[Effect of naproxen on DNA synthesis and DNA repair of human lymphocytes in in vivo experiments].

This investigation was conducted in order to evaluate the possibility of late defects caused by drugs. After their base-line blood levels had been assessed, 3 patients with classical rheumatoid arthritis (according to ARA criteria; American Rheumatism Association) received 500 mg of d-2-(6'-methoxy-2'-naphthyl)-propionic acid (naproxen) daily (in capsules). At the peak of naproxen blood levels following the first naproxen dose, and once monthly for 7 months, thereafter, blood samples were drawn. After separating the lymphocytes from the whole blood, they were damaged by means of 60-Co. Hydroxyurea was added for the suppression of their semiconservative DNA-synthesis. The incorporation of 3-H-THYMIDINE INTO THE DNA of the cells was measured after radiation at different incubation periods. The results showed normal behaviour of the DNA-synthesis following naproxen administration in all three patients. The DNA-repair capacity was normal in one female patient, but slightly lowered in the remaining two.