Establishing a Minimal Erythema Concentration of Methyl Nicotinate for Optimum Evaluation of Anti-Inflammatories

• Published in: Skin pharmacology and physiology Vol. 19; no. 3; pp. 147 - 152
• Main Authors: Jumbelic, L.C., Liebel, F.T., Southall, M.D.
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland S. Karger AG 01.01.2006
• Subjects: Administration, Topical; Adult; Anti-Inflammatory Agents, Non-Steroidal - administration & dosage; Anti-Inflammatory Agents, Non-Steroidal - therapeutic use; Dermatitis, Contact - drug therapy; Erythema - chemically induced; Erythema - drug therapy; Female; Humans; Ibuprofen - administration & dosage; Ibuprofen - therapeutic use; Male; Middle Aged; Nicotinic Acids - toxicity; Original Paper; Skin - drug effects; Skin - pathology; Anti-inflammatories; Diffuse reflectance spectrometry; Erythema concentration; Methyl nicotinate
• ISSN: 1660-5527; 1660-5535
• DOI: 10.1159/000092595

Topical administration of chemicals such as methyl nicotinate that induce erythema have been employed to measure the effectiveness of formulations containing anti-inflammatory agents. Prior studies have utilized a single concentration of methyl nicotinate, between 36.5 and 100 mM, for all test subjects in evaluations of topical formulations. However, individuals have different thresholds of response to methyl nicotinate; thus, a single concentration may not be appropriate for all individuals and could result in the apparent lack of anti-inflammatory activity of the formulation being evaluated. In the current study, we evaluated the use of a minimal erythema concentration (MEC) of methyl nicotinate, defined as the lowest concentration that produces a complete and even erythema at the test site, compared with a 36.5-mM concentration of methyl nicotinate. Hydroalcoholic gels containing the nonsteroidal anti-inflammatory drug ibuprofen were compared with placebo. Diffuse reflectance spectroscopy was employed to measure differences in cutaneous inflammatory response between the control (placebo)-treated group and the ibuprofen-treated group. When chemical erythema was induced using an MEC of methyl nicotinate, greater reductions in erythema were seen in ibuprofen-treated sites compared with sites treated with a 36.5-mM concentration of methyl nicotinate. In conclusion, for an accurate assessment method of erythema induced by methyl nicotinate, consideration should be given to determining the extent of response of an erythema-producing agent on an individual basis. An MEC of methyl nicotinate should be determined and employed for each individual to obtain more consistent and reliable efficacy results of anti-inflammatory activity.