Healthy
Conditions
Keywords
Healthy volunteers
Brief summary
The purpose of this research is to study how people respond differently to capsaicin in different racial groups and the effect it has on your pain levels. Capsaicin is a natural product made from hot chili peppers that is useful for treating the itch symptoms of skin disease.
Detailed description
To comprehensively evaluate the ethnic differences in response to topical capsaicin and its effect on thermal sensory thresholds.
Interventions
DRUGCapsaicin
Topical application, 0.1%, Capzasin HP; Chattem Inc., Chattanooga, TN, U.S.A
DRUGPlacebo moisturizing cream
Placebo moisturizing cream with no active ingredient (Cetaphil; Galderma Laboratories LP, Fort Worth, TX, U.S.A.)
Sponsors
Wake Forest University
Study design
Allocation
RANDOMIZED
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* Adult men and women who are between 18 and 50 years of age. * Subjects must be in general good health with no skin disease, disease state or physical condition which would impair evaluation of pain perception or which would increase their health risk by study participation as determined by the investigators. * Women of childbearing potential will be required to have a negative pregnancy test in order to enroll in the study.
Exclusion criteria
* Adults over age 50. * Children less than 18 years of age. * Unable to complete the required measures. * Diagnosis of diseases that would affect the measurement of pain perception. * Currently enrolled in any investigational study in which the subject is receiving any type of drug, biologic, or non-drug therapy and subjects undergoing treatment with another investigational drug or approved therapy for investigational use within 30 days prior to study participation. * Use of oral analgesic or other medications known to interfere with pain perception in the week prior to the study. * Use of emollient on the forearms on the day of the study visit. * Use of medicated topical preparations on the forearms for the week prior to the study. * Known history of neuropathy causing diseases such as uremia. * Known history of uncontrolled thyroid disease. * Known history of diabetes mellitus. * Allergy to capsaicin. * Pregnant women.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Ethnic Differences in Burning Pain Induced by Topical Capsaicin | 1 day | The primary endpoint is to test the burning pain effect of topical capsaicin by using an continuous visual analog scale (CoVAS) intensity scale as an outcome measure. Participants will rate burning pain intensity after topical capsaicin application. The burning or pain sensation intensity was recorded continuously on a 100-mm COVAS (0, no sensation to 100, maximum, strongest imaginable pain sensation). The subjects were also asked to indicate whether they experienced any nonpainful sensation. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Ethnic Differences on the Effects of Topical Capsaicin on Thermal Sensory Thermal Thresholds | 1 day | A secondary endpoint is to see if topical capsaicin has an effect on warm and heat pain thresholds. Quantitative thermosensory testing was carried out using the Medoc TSA 2001 (Medoc Ltd). The probe baseline temperature was 32 °C and the contact area was 12 cm2. The probe warmed the skin surface at a linear rate of 0·4 °C per second, up to a cut-off of 50 °C. Thermal thresholds were measured in the following order: warmth sensation threshold was measured followed by heat pain detection threshold; each of them was determined four times by the ascending method of limits. |
| The Difference in Burning/Pain Sensation Ratings Between the Capsaicin or Placebo Application. | 1 day | This secondary outcome is to see if subjects rated burning/pain differently between the topical capsaicin or placebo application. Participants will rate burning/pain intensity after topical capsaicin and placebo application. The burning/pain sensation intensity was recorded continuously on a 100-mm COVAS (0, no sensation to 100, maximum, strongest imaginable burning/pain sensation). The subjects were also asked to indicate whether they experienced any non-burning/-painful sensation. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Capsaicin and Placebo 0.1% Topical Capsaicin cream was appled to one forearm and a placebo moisturizing cream with no active ingredient (Cetaphil; Galderma Laboratories LP, Fort Worth, TX, U.S.A.) was applied to the other forearm.
A volume of 0·3 mL cream was applied in a thin layer of virtually equal thickness, on a 4 × 4 cm area, around midline. The creams were applied at a 40-min interval in a random order to minimize an order effect. The creams were randomized for right and left arm application. | 40 |
| Total | 40 |
Baseline characteristics
| Characteristic | Capsaicin and Placebo |
|---|---|
| Age, Categorical <=18 years | 0 Participants |
| Age, Categorical >=65 years | 0 Participants |
| Age, Categorical Between 18 and 65 years | 40 Participants |
| Race/Ethnicity, Customized African Americans | 10 Participants |
| Race/Ethnicity, Customized Caucasians | 10 Participants |
| Race/Ethnicity, Customized East Asians | 10 Participants |
| Race/Ethnicity, Customized Hispanic | 10 Participants |
| Region of Enrollment United States | 40 Participants |
| Sex: Female, Male Female | 20 Participants |
| Sex: Female, Male Male | 20 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 0 / 40 | 0 / 40 |
| serious Total, serious adverse events | 0 / 40 | 0 / 40 |
Outcome results
Primary
Ethnic Differences in Burning Pain Induced by Topical Capsaicin
The primary endpoint is to test the burning pain effect of topical capsaicin by using an continuous visual analog scale (CoVAS) intensity scale as an outcome measure. Participants will rate burning pain intensity after topical capsaicin application. The burning or pain sensation intensity was recorded continuously on a 100-mm COVAS (0, no sensation to 100, maximum, strongest imaginable pain sensation). The subjects were also asked to indicate whether they experienced any nonpainful sensation.
Time frame: 1 day
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| African Americans | Ethnic Differences in Burning Pain Induced by Topical Capsaicin | Capsaicin | 0.81 units on a scale | Standard Error 0.68 |
| African Americans | Ethnic Differences in Burning Pain Induced by Topical Capsaicin | Placebo | 0 units on a scale | Standard Error 0 |
| Caucasians | Ethnic Differences in Burning Pain Induced by Topical Capsaicin | Placebo | 0 units on a scale | Standard Error 0 |
| Caucasians | Ethnic Differences in Burning Pain Induced by Topical Capsaicin | Capsaicin | 4.07 units on a scale | Standard Error 1.61 |
| East Asians | Ethnic Differences in Burning Pain Induced by Topical Capsaicin | Capsaicin | 17.05 units on a scale | Standard Error 5.8 |
| East Asians | Ethnic Differences in Burning Pain Induced by Topical Capsaicin | Placebo | 0 units on a scale | Standard Error 0 |
| Hispanics | Ethnic Differences in Burning Pain Induced by Topical Capsaicin | Capsaicin | 13.3 units on a scale | Standard Error 4.67 |
| Hispanics | Ethnic Differences in Burning Pain Induced by Topical Capsaicin | Placebo | 0 units on a scale | Standard Error 0 |
Comparison: One-way anova was used to compare the mean COVAS values between groups.p-value: <0.05ANOVA
p-value: 0.55t-test, 2 sided
p-value: 0.005t-test, 2 sided
p-value: 0.027t-test, 2 sided
Secondary
Ethnic Differences on the Effects of Topical Capsaicin on Thermal Sensory Thermal Thresholds
A secondary endpoint is to see if topical capsaicin has an effect on warm and heat pain thresholds. Quantitative thermosensory testing was carried out using the Medoc TSA 2001 (Medoc Ltd). The probe baseline temperature was 32 °C and the contact area was 12 cm2. The probe warmed the skin surface at a linear rate of 0·4 °C per second, up to a cut-off of 50 °C. Thermal thresholds were measured in the following order: warmth sensation threshold was measured followed by heat pain detection threshold; each of them was determined four times by the ascending method of limits.
Time frame: 1 day
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| African Americans | Ethnic Differences on the Effects of Topical Capsaicin on Thermal Sensory Thermal Thresholds | Heat pain detection threshold change | -2.11 Change in degrees Celsius | Standard Error 1.12 |
| African Americans | Ethnic Differences on the Effects of Topical Capsaicin on Thermal Sensory Thermal Thresholds | Warmth sensation threshold change | 2.36 Change in degrees Celsius | Standard Error 0.93 |
| Caucasians | Ethnic Differences on the Effects of Topical Capsaicin on Thermal Sensory Thermal Thresholds | Warmth sensation threshold change | -0.68 Change in degrees Celsius | Standard Error 0.68 |
| Caucasians | Ethnic Differences on the Effects of Topical Capsaicin on Thermal Sensory Thermal Thresholds | Heat pain detection threshold change | -6.10 Change in degrees Celsius | Standard Error 1.36 |
| East Asians | Ethnic Differences on the Effects of Topical Capsaicin on Thermal Sensory Thermal Thresholds | Heat pain detection threshold change | -5.01 Change in degrees Celsius | Standard Error 1.09 |
| East Asians | Ethnic Differences on the Effects of Topical Capsaicin on Thermal Sensory Thermal Thresholds | Warmth sensation threshold change | 0.56 Change in degrees Celsius | Standard Error 0.059 |
| Hispanics | Ethnic Differences on the Effects of Topical Capsaicin on Thermal Sensory Thermal Thresholds | Heat pain detection threshold change | -7.24 Change in degrees Celsius | Standard Error 0.57 |
| Hispanics | Ethnic Differences on the Effects of Topical Capsaicin on Thermal Sensory Thermal Thresholds | Warmth sensation threshold change | -3.15 Change in degrees Celsius | Standard Error 0.93 |
p-value: 0.012t-test, 2 sided
p-value: 0.06t-test, 2 sided
p-value: 0.002t-test, 2 sided
Secondary
The Difference in Burning/Pain Sensation Ratings Between the Capsaicin or Placebo Application.
This secondary outcome is to see if subjects rated burning/pain differently between the topical capsaicin or placebo application. Participants will rate burning/pain intensity after topical capsaicin and placebo application. The burning/pain sensation intensity was recorded continuously on a 100-mm COVAS (0, no sensation to 100, maximum, strongest imaginable burning/pain sensation). The subjects were also asked to indicate whether they experienced any non-burning/-painful sensation.
Time frame: 1 day
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| African Americans | The Difference in Burning/Pain Sensation Ratings Between the Capsaicin or Placebo Application. | 8.81 units on a scale | Standard Deviation 7.63 |
| Caucasians | The Difference in Burning/Pain Sensation Ratings Between the Capsaicin or Placebo Application. | 0 units on a scale | Standard Deviation 0 |
p-value: 0.06t-test, 2 sided