Background: Multiple factors are involved in the mechanism of bone cancer pain. Treatment with a single drug is not adequate to target all of the different mechanisms.
Objective: To study the analgesic effect of a combination of low-dose dexmedetomidine (DEX) and tramadol (TRA) on bone cancer pain in rats.
Design: A randomised, controlled study.
Setting: Central Laboratory of Shanghai Chest Hospital, Shanghai Jiaotong University, Shanghai China, from July 2011 to June 2012.
Animals: Adult female Wistar rats weighing 180 to 200g.
Interventions: Rats with bone cancer were divided into five groups based on drug treatment (n=12 for each group): T5 group (TRA 5 mg kg), T10 group (TRA 10 mg kg), D1 group (DEX 1 μg kg), T5+D1 group (TRA 5 mg kg+DEX 1μg kg) and IS (isotonic saline 0.5 ml) group.
Main outcome measures: The mechanical threshold and spontaneous paw withdrawal were measured in all groups.
Results: Both the T5+D1 group and T10 group showed a significantly increased mechanical threshold and a lower incidence of spontaneous paw withdrawal compared with the IS group. Interestingly, there was no significant difference between the T5+D1 and T10 groups.
Conclusion: We found that a combination of DEX and TRA at low doses provided equal or superior analgesic effects on bone cancer pain compared to high-dose TRA alone. Our animal data might indicate the clinical administration of these two drugs in bone cancer pain therapy.