Aspirin plasma monitoring in juvenile chronic arthritis

Thirty‐two patients from the Pediatric Rheumatology Clinic of the All India Institute of Medical Sciences, New Delhi, suffering from juvenile chronic arthritis (JCA) in the age group of 5–15 years were investigated for salicylate monitoring. Of these, 15 (46.9%) had polyarthritis and 11 (34.4%) suffered from systemic onset type of JCA while only 6 (18.7%) had the pauciarticular type of disease. Plasma salicylate and albumin levels were estimated on days 1, 7, 14, and 21, after initiation of therapy with aspirin. Serum SGOT and SGPT were also estimated, as well as clinical evidence of hepatotoxicity. The therapeutic plasma levels (15–25 mg/dl) of salicylates were achieved by a mean dose of aspirin of 81.8 mg/kg/day administered in three divided doses. On the surface area basis the mean dose of aspirin was 2.1 g/m2/day. Steady‐state level of aspirin in plasma was achieved by the seventh day, and the values were 2.8 times more than on the first day. In malnourished patients with low albumin levels, there was a proportional decrease in salicylate binding. Although increase in transaminase levels of 1 1/2 to 2 times the normal was observed in the patients on aspirin therapy, none of the children developed clinical evidence of hepatotoxicity during this short‐term study. The studies indicate that dosage of salicylates can be given either on a body weight or surface area basis. A malnourished child with lower levels of serum albumin may be more predisposed to salicylate toxicity, due to higher levels of free salicylates. There was no evidence of hepatotoxicity in the dosage range of 70–110 mg/kg/day or 1.9 to 2.8 g/m2/day.