Limitation of activity in an acute model of arthritis: effect of drug treatment.

OBJECTIVE AND DESIGN

The limitation of activity and its modification by therapy in an experimental arthritis was studied.

SUBJECTS

Female hamsters in groups of six per treatment were used.

TREATMENT

An acute arthritis was induced by intraarticular injection of 0.1 microgram lipopolysaccharide (LPS) in hamsters with free access to running wheels. Tenidap at 100 mg%, and piroxicam and indomethacin at 30 mg% were administered in the hamster's normal diet.

METHODS

Activity was monitored and analysed by computer. Plasma blood levels of drugs were determined by high pressure liquid chromatographic (HPLC) analysis.

RESULTS

Hamsters normally run 10-15 km/day. That distance was reduced to less than 2 km/day after arthritis induction. Speed of movement, essentially the equivalent of walking time, was reduced 40% by the arthritis. However, the time spent in movement (activity time) was more severely affected by arthritic disease. Therapy gave a modest 1.3-fold increase in speed of movement, but a highly significant 2-fold increase in activity time.

CONCLUSIONS

The effects of arthritis on activity in this animal model suggest that time spent in movement (activity time) should be considered as an outcome measure in clinical studies. These observations may also help explain why the modest disease improvements obtained with cyclooxygenase inhibition are valued. From a patient perspective, a doubling of activity time is a highly significant improvement in quality-of-life.