Effectiveness of low dose physostigmine for dose reduction of morphine in pain management

Rahul P. Bhavasar, Suyog S. Chopade, Yogita D. Sulaxane, Devendra R. Chaudhari, Bapurao M. Bite


Background: This is an interventional study, undertaken in the experimental animal models for the evaluation of the antinociceptive potential of Physostigmine and its combination with Morphine at their sub-analgesic doses. The objective of the study was to evaluate the antinociceptive potential of Physostigmine alone and in combination with morphine.

Methods: Antinociceptive effect of Physostigmine in three graded doses (50, 100 and 200 μg/kg) and combination of Physostigmine at low dose (50 μg/kg) with sub-analgesic dose of Morphine (0.1 mg/kg) and Morphine in analgesic dose (1 mg/kg) was evaluated by using Hot Water Bath method in albino rats.

Results: Comparison of maximal possible effect in percentage (MPE in %) between groups at 90 minutes in control, Morphine, Physostigmine in 50, 100, 200 μg/ kg doses and combination group respectively, demonstrated significant difference (p <0.001) when compared by one way ANOVA test. There was no much increase in maximal possible effect in the tail withdrawal latency in Physostigmine 50 μg/kg (SC) treatment at 90 min (5.50±0.88) in comparison to control (NS) treatment group. Combination treatment of low doses of both Physostigmine 50 μg/kg + Morphine 0.1 mg/kg increased in maximal possible effect the tail withdrawal latency 90 min (53.87±1.38) in-comparison to control (NS) treatment group (6.17±0.92).

Conclusions: Physostigmine is more potent antinociceptive than Morphine and Physostigmine potentiated the antinociceptive activity of low dose of standard drug Morphine.


Antinociceptive, Morphine, Pain, Physostigmine, Tail withdrawal

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