Condition category
Digestive System
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Diagnostic gastroscopy (camera examination of the gullet and stomach) provides a unique opportunity to answer specific diagnostic questions and identify lesions which develop into problems such as cancer at an early stage. There is, however, evidence to show that in the UK and the West there is a significant miss rate when assessing the identification of these early lesions. Stomach mucus and swallowed saliva can make it difficult to view the inner lining of the gullet and stomach during this procedure. Two commonly used medications (simethicone and N-acetylcysteine [NAC]) have been shown to be of potential benefit in clearing this obscuring mucus. We are trying to find out whether the use of a preparatory drink containing NAC and simethicone will improve visibility during gastroscopy.

Who can participate?
All patients aged 18 or over attending for gastroscopy are eligible to take part.

What does the study involve?
Patients undergo the standard preparation for gastroscopy at home (clear fluids only for 6 hours then nil by mouth for 2 hours). Patients are then randomly allocated into three groups.
1. Control – no further intervention.
2. Water – patients will drink sterile water 15-20 minutes before gastroscopy.
3. Solution – patients will drink sterile water containing NAC and simethicone 15-20 minutes before gastroscopy.
The endoscopist and the nursing staff are unaware of the preparation used. During the gastroscopy the visibility is assessed by documenting the amount of water required to flush away mucus to enable a clear view of the lining of the stomach/gullet at specified areas. The time taken for the procedure and the areas requiring additional flushing are also documented. The procedure is performed as normal to answer the clinical questions posed.

What are the possible benefits and risks of participating?
There will be real immediate benefits from being involved in the test, other than the potential to have a more efficient procedure if the preparation improves visibility. There are no expected risks, the gastroscopy is performed as normal. Both medications have been used for decades and large trials have demonstrated no clinical side effects from their use in low oral doses.

Where is the study run from?
University Hospital Southampton.

When is study starting and how long is it expected to run for?
The study ran from April to August 2011.

Who is funding the study?
There were minimal costs associated with this study and it was self-funded by the investigators within the department.

Who is the main contact?
Dr James Neale

Trial website

Contact information



Primary contact

Dr Praful Patel


Contact details

Department of Luminal Gastroenterology
Southampton General Hospital
Tremona Road
SO16 6YD
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Pre-medication with N-acetylcysteine and simethicone improves mucosal visualisation during gastroscopy: a randomised, controlled, endoscopist-blinded study.


Study hypothesis

We hypothesise that drinking a solution containing n-acetylcysteine (NAC) and simethicone prior to gastroscopy improves endoscopic mucosal visualisation during the procedure.

Ethics approval

NRES Committee Southampton B, 19 January 2011, ref: 10/H0504/82

Study design

Randomised controlled endoscopist blinded single centre study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Gastrointestinal endoscopy


Patients attend for gastroscopy having already undergone standard preparation at home (6 hours clear fluids only, 2 hours nil by mouth [NBM]).

On entering the study they were randomised (number tables) into 3 groups:
1. Control - no further intervention
2. Water - 100ml sterile water 15-20 minutes prior to gastroscopy
3. Solutiuon - 100ml sterile water + 3ml NAC + 2.5ml simethicone 15-20 minutes prior to gastroscopy

They will have a standard diagnostic gastroscopy performed by endoscopist blinded to this. During procedure all stubborn mucus that cannot be suctioned will be washed with water. The amount of water required, the area of the gastrointenstinal (GI) tract it is used and the time taken for the procedure will be recorded by nursing staff in the room.

Intervention type



Not Applicable

Drug names

N-acetylcysteine, simethicone

Primary outcome measure

Amount of water required to clear stubborn mucus

Secondary outcome measures

1. Area of GI tract
2. Time taken for procedure

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

All adult patients attending for clinically required diagnostic gastroscopy

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Patients with previous allergic reactions to N-acetylcysteine or simethicone
2. Patients under the age of 18 years old
3. Patients who lack capacity to consent
4. Those patients not medically fit for endoscopy
5. Those patients where it is deemed unsafe to swallow liquids

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Department of Luminal Gastroenterology
SO16 6YD
United Kingdom

Sponsor information


University Hospital Southampton NHS Foundation Trust (UK)

Sponsor details

Southampton General Hospital
Tremona Road
SO16 6YD
United Kingdom

Sponsor type

Hospital/treatment centre



Funder type

Hospital/treatment centre

Funder name

University Hospital Southampton NHS Foundation Trust (UK)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

2013 results:

Publication citations

Additional files

Editorial Notes

11/08/2016: Publication reference added