RÉSUMÉ
To determine the effect of thymoquinone and methotrexate on blood urea and serum creatinine in arthritic rats. Experimental, comparative study. Postgraduate Medical Institute, Lahore, from March to August 2013. Thirty two female Sprague-Dawley rats were randomized into four equal groups [n=8]; group A [healthy control], group B [positive control], group C [Thymoquinone treated] and group D [Methotrexate treated]. Arthritis developed within two weeks after a single pristane injection. Total leukocyte count, blood urea and serum creatinine were taken at day 0, 15 and 30. While clinical score of inflammation was taken at day 0 and then on every alternate day. Development of arthritis and renal involvement was accompanied by significant raise in total leukocyte count, clinical score of inflammation, blood urea and serum creatinine as compared to healthy control rats [group A] till day 15 [p < 0.001]. From day 15 to day 30 both thymoquinone [group C] and methotrexate [group D] significantly lowered the total leukocyte count, clinical score of inflammation and improved blood urea and serum creatinine as compared to arthritic rats [group B] [p < 0.001]. Methotrexate was found a bit more effective than thymoquinone. Evaluation of results supported the beneficial effects of thymoquinone in renal injury produced by rheumatoid arthritis