Clinical trial NCT01963910: Double-blind Trial of Mannitol Cream to Block the Effect of Capsaicin Cream
Official title: Double-blind Trial of Mannitol Cream to Block the Effect of Capsaicin Cream
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Pain
Keywords: Mannitol
TRPV1 receptor
Pain
Burning pain
neuropathy
neuropathic pain
Lead sponsor: University of British Columbia
Sponsor class: OTHER
First posted: 2013-10-16
Enrollment: 25
Sex: ALL
Minimum age (years): 19
Maximum age (years): 80
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: BASIC_SCIENCE

Brief summary: Capsaicin is a TRPV1 (transient receptor potential vanilloid 1) agonist, causing pain upon application. The investigators wish to determine whether mannitol blocks the effect of capsaicin application. As both cream bases are identical and mannitol addition is the only difference between the creams, if the mannitol cream is more effective in blocking the effect of capsaicin on the TRPV1 (transient receptor potential vanilloid 1) receptor, the investigators will have established that mannitol down-regulates or blocks the TRPV1 (transient receptor potential vanilloid 1) receptor.

Detailed description: Capsaicin cream, which stimulates the TRPV1 (transient receptor potential vanilloid 1) receptor, causing a burning sensation, will be applied to both halves of the upper lip until a burning sensation with 8/10 intensity on an NRS (Visual Analog Scale) scale is experienced or five minutes have elapsed. Following this, the capsaicin cream will be wiped off and 30% mannitol in vehicle cream ( isopropyl palmitate, caprylic capric triglyceride, propylene glycol, ceteareth 20, cetearyl alcohol, glyceryl stearate, polyethylene glycol 100 stearate, dimethicone, octyldodecanol, lecithin, ethylhexyl glycerin and phenoxy ethanol) will be applied to one half of the upper lip, and vehicle cream alone will be applied to the other half. Cream assignment will be randomized and neither the subject nor the person applying the cream will know which half upper lip has which cream. Every minute for 10 minutes, the heat sensation felt in each half upper lip will be measured, using a visual scale from 0 to 10. A repeated measures analysis of variance will compare the NRS (Visual Analog Scale) scores from the 30% mannitol cream, to the NRS (Visual Analog Scale)scores from the vehicle cream. Significance will be accepted if P less than .05.

Eligibility criteria: Inclusion Criteria:

* Age between 19 and 80 years

Exclusion Criteria:

* Diet containing capsaicin (Cayenne pepper, capsicum) (spicy foods), more than once a week.
* Meal containing capsaicin (spicy foods) within 5 days prior to the experiment.
* Any lesion, cracking, cold sore or abrasion on the lips
* Inability to tolerate capsaicin containing "spicy foods"
* Wearing lipstick or lip balm on the upper lip
* Inability to fill out an NRS pain scale
* Use of painkilling medication, within 24 hours of the study.
* Allergy to any of the ingredients of the creams, or to mannitol
* History of contact or allergic dermatitis
* Pregnant or nursing women

Primary outcomes:
measure: NRS heat score, once per minute
timeFrame: 15 minutes per subject
Secondary outcomes:
measure: Side effects of capsaicin cream on upper lip
timeFrame: One hour
Other outcomes:
measure: Side effects of test creams
timeFrame: one hour
Locations:
city: North Vancouver
country: Canada
facility: Dr. Helene Bertrand Inc., 220-1940 Lonsdale Ave.
state: British Columbia
Study officials:
affiliation: Department of family practice, University of British Columbia
name: Helene Bertrand, MD, CM, CCFP
role: PRINCIPAL_INVESTIGATOR
References:
citation: Ngom PI, Dubray C, Woda A, Dallel R. A human oral capsaicin pain model to assess topical anesthetic-analgesic drugs. Neurosci Lett. 2001 Dec 28;316(3):149-52. doi: 10.1016/s0304-3940(01)02401-6.
citation: Boudreau SA, Wang K, Svensson P, Sessle BJ, Arendt-Nielsen L. Vascular and psychophysical effects of topical capsaicin application to orofacial tissues. J Orofac Pain. 2009 Summer;23(3):253-64.
citation: Bertrand H, Kyriazis M, Reeves KD, Lyftogt J, Rabago D. Topical Mannitol Reduces Capsaicin-Induced Pain: Results of a Pilot-Level, Double-Blind, Randomized Controlled Trial. PM R. 2015 Nov;7(11):1111-1117. doi: 10.1016/j.pmrj.2015.05.002. Epub 2015 May 12.