Double-blind Trial of Mannitol Cream to Block the Effect of Capsaicin Cream

Double-blind Trial of Mannitol Cream to Block the Effect of Capsaicin Cream

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.

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.

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