PainEarly Phase 1NCT07600814
Pain Induced by m-Cresol as Preservative
A Early Phase 1 study testing m-Cresol 0.1% and m-Cresol 0.25% in people with Pain and Acute Pain, run by Medical University of Vienna.
Trial summary
Preservatives such as m-Cresol are essential components in many subcutaneously injected medications, including insulin or human growth hormone, to prevent bacterial growth. However, clinical reports have suggested that these preservatives may cause local discomfort or pain at the injection site, which can negatively… Read more about this study
- Who is it for?
- Ages 18 to 70 yearsHealthy volunteers can take part
- Conditions the study is for
- Pain, Acute Pain, Healthy Volunteer Study
- What is being tested?
- m-Cresol 0.1% and m-Cresol 0.25%
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 18 participants
- Where
- No sites listed yet
- Study dates
- 25 May 2026to 8 Jun 2026
- Phase
- Early Phase 1
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 70 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Age between 18 and 70 years
- Full legal capacity Exclusion criteria
- Participant of another study, ongoing or within the last four weeks
- Current medication intake (except hormonal contraception) or drug abuse
- Female subjects: Positive pregnancy test or breastfeeding
- Body temperature above 38°C, verified by infrared thermometer
- Known allergic diseases, in particular asthmatic disorders and skin diseases
- Sensory deficit, skin disease or hematoma of unknown origin in the examination of the test site
Who cannot join
None listed.
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: Pain Induced by m-Cresol as Preservative - A Randomised Controlled Crossover-Trial in Healthy Volunteers
Preservatives such as m-Cresol are essential components in many subcutaneously injected medications, including insulin or human growth hormone, to prevent bacterial growth. However, clinical reports have suggested that these preservatives may cause local discomfort or pain at the injection site, which can negatively impact treatment adherence. While m-Cresol is widely used, its direct contribution to injection-site pain has not yet been investigated in a prospective clinical trial.
This study aims to investigate whether subcutaneous injection of m-Cresol at concentrations commonly used in clinical practice (0.1% and 0.25%) cause significantly more pain than a preservative-free control solution. In a randomized, double-blind crossover design, healthy volunteers will receive three separate injections in a belly fold. Participants will rate their pain every 5 seconds until it subsides. The findings will help determine if m-Cresol is a primary source of injection-site pain and could lead to the development of more comfortable drug formulations.
Read the detailed description
Background and Objective:
m-Cresol has been used since 1980 to limit bacterial growth in parenteral medications. Although it is generally considered safe, evidence for local side effects has appeared in case reports and a clinical trial where changing the preservative led to a disappearance of local discomfort. This suggests that the preservative itself, rather than the active drug or the pH of the solution, may be responsible for a pain sensation. The objective of this study is to systematically evaluate if subcutaneous injection of m-Cresol at clinically relevant concentrations causes pain in humans.
Study Design:
This is a randomized, double-blind, placebo-controlled, 3-period crossover trial in healthy volunteers (n=18). To ensure an unbiased assessment and control for potential order effects, a Williams balanced design is utilized for the randomization of treatment sequences.
Methodology:
Familiarization: Participants first receive an unblinded injection of control solution to become accustomed to the experimental procedure and the numerical pain rating scale.
Interventions: Subjects receive three randomized, double-blind 300 µl subcutaneous injections at different spots on a belly fold, separated by at least 3 cm. The treatments include:
- m-Cresol at 0.1%
- m-Cresol at 0.25%
- Control solution. Pain Assessment: For each injection, pain intensity is recorded every 5 seconds using a numerical pain rating scale (0-100) until no pain is reported for 30 consecutive seconds. The pain caused by the needle insertion itself is rated separately before the injection begins to serve as a covariate for the statistical analysis.
Statistical Analysis:
The primary endpoint is the Area Under the Curve (AUC) of the subjective pain ratings over time. Comparisons will be made between the different m-Cresol concentrations and the vehicle control using a linear mixed model to test the primary hypotheses.
- Conditions
- Pain, Acute Pain, Healthy Volunteer Study
- Being tested
- m-Cresol 0.1%, m-Cresol 0.25%, Control Solution
- Keywords
- m-Cresol, Preservative, Subcutaneous Injection, Human Pain Models, Experimental Pain Models, Nociception
- Medical subject headings
- Pain, Acute Pain
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
m-Cresol 0.1%Other
A preservative administered subcutaneously at 0.1%, a common concentration used in medicines.
m-Cresol 0.25%Other
A preservative administered subcutaneously at 0.25%, a common concentration used in medicines.
Control SolutionOther
A control solution administered subcutaneously.
| Study group | Role | What they receive |
|---|---|---|
| m-Cresol 0.1% | Experimental | Participants receive a 300 µl subcutaneous injection of m-Cresol at a concentration of 0.1%. Receives: Other: m-Cresol 0.1% |
| m-Cresol 0.25% | Experimental | Participants receive a 300 µl subcutaneous injection of m-Cresol at a concentration of 0.25%. Receives: Other: m-Cresol 0.25% |
| Control solution | Placebo comparator | Participants receive a 300 µl subcutaneous injection of control solution. Receives: Other: Control Solution |
What is being measured
The primary outcome is the main question the study is designed to answer.
Area Under the Curve (AUC) of Pain Intensity
Total pain burden calculated as the Area Under the Curve of serial pain ratings (0-100 numerical pain rating scale) recorded every 5 seconds from the start of injection until no pain is reported for 30 seconds.
Measured: From injection start until pain subsides (approximately 15-60 seconds per injection).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 May 2026
- Study start25 May 2026 (estimated)
- Primary completion8 Jun 2026 (estimated)
- Study completion8 Jun 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for PainStudies of the same condition, open and under way.
- More trials run by Medical University of ViennaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Early Phase 1
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 18 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Medical University of Vienna
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Stefan Heber, Medical University of Vienna
- Investigators
- Michael J.M. Fischer, Principal investigator, Medical University of Vienna
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07600814
- Sponsor's protocol ID
- EK1688/2024
- Status last verified
- May 2026
- First submitted
- 15 May 2026
- Last updated
- 22 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual participant data (IPD), including pain ratings, time-stamped injection responses, and basic demographics (age, sex), will be shared alongside the publication of the primary results. Only data used in the main publication and relevant supplementary analyses will be included.
Study at a glance
From the registry record, last updated by the sponsor on 22 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Pain Induced by m-Cresol as Preservative - A Randomised Controlled Crossover-Trial in Healthy Volunteers
- ClinicalTrials.gov ID
- NCT07600814
- Acronym / sponsor ID
- EK1688/2024
- Conditions
- Pain, Acute Pain, Healthy Volunteer Study
- Keywords
- m-Cresol, Preservative, Subcutaneous Injection, Human Pain Models, Experimental Pain Models, Nociception
- Phase
- Early Phase 1
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 18 participants (estimated)
- Lead sponsor
- Medical University of ViennaUniversity, hospital or other
- Study start
- 25 May 2026 (estimated)
- Primary completion
- 8 Jun 2026 (estimated)
- Study completion
- 8 Jun 2026 (estimated)
- First posted
- 22 May 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Preservatives such as m-Cresol are essential components in many subcutaneously injected medications, including insulin or human growth hormone, to prevent bacterial growth. However, clinical reports have suggested that these preservatives may cause local discomfort or pain at the injection site, which can negatively impact treatment adherence. While m-Cresol is widely used, its direct contribution to injection-site pain has not yet been investigated in a prospective clinical trial.
This study aims to investigate whether subcutaneous injection of m-Cresol at concentrations commonly used in clinical practice (0.1% and 0.25%) cause significantly more pain than a preservative-free control solution. In a randomized, double-blind crossover design, healthy volunteers will receive three separate injections in a belly fold. Participants will rate their pain every 5 seconds until it subsides. The findings will help determine if m-Cresol is a primary source of injection-site pain and could lead to the development of more comfortable drug formulations.
Detailed description
Background and Objective:
m-Cresol has been used since 1980 to limit bacterial growth in parenteral medications. Although it is generally considered safe, evidence for local side effects has appeared in case reports and a clinical trial where changing the preservative led to a disappearance of local discomfort. This suggests that the preservative itself, rather than the active drug or the pH of the solution, may be responsible for a pain sensation. The objective of this study is to systematically evaluate if subcutaneous injection of m-Cresol at clinically relevant concentrations causes pain in humans.
Study Design:
This is a randomized, double-blind, placebo-controlled, 3-period crossover trial in healthy volunteers (n=18). To ensure an unbiased assessment and control for potential order effects, a Williams balanced design is utilized for the randomization of treatment sequences.
Methodology:
Familiarization: Participants first receive an unblinded injection of control solution to become accustomed to the experimental procedure and the numerical pain rating scale.
Interventions: Subjects receive three randomized, double-blind 300 µl subcutaneous injections at different spots on a belly fold, separated by at least 3 cm. The treatments include:
- m-Cresol at 0.1%
- m-Cresol at 0.25%
- Control solution. Pain Assessment: For each injection, pain intensity is recorded every 5 seconds using a numerical pain rating scale (0-100) until no pain is reported for 30 consecutive seconds. The pain caused by the needle insertion itself is rated separately before the injection begins to serve as a covariate for the statistical analysis.
Statistical Analysis:
The primary endpoint is the Area Under the Curve (AUC) of the subjective pain ratings over time. Comparisons will be made between the different m-Cresol concentrations and the vehicle control using a linear mixed model to test the primary hypotheses.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| m-Cresol 0.1% | Experimental | Other: m-Cresol 0.1%Participants receive a 300 µl subcutaneous injection of m-Cresol at a concentration of 0.1%. |
| m-Cresol 0.25% | Experimental | Other: m-Cresol 0.25%Participants receive a 300 µl subcutaneous injection of m-Cresol at a concentration of 0.25%. |
| Control solution | Placebo comparator | Other: Control SolutionParticipants receive a 300 µl subcutaneous injection of control solution. |
Who may qualify
- Ages
- 18 to 70 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (8 listed)
- Age between 18 and 70 years
- Full legal capacity Exclusion criteria
- Participant of another study, ongoing or within the last four weeks
- Current medication intake (except hormonal contraception) or drug abuse
- Female subjects: Positive pregnancy test or breastfeeding
Key exclusion criteria (0 listed)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| m-Cresol 0.1%A preservative administered subcutaneously at 0.1%, a common concentration used in medicines. | Other | m-Cresol 0.1% |
| m-Cresol 0.25%A preservative administered subcutaneously at 0.25%, a common concentration used in medicines. | Other | m-Cresol 0.25% |
| Control SolutionA control solution administered subcutaneously. | Other | Control solution |
Primary outcome
Area Under the Curve (AUC) of Pain Intensity
Time frame: From injection start until pain subsides (approximately 15-60 seconds per injection).
Total pain burden calculated as the Area Under the Curve of serial pain ratings (0-100 numerical pain rating scale) recorded every 5 seconds from the start of injection until no pain is reported for 30 seconds.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 May 2026.
- Individual participant dataSharing planned: Yes. De-identified individual participant data (IPD), including pain ratings, time-stamped injection responses, and basic demographics (age, sex), will be shared alongside the publication of the primary results. Only data used in the main publication and relevant supplementary analyses will be included.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Michael J.M. Fischer principal investigator
Medical University of Vienna
Questions about this trial
What is this clinical trial studying?
A Early Phase 1 study testing m-Cresol 0.1% and m-Cresol 0.25% in people with Pain and Acute Pain, run by Medical University of Vienna.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 8 inclusion and 0 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 22 May 2026. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Early Phase 1 (sometimes called Phase 0) studies give a very small amount of a treatment to a few people, mainly to see how the body handles it.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Felix J. Resch (+43 1 40160 31419, felix.resch@meduniwien.ac.at), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Area Under the Curve (AUC) of Pain Intensity (time frame: From injection start until pain subsides (approximately 15-60 seconds per injection).). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 May 2026.