A double-blinded randomised controlled trial of the effects of sodium citrate on olfactory thresholds
| ISRCTN | ISRCTN50895907 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN50895907 |
| Secondary identifying numbers | N0274185293 |
- Submission date
- 28/09/2007
- Registration date
- 28/09/2007
- Last edited
- 06/07/2017
- Recruitment status
- No longer recruiting
- Overall study status
- Completed
- Condition category
- Ear, Nose and Throat
Plain English summary of protocol
Background and study aims
Hyposmia is a relatively common condition where a person has a reduced sense of smell. Previous studies have shown that a chemical called sodium citrate can improves hyposmia by decreasing mucus calcium levels in the nose. The theory behind these effects relates to calcium ions (positively charged calcium atoms) and their role on olfactory receptor neurons (nerve cells in the nose that detect smell). A reduction in free calcium ions (Ca2+) is likely to make these olfactory neurons more active and therefore improve the sense of smell. The aim of this study is to find out whether spraying a sodium citrate solution into the nose of people with hyposmia is able to improve that person’s sense of smell.
Who can participate?
People with a reduced sense of smell (hyposmia)
What does the study involve?
At the start of the study, all participants complete a number of questionnaires and provide information about themselves. They then undertake a series of smell tests using increasing concentrations of four odours in 250ml bottles. Participants are then randomly allocated to one of two groups. Those in the first group use a nose spray containing sodium citrate (9% concentration) and those in the second group use a nose spray with sterile water. Participants then redo the smell tests with the different odour bottles every 15 minutes for two hours.
What are the possible benefits and risks of participating?
It is expected that some patients may benefit from a temporary improvement in their sense of smell after using the citrate spray. Risks of participating are small. The process of spraying the nose should be neither unpleasant nor painful, but some patients may find they want to sneeze. They may also experience some irritation after application of the spray.
Where is the study run from?
1. James Paget University Hospital (UK)
2. Ipswich Hospital (UK)
When is the study starting and how long is it expected to run for?
January 2015 to June 2016
Who is funding the study?
James Paget University Hospital (UK)
Who is the main contact?
Mr Carl Philpott
C.Philpott@uea.ac.uk
Contact information
Scientific
Norwich Medical School
University of East Anglia
Norwich
NR4 7TJ
United Kingdom
 ORCID ID |
0000-0002-1125-3236 |
|---|---|
| Phone | +44 1603 591105 |
| C.Philpott@uea.ac.uk |
Study information
| Study design | Randomised controlled trial |
|---|---|
| Primary study design | Interventional |
| Secondary study design | Randomised controlled trial |
| Study setting(s) | Hospital |
| Study type | Treatment |
| Participant information sheet | Not available in web format, please use the contact details below to request a patient information sheet |
| Scientific title | A double-blinded randomised controlled trial of the effects of sodium citrate on olfactory thresholds |
| Study objectives | Does the application of sodium citrate to the nose improve the ability to smell of patients with a poor sense of smell when compared with a placebo? |
| Ethics approval(s) | Added September 2008: Eastern Reseach Ethics Committee (UK), 15/06/2006, ref: 06/MRE05/16 |
| Health condition(s) or problem(s) studied | Ear, Nose and Throat: Smell ability |
| Intervention | Current interventions as of 19/02/2013: The study will be undertaken at the ENT department of the Leicester Royal Infirmary and in a research laboratory at the University of Leicester and also in the ENT department at the James Paget University Hospital. Fifty subjects will be recruited. Subjects will be invited to undergo a series of smell tests using graded concentrations of 4 odours in 120ml bottles (1). This test has been described and validated by our previous work (2). The test will be fully explained to the subject beforehand by the researcher who will test the patient. The subject will be started with the smallest concentration of each odour and will ascend through the bottles until they detect 2 in a row, at which point the weaker concentration of the odour will be taken as their threshold. They will have a threshold levels determined for the odours phenethyl alcohol (roses), 1-butanol (pear-like), acetic acid (vinegar) and eucalyptol (menthol). Then, the subject will then have either 1cm3 sodium citrate 9% or sterile water (half per nostril) sprayed into the nose. Patients will be randomly allocated to one of the two groups using a coded bottle system controlled by the pharmacies at both sites. Both patient and tester will be blinded to the solution used as these will be made in the pharmacy and coded for anonymity - the code will be broken at the end of the trial. Subjects will then be retested with the bottles and threshold levels will be observed for the four odours at 15 minute intervals over 2 hours. The purpose of the repeated tests is to determine the length of the effect (if present) of the citrate on the olfactory ability of the patients (NB: sodium citrate is a licensed product for use in body cavities (e.g. stomach, bladder) and can be found in the British National Formulary - the concentrations proposed do not exceed those used elsewhere). Previous interventions until 19/02/2013: The study will be undertaken at the ENT department of the Leicester Royal Infirmary and in a research laboratory at the University of Leicester and also in the ENT department at the West Suffolk Hospital. One hundred subjects will be recruited. Subjects will be invited to undergo a series of smell tests using graded concentrations of 4 odours in 120ml bottles (1). This test has been described and validated by our previous work (2). The test will be fully explained to the subject beforehand by the researcher who will test the patient. The subject will be started with the smallest concentration of each odour and will ascend through the bottles until they detect 2 in a row, at which point the weaker concentration of the odour will be taken as their threshold. They will have a threshold levels determined for the odours phenethyl alcohol (roses), mercaptan (gas), acetic acid (vinegar) and eucalyptol (menthol). Then, the subject will undergo a sodium citrate nasal douche at a specific concentration or will douche with sterile water. There will be three concentrations used (3%, 6% and 9%) and a control solution (sterile water). Patients will be randomly allocated to one of the four groups using a coded bottle system. Both patient and tester will be blinded to the solution used as these will be made in the pharmacy and coded for anonymity - the code will be broken at the end of the trial. Subjects will then be retested with the bottles and threshold levels will be observed for the four odours at 15 minute intervals over 2 hours. The purpose of the repeated tests is to determine the length of the effect (if present) of the citrate on the olfactory ability of the patients (NB: sodium citrate is a licensed product for use in body cavities (e.g. stomach, bladder) and can be found in the British National Formulary - the concentrations proposed do not exceed those used elsewhere). |
| Intervention type | Drug |
| Pharmaceutical study type(s) | |
| Phase | Not Specified |
| Drug / device / biological / vaccine name(s) | Sodium Citrate |
| Primary outcome measure | Primary outcome measure as 29/07/2016: Olfactory threshold for PEA odour is measured using a psychophysical test (two-alternative forced choice ascending ladder technique) at baseline and 15 minute intervals up to 2 hours maximum. Original primary outcome measure: An improvement in their sense of smell and their general well-being. |
| Secondary outcome measures | Secondary outcome measure as of 29/07/2016: Olfactory thresholds for ACA, EUC and BUT odours are measured using a psychophysical test (two-alternative forced choice ascending ladder technique) at baseline and 15 minute intervals up to 2 hours maximum. Secondary outcome measures added as of 19/02/2013: A subjective improvement in their sense of smell and their general well-being |
| Overall study start date | 01/01/2015 |
| Completion date | 30/06/2016 |
Eligibility
| Participant type(s) | Patient |
|---|---|
| Age group | All |
| Sex | Both |
| Target number of participants | 100 |
| Key inclusion criteria | All patients with an objective reduction in their ability to smell. |
| Key exclusion criteria | Current inclusion criteria as of 19/02/2013: 1. Patients who are proven to have a normal sense of smell 2. Patients with nasal polyps or other sinonasal disease Previous inclusion criteria until 19/02/2013: 1. Patients who are proven to have a normal sense of smell 2. Patients with nasal polyps |
| Date of first enrolment | 11/08/2008 |
| Date of final enrolment | 01/08/2009 |
Locations
Countries of recruitment
- England
- United Kingdom
Study participating centres
Gorleston-on-Sea
Great Yarmouth
Norfolk
NR31 6LA
United Kingdom
Ipswich
IP4 5PD
United Kingdom
Sponsor information
Hospital/treatment centre
University Hospitals of Leicester NHS Trust Headquarters
Level 3, Balmoral Building
Leicester Royal Infirmary
Infirmary Square
Leicester
LE1 5WW
England
United Kingdom
| Website | http://www.leicestershospitals.nhs.uk/ |
|---|---|
"ROR" |
https://ror.org/02fha3693 |
Funders
Funder type
Hospital/treatment centre
No information available
Results and Publications
| Intention to publish date | 31/12/2016 |
|---|---|
| Individual participant data (IPD) Intention to share | Yes |
| IPD sharing plan summary | Available on request |
| Publication and dissemination plan | Planned publication in Rhinology journal. |
| IPD sharing plan |
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Results article | results | 01/12/2017 | Yes | No |
Editorial Notes
06/07/2017: Internal review.
02/06/2017: Publication reference added
30/08/2016: Plain English summary added.
29/07/2016: The overall trial dates have been updated from 11/08/2008 - 01/08/2009 to 01/01/2005 - 30/06/2016. In addition, the outcome measures have been updated.
07/06/2016: The availability of the participant level data, publication and dissemination plan, study contact ORCID ID and trial participating centres have been added.
24/05/2016: No publications found, verifying study status with principal investigator.
