[Should there be a new classification of non-steroidal anti-inflammatory agents?]. 
There are, in France, about thirty NSAIDs which are commercialized under various forms.  There are many chemical classifications but they do not present any advantage regarding the prescription, in so far as the chemical structure of a NSAID does not permit to anticipate its effectiveness nor its tolerance.  Therefore the original structure of a new NSAID has no practical implications.  However, the NSAIDs may be grouped in five main families corresponding to similar pharmaco-clinical profiles: pyrazol, indol, anthranilic or fenamates derivatives, oxicams and aryl-carboxylic derivatives.  According to their half-life of plasma clearance, the NSAIDs may be divided in three groups: short half-life of plasma clearance (2 to 4 hours) requiring several daily doses; intermediate half-life (12 to 18 hours) allowing once or twice/day administration; long half-life (exceeding 24 hours) allowing a single daily dose.  The variability of plasma kinetic parameters, the absence of correlation of the plasma levels with effectiveness, speed of action and tolerance, restrict the advantages of such a pharmaco-kinetic classification.  More than the plasma concentrations, it's the tissues levels (synovial fluid, synovial tissue) that must be taken into consideration.  NSAIDs with a short or intermediate clearance half-life and a long synovial half-life, seem to have the best pharmacokinetic profile.  It is finally the benefit/risk ratio which should guide the prescription.  The effectiveness of NSAIDs is usually demonstrated in all fields of the pathology of rheumatism, but their advantages remain to be proven in numerous extra-rheumatologic indications.  The risk is more difficult to evaluate.(ABSTRACT TRUNCATED AT 250 WORDS)