Abstract
Background: Anxiety is a widespread disorder that approximately 18% of the population experience at some stage in their lives. Pain is a common stimulus that induces anxiety in both animals and human beings. Combination of drugs with good anti-anxiety and analgesic effect can be used for the treatment of chronic pain induced anxiety, post-operative, and procedure-related pain-induced anxiety.

Aims and Objectives: The study was conducted to evaluate the anxiolytic activity of combination of gabapentin with tramadol, pregabalin with tramadol compared to standard fluoxetine, in elevated plus maze (EPM) and light-dark arena (LDA) models of anxiety in Wistar albino rats.

Materials and Methods: Twenty-four male or female albino Wistar rats from Central Animal House, MRMC, Kalaburagi, were utilized. Fluoxetine 10 mg/kg, gabapentin 30 mg/kg, tramadol 30 mg/kg, and pregabalin 30 mg/kg were used. Eddy’s hot plate method used for inducing anxiety. EPM and LDA models were used to study the effect of drugs in reducing the pain and anxiety.

Results: The present study showed that the exposure to hot plate induces pain, creates anxiety, and reduces locomotor and explorative activity among the rats when exposed to hot plate. There was reduction in anxiety after drug administration, in fluoxetine and gabapentin with tramadol groups with >75% increase in entry into the light chamber or open arm at least once or more during the time period of 5 min when compared to hot plate post-exposure readings. Whereas in pregabalin and tramadol group, it was observed that 25% increase in entry of rats into open arm at least once during the time period of 5 min and 25% decrease in entry of rats into light chamber as compared to those rats after exposure to hot plate.

Conclusion: Our study has demonstrated that tramadol, pregabalin, and gabapentin have got analgesic as well as anti-anxiety effects in rats when given in combination. All these experimental data, together with the previous experimental studies and the results reported in this work, suggest that combination of these drugs could be more effective in treating anxiety-related disorders such as chronic pain, pain-induced anxiety, post-operative, and procedure-related pain-induced anxiety with minimal side effects. Further dose ranging studies and models might be necessary to better understand the effects of these drugs in combination.

Key words: Anxiety; Pain; Gabapentin; Tramadol; Pregabalin; Fluoxetine; Pre-clinical Study