Analgesic characteristics and histopatological effetcs on the spinal cord of intratechal ketorolac tromethamine administration in rats

8. SUMMARY The objective of this study was to assess the analgesic effectiveness of ketorolac tromethamine (KT) used intratechally and also to determine its behavioral effects and evaluate the histopathologic changes of the spinal cord. In this study a polyethylene (PE) catheter was placed at the atlantoaxial membrane of 28 male Wistar rats. On the fifth day of catheterization the subjects were randomly divided into four groups and four times five days apart saline ( group S ), 50 ug KT( group K50 ), 150 ug KT( group K150 ) and 400 ug KT ( group K400 ) were applied. The motor functions of the subjects were evaluated before and after saline or ketorolac administration. As the algesiometric method, formalin test was used. After the formalin test, the subjects were sacrificed by using high doses of ether and their spinaL cords were obtained by laminectomy. Then the sections of the spinal cord taken at four different levels as C 3-4, C 7-8, T 8, and L i_2, were examined under the light microscope. One of the subjects in group K150 was paraplegic at the fourth day and therefore excluded from the study. Motor functions were not affected by saline or drug administrations. Compared to saline, decreased responses to the phases I and II of formalin test were obtained for all doses of ketorolac (p<0.008). There was no significant difference between the drug groups on the responses to phase I. However responses to phase II were significantly decreased in groups K150 and K400 when compared with the group K50 (p<0.008). There were no significant differences between groups K150 and K400 on the responses to phase II. The histopathological examination of the spinal cord revealed hemorrhage in two of the subjects ; one of them being in group S and the other one being in group K50. Intratechal administration of ketorolac produces analgesic effects. Given at larger doses then the ones causing chronic analgesic effects, no histopathological neurological defects were observed and no behavioral changes were noted. Ketorolac can be an alternative drug for intratechal usage in the treatment of chronic pain. However ; further studies are needed in other animal species with different treatment regimens. 59