability of the results. 
 

 
Simon Haroutounian, PhD © 
13 
 
 
Additional Collaborators: 
Chris Sawyer, PhD 
Washington University Genome Technology Access Center (GTAC) 
St Louis, MO 
Role: SNP genotyping 
 
Leonid Kagan, PhD 
Department of Pharmaceutics, Ernest Mario School of Pharmacy 
Rutgers, The State University of New Jersey 
Piscataway, NJ 
Role: Assistance with Pharmacokinetic modeling 
 
Only the PI, the co-PIs, and the research coordinators will have access to patient identifiers or PHI. 
The external collaborators will be blinded to any patient identifying information. 
 
5.  REFERENCES 
1. 
Dogrul, A., M.H. Ossipov, and F. Porreca, Differential mediation of descending pain 
facilitation and inhibition by spinal 5HT-3 and 5HT-7 receptors. Brain Res, 2009. 1280: p. 
52-9. 
2. 
Suzuki, R., et al., Spinal-supraspinal serotonergic circuits regulating neuropathic pain and its 
treatment with gabapentin. Pain, 2005. 117(3): p. 292-303. 
3. 
Bannister, K., et al., Diffuse noxious inhibitory controls and nerve injury: restoring an 
imbalance between descending monoamine inhibitions and facilitations. Pain, 2015. 156(9): 
p. 1803-11. 
4. 
Kimura, M., H. Obata, and S. Saito, Peripheral nerve injury reduces analgesic effects of 
systemic morphine via spinal 5-hydroxytryptamine 3 receptors. Anesthesiology, 2014. 121(2): 
p. 362-71. 
5. 
Oatway, M.A., Y. Chen, and L.C. Weaver, The 5-HT3 receptor facilitates at-level mechanical 
allodynia following spinal cord injury. Pain, 2004. 110(1-2): p. 259-68. 
6. 
Marchi, N., et al., Determinants of drug brain uptake in a rat model of seizure-associated 
malformations of cortical development. Neurobiol Dis, 2006. 24(3): p. 429-42. 
7. 
Schinkel, A.H., et al., P-glycoprotein in the blood-brain barrier of mice influences the brain 
penetration and pharmacological activity of many drugs. J Clin Invest, 1996. 97(11): p. 2517-
24. 
8. 
McCleane, G.J., R. Suzuki, and A.H. Dickenson, Does a single intravenous injection of the 
5HT3 receptor antagonist ondansetron have an analgesic effect in neuropathic pain? A 
double-blinded, placebo-controlled cross-over study. Anesth Analg, 2003. 97(5): p. 1474-8. 
9. 
Tuveson, B., A.S. Leffler, and P. Hansson, Ondansetron, a 5HT3-antagonist, does not alter 
dynamic mechanical allodynia or spontaneous ongoing pain in peripheral neuropathy. Clin J 
Pain, 2011. 27(4): p. 323-9. 
10. 
Corrigan, B.W., et al., Heterogeneity in systemic availability of ondansetron and granisetron 
following oral administration. Drug Metab Dispos, 1999. 27(1): p. 110-2. 
11. 
Babaoglu, M.O., et al., Association of the ABCB1 3435C>T polymorphism with antiemetic 
efficacy of 5-hydroxytryptamine type 3 antagonists. Clin Pharmacol Ther, 2005. 78(6): p. 619-
26. 

 
Simon Haroutounian, PhD © 
14 
 
12. 
Tzvetkov, M.V., et al., Effects of OCT1 polymorphisms on the cellular uptake, plasma 
concentrations and efficacy of the 5-HT(3) antagonists tropisetron and ondansetron. 
Pharmacogenomics J, 2012. 12(1): p. 22-9. 
13. 
Tzvetkov, M.V., et al., The effects of genetic polymorphisms in the organic cation 
transporters OCT1, OCT2, and OCT3 on the renal clearance of metformin. Clin Pharmacol 
Ther, 2009. 86(3): p. 299-306. 
14. 
Vasilopoulos, Y., et al., A pharmacogenetic study of ABCB1 polymorphisms and cyclosporine 
treatment response in patients with psoriasis in the Greek population. Pharmacogenomics J, 
2014. 
15. 
Fukudo, M., et al., Population pharmacokinetics/pharmacodynamics of erlotinib and 
pharmacogenomic analysis of plasma and cerebrospinal fluid drug concentrations in 
Japanese patients with non-small cell lung cancer. Clin Pharmacokinet, 2013. 52(7): p. 593-
609. 
16. 
Har-Even, R., et al., Plasma and cerebrospinal fluid concentrations of ibuprofen in pediatric 
patients and antipyretic effect: Pharmacokinetic-pharmacodynamic modeling analysis. J Clin 
Pharmacol, 2014. 54(9): p. 1023-30. 
17. 
VanDenBerg, C.M., et al., Pharmacokinetics of three formulations of ondansetron 
hydrochloride in healthy volunteers: 24-mg oral tablet, rectal suppository, and i.v. infusion. 
Am J Health Syst Pharm, 2000. 57(11): p. 1046-50. 
18. 
Zuo, P., et al., Integration of modeling and simulation to support changes to ondansetron 
dosing following a randomized, double-blind, placebo-, and active-controlled thorough QT 
study. J Clin Pharmacol, 2014.