Trial Outcomes & Findings for Topical Acetaminophen for Itch Relief: a Proof of Concept Study in Healthy Subjects (NCT NCT03997851)
NCT ID: NCT03997851
Last Updated: 2025-12-08
Results Overview
Peak itch intensity between the vehicle and 3 other active treatments (5%, 2.5%, and 1% acetaminophen gels) after non-histaminergic itch induction (cowhage). Itch intensity was measured on a 10cm scale visual analog scale for 10 minutes. 0 was weighted with "no itch" and 10 was weighted with "most itch imaginable".
Recruitment status
COMPLETED
Study phase
PHASE1/PHASE2
Target enrollment
17 participants
Primary outcome timeframe
10 minutes
Results posted on
2025-12-08
Participant Flow
Unit of analysis: skin arm test areas
Participant milestones
| Measure |
Topical acetaminophen and vehicle gel
Each participant will receive topical gel treatments applied for 30 minutes to 4 separate 4 x 4 cm predefined skin areas on the ventral forearms twice at 2 separate study visits.
The 4 treatments are:
5% acetaminophen gel 2.5% acetaminophen gel
1% acetaminophen gel Vehicle gel
Acetaminophen: Topical acetaminophen gel
|
|---|---|
|
Overall Study
STARTED
|
17 136
|
|
Overall Study
COMPLETED
|
17 136
|
|
Overall Study
NOT COMPLETED
|
0 0
|
Reasons for withdrawal
Withdrawal data not reported
Baseline Characteristics
Topical Acetaminophen for Itch Relief: a Proof of Concept Study in Healthy Subjects
Baseline characteristics by cohort
| Measure |
Topical Acetaminophen and Vehicle Gel
n=17 Participants
Each participant will receive topical gel treatments applied for 30 minutes to 4 separate 4 x 4 cm predefined skin areas on the ventral forearms twice at 2 separate study visits.
The 4 treatments are:
5% acetaminophen gel 2.5% acetaminophen gel
1% acetaminophen gel Vehicle gel
Acetaminophen: Topical acetaminophen gel
|
|---|---|
|
Age, Categorical
<=18 years
|
0 Participants
n=9 Participants
|
|
Age, Categorical
Between 18 and 65 years
|
17 Participants
n=9 Participants
|
|
Age, Categorical
>=65 years
|
0 Participants
n=9 Participants
|
|
Sex: Female, Male
Female
|
15 Participants
n=9 Participants
|
|
Sex: Female, Male
Male
|
2 Participants
n=9 Participants
|
|
Ethnicity (NIH/OMB)
Hispanic or Latino
|
5 Participants
n=9 Participants
|
|
Ethnicity (NIH/OMB)
Not Hispanic or Latino
|
12 Participants
n=9 Participants
|
|
Ethnicity (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=9 Participants
|
|
Race (NIH/OMB)
American Indian or Alaska Native
|
0 Participants
n=9 Participants
|
|
Race (NIH/OMB)
Asian
|
3 Participants
n=9 Participants
|
|
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
|
0 Participants
n=9 Participants
|
|
Race (NIH/OMB)
Black or African American
|
3 Participants
n=9 Participants
|
|
Race (NIH/OMB)
White
|
11 Participants
n=9 Participants
|
|
Race (NIH/OMB)
More than one race
|
0 Participants
n=9 Participants
|
|
Race (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=9 Participants
|
PRIMARY outcome
Timeframe: 10 minutesPopulation: All subjects received 4 topical cream treatments.
Peak itch intensity between the vehicle and 3 other active treatments (5%, 2.5%, and 1% acetaminophen gels) after non-histaminergic itch induction (cowhage). Itch intensity was measured on a 10cm scale visual analog scale for 10 minutes. 0 was weighted with "no itch" and 10 was weighted with "most itch imaginable".
Outcome measures
| Measure |
Topical 5% acetaminophen gel
n=17 Participants
Topical 5% acetaminophen gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Acetaminophen: Topical acetaminophen gel
|
Topical 2.5% acetaminophen gel
n=17 Participants
Topical 2.5% acetaminophen gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Acetaminophen: Topical acetaminophen gel
|
Topical 1% acetaminophen gel
n=17 Participants
Topical 1% acetaminophen gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Acetaminophen: Topical acetaminophen gel
|
Topical vehicle gel
n=17 Participants
Topical vehile gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Carbomer 980: Topical vehicle gel
|
|---|---|---|---|---|
|
Peak Itch Intensity Between the Vehicle and Active Treatments During Non-histaminergic Itch Induction
|
4.5 Intensity score
Standard Deviation 1.98
|
3.94 Intensity score
Standard Deviation 2.77
|
5.32 Intensity score
Standard Deviation 2.29
|
5.79 Intensity score
Standard Deviation 2.61
|
PRIMARY outcome
Timeframe: 10 minutesPopulation: All subjects received 4 topical cream treatments.
Peak itch intensity between the vehicle and 3 other active treatments (5%, 2.5%, and 1% acetaminophen gels) after histaminergic itch induction. Itch intensity was measured on a 10cm scale visual analog scale for 10 minutes. 0 was weighted with "no itch" and 10 was weighted with "most itch imaginable".
Outcome measures
| Measure |
Topical 5% acetaminophen gel
n=17 Participants
Topical 5% acetaminophen gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Acetaminophen: Topical acetaminophen gel
|
Topical 2.5% acetaminophen gel
n=17 Participants
Topical 2.5% acetaminophen gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Acetaminophen: Topical acetaminophen gel
|
Topical 1% acetaminophen gel
n=17 Participants
Topical 1% acetaminophen gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Acetaminophen: Topical acetaminophen gel
|
Topical vehicle gel
n=17 Participants
Topical vehile gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Carbomer 980: Topical vehicle gel
|
|---|---|---|---|---|
|
Peak Itch Intensity Between the Vehicle and Active Treatments During Histaminergic Itch Induction
|
2.04 Intensity score
Standard Deviation 2.52
|
2.38 Intensity score
Standard Deviation 2.26
|
2.91 Intensity score
Standard Deviation 2.31
|
3.07 Intensity score
Standard Deviation 2.64
|
SECONDARY outcome
Timeframe: 3 minutesPopulation: All subjects received treatment with the 4 topical cream formulations at 2 study visits. Quantitative sensory testing was performed on each area of treated skin.
Standardized quantitative sensory testing is performed to measure heat pain threshold (assesses the threshold at which heat pain sensation is first detected). Measured in Celsius.
Outcome measures
| Measure |
Topical 5% acetaminophen gel
n=17 Participants
Topical 5% acetaminophen gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Acetaminophen: Topical acetaminophen gel
|
Topical 2.5% acetaminophen gel
n=17 Participants
Topical 2.5% acetaminophen gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Acetaminophen: Topical acetaminophen gel
|
Topical 1% acetaminophen gel
n=17 Participants
Topical 1% acetaminophen gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Acetaminophen: Topical acetaminophen gel
|
Topical vehicle gel
n=17 Participants
Topical vehile gel will be applied to one 4x4 cm predefined skin area on the ventral forearm during 2 study visits. The gel will be applied to the test area and will be allowed 30 minutes to adsorb. Following this pre-treatment, residual gel will be removed and itch induction/sensory testing will commence, strictly within the pre-treated area.
Carbomer 980: Topical vehicle gel
|
|---|---|---|---|---|
|
Thermal Threshold Detection (Heat Pain)
After non-histamine itch induction
|
43.99 Degrees celsius
Standard Deviation 0.95
|
44.03 Degrees celsius
Standard Deviation 0.81
|
44.30 Degrees celsius
Standard Deviation 0.64
|
44.20 Degrees celsius
Standard Deviation 0.59
|
|
Thermal Threshold Detection (Heat Pain)
After histamine itch induction
|
43.95 Degrees celsius
Standard Deviation 2.17
|
44.51 Degrees celsius
Standard Deviation 0.72
|
43.94 Degrees celsius
Standard Deviation 0.88
|
44.07 Degrees celsius
Standard Deviation 0.56
|
Adverse Events
Topical 5% acetaminophen gel
Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths
Topical 2.5% acetaminophen gel
Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths
Topical 1% acetaminophen gel
Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths
Topical vehicle gel
Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths
Serious adverse events
Adverse event data not reported
Other adverse events
Adverse event data not reported
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place