Conditions: Pruritus
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 17
Healthy volunteers: yes

Brief summary:
Currently, topical antihistamines and corticosteroids are mainly used for itching relief. However, the over the counter antihistamines are not effective on all itch conditions. Acetaminophen is a popular and widely used OTC drug for pain relief. Although its mode of action is still unknown, recent studies have shown that acetaminophen indirectly activates cannabinoid CB1 receptors. Recent studies have shown that topical cannabinoid agonists are effective for itch relief, the efficacy of topical acetaminophen will be tested for non-histaminergic itch relief.

Detailed description:
This will be a single-blinded, vehicle-controlled randomized study in healthy controls to test the efficacy of the topical gel formulation with three differing concentrations of acetaminophen (APAP) for itch relief. To detect medium effects of the treatments with a given α of 0.5 and an error probability of 0.05, with a power of 0.95, the number of participants needed is 36 (10 within post hoc pairwise comparisons).

Arms:
arm 1: 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. arm 2: 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. arm 3: 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. arm 4: 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.

Interventions: intervention 1: Acetaminophen intervention 2: Carbomer 980
Intervention descriptions: intervention 1: Topical acetaminophen gel intervention 2: Topical vehicle gel

Protocol document:
Prot_SAP_000.pdf: 
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Topical Acetaminophen for Itch Relief: a proof of concept study in healthy subjects
IRB Number: 20190133
IND Number: 127990
NCT number: NCT03997851
       
 
SPONSOR-INVESTIGATOR:
Gil Yosipovitch, MD 
CO- INVESTIGATOR:       
Leigh Nattkemper, PhD 
                 
Address:
University of Miami
1600 NW 10th Ave
RMSB 2023
Miami, FL 33136
Address of IRB: 
University of Miami Human 
Subject Research Office IRB
1400 NW 10th Ave
Suite 1200A
Miami, FL 33136
Clinical Trial Protocol Statement of Compliance
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This clinical trial shall be conducted in compliance with the protocol, as referenced herein, 
and all applicable local, national, and international regulatory requirements to include, but 
not be limited to:
·
International Conference on Harmonization (ICH) Guidelines on Good Clinical 
Practice (GCP)
·
Ethical principles that have their origins in the Declaration of Helsinki 
·
Food and Drug Administration (FDA) Code of Federal Regulation (CFR):
o
Title 21CFR Part 50 and 45 CFR Part 46, Protection of Human Patients
o
Title 21CFR Part 54, Financial Disclosure by Clinical Investigators
o
Title 21CFR Part 56, Institutional Review Boards
o
Title 21CFR Part 312, Investigational New Drug Application
o
Title 45 CFR Parts 160, 162, and 164, Health Insurance Portability and 
Accountability Act (HIPAA)
As the Principal Investigator, I understand that my signature on the protocol constitutes my 
agreement and understanding of PI responsibilities to conduct the clinical trial in accordance 
to the protocol and applicable regulations.  Furthermore, it constitutes my understanding and 
agreement that any changes initiated by myself, without prior agreement in writing from the 
Sponsor, shall be defined as a deviation from the protocol, and shall be formally documented 
as such.
I understand that my signature constitutes agreement and understanding of acceptance of the 
defined responsibilities of a Sponsor-Investigator as defined by the protocol, applicable FDA 
Regulations, and/or business contracts, but does not in any capacity relieve me of my 
responsibilities as the Sponsor-Investigator.  Additionally, my signature constitutes my 
understanding and agreement that any changes to the protocol shall be implemented timely 
with my review and approval prior to implementation.
 
INVESTIGATOR'S STATEMENT
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I have reviewed the protocol and agree to conduct this study as outlined in the protocol and 
in compliance with ICH/GCP Guidelines.
I have read and agree to follow the Study procedures as outlined.
Print Name of PI
PI’s Signature
Date
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CLINICAL PROTOCOL SYNOPSIS
Title of Trial:
Topical Acetaminophen for Itch Relief: a proof of concept study in healthy 
subjects
UM IRB 
Number:
20190133
Sponsor-
Investigator:
Gil Yosipovitch, MD
Trial Duration:  
6 months
Phase of Trial: I/IIa
Trial 
Population:
Healthy volunteers
Trial Centers:
University of Miami, Department of Dermatology
Objectives:
Primary:  The primary endpoint is to test the antipruritic effect of 
topical acetaminophen gel formulations using an itch VAS intensity 
scale as an outcome measure.
Secondary: A secondary endpoint is to see if this topical has a relieving 
effect on heat pain using heat pain thresholds as an outcome measure.
Exploratory: An exploratory end point is to see if the topical reduces 
erythema caused by itch induction using a Likert scale as an outcome 
measure.
Trial Design:
 double-blinded, vehicle-controlled randomized study
Number of 
Patients:
40 healthy subjects, in order for 36 subjects to complete the study.
Trial Drug(s), 
Dose, and 
Mode of 
Administration:
0.4ml application of each topical gel:
5% APAP, 2.5% APAP, 1% APAP, vehicle 
Trial Drug 
Supply:
Sponsor-Investigator
Inclusion 
Criteria:
1. Healthy subjects must be between 18 and 50 years of age.
2. Must be in general good health with no disease or physical 
conditions that would impair evaluation of itch and pain perception.
3. No history of chronic itch or pain.
4. Must abstain from the use of any systemic or topical anti-histamine, 
steroid, or pain relief medications from the week prior to the study 
till the completion of the study.
5. Must abstain from the use of moisturizers on the arms 24 hours 
before study visits.
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Exclusion 
Criteria:
1. Individuals under 18 or over 50 years of age.
2. Inability to complete the required measures. 
3. The presence of an itchy skin disease.
4. Diagnosis of diseased that would affect itch or pain perception (e.g. 
neuropathies).
5. Currently enrolled in any investigational study in which the subject 
is receiving any type of drug, biological, or non-drug therapy.
6. Use of oral, topical analgesics, or other medications known to 
interfere with itch or pain perception in the week prior to the study 
and throughout the study (e.g. antihistamines, anesthetics, opioids, 
neuroleptics, etc.).
7. Use of emollients on the arms a week prior to the study and 
throughout the study.
8. Known allergies to acetaminophen and cowhage.
9. Pregnant women. (Women of child bearing potential will undergo 
an hCG pregnancy test).
10. Currently incarcerated.
Statistical 
Methodology:
Normality assessment will be tested by visual inspection and Sharpiro-
Wilks tests. A repeated measure (between–within) ANOVA will be used 
for the main analysis and post hoc comparisons will be conducted using the 
Bonferroni correction in a manner similar to Dunnett’s test.
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Table of Contents
1.
INTRODUCTION ......................................................................................................................
Background....................................................................................................................................
Investigational Product Description ..............................................................................................
Rationale for the Trial....................................................................................................................
2.
TRIAL OBJECTIVES................................................................................................................
3.
TRIAL POPULATION .............................................................................................................. 
4.
TRIAL REGISTRATION ..........................................................................................................
5.
 TRIAL DESIGN........................................................................................................................
6.
 ADMINISTRATION OF TRIAL TREATMENTS ..................................................................
7.
 DOSE MODIFICATIONS ........................................................................................................
8.
 TRIAL ASSESSMENTS AND TREATMENT........................................................................
9.
  Investigational Product .............................................................................................................
10.
RESPONSE EVALUATIONS AND MEASUREMENTS......................................................
11.    Statistical Consideration……………………………………………………………………  
12.
Safety Reporting and Analyses.................................................................................................
13.
Clinical Monitoring ..................................................................................................................
14.
ETHICAL, FINANCIAL, AND REGULATORY CONSIDERATIONS ...............................
15.
Record Retention and Documentation of the Trial...................................................................
16.
REFERENCES .........................................................................................................................
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1
INTRODUCTION
1.1
Background
Currently, topical antihistamines and corticosteroids are mainly used for itching relief. However, 
the over the counter antihistamines are not effective on all itch conditions. Acetaminophen is a 
popular and widely used OTC drug for pain relief. Although its mode of action is still unknown, 
recent studies have shown that acetaminophen indirectly activates cannabinoid CB1 receptors. 
Recent studies have shown that topical cannabinoid agonists are effective for itch relief, the 
efficacy of topical acetaminophen will be tested for non-histaminergic itch relief. 
1.2
Investigational Product Description
Topical gel formulations of APAP (5%, 2.5%, and 1%) and a vehicle control
1.3
Rationale for the Trial
There is an unmet need to develop effective topical anti-pruritic medications for acute and 
chronic itch, as currently there are few topical formulations that have a direct effect on itch.
2
TRIAL OBJECTIVES
Primary: The primary endpoint is to test the antipruritic effect of topical acetaminophen 
gel formulations using an itch VAS intensity scale as an outcome measure.
Secondary: A secondary endpoint is to see if this topical has a relieving effect on heat pain using 
a heat pain thresholds as an outcome measure. 
Exploratory: An exploratory end point is to see if the topical reduces erythema caused by itch 
induction using a Likert scale as an outcome measure.
3
TRIAL POPULATION
3.1
Inclusion Criteria 
Patients must meet the following criteria in order to be included in the clinical trial:
1. Healthy subjects must be between 18 and 50 years of age.
2. Must be in general good health with no disease or physical conditions that would 
impair evaluation of itch and pain perception.
3. No history of chronic itch or pain.
4. Must abstain from the use of any systemic or topical anti-histamine, steroid, or 
pain relief medications from the week prior to the study till the completion of the 
study.
5. Must abstain from the use of moisturizers on the arms 24 hours before study 
visits.
3.2
Exclusion Criteria
1. Individuals under 18 or over 50 years of age.
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2. Inability to complete the required measures. 
3. The presence of an itchy skin disease.
4. Diagnosis of diseased that would affect itch or pain perception (e.g. neuropathies).
5. Currently enrolled in any investigational study in which the subject is receiving 
any type of drug, biological, or non-drug therapy.
6. Use of oral, topical analgesics, or other medications known to interfere with itch 
or pain perception in the week prior to the study and throughout the study (e.g. 
antihistamines, anesthetics, opioids, neuroleptics, etc.).
7. Use of emollients on the arms a week prior to the study and throughout the study.
8. Known allergies to acetaminophen and cowhage.
9. Pregnant women. (Women of child bearing potential will undergo an hCG 
pregnancy test).
10. Currently incarcerated.
3.3
Discontinuation from Trial Treatment
If a subject experiences an adverse event assessed at  Grade 2 according to CTCAE v4, 
the subject will not receive additional treatments and will be followed until the adverse 
event resolves or stabilizes. 
3.4
Recruitment Methods
Subjects in this study will be recruited through appropriate IRB-approved flyer 
advertising around the University of Miami medical campus. 
4
TRIAL REGISTRATION
All patients and/or their legal guardians shall receive written and verbal information concerning 
the clinical trial.  This information will emphasize that participation in the clinical trial is 
voluntary and that the patient may withdraw from the clinical trial at any time and for any 
reason. All patients will be given opportunity to ask questions and will be given sufficient time 
to consider before consenting. This trial will be registered on ClinicalTrials.gov.
The signed and dated informed consent to participate in the clinical trial must be obtained prior 
to any clinical trial related procedure being carried out.
5
TRIAL DESIGN
This will be a double-blinded, vehicle-controlled randomized study in healthy controls to 
test the efficacy of the topical gel formulation with three differing concentrations of 
acetaminophen (APAP) for itch relief.  To detect medium effects of the treatments with a 
given α of 0.5 and an error probability of 0.05, with a power of 0.95, the number of 
participants needed is 36 (10 within post hoc pairwise comparisons).
6
ADMINISTRATION OF TRIAL TREATMENTS
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6.1
Trial Treatments
The treatments include topical gel APAP (5%, 2.5%, 1%) and vehicle control gel. Each subject 
will have all treatments applied to them twice in total, once at each study visit.
Application will be conducted with the investigator wearing nitrile gloves. A 0.4ml volume of 
the test formulations or the vehicle control will be rubbed gently into the skin.
6.2
Duration of Treatment
Subjects will be in the study for 2 2-hour long visits within 7 days. Each treatment will be 
applied to the skin once during each study visit. The treatment will be allowed to permeate the 
skin for 30 minutes prior to any other study procedure commencing at the test site.
6.3
End of Trial
Study stoppage will occur if 36 subjects complete the study or if a severe adverse event 
occurs. Interim analysis will be used to analyze data for statistical significance and 
power. If study reaching significance with adequate power, the study may be concluded 
before 36 subjects complete the study.
6.4
Prior and Concomitant Medications
Select prior and concomitant medications will be collected at each study visit. A history of prior 
medications in the past week will be collected for any systemic or topical anti-histamine, steroid, 
or pain relief therapies (i.e. any medications known to interfere with itch or pain perception). 
These will also be collected as concomitant medications until the last study visit. 
7
DOSE MODIFICATIONS
Does modification will not occur.
8
TRIAL ASSESSMENTS AND TREATMENT
Procedure
Visit 1
Visit 2 (± 6 days)
Informed consent
X
Inclusion/exclusion
X
Medical history/demographics
X
Pregnancy test
X
Prior/Con meds
X
X
Vitals
X
X
Selection of test sites
X
X
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Treatment with IP
X
X
Itch induction
X
X
Itch Intensity VAS
X
X
Erythema grading 
X
X
QST (HPT)
X
X
AE/SAE collection
X
X
8.1
Screening
Subjects will be asked to participate in two 2-hour study visits within a one week time 
period. Following signed informed consent, obtained in the presence of the investigator 
or designee, the inclusion and exclusion criteria will be confirmed and vitals will be 
taken. The screening can be performed the same day or within 24 hours as treatment visit 
1.
8.2
Trial Treatment Period
For each visit, four 4 cm x 4 cm square test areas will be used on the subject’s volar 
forearms (two squares on the left arm and two squares on the right arm). These squares 
will be separated by another 4 cm.  Only one area will be tested at a time, and there will 
be a 5-minute wait period before the next area will be tested. The placement of the 
treatments in these test areas will be randomized.
The itch induction method, cowhage or histamine, for visit 1 and visit 2 will be 
randomized.
For the cowhage induction study visit, each test area will be pretreated by gently rubbing 
in a 0.4ml volume of either one of the test formulations (5% APAP; 2.5% APAP or; 1% 
APAP) or the vehicle control to the skin area based on a randomization scheme. Thirty 
minutes after pretreatment, the area will be wiped clean with a dry lab wipe and itch will 
be evoked by the application of 40-45 cowhage spicules (Papoiu, Tey, Coghil 2011). The 
spicules will be rubbed gently within the test area for 45 seconds. Subjects will rate their 
itch intensity every 30 seconds until the itch sensation has completely subsided using a 
numerical 10 cm visual analog scale (VAS), from 0 (no itch) to 10 (most unbearable 
itch). After the itch has subsided, the cowhage spicules will be removed using adhesive 
tape. 
For the histamine induction study visit, each test area will be pretreated by gently rubbing 
in a 0.4ml volume of either one of the test formulations (5% APAP; 2.5% APAP or; 1% 
APAP) or the vehicle control to the skin area based on a randomization scheme. Thirty 
minutes after pretreatment, the area will be wiped clean with a dry lab wipe and itch will 
be evoked by iontophoresis of a 1% histamine solution. 0.2ml of the 1% histamine 
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solution will be placed in an anode delivery electrode placed on the test area, while a 
cathode grounding electrode is placed on the subject’s arm at a certain distance (< 10 cm 
away) from the test area (but not in the test area). The iontophoresis device, a battery-
powered stimulus isolation unit (Perimed PF 3826, Perilont Power device, Sweden) 
generates a current of no more than 500 µA for 60 sec. Subjects will rate their itch 
intensity every 30 seconds until the itch sensation has completely subsided using a 
numerical 10 cm visual analog scale (VAS), from 0 (no itch) to 10 (most unbearable 
itch).
Reduction of erythema will also be measured by using a Likert scale before itch is 
induced, 90 seconds after itch is induced, and once the itch subsides at all test sites.
Heat pain thresholds will be assessed using the TSA-II neurosensory analyzer at all test 
sites once itch as subsided for at least 5 minutes (Angst, Tingle, Phillips 2009). A 
thermode probe will warm the skin surface from a baseline of 32 °C to a maximum of 
50°C at 0.4°C increments. The threshold will be determined 3 times by the ascending 
method of limits, where the subject will be instructed to press a response button upon 
detection of a painful stimulus.
8.3
Post-Treatment Follow-up Visit
Study subjects will be instructed to report any adverse events up to one week after the study is 
completed.
8.4
Patient Withdrawal
The following medical and other reasons justify a premature termination (by patient or 
investigator) of the investigational treatments:

Withdrawal of informed consent,

SAEs,

Patient’s request,

Patient is lost to follow-up, and/or

Investigator’s judgment.
If a patient withdraws from the study, all efforts will be made to complete a final evaluation, if 
possible, including the reason for withdrawal.  
Withdrawals due to non-attendance or non-compliance must be followed up to obtain the reason 
for non-attendance or non-compliance.  Withdrawals due to intercurrent illness or adverse events 
(AEs) are to be fully documented with supplementary information where available and 
appropriate.  Patients discontinued due to an AE will be followed until the AE is resolved, a 
reasonable explanation is provided for the event, or the patient is referred to his/her own primary 
medical doctor.  The specific AE in question will be recorded on the appropriate source 
document.
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9
INVESTIGATIONAL PRODUCT
9.1
Cowhage
Cowhage (Mucuna pruriens) is a tropical legume also known as Velvet bean or cowitch 
and it is found in Latin America, the Caribbean, India, Africa and Florida. M. pruriens is 
a climbing vine and considered variously as an annual or perennial. The plant consists of 
a vine with slender stems that bear numerous alternate, trifoliolate leaves approximately 
10cm long. The flowers are typically purple, red or green-yellow. The fruit pods range 
from 3-10 cm in length, are curved and, when mature, are covered with dark 
hairs/spicules that provide a velvety appearance. The pods contain 4-6 seeds that are 
approximately 1 x 1 cm. 
The dry pods are collected by cutting the stems from the plant and letting them fall 
directly into a clean, dry polythene bag. The spicules are separated from the pods by 
shaking the bag. Forceps are used to remove the pods and retain the spicules. The 
cowhage spicules are shipped at room temperature since they are stable unless exposed to 
extreme heat and pressure via autoclaving (>100°C), which renders them chemically 
inert.
Once it reaches the lab, Dr. Yosipovitch’s staff documents on the tube the date of arrival. 
This batch is labeled the “master batch”. The tube of cowhage is then stored under dry 
conditions in a 4°C refrigerator.  Also upon arrival, the spicules are examined under a 
microscope to confirm the material is cowhage. The dimensions of the spicules (2-4 mm 
length, 1-3 µm tip diameter) are measured 40.  
The investigator then tests the spicules for the itch induction ability with the same 
application method used in studies 57. Forty to forty-five spicules (a dose found to induce 
a consistent and reproducible itch sensation) are counted under the microscope and then 
rubbed in to a 4x4 cm area on the volar forearm for 45 seconds in a circular motion. 
Approximately 0.2 mm of the spicule tip enters the skin. Forty-five spicules of cowhage 
are equivalent to 45 µg of material, containing about 90-140 ng of mucunain 45. The 
spicules usually induce itch after ~30-90 seconds of the application. If 2 minutes pass 
without itch being induced, the spicules are deemed inactive and the batch will not be 
used for itch induction in studies. If itch is induced, the itch sensation will last ~7 minutes 
and itch intensity is rated using a 0-10 numerical rating scale (NRS) every 30 seconds 
until the itching subsides. Cowhage spicules are removed from the skin using tape, which 
is disposed of in a biohazard trash bin. The itch subsides quickly once the spicules have 
been removed. Itch is only felt at the site of induction and mild temporary erythema at the 
induction site is common. 
For studies using cowhage to induce itch, a small portion of the master batch of cowhage 
is aliquoted into smaller 5 ml tubes as a “working batch”. The date of separation from the 
main batch is marked on the smaller tube. This tube then remains at room temperature for 
the duration of the study. The potency of the cowhage is preserved for many years when 
stored in a dehumidified area at room temperature or at 4°C, but the potency is checked 
every 3 months and before the start of any study.
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9.2
1% Histamine Iontophoresis Solution (200ml)
Methylcellulose (USP Hypromellose HY124; Spectrum Chemicals, New Brunswick, NJ) 
and histamine (>99% histamine dihydrochloride; Sigma-Aldrich, St. Louis, MO) is 
dissolved in 0.9% sodium chloride (USP Diluent; Hospira, Lake Forest, IL) until the 
solution thickens into a gel. The gel solution is kept in a tight, light resistant container at 
4°C. The container is labeled: “1% Histamine Solution. For Investigational Use Only.
9.3
Topical Acetaminophen
Gel Formulations
For each 100 ml:
Acetaminophen (APAP) 
5g, 2.5 g, or 1g
Stearic Acid
2.0 g
Carbomer 980
0.5 g
Triethanolamine
2.0 g
Denatured Alcohol
35 ml
Purified Water
to 100 ml
Preparation
50 ml of water is heated to 75 C.  Carbomer is added to the water with vigorous mixing.  
The APAP and Stearic Acid are added to the alcohol.  The mixture is heated to 75 C and 
mixed.  The water and alcohol mixtures are combined and triethanolamine is added 
during mixing.  The liquid gel is place in a sonic bath for 15 minutes.  The gel will form 
during cooling. A vehicle control will be prepared using the same materials and methods 
without the active ingredient.  
Labeling:
Acetaminophen or Placebo Gel
External Use Only!
"Caution: New Drug- Limited by Federal 
(or United States) law to investigational use"
Store at Room Temperature
Lot Number:  xxxxxxx
Expiration: xx/xx/xxxx.
Formation expirations: 
As per USP 795 standards on compounding with a water-containing base, these 
formulations have an expiration of 30 days. The expiration date will be on the label.
Storage: 
The formulations will be stored at room temperature in a locked cabinet in the 
Dermatology research clinic that only study personnel will have access with a key. 
Ambient temperature and min/max of the storage cabinet will be recorded once a day 
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(except on weekends). Logs of formulation delivery and use per subject will be kept. 
Application:
Application will be conducted with the investigator wearing nitrile gloves. A 0.4ml 
volume of the test formulations or the vehicle control will be rubbed gently into the skin.
9.4
Risks Associated with the Study
Topical APAP application: Liver damage is the most serious side effect of APAP overdose. The 
recommended daily dose of APAP is no more than 4,000mg to prevent overdose. Rarely serious 
skin reactions can occur. Participants will be will be instructed to contact the study team at any 
time after application of topical APAP if they have any problems.
Cowhage Application: No specific serious risks or adverse effects are associated with the 
application of cowhage spicules on the skin. At the site of application, subjects may experience a 
mild to moderate burning/stinging sensation apart from the itch sensation itself, which may last 
up to 5-7 minutes. Cowhage is not an allergen and does not cause contact dermatitis or chemical 
irritation.  We do not expect a tachyphylactic reaction or an additive affect from multiple 
cowhage applications because we will apply only once in the same site. In the event of an 
allergic reaction, the study will be stopped and appropriate treatment administered (use of 
EpiPen).
Following use of EpiPen, the patient will be referred to the emergency room, where basic vitals 
including heart rate, blood pressure, and oxygen saturation in the blood will be monitored. A 
respiratory exam will also be given to assess the quality of breathing. Steroids to prevent 
additional airway closure and fluids to maintain blood pressure will be given as necessary. The 
patient will be monitored in the emergency room for 6 hours, and then sent home with an 
additional EpiPen to guarantee immediate access to self-injectable epinephrine. The patient will 
be instructed on EpiPen usage. The patient will also be educated to watch for symptoms of 
biphasic anaphylaxis, which may occur up to 72 hours after initial symptoms of anaphylaxis.
Histamine Application: No specific serious risks or adverse effects are associated with the 
application of histamine to the skin. The histamine application will cause brief itching and 
tingling, with a standard wheel and flare response. The wheel and flare response should 
disappear about one hour after the histamine is applied to the skin. We do not expect a 
tachyphylactic reaction or an additive affect from multiple histamine applications because we 
will apply only once in the same site. In the event of an allergic reaction, the study will be 
stopped and appropriate treatment administered (use of EpiPen).
Following use of EpiPen, the patient will be referred to the emergency room, where basic vitals 
including heart rate, blood pressure, and oxygen saturation in the blood will be monitored. A 
respiratory exam will also be given to assess the quality of breathing. Steroids to prevent 
additional airway closure and fluids to maintain blood pressure will be given as necessary. The 
patient will be monitored in the emergency room for 6 hours, and then sent home with an 
additional EpiPen to guarantee immediate access to self-injectable epinephrine. The patient will 
be instructed on EpiPen usage. The patient will also be educated to watch for symptoms of 
biphasic anaphylaxis, which may occur up to 72 hours after initial symptoms of anaphylaxis.
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Heat Pain Sensory Testing: Heat pain will be assessed using a thermode probe raising the 
temperature of circulating water from 32ºC to 50ºC. This heat pain is marginally unpleasant and 
a bit bothersome, but relatively easily tolerated. If the pain is unbearable, the thermode can be 
immediately removed to alleviate the painful sensation.
10 RESPONSE EVALUATIONS AND MEASUREMENTS
The investigator(s) will make the following assessments on each patient during the study: 
1. Itch intensity after cowhage and histamine itch induction
2. Erythema grading
3. Heat pain threshold
10.1 Safety Evaluation
Local and systemic adverse events will be monitored during the study. Dermatologic 
evaluations for rash, erythema (outside of administration area), urticaria, eruptions, and 
epidermal necrolysis will be performed throughout the study visit. Anaphylaxis and 
hypersensitivity (erythema multiforme) will also be monitored for.
10.2 Statistical Considerations 
To detect medium effects of the treatments with a given α of 0.5 and an error probability of 0.05, 
with a power of 0.95, the number of participants needed is 36 (10 within post hoc pairwise 
comparisons).  
Normality assessment will be tested by visual inspection and Sharpiro-Wilks tests. A repeated 
measure (between–within) ANOVA will be used for the main analysis and post hoc comparisons 
will be conducted using the Bonferroni correction in a manner similar to Dunnett’s test.
11 SAFETY REPORTING AND ANALYSIS
Safety and tolerability assessments will consist of ongoing monitoring and recording of all 
adverse (AE) and serious adverse event (SAE) reports, the regular monitoring of signs and 
symptoms of cutaneous irritation, and regular measurements of vital signs.
11.1 Safety Analyses
Safety assessments will consist of monitoring and recording protocol-defined adverse events 
(AEs) and serious adverse events (SAEs) and other protocol-specified tests that are deemed 
critical to the safety evaluation of the trial drug.
11.2 Adverse Events
The PI is responsible for identifying, documenting and reporting adverse events to the IRB and 
FDA as applicable.  
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11.2.1 Definitions of Adverse Events
An adverse event is the development of an undesirable medical condition, or the deterioration of 
a pre-existing medical condition following or during exposure to a medicinal product, whether or 
not considered causally related to the product.  
An undesirable medical condition can be symptoms (e.g., chest pain), signs (e.g., tachycardia), or 
the abnormal results of an investigation (e.g., laboratory findings).  
11.2.2 Recording of Adverse Events
All adverse events of any patient during the course of the trial will be reported in the source 
document, and the investigator will give his opinion as to the relationship of the adverse event to 
trial drug treatment (i.e., whether the event is related or unrelated to trial drug administration).  If 
the adverse event is serious and related to the IP, it will be reported within 24 hours to the IRB as 
per UM policy.  Other untoward events occurring in the framework of a clinical trial are also to 
be recorded as AEs (i.e., AEs that occur prior to assignment of trial treatment that are related to a 
protocol-mandated intervention, including invasive procedures such as biopsies, medication 
washout, or no treatment run-in).
All AEs, regardless of seriousness or relationship to trial treatment, spanning from the start of 
trial treatment until 7 days after study completion are to be recorded in the source document. 
11.2.3 Abnormal and Vital Signs
If an abnormal vital sign is associated with clinical signs and/or symptoms, the sign or symptom 
should be reported as an AE, and the associated vital sign should be considered additional 
information that must be collected on the relevant source document.
11.2.4 Handling of Adverse Events
All adverse events resulting in discontinuation from the trial should be followed until resolution 
or stabilization.  Patients must be followed for AEs for 7 calendar days after discontinuation or 
completion of protocol-specific treatment (e.g., chemotherapy, radiation, oral medications, 
targeted therapy, and surgery).  All new AEs occurring during this period must be reported and 
followed until resolution unless, in the opinion of the investigator, these values are not likely to 
improve because of the underlying disease.  In this case, the investigators must record his or her 
reasoning for this decision in the patient’s medical record and as a comment on the source 
document. 
11.3 Serious Adverse Events
11.3.1 Definitions of Serious Adverse Events
The definitions of serious adverse events (SAEs) are given below. The principal investigator is 
responsible for ensuring that all staff involved in the trial are familiar with the content of this 
section.
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An SAE or reaction is defined as any untoward medical occurrence that: results in death, is 
immediately life-threatening, requires at least a 24-hour inpatient hospitalization or prolongation 
of existing hospitalization, results in persistent or significant disability/incapacity, or is a 
congenital anomaly/birth defect.
The definition of SAE also includes any important medical event.  Medical and scientific 
judgment should be exercised in deciding whether expedited reporting is appropriate in other 
situations, such as important medical events that may not be immediately life-threatening or 
result in death or hospitalization, but may jeopardize the patient or may require intervention to 
prevent one of the other outcomes listed in the previous definition.  These should also usually be 
considered serious.  Examples of such events are intensive treatment in an emergency room or at 
home for allergic bronchospasm; blood dyscrasias or convulsions that do not result in 
hospitalization; or development of drug dependency or drug abuse. 
Hospitalization during the trial for a pre-planned surgical or medical procedure (one which was 
planned prior to entry in the trial), does not require reporting as a serious adverse event.
11.3.2 Serious Adverse Event Reporting
It is important to distinguish between “serious” and “severe” adverse events, as the terms are not 
synonymous.  Severity is a measure of intensity; however, an AE of severe intensity need not 
necessarily be considered serious.  For example, nausea which persists for several hours may be 
considered severe nausea, but may not be considered an SAE.  On the other hand, a stroke which 
results in only a limited degree of disability may be considered only a mild stroke, but would be 
considered an SAE.  Severity and seriousness should be independently assessed when recording 
AEs on the CRF and SAEs on the SAE Report Form.
Adverse events classified by the treating investigator as serious require documentation and 
reporting to the IRB according to UM policies and procedures in order to comply with regulatory 
requirements.  Serious adverse events may occur at any time from the signing of the informed 
consent form start of trial treatment through the 7-day follow-up period after the last trial 
treatment. To report a SAE, the SAE log should be completed with the necessary information. 
All SAEs and medically confirmed deaths (regardless of causality assessment) occurring on trial 
treatment or within 7 days of last trial treatment must be reported on the SAE log and followed 
until resolution (with autopsy report if applicable). 
Investigators must report SAEs and follow-up information to their responsible IRB according to 
the policies of the responsible IRB.
11.3.3 SAE Reporting Requirements
UM is responsible for reporting relevant SAEs to the competent authority, other applicable 
regulatory authorities, and participating investigators, in accordance with ICH guidelines, FDA 
regulations, and/or local regulatory requirements.
UM is responsible for reporting unexpected fatal or life-threatening events associated with the 
use of the trial drugs to the regulatory agencies and competent authorities via telephone or fax 
within 7 calendar days after being notified of the event.  UM will report all related but 
unexpected SAEs including non-death/non-life-threatening related but unexpected SAEs 
associated with the use of the trial medication to the appropriate competent authorities 
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(according to local guidelines), investigators, and IRBs by a written safety report within 15 
calendar days of notification. 
11.4 Recording of Adverse Events and Serious Adverse Events
Investigators should use correct medical terminology/concepts when recording AEs or SAEs on 
the SAE and AE logs.  Avoid colloquialisms and abbreviations.
All AEs, including those that meet SAE reporting criteria, should be recorded on the AE/SAE 
logs and be reported accordingly.
11.4.1 Persistent or Recurrent Adverse Events
A persistent AE is one that extends continuously, without resolution, between patient evaluation 
time points.  Such events should only be recorded once on the AE log.  If a persistent AE 
becomes more severe or lessens in severity, it should be recorded separately on the AE log.  
A recurrent AE is one that occurs and resolves between patient evaluation time points, and 
subsequently recurs.  All recurrent AEs should be recorded on an AE log.
11.4.2 Deaths
All on-trial deaths, regardless of attribution, will be recorded on an SAE log.
When recording a serious adverse event with an outcome of death, the event or condition that 
caused or contributed to the fatal outcome should be recorded as the single medical concept on 
the SAE log. If the cause of death is unknown and cannot be ascertained at the time of reporting, 
record “Death NOS”.  
11.4.3 Hospitalization, Prolonged Hospitalization, or Surgery
Any AE that results in hospitalization of >24 hours or prolonged hospitalization should be 
documented and reported as an SAE.  There are some hospitalization scenarios that do not 
require reporting as an SAE when there is no occurrence of an AE. 
11.4.4 Pre-Existing Medical Conditions
A pre-existing medical condition is one that is present at the start of the trial.  Such conditions 
should be recorded on the Medical History source document. A pre-existing medical condition 
should be recorded as an AE or SAE only if the frequency, severity, or character of the condition 
worsens during the trial.  When recording such events on an AE/log, it is important to convey the 
concept that the pre-existing condition has changed by including applicable descriptors.
12 CLINICAL MONITORING
12.1 Site Monitoring Plan
Site monitoring shall be conducted to ensure the human patient protection, trial procedures, 
laboratory, trial intervention administration, and data collection processes are of high quality and 
meet Sponsor, GCP/ICH and, when appropriate, regulatory guidelines. The Site Monitoring Plan 
shall define aspects of the monitoring process.
The Sponsor-Investigator is responsible to the regulatory authorities for assuring the proper 
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conduct of the clinical trial with regard to protocol adherence and validity of the data recorded in 
the source documents. The Sponsor-Investigator is responsible for advising the investigator on 
the collection and maintenance of accurate, complete, legible, well organized, and easily 
retrievable data for the clinical trial. In addition, he/she will explain to the investigator the 
procedures for implementing the protocol, including a review of the protocol objectives, 
assessments and timelines, and source documentation requirements.  The obligations of the 
investigator in conducting investigational product studies will also be reviewed.
In order to perform their role effectively, the monitors and persons involved in quality assurance 
and inspections (see above) will need direct access to primary patient data, e.g., medical records, 
laboratory reports, appointment books, etc. Because this affects the patient’s confidentiality, this 
fact is included on the Informed Consent Form.
13 ETHICAL, FINANCIAL, AND REGULATORY CONSIDERATIONS
13.1 IRB Approval
The trial protocol, ICF, IB, available safety information, patient documents, patient recruitment 
procedures (e.g., advertisements), information about payments (i.e., PI payments) and 
compensation available to the patients and documentation evidencing the PI’s qualifications 
should be submitted to the IRB for ethical review and approval if required by local regulations, 
prior to the trial start.  
The PI will follow all necessary regulations to ensure appropriate, initial, and ongoing, IRB trial 
review. The PI must submit and, where necessary, obtain approval from the IRB for all 
subsequent protocol amendments and changes to the informed consent document.  
13.2 Regulatory Approval
As required by local regulations, the PI will ensure all legal aspects are covered, and approval of 
the appropriate regulatory bodies obtained, prior to trial initiation. If required, the PI will also 
ensure that the implementation of substantial amendment to the protocol and other relevant trial 
documents happen only after approval by the relevant regulatory authorities.
13.3 Informed Consent
Informed consent is a process by which a patient voluntarily confirms his or her willingness to 
participate in a particular trial, after having been informed of all aspects of the trial that are 
relevant to the patient's decision to participate.  Informed consent is documented by means of a 
written, signed and dated informed consent form.
The informed consent form will be submitted for approval to the IRB that is responsible for 
review and approval of the trial.  Each consent form must include all of the relevant elements 
currently required by the FDA, as well as local county authority or state regulations.
Before recruitment and enrollment into the trial, each prospective candidate will be given a full 
explanation of the trial.  Once the essential information has been provided to the prospective 
candidate, and the investigator is sure that the individual candidate understands the implications 
of participating in this trial, the candidate will be asked to give consent to participate in the trial 
by signing an informed consent form.  A notation that written informed consent has been 
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obtained will be made in the patient’s medical record.  A copy of the informed consent form, to 
include the patient’s signature, will be provided by the investigator to the patient.  
If an amendment to the protocol substantially alters the trial design or the potential risks to the 
patients, the patient’s consent to continue participation in the trial should be obtained.
13.4 Confidentiality
Confidentiality of patient’s personal data will be protected in accordance with the Health 
Insurance Portability and Accountability Act of 1996 (HIPPA). HIPPA regulations require that, 
in order to participate in the trial, a patient must sign an authorization from the trial that he or she 
has been informed of following: 
·
What protected health information (PHI) will be collected from patients in this trial;
·
Who will have access to that information and why;
·
Who will use or disclose that information; 
·
That health information may be further disclosed by the recipients of the information, 
and that if the information is disclosed the information may no longer be protected by 
federal or state privacy laws; 
·
The information collected about the research trial will be kept separate from the 
patient’s medical records, but the patient will be able to obtain the research records 
after the conclusion of the trial;
·
Whether the authorization contains an expiration date; and
·
The rights of a research patient to revoke his or her authorization. 
In the event that a patient revokes authorization to collect or use his or her PHI, the investigator, 
by regulation, retains the ability to use all information collected prior to the revocation of patient 
authorization.  For patients that have revoked authorization to collect or use PHI, attempts should 
be made to obtain permission to collect at least vital status (i.e., that the patient is alive) at the 
end of their scheduled trial period.
In compliance with ICH GCP guidelines and applicable parts of 21 CFR, it is a requirement that 
the investigator and institution permit authorised representatives, the regulatory authorities and 
the IRB direct access to review the patient’s original medical records at the site for verification 
of trial-related procedures and data. 
Measures to protect confidentiality include: only a unique trial number and initials will identify 
patients on the CRF or other documents. Patients will be informed of their rights within the ICF.
13.5 Financial Information
University of Miami will provide funding for the study. The trial drug for all trial participants 
will be provided free of charge by the sponsor-investigator for the duration of the trial.
13.6 Record Retention and Documentation of the Trial
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13.6.1 Amendments to the Protocol
Amendments to the protocol shall be planned, documented and signature authorized prior to 
implementation.  
All amendments require review and approval of the Principal Investigator supporting the trial.  
Amendments specifically involving change to trial design, risk to patient, increase to dosing or 
exposure, patient number increase, addition or removal of new tests or procedures, shall be 
reviewed and approved by the IRB at the Investigator’s facility.  
The amendment will be submitted formally to the FDA or other regulatory authorities as 
applicable, after IRB approval and specifically when an increase to dosing or patient exposure 
and/or patient number has been proposed; or, when the addition or removal of an Investigator is 
necessitated.
13.6.2 Data Collection
All study data will be collected on study source documents and logs. All of the data, including 
records of subjects, source documents, and inform consent will be kept in the study center under 
lock for 6 years after the study finished. 
13.7 Trial Monitoring, Auditing, and Inspecting
The investigator will permit trial-related monitoring, quality audits, and inspections by, 
government regulatory authorities, of all trial-related documents (e.g., source documents, 
regulatory documents, data collection instruments, case report forms).  The investigator will 
ensure the capability for inspections of applicable trial-related facilities.  The investigator will 
ensure that the trial monitor or any other compliance or QA reviewer is given access to all trial-
related documents and trial-related facilities.  
Participation as an investigator in this trial implies the acceptance of potential inspection by 
government regulatory authorities. 
13.8 Quality Assurance and Quality Control
In addition to the Clinical Monitoring component of this protocol, Quality Assurance (QA) to 
assess compliance with GCP and applicable regulatory requirements.  Data or documentation 
audited shall be assessed for compliance to the protocol, accuracy in relation to source 
documents and compliance to applicable regulations.
13.9 Disclosure and Publication Policy
All information provided regarding the trial, as well as all information collected/documented 
during the course of the trial, will be regarded as confidential.  
The financial disclosure information will be completed prior to trial participation from all PIs 
and Sub-Investigators who are involved in the trial and named on the FDA 1572 form.
The Sponsor-Investigator will register the trial on www.clinicaltrials.gov.  In addition, Sponsor-
Investigator will publish the results of the trial.
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14 REFERECES
1. Papoiu AD, Tey HL, Coghil RC, et al. Cowhage-induced itch as an experimental model 
for pruritus. A comparative study with histamine-induced itch. PLoS One. 2011; 6(3):1 
7786.
2. Angst MS, Tingle M, Phillips NG, et al. Determining heat and mechanical pain threshold 
in inflamed skin of human subjects. J Vis Exp. 2009; 23: 1092.
3. Saglam G, Cunduz O, Ulugol A. Blockade of cannabinoid CB1 and CB2 receptors does 
not prevent the antipruritic effect of systemic paracetamol. Acta Neurol Belg. 2013.
4. Onnis V, Congiu C, Bjorklund D, Hempel F, Soderstrom E, Fowler CJ. Synthesis and 
evaluation of paracetamol esters as novel fatty acid hydrolase inhibitors. J Med Chem. 
2010. 11; 53 (5): 2286-98.
5. Sinning C, Watzer B, Coste O, Nusing RM, Ott I, Ligresti A, Marzo VD, Imming P. New 
analgesics synthetically derived from paracetamol metabolite N-(4-Hydroxyphenyl)-
(5Z,8Z,11Z,14Z)-icosatetra-5,8,11,14-enamide. J Med Chem. 2008. 51: 7800-5.
6.
Bertolini A, Ferrari A, Ottani A, Guerzoni S, Tacchi R, Leone S. Paracetamol new vistas 
of an old drug. CNS Drug Reviews. 2006. 12(3-4): 250-275. 
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