Antinociceptive local activity of 4-allyl-1-hydroxy-2-methoxybenzene (eugenol) by the formalin test: an anti-inflammatory effect

Eugenol has been employed for decades as a condiment, an antimycotic, an antibacterial, an antiviral, and an antioxidant, and it is one of the natural analgesics most frequently utilized for pain and inflammation. Our objective was to determine the analgesic/anti-inflammatory effect of eugenol compared with diclofenac, naproxen, and tramadol using the formalin test. The formalin method was used in 6- to 10-week-old Wistar rats (weighing 250 g each) divided into six groups: saline (0.9%); formalin (5%); diclofenac (250 µg/kg); naproxen (400 µg/kg); tramadol (500 µg/kg), and eugenol (1,400 µg/kg), in the intraplantar part of the hind-end trunk of the rats, with n = 5 per group. Eugenol diminished 44.4% of nociceptive behavior in phase 1 and 48% in phase 2 (p ≤0.05 vs formalin). Eugenol was shown to be 1.14 times more effective than diclofenac, but 1.62 and 1.75 times less effective than naproxen and tramadol, respectively, in phase 1 and 1.45 times less effective than diclofenac and naproxen and 1.66 less effective than tramadol in phase 2 (p ≤0.05). These data suggest that eugenol possesses moderate activity in the acute pain phase and greater activity in inflammatory-type pain, and both effects are comparable to those produced by diclofenac and are less than the effects produced by naproxen and tramadol in the formalin test

Antinociceptive local effect of the combination of dexketoprofen trometamol and chlorhexidine gluconate in a formalin test: an additive effect

ABSTRACT A drug delivery system (DDS) with analgesic and antibacterial properties would be desirable for the local control of post-operatory pain and the prevention for surgical site infection (SSI). The objective of the present study was to evaluate the antinociceptive effect of the combination between dexketoprofen trometamol (DXT) and chlorhexidine gluconate (CHX) in the formalin pain model. Different doses of CHX were combined with DXT and were locally administered in rats paw simultaneously with 5% formalin dilution. Flinches were documented and the antinociceptive effect was calculated. The area under the curve of each experimental group were calculated and the % of antinociception were compared. The groups of CHX and DXT showed similar antinociceptive effect. The combination groups (DXT-CHX) showed higher antinociceptive effect that the one obtained with individual molecules. Besides the confirmation of DXT local antinociceptive properties, CHX also showed a positive effect; and an additive effect when combined with DXT

Hydrocortisone release from tablets based on bioresorbable poly(ether-ester-urethane)s

Abstract Bioresorbable linear poly(ether-ester-urethane)s with different hydrophilic characteristics were synthesized from triblock copolymers of poly(ε-caprolactone)-poly(ethylene oxide)-poly(ε-caprolactone) (PCL-PEO) as macrodiols, and L-lysine diisocyanate (LDI) or hexamethylenediisocyanate (HDI) were used as the required diisocyanates. Macrodiols were obtained by ring-opening polymerization (ROP) of ε-caprolactone (CL). Polyurethanes were synthesized by the reaction of the triblock copolymers with LDI or HDI in solution using stannous 2-ethylhexanoate as catalyst. Polyurethane tablets were fabricated and investigated as prospective drug delivery systems. The effect of the PEO content on the polymers' performance as drug carriers was evaluated. It was found that water provoked more swelling and erosion of polymers with higher contents of PEO. The hydrocortisone release profiles were analyzed using the Ritger-Peppas approximation. An anomalous release behaviour (values of n higher than 0.5) was found for most of the analyzed samples.

Toxicity and antinociceptive effects of Hamelia patens

Abstract Many medicinal herbs are used in folk medicine without taking into account their toxicity. Hamelia patens Jacq. (Rubiaceae), a Mexican endemic species, is used for the empirical treatment of pain. The aim of this work was to evaluate the toxicity and antinociceptive effects of ethanolic extracts of H. patens leaves. The toxicity of H. patens leaves (500–5000 mg/kg) was evaluated in acute (14 days) and subacute (28 days) assays. In the subacute assay, a blood analysis (both hematology and chemistry) was carried out. The antinociceptive effects of H. patens leaves (50–200 mg/kg) were evaluated using thermal-induced nociception (hot plate) and the chemical-induced nociceptive tests (acid acetic and formalin). In the acute toxicity test, the LD50 estimated for H. patens leaves was 2964 mg/kg i.p. and >5000 mg/kg p.o., whereas in the subacute test HPE did not affect hematological or biochemical parameters. In chemical-induced nociception models, H. patens (100 and 200 mg/kg p.o.) showed antinociceptive effects with similar activity than 100 mg/kg naproxen. In the hot plate test, HPE at 100 mg/kg (17%) and 200 mg/kg (25%) showed moderate antinociceptive effects. HPE could be a good source of antinociceptive agents because of its good activity and low toxicity.