RESUMO
Abstract This is a nonclinical, controlled, and triple-blind study to investigate the effects of codeine-associated geraniol on the modulation of orofacial nociception and its potential central nervous system depressing effect in an animal model. The orofacial antinociceptive activity of geraniol in combination with codeine was assessed through the following tests: (i) formalin-induced pain, (ii) glutamate-induced pain, and (iii) capsaicin-induced pain. Six animals were equally distributed into six groups and received the following treatments, given intraperitoneally (i.p.) 30 minutes before the experiments: a) geraniol/codeine 50/30 mg/kg; b) geraniol/codeine 50/15 mg/kg; c) geraniol/codeine 50/7.5 mg/kg; d) geraniol 50 mg/kg; e) codeine 30 mg/kg (positive control); or f) 0.9% sodium chloride (negative control). We performed pain behavior analysis after the injection of formalin (20 µL, 20%), glutamate (20 µL, 25 µM), and capsaicin (20 µL, 2.5 µg) into the paranasal region. Rubbing time of the paranasal region by the hind or front paw was used as a parameter. In the neurogenic phase of the formalin test, the geraniol/codeine at 50/7.5 mg/kg was able to promote the maximum antinociceptive effect, reducing nociception by 71.9% (p < 0.0001). In the inflammatory phase of the formalin test, geraniol/codeine at 50/30 mg/kg significantly reduced orofacial nociception (p < 0.005). In the glutamate test, geraniol/codeine at 50/30 mg/kg reduced the rubbing time by 54.2% and reduced nociception in the capsaicin test by 66.7% (p < 0.005). Geraniol alone or in combination does not promote nonspecific depressing effects on the central nervous system. Based on our findings, we suggest the possible synergy between geraniol and codeine in the modulation of orofacial pain.
RESUMO
Anxiety in the world population has increased significantly; the problem has encouraged studies regarding innovative alternatives for treatment. Research with Citrus aurantium L. essential oil (CEO) has revealed positive results with anxiolytic effects in both animals and humans. However, certain limitations affect its storage and preservation, its efficiency in therapy, and determination of adequate posologies. The potential use of cyclodextrins as drug carriers has been successfully explored. This study aims to assess the anxiolytic potential of a CEO/2-hydroxypropyl-ß-cyclodextrin (HP-ß-CD) inclusion complex. Preparation of the inclusion complex was performed using the Alpha 1-2 LDplus lyophilizer. To allow formation, and avoid loss of volatiles to the atmosphere, Limonene (LIM), the main compound in CEO, together with HP-ß-CD in a molar ratio of (1: 1M) was dispersed in ethanol for 36 hours using a laboratory shaker at room temperature (25°C). Non-clinical murine pharmacological tests were performed for anxiety assessment in experimental and control groups. To assess anxiety and motor impairment, the animals were evaluated using the elevated plus maze, open field, and rota-rod tests. Satisfactory results of the anxiolytic effect of the OEC complexed in HP-ß-CD were observed, with the indication of an potentiation of the effect with doses lower than 500 mg/kg and 250 mg/kg complexed, suggesting improvement in the anxiolytic properties of the OEC.