ANALGESIC AND NEUROPHARMACOLOGICAL ACTIVITY OF WITHANIA SOMNIFERA ROOT Mohammad Shahriar, Fariha Alam and Mir Muhammad Nasir Uddin This study was designed to evaluate the analgesic and neurophramacological investigations of root extracts of Withania somnifera in Swiss albino mice following oral administration. In-vivo analgesic activity test was evaluated by acetic acid induced writhing method and tail immersion test. In-vivo neurophramacological investigations were determined by open field and swimming test. There is no scientific report on analgesic activity and neuropharmacological activity of Withania somnifera, therefore the present study was undertaken to examine the possible in-vivo analgesic activity and neuropharmacological activity of this plant extracts. In-vivo analgesic activity test showed that methanol, ethanol and chloroform extract inhibited writhes in a dose dependent manner. But ethanol extract at 150 mg/kg showed highest inhibition (70.56%) which is even higher than the standard drug (25.55%). And in case of tail immersion test the basal reaction time was more for standard drug when compared to plant extracts. The ethanol extracts showed more reaction time and that is recovered after 120 min the order of potency in 60 min after dose administration is diclofenac Na > ethanol > chloroform > methanol > control. This plants root extracts also exhibit significant neuropharmacological activity. International Journal Of Pharmacy 2249-1848 2014-04-04 2 203-208 Copyright (c) Pharma Scholars. All rights reserved 2013