Enhancement of orofacial antinociceptive effect of carvacrol, a monoterpene present in oregano and thyme oils, by β-cyclodextrin inclusion complex in mice

Abstract

Orofacial pain is associated with diagnosis of chronic pain of head, face, mouth, neck and all the intraoral structures. Carvacrol, a naturally occurring isoprenoid with diverse class of biological activities including anti-inflammatory, analgesic, antitumor and antioxidant properties. Now, the antinociceptive effect was studied in mice pretreatment with carvacrol (CARV) and β-cyclodextrin complex containing carvacrol (CARV-βCD) in formalin-, capsaicin-, and glutamate- induced orofacial nociception. Mice were pretreated with vehicle (0.9% Nacl, p.o.), CARV (10 and 20mg/kg, p.o.), CARV-βCD (10 and 20mg/kg, p.o.) or MOR (10mg/kg, i.p.) before the nociceptive behavior induced by subcutaneous injections (s.c.) of formalin (20μl, 2%), capsaicin (20μl, 2.5μg) or glutamate (20μl, 25μM) into the upper lip respectively. The interference on motor coordination was determined using rotarod and grip strength meter apparatus. CARV-βCD reduced the nociceptive during the two phases of the formalin test, whereas CARV did not produced the reduction in face-rubbing behavior in the initial phase. CARV-βCD (20mg/kg, p.o.) produced 49.3% behavior pain while CARV alone at 20mg/kg, p.o, produced 28.7% of analgesic inhibition in the second phase of formalin test. CARV, CARV-βCD and Morphine (MOR) showed a significant reduction against nociception caused by capsaicin or glutamate injection. Thus the encapsulation of carvacrol in β-cyclodextrin can acts as a considerable therapeutic agent with pharmacological interest for the orofacial pain management.

Keywords: Carvacrol; Cyclodextrin; Monoterpene; Opioid; Orofacial pain; Pain.