A single daily administration of non-steroidal antiinflammatory drugs is widely recognized as the best dose regimen in chronic diseases such as degenerative osteoarthropathy, in inflammatory affections of the skeletal muscles, etc. Biomedical research has therefore developed drugs characterized either by a long half-life or available in a slow-release formulation. Isoxicam, piroxicam and benoxaprofen, which possess long half-lives, were compared with diclofenac sodium, indomethacin and ketoprofen, in their slow-release formulations, in terms of pharmacodynamics, pharmacokinetics and toxicity. Isoxicam, piroxicam and diclofenac showed excellent long lasting antiinflammatory properties: however the evidence showed that in cases of mild or severe renal pathology, drugs in their slow-release formulations are to be preferred.