Desenvolvimento de um anestésico e analgésico tópico bucal com extrato de Aspidosperma pyrifolium Mart

Abstract

Aspidosperma pyrifolium Mart is a plant native to the northeastern caatinga that presents pharmacological properties with emphasis on the analgesic and anesthetic effects. The objective of this work was to develop an anesthetic gel and buccal topical analgesic with Aspidosperma pyrifolium Mart. The bark of this plant was collected in the District of São José da Mata, Campina Grande-PB. The collected vegetal material was dried in forced ventilation oven at constant temperature, then subjected to the turbolysis and dried in Spray Dryer, used Aerosil® 200, as a pharmacotechnical adjuvant. Binary mixtures between the plant extract and the excipients sodium bicarbonate, carbopol, carboxymethylcellulose, glycerol, calcium hydroxide, hydroethylcellulose, propylene glycol, sorbitol and triethanolamine were evaluated by thermal analysis, X-ray diffraction and infrared spectroscopy with Fourier transform. In the compatibility study, only sodium bicarbonate presented chemical incompatibility with the extract. The gel developed from Aspidosperma pyrifolium Mart used carbopol (thickener), triethanolamine (alkalizing) and propylene glycol (humectant). In the pharmacological tests, 143 swiss male mice, weighing between 25 and 35 grams, were randomly divided into four pharmacological tests, motor activity evaluation (Rota-rod), orofacial formalin test, orofacial pain evaluation and blocking of the sciatic nerve. They used 5 experimental groups: negative control (pharmaceutical excipients only), 20% benzocaine (positive control) and A. pyrifolium gels with 62.5, 125 and 250 mg / kg, except for the last assay, which evaluated the activity anesthesia of the sciatic nerve extract in 62.5, 31.25, 15,62 and 7,81mg / mL, in addition to the negative and positive controls, physiological solution and lidocaine (5mg / mL), respectively. It was also evaluated the motor activity of the mouse, using the extract by 250mg / kg oral, in addition to the tests of the orofacial formalin and the thermal test operative of evaluation of orofacial pain. The extracts and gels of A. pyrifolium did not alter the motor activity of the mouse. The treatments of 62.5, 125 and 250 mg / kg significantly inhibited left mouse lip pain compared to benzocaine 20% in 5 (p <0.01) and 15-40 minutes after administration of orofacial formalin (p < 0.001). The extract at 62.5 mg / kg presented significant anesthetic activity in relation to 31.25, 15,62, 7,81mg / mL, physiological saline and 5mg / mL lidocaine (p <0.001). A. pyrifolium gels presented excellent antinociceptive activity at 125mg / kg compared to benzocaine 20% at 1 (p <0.01), 5 (p <0.001) and 10 (p <0.05) minutes after the animal insertion in the acrylic cage and in 1 (p <0.01) and 5 (p <0.01) minutes with 250 mg / kg compared to the negative control. Therefore, the extract of APM presented an excellent anesthetic activity in the sciatic nerve of the mouse in the proportion of 62.5 mg / kg when compared to lidocaine (5mg / mL). The developed gel of A. pyrifolium presented an excellent antinociceptive effect, due to its anesthetic and analgesic action, mainly in the proportions of 125 and 250mg / kg, which may favor its use in the dental clinic.