Corneal antinociceptive effect of (-)-α-bisabolol

Context: (-)-α-Bisabolol (BISA) is a sesquiterpene alcohol widely used as scent in cosmetic preparations, perfumes, shampoos, toilet soaps and other toiletries with potential for use in the pharmaceutical area. Objective: To evaluate the corneal antinociceptive efficacy of BISA and to analyze the best solubilizing agent. Materials and methods: Acute corneal nociception was induced by the local application of hypertonic saline (5 M NaCl; 20 μL) to the corneal surface of Swiss mice (n = 8/group) 60 min after topical treatment with solutions or ointment containing BISA (50–200 mg/mL). The number of eye wipes performed with the ipsilateral forepaw was counted for a period of 30 s. Control groups (vehicles) were included. Results: BISA (50, 100 or 200 mg/mL) solubilized with Tween 80 did not reduce the number of eye wipes. Animals treated with the ointment (BISA 50, 100 or 200 mg/mL; p < 0.001), as well the solution containing propylene glycol (BISA 100 mg/mL; p < 0.05), showed significant reduction in the number of nociceptive behaviours. Solutions containing propylene glycol and isopropyl myristate had no effects. Discussion and conclusion: BISA possess corneal antinociceptive activity. Although the ointment presented antinociceptive effect, it is concluded that BISA when associated with propylene glycol has better potential for corneal nociceptive pain since it is more comfortable to use, leading to greater acceptance by patients.