Rheumatoid Arthritis

Our objective is to observe the effect of repeated subcutaneous injection of ketamine for the treatment of acute period inflammatory pain.

Methods

Rats with ankle monoarthritis were given subcutaneous injection of ketamine, once a day, 5 times per week for a total of 4 weeks. Scores of pain were tested by dorsal flexion of ankle joint. Increase percentage of body weight was taken as an index of general condition, and the degree of swelling was expressed by the change of circumference of ankle.

Results

(1) Subcutaneous injection of ketamine (0.08, 0.4, 2, 10 mg·kg -1), produced significant analgesia in arthritic rats at the dose of 10 mg·kg -1 starting from the 2nd week; both 2 mg·kg -1 and 10 mg·kg -1 ketamine produced significant analgesia starting from the 3rd week (P 0.05 and P 0.01, respectively). (2) Repeated administration of ketamine produced a mild reduction of the circumference of arthritic ankle (P 0.05). (3) The body weight of the rat was not affected by long term administration of ketamine. Conclusion: Repeated substaneous injection of ketamine for 4 weeks significantly reduces inflammatory pain in the acute period of adjuvant monoarthritis, without significant aversive side effects.