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Trial registered on ANZCTR


Registration number
ACTRN12618000093280
Ethics application status
Approved
Date submitted
8/01/2018
Date registered
22/01/2018
Date last updated
21/01/2019
Date data sharing statement initially provided
21/01/2019
Type of registration
Prospectively registered

Titles & IDs
Public title
The metabolic effects of bitter taste sensing in the gut
Scientific title
Effects of a bitter taste receptor agonist (denatonium benzoate) and antagonist (probenecid), in an enema formulation, on gastrointestinal hormone secretion and appetite in healthy humans.
Secondary ID [1] 293720 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Type 2 diabetes mellitus 306068 0
obesity
306100 0
Condition category
Condition code
Metabolic and Endocrine 305205 305205 0 0
Diabetes
Metabolic and Endocrine 305221 305221 0 0
Normal metabolism and endocrine development and function
Diet and Nutrition 305222 305222 0 0
Obesity

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Following a screening visit, each subject will be studied on 5 occasions, separated by at least 7 days, in a double-blinded randomised order.
On each study day, an intravenous cannula will be inserted into a forearm vein for repeated blood sampling. The subject will then be positioned in the left lateral decubitus position, and the 20mL aqueous gel (1% carboxymethyl cellulose) containing DB (30mg), DB (30mg) + probenecid (456mg), TCA (3500mg), TCA (3500mg) + probenecid (456mg), or vehicle only, will be infused into the rectum via a soft catheter by a medically qualified investigator within 2 min and then be removed.
Intervention code [1] 299971 0
Treatment: Drugs
Comparator / control treatment
20mL aqueous gel (1% carboxymethyl cellulose) infusions into rectum during one of the 5 study visits.
Control group
Placebo

Outcomes
Primary outcome [1] 304363 0
differences in the incremental area under the curve (iAUC) for plasma GLP-1 between the 5 treatments.
Timepoint [1] 304363 0
at t = 0, 15, 30, 45, 60, 75, 90 and 120min where t=0 is when rectal infusion started.
Secondary outcome [1] 341736 0
differences in the incremental area under the curve (iAUC) for plasma PYY between the 5 treatments.
Timepoint [1] 341736 0
at t = 0, 15, 30, 45, 60, 75, 90 and 120min where t=0 is when rectal infusion started.
Secondary outcome [2] 341737 0
differences in the incremental area under the curve (iAUC) for plasma glucose between the 5 treatments.
Timepoint [2] 341737 0
at t = 0, 15, 30, 45, 60, 75, 90 and 120min where t=0 is when rectal infusion started.
Secondary outcome [3] 341738 0
differences in the incremental area under the curve (iAUC) for gastrointestinal sensations, assessed by validated visual analogue scales, between the 5 treatments.
Timepoint [3] 341738 0
at t = 0, 15, 30, 45, 60, 75, 90 and 120min where t=0 is when rectal infusion started.
Secondary outcome [4] 341739 0
differences in energy intake from a standardised cold buffet meal between the 5 treatments.
Timepoint [4] 341739 0
t= 150min where t=0 is when rectal infusion started.

Eligibility
Key inclusion criteria
Healthy male and females aged 18 – 55 years
Body mass index (BMI) 19 - 25 kg/m2
Haemoglobin above the lower limit of the normal range (ie. >135g/L for men and 115g/L for women), and ferritin above the lower limit of normal (ie. >30ng/mL for men and >20mg/mL for women)
Minimum age
18 Years
Maximum age
55 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Use of any medication that may influence gastrointestinal motor function, body weight or appetite (e.g. antihypertensive drugs, domperidone and cisapride, anticholinergic drugs (e.g. atropine), metoclopramide, erythromycin, hyoscine, orlistat, green tea extracts, Astragalus, St. John's Wort etc.)
Evidence of drug abuse, consumption of more than 20 g alcohol or 10 cigarettes on a daily basis
History of gastrointestinal disease, including significant upper or lower gastrointestinal symptoms, pancreatitis, or previous gastrointestinal surgery (other than uncomplicated appendicectomy or cholecystectomy)
Other significant illness, including epilepsy, cardiovascular or respiratory disease
Impaired renal or liver function (as assessed by calculated creatinine clearance < 90 mL/min or abnormal liver function tests (> 2 times upper limit of normal range))
Donation of blood within the previous 3 months
Participation in any other research studies within the previous 3 months
Inability to give informed consent
Female participants who are pregnant or planning for pregnancy, or are lactating
Vegetarians

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
allocation involved contacting the holder of the allocation schedule who was "off-site" or at central administration site (Royal Adelaide Hospital)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Crossover
Other design features
Phase
Phase 1
Type of endpoint(s)
Efficacy
Statistical methods / analysis
Based on data derived from our previous study, 14 healthy subjects will provide 90% power (at a=0.01, to allow for corrections of 4 subgroup comparisons: DB vs. placebo; TCA vs. placebo; DB vs. DB + probenecid; and TCA vs. TCA + probenecid) to detect a difference of 220pmol/L*min in the 2-hour incremental area under the curve (iAUC) for plasma GLP-1 between the treatments. 16 subjects will be recruited to allow for dropouts.
Data will be analysed using standardised, non-parametric or parametric statistical methods where appropriate (e.g. repeated measures ANOVA).

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
SA
Recruitment hospital [1] 9688 0
The Royal Adelaide Hospital - Adelaide
Recruitment postcode(s) [1] 18457 0
5000 - Adelaide

Funding & Sponsors
Funding source category [1] 298337 0
Government body
Name [1] 298337 0
NHMRC
Address [1] 298337 0
Level 1, 16 Marcus Clarke Street, Canberra, ACT 2601
Country [1] 298337 0
Australia
Primary sponsor type
University
Name
University of Adelaide
Address
Level 5 Adelaide Health and Medical Sciences (AHMS) Building,
North Terrace
Adelaide SA 5000
Country
Australia
Secondary sponsor category [1] 297452 0
None
Name [1] 297452 0
Address [1] 297452 0
Country [1] 297452 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 299328 0
Royal Adelaide Hospital Human Research Ethics Committee
Ethics committee address [1] 299328 0
Level 4, Women's Health Centre, Royal Adelaide Hospital,
North Terrace, Adelaide, SA 5000
Ethics committee country [1] 299328 0
Australia
Date submitted for ethics approval [1] 299328 0
01/11/2017
Approval date [1] 299328 0
04/01/2018
Ethics approval number [1] 299328 0
No: R20171101

Summary
Brief summary
Emerging evidence of preclinical studies suggests that bitter substances in the gut can reduce appetite and slow the emptying of meals from the stomach, by stimulating GI hormone release. The purpose of this study is to determine whether stimulation of intestinal bitter taste receptors (BTRs) by non-caloric BTR agonists induces GI hormone secretion in humans and, if so, whether probenecid acts as an effective BTR antagonist. In this trial, we wish to investigate whether rectal infusion of a BTR agonist, denatonium benzoate (DB), stimulates the secretion of glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) and antagonism of BTR signalling by probenecid attenuates the GLP-1 and PYY responses induced by rectal administration of bitter tastants (i.e. DB and taurocholic acid (TCA, which is known to stimulate GLP-1 and PYY secretion humans and therefore will serve as a positive control).
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 80074 0
Dr Tongzhi Wu
Address 80074 0
University of Adelaide Discipline of Medicine, Level 5 Adelaide Health and Medical Sciences (AHMS) Building, North Terrace, Adelaide, SA 5000
Country 80074 0
Australia
Phone 80074 0
+61 8 8313 6535
Fax 80074 0
Email 80074 0
tongzhi.wu@adelaide.edu.au
Contact person for public queries
Name 80075 0
Dr Tongzhi Wu
Address 80075 0
University of Adelaide Discipline of Medicine, Level 5 Adelaide Health and Medical Sciences (AHMS) Building, North Terrace, Adelaide, SA 5000
Country 80075 0
Australia
Phone 80075 0
+61 8 8313 6535
Fax 80075 0
Email 80075 0
tongzhi.wu@adelaide.edu.au
Contact person for scientific queries
Name 80076 0
Dr Tongzhi Wu
Address 80076 0
University of Adelaide Discipline of Medicine, Level 5 Adelaide Health and Medical Sciences (AHMS) Building, North Terrace, Adelaide, SA 5000
Country 80076 0
Australia
Phone 80076 0
+61 8 8313 6535
Fax 80076 0
Email 80076 0
tongzhi.wu@adelaide.edu.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
Individual participant data will be stored in the hard drive of the University of Adelaide.
What supporting documents are/will be available?
Study protocol
Statistical analysis plan
Attachments/websites
Type [1] 1099 0
Study protocol
URL/details/comments [1] 1099 0
Summary results
Not applicable