Antipruritic Effect of Topical Ketamine, Amitriptyline, and Lidocaine
Condition: Pruritus
MeSH terms: Pruritus
Intervention: Ketamine Hydrochloride; Amitriptyline Hydrochloride; Lidocaine Hydrochloride; Ketamine hydrochloride, Amitriptyline hydrochloride, and Lidocaine hydrochloride; Lipoderm Cream
Intervention description: 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.; 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.; 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.; 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.; 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.
Intervention MeSH terms: Lidocaine; Ketamine; Amitriptyline
Phase: Phase 2
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: The antipruritic effect of 4 topical treatments and 1 vehicle treatment will be explored in each subject. Study visit 1 will consist of testing 3 topical formulations, and study visit 2 will test the remaining 2 topical formulations in each subject.
Masking: Double (Participant, Investigator)
Enrollment: 13.0
Sex: All
Minimum age: 18 Years
Maximum age: 50 Years
Healthy volunteers: Accepts Healthy Volunteers

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.
    

Eligibility criteria:

        Inclusion Criteria:

          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 any systemic or topical anti-histamine, steroid, or pain
             relief medications 48 hours prior to the study visits.

          5. Must abstain from the use of moisturizers on the arms the day of study visit.

        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 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.).

          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.