A randomized, double-blind parallel group study to investigate propofol injection pain compared with placebo in healthy adult male and female participants. (PropPain)
Propofol is a medicine widely used in hospitals to relax patients or put them to sleep before operations. A common side effect is an uncomfortable stinging or burning sensation in the vein when it is injected. The PropPain study looks closely at this pain to measure how strong it is and how long it lasts. In this trial, healthy adult volunteers are placed into two groups at random. One group receives an injection of a propofol mixture, and the other receives a simple saltwater injection (placebo). Neither the volunteers nor the study doctors will know which injection is given until after the test. Participants will rate their comfort levels using digital sliders and simple number scales. While there is no direct medical benefit to taking part, the results will help doctors better understand injection pain and find ways to make procedures easier for future patients.
At a glance
What is this study about?
When people have surgery or medical scans, doctors often give them an anaesthetic medicine through a small plastic tube in their vein (a drip). Propofol is one of the most trusted medicines used for this purpose. However, many people notice a sharp stinging or aching feeling in their arm right as the liquid enters the bloodstream. Even though this pain usually lasts only a short time, it can cause unnecessary worry and distress just before a procedure.
The PropPain study is designed to measure this injection pain very carefully. To do this, researchers are testing an emulsion called Propolipid against a plain saltwater solution known as saline. Healthy volunteers will receive one of the two injections, and neither the participants nor the research staff will know who gets which treatment during the test. This 'double-blind' setup ensures the results are completely fair and unbiased.
During and immediately after the injection, volunteers will be asked to report any pain or discomfort they feel on a computerised scale. The researchers will track how quickly the pain starts, how intense it gets, and how quickly it fades away. They will also observe if volunteers feel sleepy or drowsy.
By gathering precise information from healthy adults, doctors hope to learn more about how injection pain behaves. This knowledge can help medical teams develop better techniques, adjust medications, or find new ways to prevent stinging before patients undergo routine hospital operations.
Key takeaways
- The study investigates why the anaesthetic propofol often causes brief stinging when injected into a vein.
- Healthy adult volunteers will receive either a propofol injection or a harmless saltwater injection.
- Participants will use a digital slider to rate any discomfort they feel over several minutes.
- The trial takes place during a single clinic visit and does not require an overnight hospital stay.
- Taking part is entirely voluntary, and participants can withdraw at any time.
Who may be eligible?
This study is open to healthy men and women aged 18 and older. Because this is an early-stage study looking at how a medicine feels rather than treating an illness, researchers are looking for volunteers who do not have major ongoing health conditions.
You may not be able to join if you have known allergies to anaesthetics or certain food ingredients often used in drug mixtures, such as egg or soy products. You may also be unable to take part if you are pregnant, breastfeeding, or taking regular medications that could affect how you feel pain or react to anaesthetics.
A member of the research team will carry out standard health checks before you join to make sure it is completely safe for you to take part.
Could this study suit you?
Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.
- I am aged 18 or older.
- I consider myself to be in good general health.
- I do not have a known allergy to anaesthetic medicines, egg, or soy.
- I am not currently pregnant or breastfeeding.
- I am comfortable having a standard needle and cannula placed in my vein.
What does participation involve?
Taking part usually involves one main visit to a specialist clinic or hospital unit. First, a doctor or nurse will explain the study, answer your questions, and check your basic health measurements like blood pressure and heart rate. A small needle will be used to place a cannula (a thin, soft tube) into a vein in your hand or arm.
You will receive a single injection through the cannula containing either the propofol medicine or the saltwater solution. As the liquid enters your vein, you will be asked to score any pain you feel using a digital touchscreen slider and simple 0 to 10 number ratings over the first few minutes. The staff will also check how relaxed or drowsy you feel. You will be monitored closely until you are fully alert and comfortable, which usually takes an hour or two, after which you can go home.
Potential risks and benefits
Locations (1)
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Common questions
Will this injection put me completely to sleep?
The study uses a small dose designed to measure injection sensations and mild relaxation. You will be monitored closely, but the main goal is to record your feelings while you are awake enough to use the pain scale.
Why is saltwater used in the study?
Saltwater acts as a harmless 'placebo'. Comparing the anaesthetic to plain saltwater helps researchers prove how much stinging is genuinely caused by the medicine itself.
Will I know which injection I am getting?
No. To keep the results fair and reliable, neither you nor the research team will know whether you receive propofol or saltwater until the study is finished.
How long will the pain last if I feel any?
Injection pain from propofol usually begins within seconds and typically fades away within one to two minutes.
Can I leave the study early if I want to?
Yes. You have the right to withdraw from the trial at any point, and your decision will always be respected.
How to find out more
Always speak to your GP or specialist before deciding to take part in a study.
Interested in taking part?
Discussion
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