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A Study of the Effects of Sodium Citrate on Olfactory Thresholds

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified January 2007 by University Hospitals, Leicester.
Recruitment status was:  Not yet recruiting
Information provided by:
University Hospitals, Leicester Identifier:
First received: December 8, 2006
Last updated: January 18, 2007
Last verified: January 2007

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 Phase
Anosmic and Hyposmic Patients
Early Phase 1

Study Type: Observational
Study Design: 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

Resource links provided by NLM:

Further study details as provided by University Hospitals, Leicester:

Study Start Date: February 2007

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

Inclusion Criteria:

  • Anosmia
  • Hyposmia

Exclusion Criteria:

  • Under age of 18 years of age
  Contacts and Locations
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Please refer to this study by its identifier: NCT00409812

Sponsors and Collaborators
University Hospitals, Leicester
Principal Investigator: Julian Gaskin, MBChB MRCSEd University Hospitals, Leicester
  More Information Identifier: NCT00409812     History of Changes
Other Study ID Numbers: 06/MRE05/16
Study First Received: December 8, 2006
Last Updated: January 18, 2007

Additional relevant MeSH terms:
Citric Acid
Calcium Chelating Agents
Chelating Agents
Sequestering Agents
Molecular Mechanisms of Pharmacological Action processed this record on April 26, 2017