Conditions: Pruritus
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 13
Healthy volunteers: yes

Brief summary:
The purpose of this study is to examine the antipruritic efficacy of topical ketamine, amitriptyline, lidocaine, and a tri-combination of ketamine, amitriptyline and lidocaine (hereafter referred to as "KeAmLi") using non-histaminergic itch provocations in healthy volunteers. The primary outcome is itch reduction (AUC) between the vehicle and active treatment (KeAmLi-combo). Secondary outcomes include modality-specific analgesic properties of the topically applied ketamine, amitriptyline, lidocaine, and KeAmLi-combo to controlled quantitative thermal and mechanical stimuli, which can improve our understanding of the mechanism of action of these substances in the context of topical therapy.

Detailed description:
This is a double-blind, vehicle-controlled study to evaluate the antipruritic efficacy of topical ketamine, amitriptyline, lidocaine, and a tri-combination of ketamine, amitriptyline and lidocaine (hereafter referred to as "KeAmLi") using non-histaminergic itch provocations in healthy volunteers. Each participant will be pre-treated with the vehicle and 4 active topical creams, over two study visits (3 treatments on the 1st visit and 2 treatment on the 2nd visit). Each treatment will be applied to the randomized forearm test area for 30 minute, and then sensory testing will be performed. Sensory testing includes thermal and mechanical stimuli, and itch induction using the plant cowhage. These tests will reveal mechanistic information and potential cellular and molecular targets for improved antipruritic and analgesic therapies.

Arms:
arm 1: Topical KeAmLi-combo (ketamine 10%, amitriptyline 5%, and lidocaine 5%) will be applied to one four 4 x 4 cm predefined skin areas on the ventral forearms during one of two study visits. The pre-treatment will occur under topical occlusion for 30 minutes to allow the ointment to be adsorbed. Following this, residual ointment will be removed and sensory testing, strictly within the pretreated area, will commence. arm 2: Topical ketamine 10% will be applied to one four 4 x 4 cm predefined skin areas on the ventral forearms during one of two study visits. The pre-treatment will occur under topical occlusion for 30 minutes to allow the ointment to be adsorbed. Following this, residual ointment will be removed and sensory testing, strictly within the pretreated area, will commence. arm 3: Topical amitriptyline 5% will be applied to one four 4 x 4 cm predefined skin areas on the ventral forearms during one of two study visits. The pre-treatment will occur under topical occlusion for 30 minutes to allow the ointment to be adsorbed. Following this, residual ointment will be removed and sensory testing, strictly within the pretreated area, will commence. arm 4: Topical lidocaine 5% will be applied to one four 4 x 4 cm predefined skin areas on the ventral forearms during one of two study visits. The pre-treatment will occur under topical occlusion for 30 minutes to allow the ointment to be adsorbed. Following this, residual ointment will be removed and sensory testing, strictly within the pretreated area, will commence. arm 5: Topical vehicle (PCCA Lipoderm) will be applied to one four 4 x 4 cm predefined skin areas on the ventral forearms during one of two study visits. The pre-treatment will occur under topical occlusion for 30 minutes to allow the ointment to be adsorbed. Following this, residual ointment will be removed and sensory testing, strictly within the pretreated area, will commence.

Interventions: intervention 1: Ketamine Hydrochloride intervention 2: Amitriptyline Hydrochloride intervention 3: Lidocaine Hydrochloride intervention 4: Ketamine hydrochloride, Amitriptyline hydrochloride, and Lidocaine hydrochloride intervention 5: Lipoderm Cream
Intervention descriptions: intervention 1: 2g of topical 10% Ketamine will be applied for 30 minutes on one 4x4cm area on the volar forearm in one of two study visits. intervention 2: 2g of topical 5% Amitriptyline will be applied for 30 minutes on one 4x4cm area on the volar forearm in one of two study visits. intervention 3: 2g of topical 5% Lidocaine will be applied for 30 minutes on one 4x4cm area on the volar forearm in one of two study visits. intervention 4: 2g of topical KeAmLi-combo (ketamine 10%, amitriptyline 5%, and lidocaine 5%) will be applied for 30 minutes on one 4x4cm area on the volar forearm in one of two study visits. intervention 5: 2g of topical vehicle (Lipoderm) will be applied for 30 minutes on one 4x4cm area on the volar forearm in one of two study visits.

Protocol document:
Prot_SAP_000.pdf: 
IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 1 of 24 
Revised: January 22, 2019 
1) 
Protocol Title 
Antipruritic effect of topical ketamine, amitriptyline, and lidocaine 
 
2) 
IRB Review History* 
N/A 
 
3) 
Objectives* 
The purpose of this study is to examine the antipruritic efficacy of topical 
ketamine, amitriptyline, lidocaine, and a tri-combination of ketamine, 
amitriptyline and lidocaine (hereafter referred to as “KeAmLi”) using non-
histaminergic itch provocations in healthy volunteers. The primary 
outcome is itch reduction (AUC) between the vehicle and active treatment 
(KeAmLi-combo). Secondary outcomes include modality-specific 
analgesic properties of the topically applied ketamine, amitriptyline, 
lidocaine, and KeAmLi-combo to controlled quantitative thermal and 
mechanical stimuli, which can improve our understanding of the 
mechanism of action of these substances in the context of topical therapy.  
 
4) 
Background* 
Introduction 
Chronic itch is a prominent symptom of many dermatological conditions 
such as atopic dermatitis (AD), urticaria, psoriasis and prurigo nodularis, 
as well as neuropathic itch conditions. Moreover, itch is also common in 
conditions such as biliary cirrhosis, renal deficiency as well as several 
infectious-, allergic-, neoplastic-, autoimmune-, and drug-induced 
conditions 1–3. Itch almost inevitably leads to scratching of the affected 
area which can further exacerbate the skin inflammation and deterioration, 
leading to a vicious “itch-scratch cycle” 4,5  characterized by maintenance 
of skin aberrations, cutaneous infections and pain 5,6. According to recent 
epidemiological studies, AD alone affects 5-20% of children worldwide 
with an estimated direct annual cost of nearly $3 billion in the USA alone 
7. Itch is usually the primary complaint of these patients and has been 
reported to occur in as much as 87% of adult AD patients 8. The currently 
available treatment options are suboptimal for most chronic itch 
conditions 3,9.  
 
Rational for investigation of compounds for topical application 
Ketamine is a potent N-Methyl-D-aspartate receptor (NMDAR) 
antagonist and a weak activator of µ-opioid receptors. Apart from being 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 2 of 24 
Revised: January 22, 2019 
abundantly expressed in the central nervous system, NMDAR and the µ-
opioid receptor are widely present in the periphery 10,11. All sensory and 
motor unit axons are equipped with NDMAR and µ-opioid receptors are 
also expressed by C- and Aδ-fibers 11–13 Notably, NMDAR expression is 
increased in the peripheral processes of sensory neurons as a reaction to 
inflammation 10,14. Activation of these receptors in rat skin resulted in 
mechanical allodynia and hyperalgesia. Pain behavior was attenuated 
following peripheral injection of appropriate antagonists 14–16. 
Furthermore, there are several preclinical studies indicating that NMDA 
receptors and opioid receptors interact in the modulation of pain and that 
opioid-receptors play a pivotal role in regulation of both itch and pain 17,18. 
Amitriptyline potently inhibits serotonin and norepinephrine reuptake, 
with preferential actions on the serotonin transporter, giving rise to its 
anti-depressant effect when administered systemically. However, as for 
other tri-cyclic antidepressants amitriptyline interacts with a range of 
receptors, including inhibition of 5-HT receptors, histamine receptor 1 as 
well as muscarinic and -adrenergic receptors, and sodium channels 19–21. 
The exact mechanism by which topically (and systemically) administered 
amitriptyline inhibits pain remains to be elucidated with several candidate 
mechanisms suggested 19,20,22.  
Lidocaine is a commonly applied local anesthetic that works by altering 
signal conduction in neurons by blocking the fast voltage-gated sodium-
channels in the neuronal cell membrane normally responsible for signal 
propagation. When sufficiently blocked this incapacitates depolarization 
and inhibits action potential transmission. When applied to the skin 
epicutaneously or intradermally, lidocaine prominently inhibits traffic 
from nociceptive (and pruriceptive) primary afferents thus exerting its 
analgesic and antipruritic effect. 
Several studies have shown a significant analgesic effect of topical 
amitriptyline combined with ketamine (and occasionally lidocaine 23) in 
neuropathic pain, and in one instance itch 24, patients 11,19,25–27. 
While itch is an unpleasant sensory modality, distinct from pain, it is 
principally transmitted by two parallel pathways of nociceptive afferent 
fibers: a subgroup of mechano-insensitive C-fibers (CMi) transmit 
histaminergic itch and a subgroup of polymodal C-fibers (PmC) transmit 
non-histaminergic itch 28,29. The axonal branching for both of these fibers 
classes terminates in the stratum granulosum 30,31 of the epidermis 
principally making them a very appropriate target for topical therapy. 
Given the overlap in the neuronal substrate for pain and itch it is likely 
(and previously observed) that pharmaceuticals which interfere with pain 
transmission also have an effect on itch 32,33.  
 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 3 of 24 
Revised: January 22, 2019 
In light of the recently shown analgesic efficacy of topical ketamine, 
amitriptyline and particularly these applied in combination, often also with 
lidocaine, we hypothesize that the compounds may also have a significant 
antipruritic effect 11,25,26,34. Since that the majority of poorly treatable itch 
conditions is characterized by being histamine-independent 35–37, we aim 
to assess whether cowhage evoked non-histaminergic itch can be 
alleviated by topical ketamine, amitriptyline or these two in combination 
with lidocaine. Moreover, sensory evaluations of the combined and 
individual specific anesthetic effects of the compounds will be conducted 
to provide mechanistic information and potential cellular and molecular 
targets for improved antipruritic and analgesic therapies. 
 
5) 
Inclusion and Exclusion Criteria* 
Study subjects will be healthy subjects with no itch and no known skin or 
systemic conditions. An approximately equal number of men and women 
between 18 and 50 years of age will be recruited using IRB-approved 
advertising. 
 
Inclusion: 
1) Healthy subjects (absence of disease) 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 moisturizers on the arms the day of 
study visit. 
 
Exclusion: 
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 or a painful condition. 
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 48 hours prior to the study visits (e.g. 
antihistamines, anesthetics, anti-inflammatories, opioids, neuroleptics, 
etc.). 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 4 of 24 
Revised: January 22, 2019 
7) Use of emollients on the volar aspects of the forearms arms on the day 
of the study visit. 
8) Use of anti-depressants, anti-psychotics, and illicit drugs. 
9) Known history of neuropathy, uremia, uncontrolled thyroid disease, 
and diabetes mellitus. 
10) Known history of anaphylactic shock, or allergy to cowhage and/or 
known adverse reactions to lidocaine (or other local anesthetics of the 
amide type), ketamine or amitriptyline.  
11) Pregnant (females of childbearing potential will undergo an hCG 
pregnancy test). 
12) Currently incarcerated.  
 
6) 
Number of Subjects* 
A priori power calculations were conducted in G*Power based on data 
from a previous test-retest study 38. In order to have an effect 80% power 
with a size effect of 0.30 and alpha error probability of 0.05, we will need 
36 subjects (10 within post hoc pairwise comparisons). We estimate that 
we will need to screen up to 42 individuals in order to enroll 36 healthy 
subjects. 
We will seek to recruit a sample with an approximately equal gender 
distribution. 
 
7) 
Study-Wide Recruitment Methods* 
IRB approved flyers will also be placed around the University of Miami 
medical campus, and within the waiting rooms of the Department of 
Dermatology Out Patient Clinic at UMH (South Building, suites K-M) and 
at the Lennar Foundation Medical Center. 
 
8) 
Study Timelines* 
This projected is expected to last 8 months. The first 6 months will be 
dedicated to subject enrollment. During this time each subject will be a 
part of 2 study visits; one session lasting approximately 2.75 hours and 
one lasting approximately 2 hours. The second session must be completed 
within 7 days of the first session. The second 2 months will be dedicated 
to the sample analysis and the last month will be dedicated to 
dissemination of findings. 
 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 5 of 24 
Revised: January 22, 2019 
9) 
Study Endpoints* 
The primary endpoints are visual analog scale (VAS) ratings of the 
perceived intensity of itch sensation elicited by epicutaneous application 
of cowhage spicules (non-histaminergic itch) on the volar aspects of the 
forearms comparing skin pretreated with vehicle cream with the KeAmLi-
combination. Ratings will be plotted vs. time to generate a temporal itch 
intensity graph and the area under the curve (AUC) will be calculated for 
each subject. The secondary study endpoints are the individual itch peak 
intensity, itch peak time, and itch time duration comparing skin pretreated 
with vehicle cream with ketamine, amitriptyline, lidocaine, and KeAmLi-
combination.  
 
The exploratory outcomes (for all experimental interventions vs. the 
vehicle condition) are:  
- 
Warmth detection threshold (°C needed to perceive warmth sensation) 
- 
Heat pain threshold (°C needed to perceive heat pain) 
- 
Mechanical detection threshold (mN needed to perceive touch) 
- 
Mechanical pain threshold (mN needed to perceive pain) 
- 
Development of hyperknesis (NRS ratings of itch evoked by touch 
before vs. after cowhage provocation) 
 
10) Procedures Involved* 
At the beginning of the first session, subjects will be asked to fill out an 
informed consent, and a form for demographic information including 
health information. They will also be asked if they have taken any allergy 
or pain medicine during the past 24 hours. If so they will be asked to come 
back at a later time since these drugs might interfere with the study. 
Females of childbearing potential will undergo an hCG pregnancy test. 
Finally, subjects will receive instruction on the use of the visual analog 
scale for rating the intensity of itch sensation. Below is a short procedural 
overview of the proposed study this is followed by sections introducing in 
details each of the methods applied.  
Subjects will be seated comfortably in a chair with both arms resting on 
armrests or on a pillow. Using a block-randomized design, we will deliver 
either topical vehicle (PCCA Lipoderm®), topical ketamine 10%, topical 
amitriptyline 5%, lidocaine 5% or KeAmLi-combo (ketamine 10%, 
amitriptyline 5%, and lidocaine 5%) to four 4 x 4 cm predefined skin areas 
on the ventral forearms over two study visits. The 1st visit will involve 
applying 3 of the 5 treatments (randomized), to 3 of the 4 designated test 
sites in a randomized manner. The 2nd visit will involve applying the 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 6 of 24 
Revised: January 22, 2019 
remaining 2 treatments to 2 of the 4 designated test sites in a randomized 
manner. The subject and investigator will be blinded to the identities of 
the treatments (see blinding procedure below).  
Application will be conducted with the investigator wearing nitrile gloves. 
The pre-treatment will occur under topical occlusion for 30 minutes to 
allow the ointment to be adsorbed. Following this, residual ointment will 
be removed and sensory testing, strictly within the pretreated area, will 
commence. For each of the five tested topical solutions the following 
procedures will be conducted (see also Fig. 1): 
 
1) Demarcation of 4 x 4 cm treatment area (see Fig. 2) 
a) Application of 2 g of ointment (randomized substance) 
i) 30 min pretreatment 
(1) During this time a subject familiarization procedure for the 
quantitative sensory testing will be conducted  
ii) Removal of residual ointment 
iii) Local safety assessment  
2) Thermal sensory thresholds 
a) HDT 
b) HPT 
3) Mechanical sensory thresholds 
a) MDT 
b) MPT 
4) Baseline sensitivity to touch-evoked itch (STI) assessment 
5) Cowhage provocation 
a) 40-45 spicules rubbed into the epidermis 
b) Continuous VAS-recording of itch and pain for up to 15 minutes 
6) Post-provocation STI assessment (assessment of hyperknesis) 
a) Spicules gently removed by 2-3 tape-strippings  
i) 0 
7) Procedure is repeated with next topical intervention 
 
The second session is conducted in a manner completely identical to session 
1. However, the remaining 2 ointments not used in session 1are assessed in 
the second session. The second session must be completed within 7 days of 
the first session. 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 7 of 24 
Revised: January 22, 2019 
 
 
 
Figure 1 – Overview of the course of study procedures. Grey boxes in the 
top designate inclusion of subjects for sensory and skin parameters assessment 
in the depicted test-battery below. Thermal and mechanical sensitivity 
quantitative sensory tests are performed first, then assessment of STI is 
assessed and the itch provocation is conducted. Times estimates are derived 
from the DFNS protocol 39 and may vary between subjects mainly due to 
differences in the ease of understanding instructions. Abbreviations: WDT = 
warmth detection threshold; HPT = heat pain threshold; MDT = mechanical 
detection threshold, MPT = mechanical pain threshold; NRS = numeric rating 
scale; STI = Sensitivity to Touch-evoked Itch; VAS = visual analog scale;  
 
 
 
 
 
 
 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 8 of 24 
Revised: January 22, 2019 
 
 
 
Figure 2 – Overview of application areas on the volar forearms. Notice that 
this is an exemplification. Actual substance application/familiarization will be 
randomized for order, and location. In session 1, only three of the four areas will 
be used. In session 2, only two of the four areas marked for substance application 
will be used.  
 
Computerized Visual Analog Scale (VAS) Scoring: During induction of 
itch the subjects will be asked to rate the sensation of itch, stinging/pricking 
and burning on a VAS scale from 0-10 where 0 denotes “no itch” and 10 
denotes “worst imaginable itch” and similarly for sensations of 
stinging/pricking and burning, both of which are frequently associated with 
the sensation of itch. The subjects will report the sensation using a horizontal 
electronic scroll bar giving a digital output in a frequent (i.e., every 15 
seconds) discrete manner. Rating of the itch intensity will continue until ≥ 3 
subsequent ratings are below 1 (assessed for itch) or after a maximum 
duration of 15 minutes. Based on similar studies this is typically between 5-15 
minutes after the itch has been induced. Nociceptive sensations associated 
with non-histaminergic itch are usually subtle; typically rated 1-3 on a 0-10 
VAS and “weak” on a generalized Labeled Magnitude Scale (gLMS) 38,40,41. 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 9 of 24 
Revised: January 22, 2019 
Itch scores are typically rated 3-8 on a 0-10 VAS scale and “moderate” to 
“strong” on a gLMS (depending on induction paradigm).  
 
Application of cowhage spicules: Each 4 x 4 cm test area on the forearm will 
undergo itch induction with cowhage after a 5-minute rest from the thermal 
testing. Ratings of itch intensity will be taken on a VAS scale (0-10) 
continuously for 10 minutes. Subjects will be asked to not scratch the areas.  
Cowhage itch will be induced by the application of cowhage spicules on the 
skin. Cowhage or the velvet bean (Mucuna pruriens var. pruriens) is a tropical 
plant whose pods are covered with short, fine hairs (also called trichomes or 
“spicules”). Cowhage spicules are 1-2 mm in length and have diameter of 1-3 
um at their tip. Inserted into the epidermis, the spicules evoke a moderate to 
intense sensation of itch and occasionally mild sensations of burning and 
stinging pain. The insertion is associated with a light prick/sting lasting a few 
seconds followed by a latency period of no sensations of approximately 30 
seconds and then a rapid onset of itch. The model is a well-established method 
for human non-histaminergic itch induction and has been thoroughly tested 
38,41–43. A number of 40 to 45 cowhage spicules will be applied to one area of 
the volar forearm. The spicules will be gently rubbed for 30-45 seconds onto 
the skin with a circular motion to facilitate contact until a substantial itch 
sensation is induced. After itch sensation is gone, the cowhage spicules will be 
removed using adhesive tapes. 
 
Thermal stimuli (TSA-II, Medoc, Israel): A thermode surface probe of 3 x 
3 cm is used to test skin areas for warmth detection and heat pain thresholds. 
The probe works by warming and cooling the skin by circulating fluid (water) 
close to a thin ceramic plate attached to the relevant skin area. Two 
standardized quantitative sensory tests are performed: 1) warmth detection 
threshold (HDT, assesses the threshold of which warmth sensation is first 
detected and reflect non-nociceptive warmth C-fiber function), 2) heat pain 
threshold (HPT, assesses the threshold at which heat pain sensation is first 
detected and reflect function of nociceptive heat-sensitive C-fibers). Ramp 
stimuli are delivered starting at 32°C, ramping upwards with 1°C/s and 
proceeding until the subject first experience warmth sensation (HDT) or pain 
(HPT) and presses a stop button to mark his/her perception threshold. 
Immediately as the subject presses the button the probe returns to the baseline 
temperature of 32 °C at a rate of 5°C/s and thus the subject will only 
experience brief pain just around his/her perception threshold. Both HDT and 
HPT are always assessed in triplicates (the final threshold is the arithmetic 
mean of 3 stimuli) and HDT is always assessed before HPT. The quantitative 
sensory assessment of HDT and HPT is based on the standardized and 
thoroughly tested methodology developed by the German Association for the 
Study of Neuropathic Pain (DFNS) and follows the published protocol 39,44.  


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 10 of 24 
Revised: January 22, 2019 
 
Mechanical stimuli:  
Mechanical detection thresholds (Von Frey Filaments, Stoelting, CA, US) 
To assess mechanical detection thresholds standardized, CE-approved and 
commercially available von Frey filaments stimulators (North Coast Medical, 
Stoelting, CA, US) are used. The set consists of 20 calibrated nylon filaments 
with bending forces from 0.078 mN to 2.9 N (with slightly increasing exerted 
force surface). Starting with the lightest filament each probe is applied 
perpendicularly to the skin area for 1-2 seconds with a soft “landing” and 
removal in an ascending/descending order. The stimulators are designed to 
detect the mechanical detection threshold (MDT), which is considered the 
perceptual correlate of cutaneous Aβ-fiber sensitivity. The final threshold is 
the geometric mean of five series of ascending and descending stimuli. The 
quantitative sensory assessment of MDT is based on the standardized and 
thoroughly tested methodology developed by the German Association for the 
Study of Neuropathic Pain (DFNS) and follows the published protocol 39,44. 
Due to the completely non-invasive nature of the procedure it is not associated 
with any risks.  
Mechanical pain thresholds (The Pinprick, MRC, Germany) 
To test mechanical pain sensitivity standardized, CE-approved and 
commercially available pinprick stimulators (The PinPrick, MRC, Germany) 
are used. This set consists of 7 pins with exponentially increasing force 
increments from 0.8 mN to 512 mN (0.8, 1.6, 3.2, 6.4, 128, 256, and 512 mN). 
The pinprick stimulators have a 0.2 mm blunted tips designed to deliver a 
sharp needle-like stimulus without penetrating the epidermis. Starting with the 
lightest (0.8 mN), each stimulator is applied in an ascending/descending order 
at a rate of 2s on, 5s off until the first perception of sharpness/pain is reached. 
This is denoted the mechanical pain threshold (MPT) and represents function 
of mechano-receptive C- and Aδ-nociceptors. The final threshold is the 
geometric mean of five series of ascending and descending stimuli. The 
quantitative sensory assessment of MPT is based on the standardized and 
thoroughly tested methodology developed by the German Association for the 
Study of Neuropathic Pain (DFNS) and follows the published protocol 39,44. 
 
Statistical Analysis: Data will be entered into a database program, such as 
Microsoft Excel and/or IBM SPSS, and analyzed at using Prism GraphPad 6 
and/or IBM SPSS. Basic descriptive statistics using mean (SEM), range, and n 
(%) will be calculated in Excel and presented. Statistical significance will be 
set at p < 0.05. Analysis will be performed within and between groups.  
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. 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 11 of 24 
Revised: January 22, 2019 
 
Blinding procedures: The study will be conducted under double-blinded 
conditions. The investigators responsible for the data collection, i.e. 
application, sensory tests, itch provocations, and data entry, will be blinded to 
the substance being applied. Blinding will be carried out by random allocation 
of letters “A” to “E” to labels on the pharmaceuticals (including the vehicle). 
This task is carried out at the compounding pharmacy. With delivery of the 
pharmaceuticals a list specifying the compounds corresponding to allocated 
letters is supplied to the PI. In case of serious adverse effects, the PI will 
breach the blinding. Otherwise unblinding will not occur until after the 
primary analysis has been conducted.  
 
Local safety assessment: After pretreatment with each ointment (before any 
sensory testing is performed), and after each cowhage application a local 
safety assessment will be done. Erythema, edema, and any other local reaction 
will be recorded on a 5-point Likert scale (0=clear, 1=almost clear, 2=mild, 
3=moderate, 4=severe).  
 
11) Data Management* 
All of the data, including records of subjects, source documents, and 
inform consent will be kept in the study center office under lock for 6 
years after the study finished. The study center office is located at: 1600 
NW 10th Ave, RMSB 7167, Miami FL 33136. 
 
12) Provisions to Monitor the Data to Ensure the Safety of Subjects* 
The study team will be responsible for protecting the safety, rights, and 
well-being of study participants. When testing is performed the subjects’ 
vital signs (blood pressure, heart rate, and respiratory rate) will be 
monitored.  
Recording and reporting of adverse events that occur during the course of 
the study will help to ensure the continuing safety of participants. 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. 
Study subjects will be instructed to report any adverse events up to one 
week after the study is completed. In case an adverse event does take 
place, a documentation system will be used to record the following 
information: description of event, time/date of onset, duration of reaction, 
does/frequency/route of drug administration, reversibility or sequelae, 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 12 of 24 
Revised: January 22, 2019 
therapy (if any), and seriousness/severity (based on Common Terminology 
Criteria for Adverse Events v4). If a subject experiences an adverse event 
assessed at ³ Grade 2 according to CTCAE v4, the subject will not receive 
additional treatments and will be followed until the adverse event resolves 
or stabilizes.  
Study stoppage will occur if 36 subjects complete the study or if a severe 
adverse event occurs. 
The PI will be responsible for monitoring ongoing activates to ensure 
compliance with regulator ad protocol requirements, data quality, and 
participant safety.  
 
13) Withdrawal of Subjects* 
All subjects are free to withdraw from participation in this study at any 
time, for any reason, and without prejudice. 
Subjects must be withdrawn from the study if: 
1) A subject withdraws consent.  
2) The Investigator believes it is in the best interest of the subject to be 
removed from the study. 
3) If the subject experiences greater than a mild adverse event. (Subjects 
that experience a mild adverse event will be asked if they would like to 
continue the study. The occurrence of a severe adverse event will 
trigger the study to stop for safety purposes.) 
If withdrawal occurs, subjects will receive prorated compensation. The 
data collected before the withdrawal will still be used in data analysis.  
 
14) Risks to Subjects* 
1. Discomfort. The researchers will take care to minimize discomfort and 
pain during the measurement of pain thresholds and cowhage application. 
These procedures are already designed to limit magnitude and duration of 
discomfort. 
 
2. Cowhage application. No specific serious risks or adverse effects are 
associated with the application of cowhage spicules to 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 from 1-7 minutes 40,41,45. Cowhage is not an allergen and does not 
cause contact dermatitis, chemical irritation or erythema. No serious 
adverse reactions to cutaneous cowhage application have been described 
in the literature. We do not expect a tachyphylactic reaction or an additive 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 13 of 24 
Revised: January 22, 2019 
affect from multiple cowhage applications because we are not applying 
cowhage more than once to the same location during the same study visit. 
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. 
 
3. Sensory testing of heat pain thresholds. Heat pain will be assessed using 
a thermode probe raising the temperature of circulating water from 32ºC 
up to 50ºC. Since we only assess the pain perception threshold (i.e. the 
first temperature at which pain is experienced) this heat pain is marginally 
unpleasant and only persists for a few seconds. If the pain is unbearable, 
the thermode can be immediately removed to alleviate the painful 
sensation. Although the thermode is computer-controlled, it may 
potentially produce hot temperatures, which causes pain. In this case, the 
subjects are allowed to withdraw their arm from a thermode. The Medoc 
analysis station controls and monitors the thermode temperature for the 
TSA-II. This software has a built in safety feature, which has an automatic 
shut-off if the thermode reaches 50°C. This build-in shut-off, along with 
the ability for the investigator to monitor the thermode’s temperature in 
real-time makes the chance of even superficial burns occurring minimal. 
Several large multicenter studies have safely used identical equipment and 
test paradigms without the occurrence of adverse events 39,44,46,47. 
 
4. Sensory testing of mechanical pain thresholds. Mechanical pain 
thresholds will be assessed with 7 weighted pinprick stimulators in 
accordance with the manufacturer’s directions. The assessment is 
associated with mild pain, but since we only assess the pain perception 
threshold (i.e. the first pin at which pain is experienced) the pain only 
persists for a few seconds. The pinprick stimulators do not penetrate the 
epidermis on normal skin. However, as a precautionary measure the 
pinprick stimulator tips are sterilized with 70% ethanol prior to each new 
test session. Several large multicenter studies have safely used identical 
equipment and test paradigms without the occurrence of adverse events 
39,44,46,47. 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 14 of 24 
Revised: January 22, 2019 
 
5. Topical administration of ketamine, amitriptyline and lidocaine.  
a. Ketamine. In the present study topical ketamine 10% is applied. 
Topical ketamine has previous previously been applied in various 
concentrations and vehicles (usually to treat neuropathic pain) and 
is generally considered devoid of serious side effects 11,48,49. 
Notably, in studies investigating plasma levels of ketamine 
following topical exposure the concentration has generally been 
below the assay detection limits and/or below physiologically 
significant levels 19,25,34,49. Minor side effects occasionally include 
local skin rashes and hives, as well as dizziness and light-
headedness 11,22,49. Only one serious adverse event case has been 
described in the literature for topical ketamine and it concerns 
application of a non-prescribed compounded ointment containing 
ketamine in an infant 50. In the present study ketamine will only be 
applied to intact skin, in adults, and to a relatively small area (4 x 4 
cm) and as such the potential systemic exposure is negligible. 
b. Amitriptyline. In the present study topical amitriptyline 5% is 
applied. Amitriptyline has previous previously been applied in 
various concentrations, in different vehicle creams and combined 
with other topical agents (usually to treat neuropathic pain) 
19,20,24,25,27. It is generally considered safe and the systemic 
exposure associated with topical usage is many times lower than 
the therapeutic dosage for systemic therapy. In a clinical trial with 
140 participants receiving 4% amitriptyline no serious adverse 
effects occurred 51. Minor side effects include skin rashes, sedation 
and palpitations 20,22,24,27. In the present study amitriptyline will 
only be applied in adults and to a relatively small area (4 x 4 cm) 
and as such the potential systemic exposure is negligible. 
c. Lidocaine. In the present study topical lidocaine 5% is applied. 
Lidocaine is an extremely well-studied and generally safe local 
anesthetic available for OTC use 26,48,52–54. Common side effects 
include local blanching and erythema. Contact hypersensitivity to 
lidocaine is rare but has been described 52,54. Systemic allergic 
(anaphylactic) reactions to lidocaine are exceedingly rare, 
particularly in response to percutaneous application 52,55,56. A 
systematic review on the use of ointment containing lidocaine 
found single dose percutaneous administration to be safe in 
neonates 53. In the present study lidocaine alone and in 
combination with amitriptyline and ketamine will only be applied 
in adults and to a relatively small area (4 x 4 cm) and as such the 
systemic exposure is negligible. 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 15 of 24 
Revised: January 22, 2019 
In the previous studies applying combinational use of above-mentioned 
substances no tendencies towards more frequent or more severe side 
effects have been reported.  
 
15) Potential Benefits to Subjects* 
There is no direct benefit to the subjects.  
 
16) Vulnerable Populations* 
No vulnerable populations will be enrolled in this study.  
 
17) Sharing of Results with Subjects* 
Results of this study will not be shared with the subjects, unless through 
scientific publication. 
 
18) Setting 
Potential subjects will be identified and recruited through IRB approved 
flyers.  
Research procedures will be performed at the Miami Itch Center at the 
Lennar Foundation Medical Center or at the Department of Dermatology 
Research Clinic at UMH (West Building, rooms 504, 505, 506, &508). 
 
19) Resources Available 
The Principal Investigator Gil Yosipovitch, MD, is a Professor from the 
Department of Dermatology & Cutaneous Surgery at the University of 
Miami. Dr. Yosipovitch’s primary research interest is in pruritus (itch) and 
the neurophysiology and innervation of skin in chronic itch. Dr. 
Yosipovitch has conducted research in the field of skin physiology, 
pharmacology, and neurophysiology of itch over the past 20 years. His 
research activities have centered on basic and clinical studies on itch 
neurophysiology and on clinical topics in dermatology, including topical 
and systemic formulations of anti-pruritics and skin barrier function and in 
itch in atopic eczema and psoriasis. Dr. Yosipovitch will assist with 
recruitment, study procedures, and assess adverse events.  
Sub-Investigator Leigh A. Nattkemper, PhD, is an Instructor from the 
Department of Dermatology & Cutaneous Surgery at the University of 
Miami. Dr. Nattkemper uses advanced molecular biology and genetic 
approaches to understand the patho-mechanisms of chronic itch, with a 
special interest in the neurological processes. She has conducted research 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 16 of 24 
Revised: January 22, 2019 
in the field of chronic itch for over 6 years and will act as Study 
Coordinator. 
Sub-investigator Lars Arendt-Nielsen, Prof, Dr. Med., PhD, is a research 
collaborator from Aalborg University, Denmark. Prof. Arendt-Nielsen has 
conducted research in the field of pain neurobiology, pharmacology and 
assessment for the last 28 years. His research activities have centered on 
basic, translational and clinical studies primarily in the field of pain 
neurophysiology, pharmacological proof-of-concept studies, quantitative 
sensory testing and development of human surrogate models of pain 
symptomatology. Prof. Arendt-Nielsen has been using cowhage itch 
provocations in several previous projects starting from 2013 as well as 
quantitative thermal and mechanical sensory testing starting from 1987. 
Prof. Arendt-Nielsen has conducted numerous pharmacological trials and 
early human mechanistic studies to test the efficacy of novel or off-label 
purported analgesic compounds. Prof. Arendt-Nielsen will assist with 
protocol design and development, data interpretation of non-identifiable 
data, as well as manuscript preparation. 
Sub-investigator Hjalte H. Andersen, MS Med., is a PhD fellow, from 
Center for Sensory Motor Interaction, Aalborg University, Denmark. He 
will conduct research out of the Dermatology Department at University of 
Miami during a 6-month research stay. Hjalte H. Andersen has conducted 
cowhage itch provocations in several previous projects starting from 2013 
as well as quantitative thermal and mechanical sensory testing starting 
from 2011. Hjalte H. Andersen will assist with protocol design and 
writing, study coordination, subject recruitment, research fieldwork, data 
collection, data analysis, as well as draft and revise the manuscript. 
Pharmacist: Jack Korbutov, RPh, PharmD, FACA, is working out of the 
Art of Medicine Compounding Pharmacy located in Philadelphia. The 
pharmacy has been compounding the combination ointment KeAmLi for 
approximately 3 years. Jack Korbutov will compound the applied topical 
formulations, advise on its storage, and label the tubes for the purpose of 
blinding.  
Student researcher Jeremy Hsiang, BS, is medical student at the University 
of Miami. He will will assist in subject recruitment, and study procedures, 
and data entry.  
All study personnel will complete their CITI training and be adequately 
informed about the protocol and study procedures. All duties and 
functions are appointed and overseen by the PI. 
 
20) Prior Approvals 
Approved under FDA IND 134066. 
 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 17 of 24 
Revised: January 22, 2019 
21) Recruitment Methods 
IRB approved flyers will be placed around the University of Miami 
medical campus, and within the waiting rooms of the Department of 
Dermatology Out Patient Clinic at UMH (South Building, suites K-M) and 
at the Lennar Foundation Medical Center. 
Subjects are compensated $25 at the completion of each study visit for a 
total of $50 for 2 visits. 
 
22) Confidentiality 
We will not be accessing or adding to any medical records. Information 
will be collected directly from the subject, and will be used for research 
purposes only. Every attempt will be made to ensure any information 
gathered is kept secure. All study data will be kept in a locked office and 
kept under password protection on a computer that is only accessible by 
study personnel. 
 
23) Provisions to Protect the Privacy Interests of Subjects 
Study subjects will only be asked to provide personal information to 
approved study personnel, who will ensure the subject is at ease with the 
situation. Study personnel will clearly explain that the subject does not 
have to answer any questions or provide any sample they are 
uncomfortable about.  
 
24) Compensation for Research-Related Injury 
Treatment will be available if enrolled subjects get sick or injured. 
However, the subject or the subject’s insurance will be responsible for 
these costs. Funds to compensate for pain, expenses, lost wages, and other 
damages caused by injury are not available.  
 
25) Economic Burden to Subjects 
There will be no charges to the subjects that agree in participating in this 
study. 
 
26) Consent Process 
The research team will follow the “HRP-090 SOP: Informed Consent 
Process for Research” to obtain informed consent and the “HRP-091 SOP: 
Written Documentation of Informed Consent” to document informed 
consent in writing. 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 18 of 24 
Revised: January 22, 2019 
Study personnel will meet with each potential subject to discuss the study 
in detail, answer questions, and allow the subject to read the entire consent 
form. The informed consent form explicitly states the rationale for the study 
and requirements for participation, both before and during the session. The 
informed consent form states that subjects may discontinue participation or 
be terminated from the study at any time.  
All pertinent aspects of the study will be explained to the subject before he 
or she signs the informed consent form. A signed informed consent form 
will be obtained from the subject before any activity or treatment is 
undertaken as part of the study.  
Non-English Speaking Subjects will not be enrolled. Our current research 
team does not have a member that fluently speaks Spanish. We are 
actively trying to recruit such a member and will submit translated 
consent forms once we hire such personnel. Subjects who are not yet 
adults (infants, children, teenagers), cognitively impaired adults, and 
adults unable to consent will not be enrolled.  
 
27) Process to Document Consent in Writing 
The research team will follow the “HRP--091 SOP: Written Documentation 
of Informed Consent” to document informed consent in writing. 
 
28) Drugs 
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 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 19 of 24 
Revised: January 22, 2019 
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. 
 
Drug Formula for Ketamine 10% - Amitriptyline 5% - Lidocaine 5% (Per 
100gm of cream) 
• Ketamine HCl (Fagron Pharmaceuticals NDC 51552-0697-07): 
10grams 
• Amitriptyline HCl (Medisca NDC 38779-0189-09): 5 grams 
• Lidocaine HCl (Medisca NDC 38779-0082-03): 5 grams 
• Ethoxy Diglycol (Fagron Pharmaceuticals NDC 38779-1903-07): 
5mL 
• Liquigel (Medisca NDC 38779-2531-01): 3 grams 
• Lipoderm Cream Base (PCCA NDC 51927-3338-00): 72 grams 
 
Drug Formula for Ketamine 10% (Per 100gm of cream) 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 20 of 24 
Revised: January 22, 2019 
• Ketamine HCl (Fagron Pharmaceuticals NDC 51552-0697-07): 
10grams 
• Ethoxy Diglycol (Fagron Pharmaceuticals NDC 38779-1903-07): 
4mL 
• Liquigel (Medisca NDC 38779-2531-01): 3 grams 
• Lipoderm Cream Base (PCCA NDC 51927-3338-00): 83 grams 
 
Drug Formula for Amitriptyline 5% (Per 100gm of cream) 
• Amitriptyline HCl (Medisca NDC 38779-0189-09): 5 grams 
• Ethoxy Diglycol (Fagron Pharmaceuticals NDC 38779-1903-07): 
3mL 
• Liquigel (Medisca NDC 38779-2531-01): 3 grams 
• Lipoderm Cream Base (PCCA NDC 51927-3338-00): 89 grams 
 
Drug Formula For Lidocaine 5% (Per 100gm of cream) 
• Lidocaine HCl (Medisca NDC 38779-0082-03): 5grams 
• Ethoxy Diglycol (Fagron Pharmaceuticals NDC 38779-1903-07): 3mL 
• Liquigel (Medisca NDC 38779-2531-01): 3 grams 
• Lipoderm Cream Base (PCCA NDC 51927-3338-00): 89 grams 
 
Drug Formula for Vehicle (Per 100gm of cream) 
• Lipoderm Cream Base (PCCA NDC 51927-3338-00): 100 grams 
 
Formulation Instructions: 
1. Weigh powder reagents in weigh boats and set aside.  
2. Tare 100mL unguator jar 
3. Place all powders in jar, and top with wetting agent (Ethoxy Diglycol).  
4. Mix with a spatula until a thick paste is formed 
5. Place emulsifier/thickiner (Liquigel) on top of the paste. 
6. Pour Lipoderm cream on top (total weight of ingredients should equal 
100gm). 
7. Using Mixing blade and Unguator e/s, Mix the compound for 2:30 at a 
mixing speed of 5. 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 21 of 24 
Revised: January 22, 2019 
8. Pour contents into jar/pump for patient use. 
 
Labeling: 
The formulations will be labeled “For Research Only” and will a coded in 
order to ensure double-blinding. Blinding will be carried out by random 
allocation of letters “A” to “E” to label the pharmaceuticals (including the 
vehicle). This task is carried out at the compounding pharmacy. With 
delivery of the pharmaceuticals and a list specifying the compounds 
corresponding to allocated letters is supplied to the PI. 
 
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 lab that only study personnel will have access with a key. 
Ambient temperature of the storage cabinet will be recorded once a day 
(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. 
The pre-treatment will occur under topical occlusion for 30 minutes to 
allow the ointment to be adsorbed. Following this, residual ointment will 
be removed and sensory testing, strictly within the pretreated area, will 
commence. 
 
IND: 
The holder of this IND is Gil Yosipovitch, MD (21 CFR 312). No 
electronic source data will be captured using an eCRF (21 CFR 11). The 
investigators declare no conflict of interests or financial disclosures and 
will be sure to maintain updated disclosures with the University of Miami 
(21 CFR 54). Pharmacist Jack Korbutov, RPh, PharmD, FACA at the Art 
of Medicine Compounding Pharmacy will compound the formulations 
under cGMP standards (21 CFR 211).   
 
 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 22 of 24 
Revised: January 22, 2019 
29) References  
 
1 
Weisshaar E, Gieler U, Kupfer J, et al. Questionnaires to Assess Chronic Itch: A Consensus Paper of the 
Special Interest Group of the International Forum on the Study of Itch. Acta Derm Venereol 2012; 
92:493–6. 
2 
Matterne U, Apfelbacher CJ, Vogelgsang L, et al. Incidence and determinants of chronic pruritus: A 
population-based cohort study. Acta Derm Venereol 2013; 93:532–7. 
3 
Matterne U, Apfelbacher CJ, Loerbroks A, et al. Prevalence, correlates and characteristics of chronic 
pruritus: a population-based cross-sectional study. Acta Derm Venereol 2011; 91:674–9. 
4 
Leknes SG, Bantick S, Willis CM, et al. Itch and motivation to scratch: an investigation of the central 
and peripheral correlates of allergen- and histamine-induced itch in humans. J Neurophysiol 2007; 
97:415–22. 
5 
Wahlgren CF. Itch and atopic dermatitis: An overview. J Dermatol 1999; 26:770–9. 
6 
Brenaut E, Garlantezec R, Talour K, Misery L. Itch characteristics in five dermatoses: Non-atopic 
eczema, atopic dermatitis, urticaria, psoriasis and scabies. Acta Derm Venereol 2013; 93:573–4. 
7 
Carroll CL, Balkrishnan R, Feldman SR, et al. The burden of atopic dermatitis: Impact on the patient, 
family, and society. Pediatr Dermatol 2005; 22:192–9. 
8 
Yosipovitch G, Ansari N, Goon A, et al. Clinical and Laboratory Investigations Clinical characteristics 
of pruritus in chronic idiopathic urticaria. 2002; :32–6. 
9 
Patel T, Yosipovitch G. Therapy of Pruritus. Expert Opin Pharmacother 2010; 11:1673–82. 
10 
Carlton SM. Peripheral NMDA receptors revisited - Hope floats. Pain 2009; 146:1–2. 
11 
Kopsky DJ, Keppel Hesselink JM, Bhaskar A, et al. Analgesic effects of topical ketamine. Minerva 
Anestesiol 2015; 81:440–9. 
12 
Stein C. Opioid Receptors on Peripheral Sensory Neurons [WWW Document]. Madame Curie Biosci. 
Database , Landes Biosci. 2013.URL https://www.ncbi.nlm.nih.gov/books/NBK6242/ [accessed on 2 
January 2017]. 
13 
Coggeshall RE, Carlton SM. Ultrastructural analysis of NMDA, AMPA, and kainate receptors on 
unmyelinated and myelinated axons in the periphery. J Comp Neurol 1998; 391:78–86. 
14 
Carlton SM, Coggeshall RE. Inflammation-induced changes in peripheral glutamate receptor 
populations. Brain Res 1999; 820:63–70. 
15 
Zhou S, Bonasera L, Carlton SM. Peripheral administration of NMDA, AMPA or KA results in pain 
behaviors in rats. Neuroreport. 1996; 7:895–900. 
16 
Davidson EM, Coggeshall RE, Carlton SM. Peripheral NMDA and non-NMDA glutamate receptors 
contribute to nociceptive behaviors in the rat formalin test. Neuroreport 1997; 8:941–6. 
17 
Mehta AK, Halder S, Khanna N, et al. Role of NMDA and opioid receptors in neuropathic pain induced 
by chronic constriction injury of sciatic nerve in rats. J Basic Clin Physiol Pharmacol 2012; 23:49–55. 
18 
Tandon OP, Mehta AK, Halder S, et al. Peripheral interaction of opioid and nmda receptors in 
inflammatory pain in rats. Indian J Physiol Pharmacol 2010; 54:21–31. 
19 
Sandroni P, Davis MDP. Combination gel of 1% amitriptyline and 0.5% ketamine to treat refractory 
erythromelalgia pain: a new treatment option? Arch Dermatol 2006; 142:283–6. 
20 
Gerner P, Kao G, Srinivasa V, et al. Topical amitriptyline in healthy volunteers. Reg Anesth Pain Med 
2003; 28:289–93. 
21 
Drugbank.ca - Amitriptyline [WWW Document]. Drugbank.ca. 2017.URL 
https://www.drugbank.ca/drugs/DB00321 [accessed on 3 January 2017]. 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 23 of 24 
Revised: January 22, 2019 
22 
Lynch ME, Clark AJ, Sawynok J, Sullivan MJ. Topical amitriptyline and ketamine in neuropathic pain 
syndromes: An open-label study. J Pain 2005; 6:644–9. 
23 
Uzaraga I, Gerbis B, Holwerda E, et al. Topical amitriptyline, ketamine, and lidocaine in neuropathic 
pain caused by radiation skin reaction: A pilot study. Support Care Cancer 2012; 20:1515–24. 
24 
Griffin JR, Davis MDP. Amitriptyline/Ketamine as therapy for neuropathic pruritus and pain secondary 
to herpes zoster. J Drugs Dermatol 2015; 14:115–8. 
25 
Lynch ME, Clark AJ, Sawynok J. A pilot study examining topical amitriptyline, ketamine, and a 
combination of both in the treatment of neuropathic pain. Clin J Pain 2003; 19:323–8. 
26 
Sawynok J. Topical Analgesics for Neuropathic Pain in the Elderly: Current and Future Prospects. Drugs 
Aging 2014; 31:853–62. 
27 
Everton D, Bhagwat D, Damask M. An open-label pharmacokinetic study in humans of a 4% 
amitriptyline 2% ketamine topical cream (789). J Pain 2007; 8:S48. 
28 
LaMotte RH, Dong X, Ringkamp M. Sensory neurons and circuits mediating itch. Nat Rev Neurosci 
2014; 15:19–31. 
29 
Schmelz M, Schmidt R, Bickel  a, et al. Specific C-receptors for itch in human skin. J Neurosci 1997; 
17:8003–8. 
30 
Abels C. Intra-epidermal nerve fibres in human skin: back to the roots. Exp Dermatol 2014; 23:232–3. 
31 
Zylka MJ, Rice FL, Anderson DJ. Topographically distinct epidermal nociceptive circuits revealed by 
axonal tracers targeted to Mrgprd. Neuron 2005; 45:17–25. 
32 
Namer B, Carr R, Johanek LM, et al. Separate Peripheral Pathways for Pruritus in Man. J Neurophysiol 
2008; 100:2062–9. 
33 
Ständer S, Schmelz M. Chronic itch and pain--similarities and differences. Eur J Pain 2006; 10:473–8. 
34 
Lynch ME, Clark AJ, Sawynok J, Sullivan MJL. Topical 2% amitriptyline and 1% ketamine in 
neuropathic pain syndromes: a randomized, double-blind, placebo-controlled trial. Anesthesiology 2005; 
103:140–6. 
35 
Tey HL, Yosipovitch G. Targeted treatment of pruritus: a look into the future. Br J Dermatol 2011; 
165:5–17. 
36 
Patel T, Yosipovitch G. Therapy of Pruritus. Expert Opin Pharmacother 2011; 11:1673–82. 
37 
Hoeck EA, Marker JB, Gazerani P, et al. Preclinical and Human Surrogate Models of Itch. Exp 
Dermatol 2016. doi:10.1111/exd.13078. 
38 
Andersen HH, Sørensen A-KR, Nielsen GAR, et al. A Test-retest Reliability Study of Human 
Experimental Models of Histaminergic and Non-histaminergic Itch. Acta Derm Venereol 2016; :[In 
press]. 
39 
Rolke R, Baron R, Maier C, et al. Quantitative sensory testing in the German Research Network on 
Neuropathic Pain (DFNS): Standardized protocol and reference values. Pain 2006; 123:231–43. 
40 
LaMotte RH, Shimada SG, Green BG, Zelterman D. Pruritic and Nociceptive Sensations and 
Dysesthesias From a Spicule of Cowhage. J Neurophysiol 2009; 101:1430–43. 
41 
Sikand P, Shimada SG, Green BG, LaMotte RH. Similar itch and nociceptive sensations evoked by 
punctate cutaneous application of capsaicin, histamine and cowhage. Pain 2009; 144:66–75. 
42 
Sikand P, Shimada SG, Green BG, LaMotte RH. Sensory responses to injection and punctate application 
of capsaicin and histamine to the skin. Pain 2011; 152:2485–94. 
43 
Papoiu ADP, Coghill RC, Kraft RA, et al. A tale of two itches. Common features and notable 
differences in brain activation evoked by cowhage and histamine induced itch. Neuroimage 2012; 
59:3611–23. 


IRB Study Number: 20170087 
Version 1, Date: 03/29/2017 
 
 
Page 24 of 24 
Revised: January 22, 2019 
44 
Rolke R, Magerl W, Campbell KA, et al. Quantitative sensory testing: a comprehensive protocol for 
clinical trials. Eur J Pain 2006; 10:77–88. 
45 
Reddy VB, Iuga AO, Shimada SG, et al. Cowhage-Evoked Itch Is Mediated by a Novel Cysteine 
Protease: A Ligand of Protease-Activated Receptors. J Neurosci 2008; 28:4331–5. 
46 
Maier C, Baron R, Tölle TR, et al. Quantitative sensory testing in the German Research Network on 
Neuropathic Pain (DFNS): somatosensory abnormalities in 1236 patients with different neuropathic pain 
syndromes. Pain 2010; 150:439–50. 
47 
Mainka T, Malewicz NM, Baron R, et al. Presence of hyperalgesia predicts analgesic efficacy of 
topically applied capsaicin 8% in patients with peripheral neuropathic pain. Eur J Pain 2016; 20:116–29. 
48 
Tam E, Furlan AD. Transdermal lidocaine and ketamine for neuropathic pain: a study of effectiveness 
and tolerability. Open Neurol J 2012; 6:58–64. 
49 
Gammaitoni  a, Gallagher RM, Welz-Bosna M. Topical ketamine gel: possible role in treating 
neuropathic pain. Pain Med 2000; 1:97–100. 
50 
Sullivan RW, Ryzewski M, Holland MG, Marraffa JM. Compounded ointment results in severe toxicity 
in a pediatric patient. Pediatr Emerg Care 2013; 29:1220–2. 
51 
Dworkin RH. A Comparison of EpiCeptTM NP-1 Topical Cream vs. Oral Gabapentin in Postherpetic 
Neuralgia (PHN) [WWW Document]. Clin. Trials. 2011.URL 
https://www.clinicaltrials.gov/ct2/show/study/NCT00475904?term=NCT00475904&rank=1&sect=X430
156. 
52 
Jackson D, Chen AH, Bennett CR. Identifying true lidocaine allergy. J Am Dent Assoc 1994; 125:1362–
6. 
53 
Taddio A, Ohlsson A, Einarson TR, et al. A systematic review of lidocaine-prilocaine cream (EMLA) in 
the treatment of acute pain in neonates. Pediatrics 1998; 101:E1. 
54 
Friedman PM, Mafong EA, Friedman ES, Geronemus RG. Topical anesthetics update: EMLA and 
beyond. Dermatologic Surg 2001; 27:1019–26. 
55 
Gammaitoni AR, Alvarez NA, Galer BS. Safety and tolerability of the lidocaine patch 5%, a targeted 
peripheral analgesic: a review of the literature. J Clin Pharmacol 2003; 43:111–7. 
56 
Selcuk E, Ertürk S, Afrashi A. An adverse reaction to local anaesthesia: report of a case. Dent Update 
1996; 23:345–6. 
57 
Papoiu ADP, Tey HL, Coghill RC, et al. Cowhage-induced itch as an experimental model for pruritus. A 
comparative study with histamine-induced itch. PLoS One 2011; 6:e17786.