A New Concept for Evaluation of Long-Term Medication Effects on Gait Parameters

Schmid Oskar A., Than Peter

To have no side effects of medication is essential for the acceptance by the patient. Therefore the evaluation of possible side-effects of medication is an important part in drug development or after launch evaluations. But also on the primary effect, especially in pain killers, must be focused.

Most of the methods are invasive or painful, like the CO2-Inflation into to nose to measure the cortex activity after pain killer application.

A common side effect of drugs, especially pain killers, is the negative alteration of the gait in patients due to inconstancy or even falls due to side effects. Therefore the evaluation of the effects of drugs on gait parameters is of importance.

Different drug application, e.g. neuropathic pain killers, opioids or Cox-2-inhibitors, may have different effects on the gait parameters.

The new concept consists of noninvasive parameters which could be accomplished in different environments and with low side costs. The gait of the person to be evaluated is monitored by the system. The gait analysis consists of a walkway or treadmill in order to measure the velocity of gait. The other parameters are conducted by EMG of different leg muscles and a pressure distribution measurement.

The present pilot study evaluates for the first time the long-term effect of a Cox-2 Inhibitor (Celecoxib 200mg, once a day) on the gait parameters during 4 weeks of application. The patients suffered from pain during walking or standing in one hip unilaterally. The gait velocity increased by 0.66km/h (SD 0,52) or 25.4% from baseline to the 4 weeks measurement. Effects on the EMG patters and the pressure distribution were seen in the pilot study, but numbers of patients were too few for a real statistically relevant effect. The new concept shows that the less cost effective parameter of gait velocity is a good parameter to show effects on gait. But the further parameters of pressure distribution and EMG may show in larger numbers of investigated patients more difficile effects of brain affecting drugs.