A Study of the Effects of Sodium Citrate on Olfactory Thresholds

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00409812
Recruitment Status : Unknown
Verified January 2007 by University Hospitals, Leicester.
Recruitment status was:  Not yet recruiting
First Posted : December 11, 2006
Last Update Posted : January 19, 2007
Information provided by:
University Hospitals, Leicester

Brief Summary:

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.

(N.B. 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.)

  1. Wudarski TJ, Doty RL. Comparison of detection threshold values determined using glass sniff bottles and plastic squeeze bottles.Percept Mot Skills. 2004 Feb;98(1):192-6
  2. Gaskin J, Robinson A, Philpott CM, Goodenough P, Murty G. Are patients cross-sensitive to odours in parallel threshold tests? Chemical Senses 2006; in progress

Condition or disease
Anosmic and Hyposmic Patients

Study Type : Observational
Allocation: Random Sample
Time Perspective: Longitudinal
Time Perspective: Prospective
Official Title: A Double Blinded Randomised Controlled Trial of the Effects of Sodium Citrate on Olfactory Thresholds
Study Start Date : February 2007

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Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Anosmia
  • Hyposmia

Exclusion Criteria:

  • Under age of 18 years of age

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00409812

Sponsors and Collaborators
University Hospitals, Leicester
Principal Investigator: Julian Gaskin, MBChB MRCSEd University Hospitals, Leicester Identifier: NCT00409812     History of Changes
Other Study ID Numbers: 06/MRE05/16
First Posted: December 11, 2006    Key Record Dates
Last Update Posted: January 19, 2007
Last Verified: January 2007

Additional relevant MeSH terms:
Citric Acid
Calcium Chelating Agents
Chelating Agents
Sequestering Agents
Molecular Mechanisms of Pharmacological Action