A study on analgesic effect of Caryophyllus aromaticus by formalin test in albino rats

Objective: To study the analgesic effect of Caryophyllus aromaticus (flower buds) by formalin test in albino rats. Materials & Methods: Albino rats of either sex were taken and divided into 7 groups with 6 animals in each for central and peripheral analgesic activity by formalin test. 5% formalin is injected into the right dorsal surface of a hind paw of rat after half an hour of drug administration and the time the animal spent licking the paw was recorded as early phase (0-5 min after injection) and late phase (15-30 min after injection). Caryophyllus aromaticus was used in a dose of 150,300 and 600mg/kg i.p. The drug used for central analgesic activity was Pethidine (5mg/kg, i.p), and Naloxone (1mg/kg) with 300mg/kg of Caryophyllus aromaticusi.p to study the central analgesic activity. The drug used for peripheral analgesic activity was Ketorolac (10mg/kg, i.p). A control group was maintained in all models. Results: Caryophyllus aromaticus300mg/kg significantly decreased the reaction time of early phase in formalin test similar to Pethidine whereas the combination of Naloxone and Caryophyllus aromaticus300mg/kg increased the reaction time of early phase, indicating that Naloxone inhibits the analgesic effect of Caryophyllus aromaticus. Caryophyllus aromaticus300mg/kg significantly decreased the reaction time of late phase also. Conclusion: Caryophyllus aromaticus (flower buds) possesses significant central and peripheral analgesic activity and acts through opioid receptors. Key-words: Caryophyllus aromaticus, analgesia, naloxone, pethidine, ketorolac