Monitoring plasma concentrations of salicylate.

Measurement of the plasma concentration of salicylate has been made in the majority of clinical settings where salicylates, mostly in the form of acetylsalicylic acid (aspirin), are used extensively to treat chronic rheumatic conditions. At the same time, studies on the kinetics of salicylates have increased in the specialised literature. Analysis of published papers suggests a surprising difference between principles documented in controlled situations and what happens in routine clinical practice. Recommended dosage regimens are based on a rather narrow amount of data, as relevant studies include few patients and have not used readily comparable protocols. The wealth of information available on the kinetics and metabolism of salicylates has not yet produced generally accepted agreement on how to achieve optimum therapeutic results. Plasma concentration monitoring programmes aim mainly at avoiding side effects and checking compliance, but do not deal specifically with overall evaluation of therapeutic outcome. In the longer term, aspirin may possibly become less favoured as the initial drug of choice for the treatment of chronic rheumatic conditions, and the merits of monitoring plasma salicylate levels could be even less favoured. In the meantime, however, as clinical practice still largely involves use of aspirin, prospective collection of more controlled data on larger population groups seems warranted, not only for the benefit of treated patients but also for the purpose of assessing more thoroughly the clinical relevance of therapeutic drug monitoring in this area.